/* ==========================================================================
   LET'S CODE TOGETHER — DEDICATED MOBILE STYLESHEET (mobile.css)
   Clean, modern, touch-friendly UI enhancements for all mobile viewports
   ========================================================================== */

/* 1. Global Viewport & Base Touch Rules */
@media (max-width: 900px) {
  html, body {
    overflow-x: hidden !important;
    width: 100% !important;
    max-width: 100vw !important;
    -webkit-text-size-adjust: 100% !important;
    -webkit-tap-highlight-color: rgba(37, 99, 235, 0.08) !important;
  }

  *, *::before, *::after {
    box-sizing: border-box !important;
  }

  /* Prevent iOS automatic input zoom by ensuring font-size >= 16px */
  input[type="text"],
  input[type="email"],
  input[type="password"],
  input[type="search"],
  input[type="number"],
  select,
  textarea {
    font-size: 16px !important;
  }

  /* Disable heavy background 3D drifts on mobile for smooth performance */
  body::before {
    opacity: 0.6 !important;
    animation: none !important;
  }
  body::after {
    display: none !important;
  }

  /* 2. Responsive Mobile Navigation Bar */
  .light-navbar {
    padding: 10px 16px !important;
    height: 60px !important;
    display: flex !important;
    align-items: center !important;
    justify-content: space-between !important;
    position: sticky !important;
    top: 0 !important;
    z-index: 1000 !important;
    background: rgba(255, 255, 255, 0.92) !important;
    backdrop-filter: blur(18px) !important;
    -webkit-backdrop-filter: blur(18px) !important;
  }

  .navbar-brand {
    font-size: 1.05rem !important;
    gap: 8px !important;
    white-space: nowrap !important;
    overflow: hidden !important;
    text-overflow: ellipsis !important;
    max-width: calc(100% - 60px) !important;
  }

  .navbar-brand img {
    width: 30px !important;
    height: 30px !important;
    border-radius: 8px !important;
    flex-shrink: 0 !important;
  }

  /* Hamburger Menu Toggle Button */
  .mobile-nav-toggle {
    display: flex !important;
    flex-direction: column !important;
    justify-content: center !important;
    align-items: center !important;
    width: 40px !important;
    height: 40px !important;
    min-width: 40px !important;
    background: rgba(37, 99, 235, 0.06) !important;
    border: 1px solid rgba(37, 99, 235, 0.18) !important;
    border-radius: 10px !important;
    cursor: pointer !important;
    padding: 0 !important;
    gap: 5px !important;
    transition: all 0.25s ease !important;
    z-index: 1002 !important;
  }

  .mobile-nav-toggle:active {
    transform: scale(0.92) !important;
  }

  .mobile-nav-toggle .bar {
    width: 20px;
    height: 2px;
    background-color: #0f172a;
    border-radius: 2px;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    transform-origin: center;
  }

  /* Hamburger open animation */
  .mobile-nav-toggle.is-active {
    background: rgba(239, 68, 68, 0.08) !important;
    border-color: rgba(239, 68, 68, 0.25) !important;
  }
  .mobile-nav-toggle.is-active .bar-1 {
    transform: translateY(7px) rotate(45deg);
    background-color: #dc2626;
  }
  .mobile-nav-toggle.is-active .bar-2 {
    opacity: 0;
    transform: scaleX(0);
  }
  .mobile-nav-toggle.is-active .bar-3 {
    transform: translateY(-7px) rotate(-45deg);
    background-color: #dc2626;
  }

  /* Mobile Backdrop Overlay */
  .mobile-nav-backdrop {
    display: block !important;
    position: fixed !important;
    inset: 0 !important;
    background: rgba(15, 23, 42, 0.5) !important;
    backdrop-filter: blur(6px) !important;
    -webkit-backdrop-filter: blur(6px) !important;
    z-index: 998 !important;
    opacity: 0 !important;
    pointer-events: none !important;
    transition: opacity 0.3s ease !important;
  }

  .mobile-nav-backdrop.is-active {
    opacity: 1 !important;
    pointer-events: auto !important;
  }

  /* Mobile Navigation Drawer Sheet */
  .navbar-links {
    display: flex !important;
    flex-direction: column !important;
    position: fixed !important;
    top: 68px !important;
    left: 12px !important;
    right: 12px !important;
    background: rgba(255, 255, 255, 0.97) !important;
    backdrop-filter: blur(24px) !important;
    -webkit-backdrop-filter: blur(24px) !important;
    border: 1px solid rgba(226, 232, 240, 0.95) !important;
    border-radius: 20px !important;
    box-shadow: 0 20px 45px -10px rgba(15, 23, 42, 0.2), 0 0 1px rgba(0,0,0,0.1) !important;
    padding: 16px !important;
    gap: 6px !important;
    z-index: 999 !important;
    max-height: calc(100vh - 86px) !important;
    overflow-y: auto !important;
    -webkit-overflow-scrolling: touch !important;
    opacity: 0 !important;
    transform: translateY(-12px) scale(0.98) !important;
    pointer-events: none !important;
    transition: opacity 0.25s cubic-bezier(0.16, 1, 0.3, 1), transform 0.25s cubic-bezier(0.16, 1, 0.3, 1) !important;
  }

  .navbar-links.mobile-open {
    opacity: 1 !important;
    transform: translateY(0) scale(1) !important;
    pointer-events: auto !important;
  }

  .navbar-links li {
    width: 100% !important;
    list-style: none !important;
  }

  .navbar-links a {
    display: flex !important;
    align-items: center !important;
    width: 100% !important;
    padding: 12px 16px !important;
    border-radius: 12px !important;
    font-size: 0.95rem !important;
    font-weight: 600 !important;
    color: #1e293b !important;
    text-decoration: none !important;
    transition: background 0.15s ease, color 0.15s ease !important;
  }

