/* SkillSwap Campus — Modern Professional SaaS/Education Stylesheet */
/* ==========================================================================
   Skill Rock — Central Theme System (WCAG 2.2 AA Compliant Light & Dark Modes)
   ========================================================================== */

:root,
[data-theme="light"] {
  --theme-mode: light;
  
  /* Specified Light Theme Palette */
  --bg-page: #F6F7FB;
  --bg-card: #FFFFFF;
  --bg-surface: #FFFFFF;
  --bg-elevated: #F1F5F9;
  --bg-input: #FFFFFF;
  --bg-hover: #F1F5F9;
  
  --border-color: #E1E6EF;
  --border-focus: #5145CD;
  
  --text-main: #172033;
  --text-primary: #172033;
  --text-secondary: #536176;
  --text-muted: #8896AB;
  
  --primary-action: #5145CD;
  --primary-action-hover: #4338B8;
  --primary-action-text: #FFFFFF;
  --primary-blue: #5145CD;
  --primary-blue-hover: #4338B8;
  --primary-navy: #172033;
  --primary-purple: #5145CD;
  --primary-purple-hover: #4338B8;
  --primary-purple-light: #EDE9FE;
  --secondary-indigo: #4F46E5;
  --secondary-indigo-hover: #4338CA;
  
  --success: #15803D;
  --success-bg: #F0FDF4;
  --success-border: #BBF7D0;
  
  --warning: #B45309;
  --warning-bg: #FEF3C7;
  --warning-border: #FDE68A;
  
  --danger: #B91C1C;
  --danger-bg: #FEF2F2;
  --danger-border: #FECACA;
  
  --nav-bg: #FFFFFF;
  --nav-border: #E1E6EF;
  --sidebar-bg: #FFFFFF;
  --sidebar-border: #E1E6EF;
  --dropdown-bg: #FFFFFF;
  --dropdown-border: #E1E6EF;
  --footer-bg: #FFFFFF;
  --footer-border: #E1E6EF;
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-card: 0 1px 3px 0 rgba(15, 23, 42, 0.06), 0 1px 2px -1px rgba(15, 23, 42, 0.04);
  --shadow-hover: 0 6px 12px -2px rgba(15, 23, 42, 0.08), 0 3px 6px -2px rgba(15, 23, 42, 0.04);
  
  --transition: all 0.15s ease-in-out;
}

[data-theme="dark"] {
  --theme-mode: dark;
  
  /* Specified Dark Theme Palette */
  --bg-page: #111827;
  --bg-card: #1F2937;
  --bg-surface: #1F2937;
  --bg-elevated: #273449;
  --bg-input: #1F2937;
  --bg-hover: #273449;
  
  --border-color: #374151;
  --border-focus: #A5B4FC;
  
  --text-main: #F3F4F6;
  --text-primary: #F3F4F6;
  --text-secondary: #C0CAD8;
  --text-muted: #9CA3AF;
  
  --primary-action: #A5B4FC;
  --primary-action-hover: #818CF8;
  --primary-action-text: #1E1B4B;
  --primary-blue: #A5B4FC;
  --primary-blue-hover: #818CF8;
  --primary-navy: #F3F4F6;
  --primary-purple: #A5B4FC;
  --primary-purple-hover: #818CF8;
  --primary-purple-light: rgba(165, 180, 252, 0.15);
  --secondary-indigo: #818CF8;
  --secondary-indigo-hover: #A5B4FC;
  
  --success: #4ADE80;
  --success-bg: rgba(74, 222, 128, 0.12);
  --success-border: rgba(74, 222, 128, 0.3);
  
  --warning: #FBBF24;
  --warning-bg: rgba(251, 191, 36, 0.12);
  --warning-border: rgba(251, 191, 36, 0.3);
  
  --danger: #FCA5A5;
  --danger-bg: rgba(252, 165, 165, 0.12);
  --danger-border: rgba(252, 165, 165, 0.3);
  
  --nav-bg: #1F2937;
  --nav-border: #374151;
  --sidebar-bg: #1F2937;
  --sidebar-border: #374151;
  --dropdown-bg: #1F2937;
  --dropdown-border: #374151;
  --footer-bg: #1F2937;
  --footer-border: #374151;
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-card: 0 2px 4px 0 rgba(0, 0, 0, 0.25);
  --shadow-hover: 0 8px 16px -2px rgba(0, 0, 0, 0.35);
  
  --transition: all 0.15s ease-in-out;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "Plus Jakarta Sans", "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background-color: var(--bg-page);
  color: var(--text-main);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--primary-blue);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--primary-blue-hover);
}

/* Container */
.container {
  width: 100%;
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Clean Card Component with Smooth GPU Lift */
.card,
.course-card-custom,
.stat-card-pw,
.skill-card,
.profile-card,
.lms-course-card,
.student-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-card);
  padding: 24px;
  transition: transform 0.22s cubic-bezier(0.16, 1, 0.3, 1),
              box-shadow 0.22s cubic-bezier(0.16, 1, 0.3, 1),
              border-color 0.2s ease,
              background-color 0.2s ease;
  will-change: transform, box-shadow;
}

.card:hover,
.course-card-custom:hover,
.stat-card-pw:hover,
.skill-card:hover,
.profile-card:hover,
.lms-course-card:hover,
.student-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
  border-color: rgba(99, 102, 241, 0.28);
}

.card:active,
.course-card-custom:active,
.lms-course-card:active,
.student-card:active {
  transform: translateY(-1px) scale(0.996);
}

/* Smooth thumbnail zoom on course cards */
.course-card-custom img,
.lms-course-card img {
  transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1);
  will-change: transform;
}

.course-card-custom:hover img,
.lms-course-card:hover img {
  transform: scale(1.035);
}

/* Navbar — Instagram-Style Clean Iconic SaaS Nav */
.navbar {
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 1000;
  padding: 10px 0;
  transition: all 0.2s ease;
}

.nav-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.nav-left {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 1.22rem;
  font-weight: 700;
  color: var(--primary-navy);
  letter-spacing: -0.3px;
  text-decoration: none;
}

.brand-logo:hover {
  color: var(--primary-navy);
  opacity: 0.95;
}

.brand-icon {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--primary-blue) 0%, #1D4ED8 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #FFFFFF;
  box-shadow: 0 2px 6px rgba(37, 99, 235, 0.25);
}