  .navbar-links a:hover,
  .navbar-links a:active {
    background: rgba(37, 99, 235, 0.08) !important;
    color: #2563eb !important;
  }

  .navbar-btn-admin {
    margin-top: 6px !important;
    justify-content: center !important;
    background: #2563eb !important;
    color: #ffffff !important;
    border: none !important;
    text-align: center !important;
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25) !important;
  }

  .navbar-btn-admin:hover,
  .navbar-btn-admin:active {
    background: #1d4ed8 !important;
    color: #ffffff !important;
  }

  /* 3. Hero Section Stacking & Typography */
  .hero-container {
    grid-template-columns: 1fr !important;
    padding: 24px 16px 36px 16px !important;
    gap: 28px !important;
    perspective: none !important;
  }

  .hero-content {
    text-align: center !important;
    transform: none !important;
  }

  .hero-badge {
    margin: 0 auto 16px auto !important;
    font-size: 0.78rem !important;
    padding: 6px 14px !important;
  }

  .hero-title {
    font-size: 2.1rem !important;
    line-height: 1.22 !important;
    margin-bottom: 14px !important;
    letter-spacing: -0.03em !important;
  }

  .hero-subtitle {
    font-size: 0.94rem !important;
    line-height: 1.55 !important;
    margin-bottom: 24px !important;
    padding: 0 4px !important;
  }

  /* Mobile Feature Pills */
  .hero-features-list {
    justify-content: center !important;
    gap: 8px !important;
    margin-bottom: 24px !important;
  }

  .hero-feature-pill {
    font-size: 0.82rem !important;
    padding: 8px 12px !important;
    border-radius: 10px !important;
    transform: none !important;
  }

  /* Hero Action Buttons */
  .hero-content > div[style*="display:flex"] {
    flex-direction: column !important;
    width: 100% !important;
    gap: 12px !important;
    align-items: stretch !important;
  }

  .btn-hero-guest {
    width: 100% !important;
    justify-content: center !important;
    padding: 13px 20px !important;
    font-size: 0.95rem !important;
    border-radius: 12px !important;
    transform: none !important;
  }

  .hero-browse-link {
    justify-content: center !important;
    padding: 8px !important;
    font-size: 0.9rem !important;
  }

  /* 4. Auth Card Stage on Mobile */
  .auth-3d-stage {
    max-width: 100% !important;
    width: 100% !important;
    margin: 0 auto !important;
    perspective: none !important;
  }

  .auth-3d-flipper {
    transform: none !important;
    transition: transform 0.65s cubic-bezier(0.34, 1.25, 0.64, 1) !important;
  }

  .auth-3d-flipper.is-flipped {
    transform: rotateY(180deg) !important;
  }

  .auth-card-face {
    padding: 22px 18px 20px 18px !important;
    border-radius: 20px !important;
    box-shadow: 0 16px 36px -10px rgba(37, 99, 235, 0.14), 0 4px 12px rgba(15, 23, 42, 0.05) !important;
    transform-style: preserve-3d !important;
  }

  .auth-card-front {
    transform: rotateY(0deg) translateZ(1px) !important;
  }

  .auth-card-back {
    transform: rotateY(180deg) translateZ(1px) !important;
  }

  .auth-face-header {
    text-align: center !important;
    margin-bottom: 16px !important;
    transform: none !important;
  }

  .auth-face-title {
    font-size: 1.3rem !important;
    letter-spacing: -0.02em !important;
  }

  .auth-face-subtitle {
    font-size: 0.82rem !important;
    line-height: 1.4 !important;
  }

  /* Nav Tabs */
  .auth-nav-tabs {
    margin-bottom: 16px !important;
    padding: 3px !important;
    transform: none !important;
  }

  .auth-tab-btn {
    font-size: 0.82rem !important;
    padding: 8px 4px !important;
    min-height: 36px !important;
  }

  /* Form Elements */
  .form-group {
    margin-bottom: 14px !important;
  }

  .form-label {
    font-size: 0.82rem !important;
    margin-bottom: 6px !important;
  }

  .form-input {
    height: 44px !important;
    padding: 10px 14px 10px 42px !important;
    border-radius: 11px !important;
  }

  .input-icon {
    width: 17px !important;
    height: 17px !important;
    left: 14px !important;
  }

  .password-toggle-btn {
    right: 12px !important;
    width: 28px !important;
    height: 28px !important;
  }

  /* First Name & Last Name row in register */
  form[id="registerFormElement"] > div[style*="display:grid"] {
    grid-template-columns: 1fr 1fr !important;
    gap: 8px !important;
  }

  /* OTP button and row */
  .btn-send-otp {
    height: 44px !important;
    padding: 0 14px !important;
    font-size: 0.8rem !important;
    border-radius: 10px !important;
  }

  .btn-auth-primary {
    height: 46px !important;
    font-size: 0.95rem !important;
    border-radius: 12px !important;
    transform: none !important;
  }

  .btn-auth-guest {
    height: 44px !important;
    font-size: 0.88rem !important;
    border-radius: 11px !important;
    transform: none !important;
  }

  /* 5. Scroll Sections & Showcase Grids */
  .scroll-section {
    padding: 36px 16px !important;
    max-width: 100% !important;
  }

  .section-header {
    margin-bottom: 28px !important;
  }

  .section-tag {
    font-size: 0.76rem !important;
    padding: 4px 10px !important;
  }

  .section-title {
    font-size: 1.65rem !important;
    line-height: 1.25 !important;
    margin-bottom: 8px !important;
  }

  .section-desc {
    font-size: 0.9rem !important;
    line-height: 1.55 !important;
  }

  /* Single Column Stack on Mobile to prevent squished cards */
  .grid-cards-3,
  .grid-cards-4 {
    grid-template-columns: 1fr !important;
    gap: 16px !important;
  }

  .light-glass-card {
    padding: 20px 18px !important;
    border-radius: 16px !important;
    transform: none !important;
    perspective: none !important;
    box-shadow: 0 4px 18px rgba(15, 23, 42, 0.05) !important;
  }

  .light-glass-card:hover {
    transform: translateY(-2px) !important;
  }

  .card-icon-badge {
    width: 42px !important;
    height: 42px !important;
    font-size: 1.25rem !important;
    margin-bottom: 12px !important;
    transform: none !important;
  }

  .card-title-text {
    font-size: 1.1rem !important;
    margin-bottom: 6px !important;
    transform: none !important;
  }

  .card-body-text {
    font-size: 0.88rem !important;
    line-height: 1.5 !important;
    margin-bottom: 14px !important;
    transform: none !important;
  }

  .card-link-btn {
    font-size: 0.86rem !important;
    min-height: 38px !important;
    display: inline-flex !important;
    align-items: center !important;
    transform: none !important;
  }

  /* 6. Footer on Mobile */
  .light-footer {
    padding: 32px 16px 24px 16px !important;
    margin-top: 36px !important;
  }

  .footer-inner {
    flex-direction: column !important;
    text-align: center !important;
    gap: 16px !important;
    align-items: center !important;
  }

  .footer-brand {
    font-size: 1.05rem !important;
  }

  .footer-copy {
    font-size: 0.82rem !important;
    margin-top: 4px !important;
  }

  .footer-links {
    flex-wrap: wrap !important;
    justify-content: center !important;
    gap: 14px !important;
  }

  .footer-links a {
    font-size: 0.85rem !important;
    padding: 6px 4px !important;
  }

  /* 7. About & Help Pages */
  .about-wrapper,
  .help-wrapper {
    padding: 0 14px !important;
    margin: 20px auto 40px auto !important;
  }

  .about-hero-card,
  .help-header {
    padding: 24px 18px !important;
    border-radius: 18px !important;
    margin-bottom: 24px !important;
  }

  .about-hero-card h1,
  .help-header h1 {
    font-size: 1.75rem !important;
    line-height: 1.25 !important;
    margin-bottom: 10px !important;
  }

  .about-hero-card p,
  .help-header p {
    font-size: 0.95rem !important;
    line-height: 1.55 !important;
  }

  .about-grid {
    grid-template-columns: 1fr !important;
    gap: 16px !important;
    margin-bottom: 28px !important;
  }

  .faq-grid {
    gap: 14px !important;
  }

  .faq-card {
    padding: 18px 16px !important;
    border-radius: 16px !important;
  }

  .faq-card h3 {
    font-size: 1.05rem !important;
  }

  .faq-card p {
    font-size: 0.88rem !important;
    line-height: 1.55 !important;
  }

  /* 8. Academy Dashboard Widgets: Learning Log & Leaderboard Mobile Overrides */
  .academy-widgets-grid {
    grid-template-columns: 1fr !important;
    gap: 16px !important;
  }

  .dashboard-widget-box {
    padding: 16px 14px !important;
    border-radius: 18px !important;
    min-height: auto !important;
  }

  .log-widget-stats-strip,
  .leaderboard-stats-strip {
    grid-template-columns: repeat(3, 1fr) !important;
    padding: 8px 4px !important;
    gap: 4px !important;
  }

  .log-stat-item,
  .leaderboard-stat-item {
    flex-direction: column !important;
    text-align: center !important;
    gap: 2px !important;
    padding: 4px 2px !important;
  }

  .log-stat-val,
  .leaderboard-stat-val {
    font-size: 0.85rem !important;
  }

  .log-stat-lbl,
  .leaderboard-stat-lbl {
    font-size: 0.62rem !important;
  }

  .log-item-card {
    flex-direction: column !important;
    align-items: stretch !important;
    padding: 12px 10px !important;
    gap: 10px !important;
  }

  .log-item-right {
    justify-content: space-between !important;
    width: 100% !important;
    border-top: 1px solid rgba(255, 255, 255, 0.05) !important;
    padding-top: 8px !important;
  }

  body.light-mode .log-item-right {
    border-top-color: #f1f5f9 !important;
  }

  .leaderboard-table th,
  .leaderboard-table td {
    padding: 8px 6px !important;
    font-size: 0.8rem !important;
  }

  /* 9. Course Concept Reading View & Wide Typography Optimization */
  .course-details-section {
    height: auto !important;
    padding: 0 !important;
    margin: 0 !important;
    width: 100% !important;
  }

  .course-layout {
    flex-direction: column !important;
    height: auto !important;
    width: 100% !important;
    max-width: 100% !important;
    margin: 0 !important;
    border-radius: 10px !important;
    border: 1px solid var(--border-soft) !important;
    box-shadow: none !important;
    overflow: visible !important;
  }

  /* Maximize reading canvas width by minimizing side padding */
  .course-main-content {
    padding: 12px 6px !important;
    width: 100% !important;
    max-width: 100% !important;
    box-sizing: border-box !important;
    overflow-x: hidden !important;
  }

  /* Concept block containers */
  #java-content-concepts,
  #python-content-concepts,
  #python-content-basics,
  #sql-content-concepts,
  .java-content-block,
  .python-content-block,
  .cpp-content-block,
  .sql-content-block,
  .dsa-content-block {
    width: 100% !important;
    max-width: 100% !important;
    margin: 0 !important;
    padding: 0 !important;
    box-sizing: border-box !important;
  }