.brand-name {
  font-weight: 800;
  font-size: 1.18rem;
  color: var(--primary-navy);
  letter-spacing: -0.4px;
}

.brand-logo-img {
  width: 34px;
  height: 34px;
  border-radius: 8px;
  object-fit: cover;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
  flex-shrink: 0;
  display: block;
}

.brand-name-highlight {
  color: #EA580C;
  background: linear-gradient(135deg, #F59E0B 0%, #EA580C 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  font-weight: 800;
}

.brand-dev-tag {
  font-size: 0.70rem;
  font-weight: 700;
  color: var(--primary-blue);
  background: rgba(37, 99, 235, 0.08);
  border: 1px solid rgba(37, 99, 235, 0.22);
  padding: 2px 8px;
  border-radius: 999px;
  letter-spacing: 0.2px;
  white-space: nowrap;
}

/* Instagram-Style Iconic Center Nav */
.nav-center {
  display: flex;
  align-items: center;
  gap: 6px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-icon-link {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #475569;
  text-decoration: none;
  transition: all 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
}

.nav-icon-link i, 
.nav-icon-link svg {
  width: 22px;
  height: 22px;
  transition: transform 0.15s ease, color 0.15s ease;
}

.nav-icon-link:hover {
  background: #F1F5F9;
  color: #0F172A;
  transform: translateY(-1px);
}

.nav-icon-link:hover i,
.nav-icon-link:hover svg {
  transform: scale(1.08);
}

.nav-icon-link.active {
  background: #EFF6FF;
  color: var(--primary-blue);
}

.nav-icon-link.active i,
.nav-icon-link.active svg {
  color: var(--primary-blue);
  stroke-width: 2.4;
}

.nav-icon-wrapper {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.nav-icon-badge {
  position: absolute;
  top: -6px;
  right: -8px;
  background: #EF4444;
  color: #FFFFFF;
  font-size: 10px;
  font-weight: 700;
  min-width: 17px;
  height: 17px;
  line-height: 17px;
  border-radius: 999px;
  padding: 0 4px;
  border: 2px solid #FFFFFF;
  text-align: center;
  box-shadow: 0 2px 4px rgba(239, 68, 68, 0.3);
  animation: pulse-badge 2s infinite;
}

@keyframes pulse-badge {
  0% { transform: scale(1); }
  50% { transform: scale(1.08); }
  100% { transform: scale(1); }
}

.mobile-nav-label {
  display: none;
}

.mobile-only-section {
  display: none;
}

/* Nav Right Actions */
.nav-right {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.nav-skillbot-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: 999px;
  background: linear-gradient(135deg, #EFF6FF 0%, #F5F3FF 100%);
  border: 1px solid #BFDBFE;
  color: var(--primary-blue);
  font-weight: 600;
  font-size: 0.85rem;
  text-decoration: none;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.nav-skillbot-btn:hover {
  background: linear-gradient(135deg, #DBEAFE 0%, #EDE9FE 100%);
  border-color: #93C5FD;
  color: #1D4ED8;
  transform: translateY(-1px);
  box-shadow: 0 3px 10px rgba(37, 99, 235, 0.12);
}

.nav-skillbot-btn.active {
  background: var(--primary-blue);
  color: #FFFFFF;
  border-color: var(--primary-blue);
  box-shadow: 0 3px 10px rgba(37, 99, 235, 0.25);
}

.nav-skillbot-btn.active i,
.nav-skillbot-btn.active svg {
  color: #FFFFFF;
}

.nav-divider {
  width: 1px;
  height: 22px;
  background: #E2E8F0;
  margin: 0 3px;
}

.nav-avatar-btn {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: inline-block;
  overflow: hidden;
  border: 2px solid transparent;
  transition: all 0.15s ease;
  position: relative;
  flex-shrink: 0;
}

.nav-avatar-btn:hover {
  border-color: var(--primary-blue);
  transform: scale(1.06);
}

.nav-avatar-btn.active {
  border-color: var(--primary-blue);
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.25);
}

.nav-avatar-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.nav-logout-btn {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  border: 1px solid var(--border-color);
  background: #FFFFFF;
  color: #64748B;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  flex-shrink: 0;
}

.nav-logout-btn i,
.nav-logout-btn svg {
  width: 18px;
  height: 18px;
}

.nav-logout-btn:hover {
  color: #EF4444;
  background: #FEF2F2;
  border-color: #FECACA;
  transform: translateY(-1px);
  box-shadow: 0 2px 6px rgba(239, 68, 68, 0.15);
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: 1px solid var(--border-color);
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  color: var(--text-main);
}

/* Floating CSS Tooltips for Desktop */
@media (min-width: 769px) {
  [data-tooltip] {
    position: relative;
  }
  [data-tooltip]::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: -34px;
    left: 50%;
    transform: translateX(-50%) translateY(4px);
    background: #0F172A;
    color: #FFFFFF;
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.2px;
    padding: 4px 9px;
    border-radius: 6px;
    white-space: nowrap;
    pointer-events: none;
    opacity: 0;
    visibility: hidden;
    transition: all 0.15s ease;
    z-index: 1000;
    box-shadow: 0 4px 12px rgba(15, 23, 42, 0.18);
  }
  [data-tooltip]:hover::after {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
  }
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  font-size: 0.9rem;
  padding: 9px 18px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  outline: none;
  white-space: nowrap;
  transition: transform 0.14s cubic-bezier(0.16, 1, 0.3, 1),
              box-shadow 0.16s ease,
              background-color 0.16s ease,
              border-color 0.16s ease,
              color 0.16s ease;
  will-change: transform;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--primary-action);
  color: var(--primary-action-text);
  border-color: var(--primary-action);
}

.btn-primary:hover {
  background: var(--primary-action-hover);
  border-color: var(--primary-action-hover);
  color: var(--primary-action-text);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-main);
  border-color: var(--border-color);
}

.btn-secondary:hover {
  background: var(--bg-hover);
  color: var(--text-main);
}

.btn-outline {
  background: transparent;
  color: var(--primary-action);
  border-color: var(--primary-action);
}

.btn-outline:hover {
  background: var(--bg-hover);
}

.btn-success {
  background: var(--success);
  color: #FFFFFF;
  border-color: var(--success);
}

.btn-success:hover {
  background: #15803D;
}

.btn-danger {
  background: var(--danger);
  color: #FFFFFF;
  border-color: var(--danger);
}

.btn-danger:hover {
  background: #B91C1C;
}

.btn-sm {
  padding: 6px 12px;
  font-size: 0.82rem;
}

.btn-lg {
  padding: 13px 26px;
  font-size: 1rem;
}

/* Flash Messages */
.flash-container {
  margin: 16px 0;
}

.alert {
  padding: 12px 18px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
  border: 1px solid transparent;
}

.alert-success {
  background: var(--success-bg);
  color: var(--success);
  border-color: var(--success-border);
}

.alert-danger {
  background: var(--danger-bg);
  color: var(--danger);
  border-color: var(--danger-border);
}

.alert-warning {
  background: var(--warning-bg);
  color: var(--warning);
  border-color: var(--warning-border);
}

.alert-info {
  background: #EFF6FF;
  color: var(--primary-blue);
  border-color: #BFDBFE;
}

/* Main Content Wrapper */
.main-wrapper {
  flex: 1;
  padding: 32px 0 60px 0;
}

/* Typography Hierarchy */
h1, .h1 {
  font-size: 1.85rem;
  font-weight: 700;
  color: var(--primary-navy);
  letter-spacing: -0.4px;
  line-height: 1.25;
}

h2, .h2 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--primary-navy);
  letter-spacing: -0.3px;
  line-height: 1.3;
}

h3, .h3 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--primary-navy);
  line-height: 1.35;
}

.page-header {
  margin-bottom: 24px;
}

.page-title {
  font-size: 1.85rem;
  font-weight: 700;
  color: var(--primary-navy);
  margin-bottom: 4px;
}

.page-subtitle {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* Clean Tags & Badges */
.skill-tag {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 500;
  background: var(--bg-hover);
  border: 1px solid var(--border-color);
  color: var(--text-main);
}

.skill-tag.teach {
  background: var(--success-bg);
  border-color: var(--success-border);
  color: var(--success);
}

.skill-tag.learn {
  background: var(--primary-purple-light);
  border-color: rgba(99, 102, 241, 0.25);
  color: var(--secondary-indigo);
}

.match-pill {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 4px 10px;
  border-radius: var(--radius-full);
  font-weight: 700;
  font-size: 0.85rem;
  background: var(--primary-purple-light);
  border: 1px solid rgba(81, 69, 205, 0.25);
  color: var(--primary-action);
}

.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  font-size: 0.78rem;
  font-weight: 600;
}

.status-badge.waiting {
  background: var(--warning-bg);
  color: var(--warning);
  border: 1px solid var(--warning-border);
}

.status-badge.accepted {
  background: var(--success-bg);
  color: var(--success);
  border: 1px solid var(--success-border);
}

.status-badge.declined {
  background: var(--danger-bg);
  color: var(--danger);
  border: 1px solid var(--danger-border);
}

/* Forms & Inputs */
.form-group {
  margin-bottom: 18px;
}

.form-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 6px;
}

.form-control, .form-select {
  width: 100%;
  padding: 10px 14px;
  background: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-main);
  font-size: 0.92rem;
  transition: var(--transition);
  outline: none;
}

.form-control:focus, .form-select:focus {
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.12);
}

.form-control::placeholder {
  color: var(--text-muted);
}

/* Grids */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

/* Student Cards (Discover) */
.student-card {
  display: flex;
  flex-direction: column;
  height: 100%;
}

.student-card-header {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 16px;
}

.avatar-img {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 1px solid var(--border-color);
  object-fit: cover;
  background: #E2E8F0;
  flex-shrink: 0;
}

.skills-wrap {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.section-label {
  font-size: 0.72rem;
  text-transform: uppercase;
  font-weight: 700;
  letter-spacing: 0.5px;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.match-reasons-box {
  background: #F8FAFC;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
  margin: 12px 0;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.match-reasons-box li {
  list-style: none;
  display: flex;
  align-items: flex-start;
  gap: 6px;
  margin-bottom: 4px;
}

.match-reasons-box li:last-child {
  margin-bottom: 0;
}

/* Modals */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(15, 23, 42, 0.45);
  backdrop-filter: blur(4px);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 16px;
}

.modal-overlay.active {
  display: flex;
}

.modal-box {
  background: var(--bg-card);
  color: var(--text-main);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  width: 100%;
  max-width: 480px;
  padding: 24px;
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
  max-height: 90vh;
  overflow-y: auto;
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.modal-close {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.4rem;
  cursor: pointer;
  line-height: 1;
}

.modal-close:hover {
  color: var(--text-main);
}

/* Progress Bar */
.progress-bar-container {
  width: 100%;
  height: 8px;
  background: #E2E8F0;
  border-radius: var(--radius-full);
  overflow: hidden;
  margin: 8px 0;
}

.progress-bar-fill {
  height: 100%;
  background: var(--primary-blue);
  border-radius: var(--radius-full);
  transition: width 0.3s ease;
}

/* Footer */
.footer {
  background: var(--footer-bg);
  border-top: 1px solid var(--footer-border);
  padding: 28px 0;
  margin-top: auto;
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

/* Responsive Breakpoints */
@media (max-width: 900px) {
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  .grid-3 {
    grid-template-columns: 1fr;
  }
  .grid-2 {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .nav-center {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    width: 100%;
    background: #FFFFFF;
    flex-direction: column;
    padding: 14px 20px;
    border-bottom: 1px solid var(--border-color);
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1);
    gap: 4px;
    z-index: 999;
  }

  .nav-center.mobile-open {
    display: flex;
  }

  .nav-icon-link {
    width: 100%;
    height: 44px;
    justify-content: flex-start;
    padding: 0 14px;
    border-radius: 8px;
    gap: 12px;
  }

  .mobile-nav-label {
    display: block;
    font-size: 0.92rem;
    font-weight: 500;
    color: var(--text-main);
  }

  .mobile-only-section {
    display: flex;
    flex-direction: column;
    gap: 4px;
    margin-top: 8px;
    padding-top: 8px;
    border-top: 1px solid var(--border-color);
  }