  /* Override the heavy 36px 42px desktop padding on concept reading boxes */
  #java-concept-content,
  #python-concept-content,
  #sql-concept-content {
    width: 100% !important;
    max-width: 100% !important;
    padding: 16px 12px !important; /* Wide readable canvas */
    margin: 0 !important;
    box-sizing: border-box !important;
    border-radius: 12px !important;
    line-height: 1.65 !important;
    font-size: 0.98rem !important;
    word-break: normal !important;
    overflow-wrap: break-word !important;
    scroll-margin-top: 80px !important;
  }

  /* Section wrappers within concepts */
  .section,
  .java-content-block .section,
  .python-content-block .section {
    width: 100% !important;
    max-width: 100% !important;
    margin: 0 0 16px 0 !important;
    padding: 0 !important;
    box-sizing: border-box !important;
  }

  /* Headings: Proportional, clean hierarchy without clipping */
  #java-concept-content h1,
  #python-concept-content h1,
  #sql-concept-content h1,
  .course-main-content h1 {
    font-size: 1.38rem !important;
    line-height: 1.28 !important;
    margin-top: 14px !important;
    margin-bottom: 10px !important;
    padding-bottom: 8px !important;
    word-break: break-word !important;
  }

  #java-concept-content h2,
  #python-concept-content h2,
  #sql-concept-content h2,
  .course-main-content h2 {
    font-size: 1.18rem !important;
    line-height: 1.32 !important;
    margin-top: 16px !important;
    margin-bottom: 8px !important;
    word-break: break-word !important;
  }

  #java-concept-content h3,
  #python-concept-content h3,
  #sql-concept-content h3,
  .course-main-content h3 {
    font-size: 1.02rem !important;
    line-height: 1.38 !important;
    margin-top: 12px !important;
    margin-bottom: 6px !important;
  }

  /* Body text: Wide line length, crisp spacing, character fit */
  #java-concept-content p,
  #python-concept-content p,
  #sql-concept-content p,
  .course-main-content p {
    font-size: 0.98rem !important;
    line-height: 1.68 !important;
    letter-spacing: 0.01em !important;
    margin-bottom: 12px !important;
    max-width: 100% !important;
    width: 100% !important;
    box-sizing: border-box !important;
    word-break: normal !important;
    overflow-wrap: break-word !important;
  }

  /* Lists inside concepts */
  #java-concept-content ul,
  #java-concept-content ol,
  #python-concept-content ul,
  #python-concept-content ol,
  #sql-concept-content ul,
  #sql-concept-content ol,
  .course-main-content ul,
  .course-main-content ol {
    padding-left: 20px !important;
    margin-bottom: 14px !important;
    width: 100% !important;
    box-sizing: border-box !important;
  }

  #java-concept-content li,
  #python-concept-content li,
  #sql-concept-content li,
  .course-main-content li {
    font-size: 0.95rem !important;
    line-height: 1.62 !important;
    margin-bottom: 6px !important;
    overflow-wrap: break-word !important;
  }

  /* Code blocks & Pre tags: Full width with smooth touch scroll */
  #java-concept-content pre,
  #python-concept-content pre,
  #sql-concept-content pre,
  .course-main-content pre {
    width: 100% !important;
    max-width: 100% !important;
    padding: 12px 14px !important;
    border-radius: 10px !important;
    margin: 14px 0 !important;
    overflow-x: auto !important;
    -webkit-overflow-scrolling: touch !important;
    box-sizing: border-box !important;
    font-size: 0.85rem !important;
    line-height: 1.5 !important;
  }

  #java-concept-content code,
  #python-concept-content code,
  #sql-concept-content code,
  .course-main-content code {
    font-size: 0.88rem !important;
    word-break: break-word !important;
  }

  #java-concept-content pre code,
  #python-concept-content pre code,
  #sql-concept-content pre code,
  .course-main-content pre code {
    font-size: 0.85rem !important;
    word-break: normal !important;
    white-space: pre !important;
  }

  /* Concepts Submenu: Vertical down-scroll list (NO side scroll) */
  .concepts-submenu {
    display: flex !important;
    flex-direction: column !important;
    flex-wrap: nowrap !important;
    overflow-x: hidden !important;
    overflow-y: auto !important;
    max-height: 420px !important;
    -webkit-overflow-scrolling: touch !important;
    gap: 8px !important;
    padding: 10px 8px !important;
    margin-bottom: 16px !important;
    border-radius: 12px !important;
    background: rgba(15, 23, 42, 0.5) !important;
    border: 1px solid var(--border-soft, rgba(255, 255, 255, 0.1)) !important;
    width: 100% !important;
    box-sizing: border-box !important;
    scrollbar-width: thin !important;
  }

  .concepts-submenu::-webkit-scrollbar {
    width: 5px;
  }
  .concepts-submenu::-webkit-scrollbar-track {
    background: rgba(0, 0, 0, 0.1);
    border-radius: 4px;
  }
  .concepts-submenu::-webkit-scrollbar-thumb {
    background: rgba(0, 245, 160, 0.35);
    border-radius: 4px;
  }

  body.light-mode .concepts-submenu {
    background: #f8fafc !important;
    border: 1px solid #cbd5e1 !important;
  }

  body.light-mode .concepts-submenu::-webkit-scrollbar-thumb {
    background: rgba(16, 185, 129, 0.4);
  }

  .concepts-submenu button {
    display: flex !important;
    align-items: center !important;
    justify-content: flex-start !important;
    width: 100% !important;
    flex-shrink: 0 !important;
    white-space: normal !important;
    text-align: left !important;
    padding: 12px 16px !important;
    font-size: 0.88rem !important;
    border-radius: 10px !important;
    gap: 10px !important;
    box-sizing: border-box !important;
    transition: all 0.2s ease !important;
  }

  /* Search input in concepts view */
  #concept-search,
  #python-concept-search,
  #sql-concept-search {
    max-width: 100% !important;
    width: 100% !important;
    font-size: 0.92rem !important;
    padding: 10px 14px !important;
    margin-bottom: 12px !important;
    box-sizing: border-box !important;
  }

  /* Fullscreen toggle button */
  .fullscreen-toggle-btn {
    width: auto !important;
    padding: 7px 12px !important;
    font-size: 0.8rem !important;
    margin-bottom: 8px !important;
  }

  /* Concept Reading View Header & Controls on Mobile */
  .concept-reading-header {
    display: flex !important;
    flex-direction: column !important;
    align-items: stretch !important;
    padding: 10px 12px !important;
    margin-bottom: 14px !important;
    gap: 8px !important;
  }

  .concept-reading-header-actions {
    display: flex !important;
    align-items: center !important;
    justify-content: space-between !important;
    width: 100% !important;
    gap: 8px !important;
  }

  .concept-reading-header-actions .fullscreen-toggle-btn {
    padding: 6px 12px !important;
    font-size: 0.78rem !important;
    margin: 0 !important;
    border-radius: 7px !important;
    white-space: nowrap !important;
  }

  .btn-back-to-topics {
    padding: 7px 12px !important;
    font-size: 0.84rem !important;
    border-radius: 8px !important;
  }

  .concept-breadcrumbs {
    display: flex !important;
    align-items: center !important;
    flex-wrap: wrap !important;
    gap: 4px 6px !important;
    font-size: 0.82rem !important;
    width: 100% !important;
    max-width: 100% !important;
    overflow: visible !important;
    text-overflow: clip !important;
    white-space: normal !important;
  }

  .concept-breadcrumbs .crumb-active-topic {
    white-space: normal !important;
    word-break: break-word !important;
    max-width: 100% !important;
  }

  .concept-bottom-nav {
    margin-top: 24px !important;
    padding: 16px 0 !important;
  }

  .concept-bottom-nav .btn-back-to-topics {
    width: 100% !important;
    justify-content: center !important;
    padding: 11px 16px !important;
    font-size: 0.92rem !important;
  }

  /* Difficulty & Read Time badges */
  .concept-meta-badge {
    display: flex !important;
    flex-wrap: wrap !important;
    gap: 6px !important;
    margin: 6px 0 12px 0 !important;
  }

  .concept-meta-badge span {
    padding: 4px 10px !important;
    font-size: 0.78rem !important;
    border-radius: 12px !important;
  }

  /* Warning Callouts */
  .warning-callout {
    background: rgba(245, 158, 11, 0.08) !important;
    border-left: 4px solid #f59e0b !important;
    border-radius: 8px !important;
    padding: 10px 12px !important;
    margin: 14px 0 !important;
    width: 100% !important;
    box-sizing: border-box !important;
  }

  .warning-callout h3 {
    font-size: 0.98rem !important;
    margin: 0 0 6px 0 !important;
    color: #f59e0b !important;
  }

  .warning-callout p {
    font-size: 0.9rem !important;
    line-height: 1.55 !important;
    margin: 0 !important;
  }

  body.light-mode .warning-callout {
    background: #fffbeb !important;
    border-left-color: #d97706 !important;
  }

  body.light-mode .warning-callout h3 {
    color: #b45309 !important;
  }

  body.light-mode .warning-callout p {
    color: #78350f !important;
  }

  /* Interview Q&A Cards inside concepts */
  .interview-section,
  .interview-card {
    width: 100% !important;
    max-width: 100% !important;
    box-sizing: border-box !important;
  }

  .interview-card {
    padding: 14px !important;
    border-radius: 12px !important;
    margin-bottom: 12px !important;
    background: rgba(255, 255, 255, 0.03) !important;
    border: 1px solid var(--border-soft) !important;
  }

  body.light-mode .interview-card {
    background: #f8fafc !important;
    border-color: #e2e8f0 !important;
  }

  .interview-card h4 {
    font-size: 0.98rem !important;
    line-height: 1.4 !important;
    margin: 8px 0 !important;
  }

  .interview-card p {
    font-size: 0.92rem !important;
    line-height: 1.6 !important;
  }

  /* Compact floating scroll buttons on mobile */
  .floating-scroll-controls {
    bottom: 20px !important;
    right: 12px !important;
    gap: 8px !important;
    z-index: 999999 !important;
    pointer-events: auto !important;
  }

  .scroll-btn {
    width: 42px !important;
    height: 42px !important;
    font-size: 1.05rem !important;
    opacity: 0.95 !important;
    pointer-events: auto !important;
    user-select: none !important;
    -webkit-tap-highlight-color: transparent !important;
    touch-action: manipulation !important;
  }

  /* ================================================================
     10. CAMPUS COMMUNICATION HUB (PUBLIC & PRIVATE CHAT) MOBILE SUITE
     Native-app feel, compact header, horizontal contact tray, full-height chat
     ================================================================ */

  /* Main communication wrapper takes full screen height on mobile */
  .user-communication-section {
    height: calc(100vh - 80px) !important;
    max-height: calc(100vh - 80px) !important;
    flex-direction: column !important;
    overflow: hidden !important;
    padding: 0 !important;
    margin: 0 !important;
    width: 100% !important;
    box-sizing: border-box !important;
  }