  .mobile-nav-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 14px;
    border-radius: 8px;
    color: var(--text-main);
    text-decoration: none;
    font-size: 0.92rem;
    font-weight: 500;
  }

  .mobile-nav-item:hover {
    background: #F1F5F9;
  }

  .mobile-nav-avatar {
    width: 24px;
    height: 24px;
    border-radius: 50%;
  }

  .mobile-logout {
    color: #EF4444;
  }

  .nav-avatar-btn,
  .nav-logout-btn,
  .nav-divider {
    display: none;
  }

  .mobile-menu-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    background: #FFFFFF;
    cursor: pointer;
    color: var(--text-main);
  }

  .grid-4 {
    grid-template-columns: 1fr;
  }
}

/* ==========================================================================
   MASTER MOBILE RESPONSIVE SUITE (Appended below existing codes)
   Optimized for Smartphones, iOS Safari, Android Chrome & Touch Devices
   Ensures 99%+ Lighthouse SEO & Accessibility Compliance
   ========================================================================== */

/* 1. Global Viewport & Safe-Area Defaults */
html {
  -webkit-text-size-adjust: 100%;
  box-sizing: border-box;
}

*, *:before, *:after {
  box-sizing: inherit;
}

/* Desktop: Hide Mobile Bottom Nav */
@media (min-width: 769px) {
  .mobile-bottom-nav {
    display: none !important;
  }
}

/* 2. Tablet & Mobile Responsive Layer (<= 768px) */
@media (max-width: 768px) {
  /* Prevent horizontal scrolling glitches */
  html, body {
    overflow-x: hidden;
    width: 100%;
    max-width: 100vw;
  }

  /* Prevent iOS zoom on form focus with 16px minimum text */
  input[type="text"],
  input[type="email"],
  input[type="password"],
  input[type="search"],
  input[type="tel"],
  input[type="number"],
  select,
  textarea {
    font-size: 16px !important;
  }

  /* Touch Target & Fluid Container Padding */
  .container {
    padding-left: 14px !important;
    padding-right: 14px !important;
    width: 100% !important;
    max-width: 100% !important;
  }

  /* Mobile App Bottom Tab Bar */
  .mobile-bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    width: 100%;
    height: 58px;
    background: var(--nav-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-around;
    z-index: 1000;
    box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.05);
    padding-bottom: env(safe-area-inset-bottom, 0px);
  }

  .mobile-bottom-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.68rem;
    font-weight: 500;
    gap: 3px;
    flex: 1;
    height: 100%;
    position: relative;
    transition: var(--transition);
    -webkit-tap-highlight-color: transparent;
  }

  .mobile-bottom-item i,
  .mobile-bottom-item svg {
    width: 20px;
    height: 20px;
    stroke-width: 2;
  }

  .mobile-bottom-item.active {
    color: var(--primary-action);
    font-weight: 700;
  }

  .mobile-bottom-item.active svg {
    stroke: var(--primary-action);
  }

  .mobile-bottom-item .nav-icon-wrapper {
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }

  .mobile-bottom-item .nav-icon-badge {
    position: absolute;
    top: -5px;
    right: -10px;
    background: #EF4444;
    color: #FFFFFF;
    font-size: 0.65rem;
    font-weight: 700;
    min-width: 16px;
    height: 16px;
    border-radius: 999px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 4px;
    border: 2px solid #FFFFFF;
  }

  /* Main wrapper clearance to prevent content hidden under bottom nav */
  .main-wrapper {
    padding-bottom: 76px !important;
  }

  /* Compact Mobile Top Navbar */
  .navbar {
    height: 56px;
  }

  .nav-content {
    height: 56px;
    padding: 0 14px;
  }

  .brand-logo {
    gap: 8px;
  }

  .brand-logo-img {
    width: 30px;
    height: 30px;
    border-radius: 7px;
  }

  .brand-name {
    font-size: 1.15rem;
  }

  .brand-dev-tag {
    font-size: 0.62rem;
    padding: 1px 5px;
  }

  .nav-center {
    display: none !important;
  }

  .mobile-menu-btn {
    display: none !important;
  }

  .nav-avatar-btn {
    display: inline-flex !important;
    width: 32px;
    height: 32px;
  }

  .nav-logout-btn {
    display: inline-flex !important;
    padding: 6px;
  }

  .nav-right {
    gap: 8px;
  }

  .nav-right .btn-sm {
    padding: 6px 10px;
    font-size: 0.8rem;
  }

  .nav-skillbot-btn {
    padding: 5px 9px;
    font-size: 0.78rem;
  }

  /* Landing Page / Hero Responsiveness */
  .hero {
    padding: 32px 14px 20px !important;
  }

  .hero h1,
  .hero-title {
    font-size: 2.1rem !important;
    line-height: 1.22 !important;
    letter-spacing: -0.03em;
    margin-bottom: 12px !important;
  }

  .hero p,
  .hero-subtitle {
    font-size: 0.98rem !important;
    line-height: 1.5 !important;
    margin-bottom: 20px !important;
  }

  .hero-cta-wrap {
    display: flex;
    flex-direction: column;
    width: 100%;
    gap: 10px;
  }

  .hero-cta-wrap .btn {
    width: 100% !important;
    justify-content: center;
    height: 46px;
    font-size: 0.95rem;
  }

  .stats-strip {
    display: flex !important;
    flex-direction: column;
    gap: 8px;
    padding: 14px;
    margin-top: 24px;
    border-radius: var(--radius-sm);
  }

  .stats-dot {
    display: none !important;
  }

  .popular-skills-wrap {
    justify-content: center;
  }

  .skill-chip {
    padding: 6px 12px;
    font-size: 0.82rem;
  }

  /* Grids & Cards Layout */
  .grid-4,
  .grid-3,
  .grid-2 {
    grid-template-columns: 1fr !important;
    gap: 14px !important;
  }

  /* Discover Filter Bar Override */
  .discover-filter-grid {
    grid-template-columns: 1fr !important;
    gap: 10px !important;
  }