  /* Compact top header bar */
  .user-communication-section .chat-app-header {
    padding: 8px 12px !important;
    margin-bottom: 8px !important;
    border-radius: 14px !important;
    flex-shrink: 0 !important;
    display: flex !important;
    flex-direction: column !important;
    gap: 8px !important;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05) !important;
  }

  .chat-app-title {
    gap: 8px !important;
    align-items: center !important;
  }

  .chat-title-icon {
    font-size: 1.15rem !important;
    padding: 6px !important;
    border-radius: 10px !important;
  }

  .chat-app-title h2 {
    font-size: 1.05rem !important;
    margin: 0 !important;
    font-weight: 700 !important;
  }

  /* Hide verbose descriptive subtitle to maximize chat canvas */
  .chat-app-title p {
    display: none !important;
  }

  /* Segmented pill switch buttons for Public Lounge vs Private Messages */
  .chat-toggle-buttons {
    width: 100% !important;
    display: flex !important;
    gap: 6px !important;
    background: rgba(15, 23, 42, 0.06) !important;
    padding: 3px !important;
    border-radius: 11px !important;
    box-sizing: border-box !important;
  }

  body.light-mode .chat-toggle-buttons {
    background: #f1f5f9 !important;
  }

  .chat-toggle-buttons .toggle-btn {
    flex: 1 !important;
    padding: 8px 10px !important;
    font-size: 0.82rem !important;
    font-weight: 600 !important;
    border-radius: 8px !important;
    justify-content: center !important;
    text-align: center !important;
    border: none !important;
    min-height: 36px !important;
    transition: all 0.2s ease !important;
  }

  .chat-toggle-buttons .toggle-btn.active {
    background: #10b981 !important;
    color: #ffffff !important;
    box-shadow: 0 2px 8px rgba(16, 185, 129, 0.3) !important;
  }

  /* Chat section containers (Public & Private) - display is controlled by JS */
  .user-communication-section .chat-section-container {
    flex: 1 !important;
    min-height: 0 !important;
    height: auto !important;
    flex-direction: column !important;
    border-radius: 16px !important;
    overflow: hidden !important;
    margin: 0 !important;
    box-sizing: border-box !important;
  }

  /* ----------------------------------------------------
     PUBLIC CHAT ON MOBILE
     ---------------------------------------------------- */
  #public-chat {
    flex: 1 !important;
    min-height: 0 !important;
    height: auto !important;
    flex-direction: column !important;
    overflow: hidden !important;
  }

  #public-chat .channel-header-bar {
    padding: 8px 12px !important;
    flex-shrink: 0 !important;
    gap: 8px !important;
  }

  #public-chat-messages {
    flex: 1 !important;
    min-height: 0 !important;
    height: auto !important;
    max-height: none !important;
    overflow-y: auto !important;
    -webkit-overflow-scrolling: touch !important;
    padding: 12px 10px !important;
    margin-bottom: 0 !important;
  }

  /* ----------------------------------------------------
     PRIVATE CHAT ON MOBILE
     ---------------------------------------------------- */
  .private-chat-grid {
    flex: 1 !important;
    min-height: 0 !important;
    height: 100% !important;
    display: flex !important;
    flex-direction: column !important;
    overflow: hidden !important;
  }

  /* Transform vertical contact sidebar into a sleek horizontal contact tray */
  .private-chat-sidebar {
    flex-shrink: 0 !important;
    max-height: none !important;
    height: auto !important;
    padding: 8px 10px !important;
    gap: 6px !important;
    border-right: none !important;
    border-bottom: 1px solid var(--border-soft) !important;
    background: var(--surface) !important;
    display: flex !important;
    flex-direction: column !important;
    box-sizing: border-box !important;
  }

  .sidebar-search-box {
    width: 100% !important;
  }

  .sidebar-search-box input {
    height: 34px !important;
    min-height: 34px !important;
    padding: 6px 30px 6px 32px !important;
    font-size: 0.82rem !important;
    border-radius: 18px !important;
  }

  .sidebar-search-box .search-icon-svg {
    width: 14px !important;
    height: 14px !important;
    left: 10px !important;
  }

  /* Hide redundant ACTIVE CONTACTS label on mobile */
  .sidebar-label {
    display: none !important;
  }

  /* Horizontally scrollable contact pills */
  .user-list-container {
    display: flex !important;
    flex-direction: row !important;
    overflow-x: auto !important;
    -webkit-overflow-scrolling: touch !important;
    gap: 6px !important;
    padding: 2px 0 4px 0 !important;
    scrollbar-width: none !important;
    max-height: 48px !important;
    align-items: center !important;
  }

  .user-list-container::-webkit-scrollbar {
    display: none !important;
  }

  .user-item {
    flex-shrink: 0 !important;
    display: inline-flex !important;
    align-items: center !important;
    padding: 4px 10px !important;
    border-radius: 20px !important;
    margin: 0 !important;
    gap: 6px !important;
    background: rgba(255, 255, 255, 0.05) !important;
    border: 1.5px solid var(--border-soft) !important;
    cursor: pointer !important;
    transition: all 0.15s ease !important;
  }

  body.light-mode .user-item {
    background: #ffffff !important;
    border-color: #e2e8f0 !important;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04) !important;
  }

  .user-item.active {
    background: rgba(16, 185, 129, 0.16) !important;
    border-color: #10b981 !important;
  }

  body.light-mode .user-item.active {
    background: rgba(16, 185, 129, 0.12) !important;
    border-color: #10b981 !important;
  }

  .user-item-avatar {
    width: 24px !important;
    height: 24px !important;
    min-width: 24px !important;
    font-size: 0.7rem !important;
    border-radius: 50% !important;
  }