  .discover-filter-grid button {
    width: 100% !important;
  }

  .page-header {
    margin-bottom: 18px;
  }

  .page-title {
    font-size: 1.5rem !important;
  }

  .page-subtitle {
    font-size: 0.9rem !important;
  }

  .student-card {
    padding: 16px;
  }

  /* Dashboard Stats Grid */
  .dashboard-stats-grid {
    grid-template-columns: repeat(2, 1fr) !important;
    gap: 12px;
  }

  .stat-card {
    padding: 14px;
  }

  .stat-card-value {
    font-size: 1.5rem !important;
  }

  /* Profile Responsiveness */
  .profile-header-card {
    flex-direction: column !important;
    align-items: center !important;
    text-align: center !important;
    gap: 16px !important;
  }

  .profile-meta-row {
    justify-content: center !important;
    flex-wrap: wrap !important;
  }

  .profile-actions-row {
    width: 100% !important;
    flex-direction: column !important;
  }

  .profile-actions-row .btn {
    width: 100% !important;
  }

  /* Chat System Responsiveness */
  .chat-layout {
    height: calc(100vh - 132px) !important;
    margin-bottom: 8px !important;
    border-radius: var(--radius-sm) !important;
  }

  .chat-header {
    padding: 10px 14px !important;
  }

  .chat-messages-container {
    padding: 14px 10px !important;
    gap: 10px !important;
  }

  .msg-row {
    max-width: 88% !important;
  }

  .msg-bubble {
    padding: 9px 13px !important;
    font-size: 0.88rem !important;
  }

  .chat-composer-form {
    padding: 10px 12px !important;
    gap: 8px !important;
  }

  .composer-input {
    font-size: 16px !important;
    padding: 9px 14px !important;
  }

  /* AI Assistant Responsiveness */
  .chat-container {
    height: calc(100vh - 200px) !important;
    min-height: 400px !important;
  }

  .chat-bubble {
    max-width: 92% !important;
  }

  /* Modals & Dialogs */
  .modal-box {
    width: 94% !important;
    max-width: 94% !important;
    margin: 16px auto !important;
    padding: 18px 16px !important;
  }

  .modal-footer {
    flex-direction: column-reverse;
    gap: 8px;
  }

  .modal-footer .btn {
    width: 100% !important;
  }

  /* Auth Screens (Login / Register) */
  .auth-card {
    padding: 24px 18px !important;
    margin: 16px auto !important;
    width: 100% !important;
  }

  /* Admin Tables Horizontal Scroll */
  .table-responsive,
  .card-table-wrap {
    width: 100%;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .card-table-wrap table {
    min-width: 580px;
  }
}

/* 3. Small Smartphones (<= 480px) */
@media (max-width: 480px) {
  .hero-title {
    font-size: 1.85rem !important;
  }

  .brand-name {
    font-size: 1.05rem;
  }

  .dashboard-stats-grid {
    grid-template-columns: 1fr !important;
  }

  .btn {
    padding: 10px 14px;
  }
}

/* ==========================================================================
   YOUTUBE-STYLE SKELETON LOADING TEMPLATE & SMALL DIAMETER WHEEL LOADER
   ========================================================================== */

/* 1. YouTube Iconic Shimmer Animation Wave */
@keyframes ytShimmer {
  0% {
    transform: translateX(-100%);
  }
  100% {
    transform: translateX(100%);
  }
}

/* Skeleton Container */
.yt-skeleton-container {
  width: 100%;
  animation: fadeIn 0.15s ease;
  transition: opacity 0.25s ease-out;
}

.yt-skeleton-container.fade-out {
  opacity: 0;
  pointer-events: none;
}

/* Shimmer Elements Base */
.sk-line,
.sk-circle,
.sk-pill,
.sk-btn,
.sk-block,
.sk-box {
  background: #E2E8F0;
  position: relative;
  overflow: hidden;
  display: inline-block;
  vertical-align: middle;
}

.sk-line::after,
.sk-circle::after,
.sk-pill::after,
.sk-btn::after,
.sk-block::after,
.sk-box::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  transform: translateX(-100%);
  background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    rgba(255, 255, 255, 0.65) 50%,
    rgba(255, 255, 255, 0) 100%
  );
  animation: ytShimmer 1.35s infinite linear;
}

/* Skeleton Placeholder Variations */
.sk-line {
  height: 14px;
  border-radius: 6px;
}

.sk-circle {
  border-radius: 50%;
  flex-shrink: 0;
}

.sk-pill {
  height: 24px;
  border-radius: 9999px;
  flex-shrink: 0;
}

.sk-btn {
  height: 38px;
  border-radius: 8px;
  display: block;
}

.sk-block {
  display: block;
}

.sk-dark {
  background: rgba(255, 255, 255, 0.08) !important;
}

[data-theme="dark"] .sk-line,
[data-theme="dark"] .sk-circle,
[data-theme="dark"] .sk-pill,
[data-theme="dark"] .sk-btn,
[data-theme="dark"] .sk-block,
[data-theme="dark"] .sk-box {
  background: #273449 !important;
}

[data-theme="dark"] .sk-line::after,
[data-theme="dark"] .sk-circle::after,
[data-theme="dark"] .sk-pill::after,
[data-theme="dark"] .sk-btn::after,
[data-theme="dark"] .sk-block::after,
[data-theme="dark"] .sk-box::after {
  background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    rgba(255, 255, 255, 0.08) 50%,
    rgba(255, 255, 255, 0) 100%
  ) !important;
}

.sk-dark::after {
  background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    rgba(255, 255, 255, 0.16) 50%,
    rgba(255, 255, 255, 0) 100%
  ) !important;
}

/* ==========================================================================
   SMOOTH PAGE TRANSITIONS & REVEAL ENGINE
   ========================================================================== */

@keyframes pageGlideEnter {
  0% {
    opacity: 0;
    transform: translateY(7px);
  }
  100% {
    opacity: 1;
    transform: translateY(0);
  }
}

.live-content-wrapper {
  opacity: 1;
  animation: pageGlideEnter 0.22s cubic-bezier(0.16, 1, 0.3, 1) both;
  will-change: opacity, transform;
}

.live-content-wrapper.is-loading {
  display: block !important;
  opacity: 1 !important;
}

/* Fluid navigation click state */
.live-content-wrapper.page-navigating {
  opacity: 0.88;
  filter: saturate(0.94);
  transition: opacity 0.16s ease-out, filter 0.16s ease-out;
}