  .user-item-header {
    width: auto !important;
  }

  .user-item-name {
    font-size: 0.8rem !important;
    font-weight: 600 !important;
    white-space: nowrap !important;
  }

  .user-item-name span {
    display: none !important; /* Hide @handle on mobile chips for concise view */
  }

  .user-item-sub,
  .user-item-time {
    display: none !important; /* Hide preview text on horizontal chips */
  }

  .online-dot {
    width: 7px !important;
    height: 7px !important;
    min-width: 7px !important;
    margin-left: 2px !important;
  }

  /* Private chat main messages canvas */
  .private-chat-main {
    flex: 1 !important;
    min-height: 0 !important;
    height: 100% !important;
    display: flex !important;
    flex-direction: column !important;
    overflow: hidden !important;
    box-sizing: border-box !important;
  }

  .private-chat-main .channel-header-bar {
    padding: 8px 12px !important;
    flex-shrink: 0 !important;
    gap: 8px !important;
    box-sizing: border-box !important;
  }

  #private-target-avatar {
    width: 32px !important;
    height: 32px !important;
    font-size: 0.88rem !important;
  }

  #private-target-name {
    font-size: 0.92rem !important;
    margin: 0 !important;
    font-weight: 700 !important;
  }

  #selected-user-info {
    font-size: 0.72rem !important;
    margin: 0 !important;
  }

  #block-user-btn {
    padding: 4px 8px !important;
    font-size: 0.75rem !important;
    border-radius: 6px !important;
  }

  .clear-chat-btn {
    width: 32px !important;
    height: 32px !important;
    min-width: 32px !important;
    padding: 0 !important;
    font-size: 0 !important;
    border-radius: 50% !important;
    display: flex !important;
    align-items: center !important;
    justify-content: center !important;
  }

  .clear-chat-btn::before {
    content: "🗑️" !important;
    font-size: 0.9rem !important;
  }

  #private-chat-messages {
    flex: 1 !important;
    min-height: 0 !important;
    height: auto !important;
    max-height: none !important;
    overflow-y: auto !important;
    -webkit-overflow-scrolling: touch !important;
    padding: 12px 10px !important;
    margin-bottom: 0 !important;
  }

  #admin-messages {
    max-height: 60px !important;
    overflow-y: auto !important;
    flex-shrink: 0 !important;
    padding: 6px 10px !important;
  }

  /* ----------------------------------------------------
     MESSENGER INPUT BAR & ACTION BUTTONS
     ---------------------------------------------------- */
  .messenger-input-bar {
    flex-shrink: 0 !important;
    display: flex !important;
    align-items: center !important;
    padding: 8px 10px !important;
    gap: 6px !important;
    background: var(--surface) !important;
    border-top: 1px solid var(--border-medium) !important;
    box-sizing: border-box !important;
    width: 100% !important;
  }

  .chat-action-btn {
    width: 36px !important;
    height: 36px !important;
    min-width: 36px !important;
    font-size: 1.1rem !important;
    padding: 0 !important;
    border-radius: 50% !important;
  }

  .messenger-input-bar textarea {
    min-height: 38px !important;
    max-height: 75px !important;
    height: 38px !important;
    padding: 9px 12px !important;
    font-size: 0.88rem !important;
    border-radius: 18px !important;
    resize: none !important;
    line-height: 1.4 !important;
    flex: 1 !important;
    box-sizing: border-box !important;
  }

  .chat-send-btn {
    width: 38px !important;
    height: 38px !important;
    min-width: 38px !important;
    border-radius: 50% !important;
    padding: 0 !important;
    display: flex !important;
    align-items: center !important;
    justify-content: center !important;
    flex-shrink: 0 !important;
    background: linear-gradient(135deg, #10b981, #059669) !important;
    border: none !important;
  }

  .chat-send-btn span:first-child {
    display: none !important;
  }

  .chat-send-btn .send-icon {
    font-size: 1.1rem !important;
    margin: 0 !important;
  }

  /* Chat message bubbles on mobile */
  .chat-row {
    margin-bottom: 8px !important;
    display: flex !important;
  }

  .chat-bubble {
    max-width: 86% !important;
    padding: 9px 13px !important;
    border-radius: 16px !important;
    font-size: 0.92rem !important;
    line-height: 1.48 !important;
  }

  .my-bubble {
    border-bottom-right-radius: 4px !important;
  }

  .other-bubble {
    border-bottom-left-radius: 4px !important;
  }

  .bubble-meta {
    font-size: 0.68rem !important;
    margin-top: 3px !important;
  }

  /* ----------------------------------------------------
     ZETROX AI FLOATING ROBOT FAB - AVOID BLOCKING INPUT BAR
     ---------------------------------------------------- */
  .zetrox-chat-fab-circle,
  .zetrox-chat-fab {
    bottom: 80px !important; /* Floats safely above messenger input bar */
    right: 12px !important;
    width: 44px !important;
    height: 44px !important;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.22) !important;
  }

  .zetrox-chat-fab-circle img,
  .zetrox-chat-fab img {
    width: 26px !important;
    height: 26px !important;
  }

  .zetrox-fab-status-dot {
    width: 8px !important;
    height: 8px !important;
  }