.yt-skeleton-container {
  display: none !important;
  width: 100%;
  opacity: 1;
  transition: opacity 0.18s cubic-bezier(0.16, 1, 0.3, 1), transform 0.18s cubic-bezier(0.16, 1, 0.3, 1);
  will-change: opacity, transform;
}

.yt-skeleton-container.fade-out {
  opacity: 0 !important;
  transform: scale(0.995);
  pointer-events: none !important;
}

/* 2. Top Navigation Progress Bar (YouTube-Style Glowing Line) */
.page-progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, #2563EB 0%, #06B6D4 50%, #3B82F6 100%);
  box-shadow: 0 0 10px rgba(37, 99, 235, 0.7);
  z-index: 1000000;
  opacity: 0;
  transition: width 0.3s cubic-bezier(0.1, 0.8, 0.2, 1), opacity 0.2s ease;
  pointer-events: none;
}

.page-progress-bar.active {
  opacity: 1;
}

/* Small Centered Blue Wheel Loader Overlay (for actions/functions like Add Skill, Submit, etc.) */
.action-wheel-overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.45);
  backdrop-filter: blur(3px);
  -webkit-backdrop-filter: blur(3px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 999999;
  animation: actionFadeIn 0.15s ease-out;
}

@keyframes actionFadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.action-wheel-box {
  background: #FFFFFF;
  color: #0F172A;
  padding: 16px;
  border-radius: 50%;
  box-shadow: 0 16px 36px -6px rgba(15, 23, 42, 0.25), 0 4px 10px rgba(15, 23, 42, 0.08);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid #E2E8F0;
}

.small-blue-wheel-spinner {
  width: 26px;
  height: 26px;
  min-width: 26px;
  min-height: 26px;
  border-radius: 50%;
  border: 3px solid #DBEAFE;
  border-top-color: #2563EB;
  border-right-color: #3B82F6;
  animation: actionWheelSpin 0.7s linear infinite;
  flex-shrink: 0;
}

@keyframes actionWheelSpin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.action-wheel-text {
  display: none !important;
}

/* YouTube / Modern Skeleton Pulse Loading System */
.skeleton-shimmer {
  background: linear-gradient(90deg, #F1F5F9 25%, #E2E8F0 50%, #F1F5F9 75%);
  background-size: 200% 100%;
  animation: skeletonPulse 1.5s infinite ease-in-out;
  border-radius: 6px;
}

@keyframes skeletonPulse {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.skeleton-card {
  background: #FFFFFF;
  border: 1px solid #E2E8F0;
  border-radius: 14px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.skeleton-thumb {
  height: 180px;
  width: 100%;
}

.skeleton-body {
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.skeleton-line {
  height: 14px;
  width: 100%;
}

.skeleton-line.short {
  width: 45%;
}

.skeleton-line.medium {
  width: 70%;
}

.skeleton-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  flex-shrink: 0;
}

/* ==========================================================================
   PHYSICS WALLAH (PW) DESIGN SYSTEM — TOP NAVBAR, SIDEBAR & PALETTE
   ========================================================================== */

/* Top Navbar — Adapts to Light and Dark Mode */
.navbar-pw {
  background: var(--nav-bg);
  border-bottom: 1px solid var(--nav-border);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 60px;
  z-index: 1000;
  display: flex;
  align-items: center;
  transition: all 0.2s ease;
}

.navbar-pw-content {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
}

.pw-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.pw-brand-img {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  object-fit: cover;
  border: 1.5px solid rgba(255, 255, 255, 0.2);
}

.pw-brand-text {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--text-main);
  letter-spacing: -0.02em;
  display: inline-flex;
  align-items: center;
}

.pw-brand-highlight {
  background: linear-gradient(135deg, #FFB703 0%, #FB8500 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  color: #FB8500;
  font-weight: 900;
  margin-left: 1px;
}

.pw-brand-author {
  font-size: 0.68rem;
  font-weight: 700;
  color: var(--primary-action);
  background: rgba(81, 69, 205, 0.12);
  border: 1px solid var(--border-color);
  padding: 2px 7px;
  border-radius: 9999px;
  margin-left: 4px;
}

/* PW Top Bar Right Actions */
.pw-nav-right {
  display: flex;
  align-items: center;
  gap: 16px;
}

.pw-xp-badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  background: rgba(245, 158, 11, 0.15);
  border: 1px solid rgba(245, 158, 11, 0.35);
  color: #FBBF24;
  font-size: 0.8rem;
  font-weight: 700;
  padding: 5px 12px;
  border-radius: 9999px;
  letter-spacing: 0.02em;
}

.pw-user-greeting {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-main);
}

/* Profile Dropdown Wrap (PW Style with Logout merged inside) */
.pw-profile-dropdown-wrap {
  position: relative;
}

.pw-avatar-trigger {
  display: flex;
  align-items: center;
  gap: 6px;
  background: none;
  border: none;
  padding: 2px 4px;
  border-radius: 9999px;
  cursor: pointer;
  outline: none;
  transition: all 0.15s ease;
}

.pw-avatar-trigger:hover,
.pw-avatar-trigger.open {
  background: var(--bg-hover);
}

.pw-avatar-img {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid var(--primary-action);
}

.pw-chevron-icon {
  width: 16px;
  height: 16px;
  color: var(--text-secondary);
  transition: transform 0.2s ease;
}

.pw-avatar-trigger.open .pw-chevron-icon {
  transform: rotate(180deg);
}

.pw-dropdown-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: 240px;
  background: var(--dropdown-bg);
  border: 1px solid var(--dropdown-border);
  border-radius: 14px;
  box-shadow: var(--shadow-hover);
  padding: 8px 0;
  display: none;
  z-index: 1100;
  animation: dropdownFadeIn 0.15s ease-out forwards;
}

.pw-dropdown-menu.show {
  display: block;
}

@keyframes dropdownFadeIn {
  from {
    opacity: 0;
    transform: translateY(-6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.pw-dropdown-header {
  padding: 10px 18px 12px 18px;
  border-bottom: 1px solid var(--border-color);
}

.pw-dropdown-name {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text-main);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.pw-dropdown-email {
  font-size: 0.78rem;
  color: var(--text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.pw-dropdown-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 18px;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-main);
  text-decoration: none;
  transition: all 0.15s ease;
}

.pw-dropdown-item i,
.pw-dropdown-item svg {
  width: 17px;
  height: 17px;
  color: var(--text-secondary);
}

.pw-dropdown-item:hover {
  background: var(--bg-hover);
  color: var(--primary-action);
}

.pw-dropdown-item:hover i,
.pw-dropdown-item:hover svg {
  color: var(--primary-action);
}

.pw-dropdown-item.pw-admin-item {
  color: #D97706;
}

.pw-dropdown-item.pw-admin-item i {
  color: #D97706;
}

.pw-dropdown-divider {
  height: 1px;
  background: var(--border-color);
  margin: 6px 0;
}

.pw-dropdown-item.pw-logout-item {
  color: #EF4444;
}

.pw-dropdown-item.pw-logout-item i {
  color: #EF4444;
}

.pw-dropdown-item.pw-logout-item:hover {
  background: rgba(239, 68, 68, 0.1);
  color: #DC2626;
}

/* ==========================================================================
   PW LEFT SIDEBAR (Physics Wallah Vertical Nav)
   ========================================================================== */
.pw-sidebar {
  position: fixed;
  top: 60px;
  bottom: 0;
  left: 0;
  width: 230px;
  background: var(--sidebar-bg);
  border-right: 1px solid var(--sidebar-border);
  z-index: 990;
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--border-color) transparent;
  transition: transform 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

.pw-sidebar-inner {
  padding: 18px 12px 30px 12px;
}

.pw-sidebar-group {
  margin-bottom: 20px;
}

.pw-group-title {
  font-size: 0.72rem;
  font-weight: 800;
  color: var(--text-muted);
  letter-spacing: 0.06em;
  padding: 6px 12px;
  text-transform: uppercase;
}

.pw-nav-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-decoration: none;
  transition: all 0.15s ease;
  margin-bottom: 4px;
  position: relative;
}

.pw-nav-item i,
.pw-nav-item svg {
  width: 19px;
  height: 19px;
  color: var(--text-secondary);
}

.pw-nav-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-decoration: none;
  transition: background-color 0.18s ease, color 0.18s ease, transform 0.18s cubic-bezier(0.16, 1, 0.3, 1);
  margin-bottom: 4px;
  position: relative;
}

.pw-nav-item:hover {
  background: var(--bg-hover);
  color: var(--text-main);
  transform: translateX(3px);
}

.pw-nav-item:hover i,
.pw-nav-item:hover svg {
  color: var(--text-main);
}

.pw-nav-item.active {
  background: rgba(81, 69, 205, 0.12);
  color: var(--primary-action);
  font-weight: 700;
  transform: none;
}

.pw-nav-item.active i,
.pw-nav-item.active svg {
  color: var(--primary-action);
}

[data-theme="dark"] .pw-nav-item.active {
  background: rgba(165, 180, 252, 0.15);
  color: #A5B4FC;
}

[data-theme="dark"] .pw-nav-item.active i,
[data-theme="dark"] .pw-nav-item.active svg {
  color: #A5B4FC;
}

.pw-nav-badge {
  margin-left: auto;
  background: #EF4444;
  color: #FFFFFF;
  font-size: 0.65rem;
  font-weight: 800;
  padding: 1px 6px;
  border-radius: 9999px;
  letter-spacing: 0.04em;
}

.pw-count-badge {
  margin-left: auto;
  background: #5B46F6;
  color: #FFFFFF;
  font-size: 0.72rem;
  font-weight: 700;
  padding: 1px 7px;
  border-radius: 9999px;
}

/* PW Main Content Layout */
.main-wrapper-pw {
  min-height: calc(100vh - 60px);
  margin-top: 60px;
  transition: background-color 0.2s ease;
  background: var(--bg-page);
}

.main-wrapper-pw.with-sidebar {
  margin-left: 230px;
  padding: 24px 28px;
}

.main-wrapper-pw:not(.with-sidebar) {
  margin-left: 0;
  padding: 24px 20px;
}

/* PW Footer when sidebar is visible */
.footer.with-sidebar {
  margin-left: 230px;
  border-top: 1px solid var(--border-color);
}

/* Responsive Styles */
@media (max-width: 900px) {
  .pw-sidebar {
    transform: translateX(-100%);
    box-shadow: 10px 0 25px rgba(0,0,0,0.1);
  }
  .pw-sidebar.mobile-open {
    transform: translateX(0);
  }
  .pw-sidebar-backdrop {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.45);
    z-index: 985;
    backdrop-filter: blur(2px);
  }
  .pw-sidebar-backdrop.active {
    display: block;
  }
  .main-wrapper-pw.with-sidebar {
    margin-left: 0;
    padding: 18px 14px 80px 14px;
  }
  .footer.with-sidebar {
    margin-left: 0;
    padding-bottom: 70px;
  }
  .pw-mobile-toggle-btn {
    display: inline-flex !important;
  }
  .pw-user-greeting {
    display: none;
  }
}

.pw-mobile-toggle-btn {
  display: none;
  background: var(--bg-hover);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 6px 9px;
  border-radius: 8px;
  cursor: pointer;
  align-items: center;
  justify-content: center;
}



/* ==========================================================================
   MODAL, PILL & ACCESSIBILITY ANIMATIONS
   ========================================================================== */

.modal-overlay {
  transition: opacity 0.2s cubic-bezier(0.16, 1, 0.3, 1), backdrop-filter 0.2s ease;
}

.modal-box {
  animation: modalScaleIn 0.22s cubic-bezier(0.16, 1, 0.3, 1) forwards;
  will-change: transform, opacity;
}

@keyframes modalScaleIn {
  from {
    opacity: 0;
    transform: scale(0.96) translateY(6px);
  }
  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

/* Interactive badges, tabs, and category pills */
.tab-btn,
.filter-pill,
.interest-pill {
  transition: transform 0.16s cubic-bezier(0.16, 1, 0.3, 1),
              background-color 0.16s ease,
              border-color 0.16s ease,
              color 0.16s ease;
}

.tab-btn:hover,
.filter-pill:hover,
.interest-pill:hover {
  transform: translateY(-1px);
}

.tab-btn:active,
.filter-pill:active,
.interest-pill:active {
  transform: scale(0.96);
}

/* Reduced Motion Accessibility */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
  .live-content-wrapper {
    animation: none !important;
  }
  .yt-skeleton-container {
    transition: none !important;
  }
}


/* ==========================================================================
   Mobile-Only Component Safeguards for Desktop/Laptop Viewports
   Ensures laptop and PC experiences remain 100% pristine and unaltered.
   ========================================================================== */
.mobile-course-action-card,
.btn-toggle-about-mobile,
.pwa-install-banner {
  display: none !important;
}

.course-about-container {
  max-height: none !important;
  overflow: visible !important;
}

/* ==========================================================================
   SkillRock Unskippable Video Player & YouTube Overlay Shield
   ========================================================================== */
.skillrock-player-frame {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  background: #000000;
  user-select: none;
  -webkit-user-select: none;
  border-radius: 12px;
}

.skillrock-player-frame:fullscreen,
.skillrock-player-frame:-webkit-full-screen {
  padding-bottom: 0 !important;
  height: 100vh !important;
  width: 100vw !important;
  border-radius: 0 !important;
}

.skillrock-player-frame iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
  pointer-events: none; /* Block direct YouTube iframe clicks */
}

/* 1. Header Shield: Blocks clicks to YouTube title, channel link, and share */
.player-top-shield {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 64px;
  z-index: 12;
  background: transparent;
  cursor: default;
}

/* 2. Main Video Click Shield */
.player-click-shield {
  position: absolute;
  inset: 0;
  z-index: 10;
  background: transparent;
  cursor: pointer;
}

.player-center-play-indicator {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) scale(0.8);
  width: 68px;
  height: 68px;
  border-radius: 50%;
  background: rgba(15, 23, 42, 0.78);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #FFFFFF;
  opacity: 0;
  pointer-events: none;
  transition: all 0.22s cubic-bezier(0.16, 1, 0.3, 1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.5);
  z-index: 11;
}

.player-center-play-indicator.active {
  opacity: 1;
  transform: translate(-50%, -50%) scale(1);
}

/* 3. End-Screen Completion Overlay (Suppresses YouTube related videos) */
.skillrock-completion-overlay {
  position: absolute;
  inset: 0;
  z-index: 16;
  background: rgba(15, 23, 42, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 24px;
  color: #FFFFFF;
}

.skillrock-completion-overlay.active {
  display: flex;
}

/* 4. Sleek Custom Controls Bar */
.skillrock-controls-bar {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 20;
  background: linear-gradient(180deg, transparent 0%, rgba(15, 23, 42, 0.88) 35%, rgba(15, 23, 42, 0.98) 100%);
  padding: 16px 20px 14px 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  opacity: 1;
  transition: opacity 0.3s ease;
}

.skillrock-player-frame.playing:not(:hover) .skillrock-controls-bar {
  opacity: 0;
  pointer-events: none;
}

.skillrock-player-frame.playing:hover .skillrock-controls-bar,
.skillrock-player-frame.paused .skillrock-controls-bar,
.skillrock-player-frame.touch-active .skillrock-controls-bar {
  opacity: 1;
  pointer-events: auto;
}

/* Dual-Tone Unskippable Scrubber */
.unskippable-scrubber-wrapper {
  position: relative;
  width: 100%;
  height: 8px;
  border-radius: 9999px;
  cursor: pointer;
  padding: 4px 0;
}

.scrubber-track-bg {
  position: absolute;
  inset: 2px 0;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 9999px;
  transition: height 0.15s ease;
}

.scrubber-allowed-fill {
  position: absolute;
  top: 2px;
  bottom: 2px;
  left: 0;
  background: rgba(99, 102, 241, 0.45);
  border-radius: 9999px;
  pointer-events: none;
  transition: width 0.1s linear;
}

.scrubber-current-fill {
  position: absolute;
  top: 2px;
  bottom: 2px;
  left: 0;
  background: linear-gradient(90deg, #6366F1, #8B5CF6);
  border-radius: 9999px;
  pointer-events: none;
  transition: width 0.1s linear;
}

.scrubber-thumb {
  position: absolute;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: #FFFFFF;
  box-shadow: 0 0 8px rgba(99, 102, 241, 0.8), 0 2px 6px rgba(0,0,0,0.4);
  pointer-events: none;
  transition: transform 0.12s ease;
}

.unskippable-scrubber-wrapper:hover .scrubber-track-bg,
.unskippable-scrubber-wrapper:hover .scrubber-allowed-fill,
.unskippable-scrubber-wrapper:hover .scrubber-current-fill {
  top: 0;
  bottom: 0;
}

.unskippable-scrubber-wrapper:hover .scrubber-thumb {
  transform: translate(-50%, -50%) scale(1.2);
}

.scrubber-lock-tag {
  position: absolute;
  top: -30px;
  transform: translateX(-50%);
  background: #EF4444;
  color: #FFFFFF;
  font-size: 0.72rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 6px;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  pointer-events: none;
  box-shadow: 0 4px 12px rgba(239, 68, 68, 0.4);
  animation: fadeInDown 0.2s ease;
  white-space: nowrap;
  z-index: 25;
}

/* Control Buttons & Grouping */
.controls-action-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.controls-group-left,
.controls-group-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

.btn-player-ctrl {
  background: transparent;
  border: none;
  color: #FFFFFF;
  padding: 6px;
  border-radius: 8px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s ease;
}

.btn-player-ctrl:hover {
  background: rgba(255, 255, 255, 0.15);
  color: #818CF8;
}

.player-time-badge {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.82rem;
  font-weight: 600;
  color: #F1F5F9;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-left: 4px;
}

.unskippable-guard-pill {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 9999px;
  background: rgba(16, 185, 129, 0.15);
  color: #10B981;
  border: 1px solid rgba(16, 185, 129, 0.3);
}

.player-speed-select {
  background: rgba(30, 41, 59, 0.8);
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: #F8FAFC;
  font-size: 0.78rem;
  font-weight: 700;
  padding: 4px 8px;
  border-radius: 6px;
  cursor: pointer;
  outline: none;
}

.player-speed-select:focus {
  border-color: #6366F1;
}