  /* ----------------------------------------------------
     PREMIUM MOBILE BOTTOM-SHEET VIEW FOR ZETROX AI
     ---------------------------------------------------- */
  .zetrox-drawer {
    position: fixed !important;
    left: 0 !important;
    right: 0 !important;
    bottom: 0 !important;
    top: auto !important;
    width: 100vw !important;
    max-width: 100vw !important;
    height: 85vh !important;
    max-height: 88dvh !important;
    border-radius: 24px 24px 0 0 !important;
    border: none !important;
    border-top: 2px solid rgba(56, 189, 248, 0.6) !important;
    box-shadow: 0 -12px 50px rgba(0, 0, 0, 0.85), 0 0 35px rgba(56, 189, 248, 0.25) !important;
    margin: 0 !important;
    transform-origin: bottom center !important;
    z-index: 99999 !important;
    flex-direction: column !important;
    backdrop-filter: blur(28px) !important;
    -webkit-backdrop-filter: blur(28px) !important;
    opacity: 0 !important;
    transform: translateY(100%) !important;
    transition: transform 0.28s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.28s cubic-bezier(0.16, 1, 0.3, 1) !important;
    animation: none !important;
  }

  .zetrox-drawer.open {
    opacity: 1 !important;
    transform: translateY(0) !important;
    display: flex !important;
  }

  .zetrox-drawer.closing {
    opacity: 0 !important;
    transform: translateY(100%) !important;
    pointer-events: none !important;
  }

  /* Explicitly obey hidden/closed state on mobile */
  .zetrox-drawer[style*="display: none"],
  .zetrox-drawer[style*="display:none"],
  .zetrox-drawer.hidden {
    display: none !important;
  }

  .zetrox-drawer-header {
    padding: 16px 16px 12px 16px !important;
    position: relative !important;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08) !important;
    flex-shrink: 0 !important;
  }

  /* Elegant grab handle on top */
  .zetrox-drawer-header::before {
    content: "" !important;
    position: absolute !important;
    top: 6px !important;
    left: 50% !important;
    transform: translateX(-50%) !important;
    width: 44px !important;
    height: 4px !important;
    background: rgba(255, 255, 255, 0.3) !important;
    border-radius: 4px !important;
  }

  body.light-mode .zetrox-drawer-header::before {
    background: rgba(0, 0, 0, 0.22) !important;
  }

  .zetrox-drawer-brand {
    gap: 10px !important;
    min-width: 0 !important;
    flex: 1 !important;
  }

  .zetrox-header-logo {
    width: 34px !important;
    height: 34px !important;
  }

  .zetrox-badge {
    font-size: 0.65rem !important;
    padding: 2px 7px !important;
    letter-spacing: 0.5px !important;
  }

  .zetrox-drawer-title h4 {
    font-size: 0.84rem !important;
    white-space: nowrap !important;
    overflow: hidden !important;
    text-overflow: ellipsis !important;
    max-width: 210px !important;
  }

  .zetrox-drawer-close {
    width: 38px !important;
    height: 38px !important;
    min-width: 38px !important;
    min-height: 38px !important;
    font-size: 1.5rem !important;
    flex-shrink: 0 !important;
    background: rgba(255, 255, 255, 0.15);
    color: #f8fafc;
    display: flex !important;
    align-items: center !important;
    justify-content: center !important;
    cursor: pointer !important;
    touch-action: manipulation !important;
    -webkit-tap-highlight-color: transparent !important;
    border-radius: 50% !important;
    z-index: 10 !important;
  }

  .zetrox-messages-container {
    padding: 14px !important;
    gap: 12px !important;
    -webkit-overflow-scrolling: touch !important;
    flex: 1 !important;
  }

  .zetrox-bubble {
    font-size: 0.9rem !important;
    line-height: 1.55 !important;
    padding: 10px 14px !important;
    border-radius: 16px !important;
  }

  .zetrox-msg.agent {
    max-width: 96% !important;
  }

  .zetrox-msg.user {
    max-width: 90% !important;
  }

  .zetrox-msg.user .zetrox-bubble {
    font-size: 0.9rem !important;
    padding: 10px 14px !important;
  }

  /* Clean finger-friendly bottom input bar */
  .zetrox-input-area {
    padding: 10px 12px max(14px, env(safe-area-inset-bottom)) 12px !important;
    gap: 8px !important;
    background: rgba(15, 23, 42, 0.98) !important;
    border-top: 1px solid rgba(255, 255, 255, 0.08) !important;
  }

  .zetrox-input-area input {
    font-size: 16px !important; /* Prevents auto-zoom on iOS */
    padding: 10px 14px !important;
    border-radius: 12px !important;
    min-height: 44px !important;
    box-sizing: border-box !important;
    flex: 1 !important;
  }

  .zetrox-send-btn {
    padding: 10px 16px !important;
    font-size: 0.88rem !important;
    border-radius: 12px !important;
    white-space: nowrap !important;
    flex-shrink: 0 !important;
    min-height: 44px !important;
    display: inline-flex !important;
    align-items: center !important;
    justify-content: center !important;
  }

  /* Mobile Light mode support */
  body.light-mode .zetrox-drawer {
    background: rgba(255, 255, 255, 0.98) !important;
    border-top: 2px solid #0284c7 !important;
    box-shadow: 0 -12px 40px rgba(0, 0, 0, 0.15) !important;
  }

  body.light-mode .zetrox-drawer-close,
  html.light-mode .zetrox-drawer-close {
    color: #000000 !important;
    background: rgba(0, 0, 0, 0.08) !important;
    border: 1px solid rgba(0, 0, 0, 0.16) !important;
  }

  body.light-mode .zetrox-drawer-close:hover,
  html.light-mode .zetrox-drawer-close:hover,
  body.light-mode .zetrox-drawer-close:active,
  html.light-mode .zetrox-drawer-close:active {
    color: #000000 !important;
    background: rgba(239, 68, 68, 0.18) !important;
    border-color: rgba(239, 68, 68, 0.35) !important;
  }

  body.light-mode .zetrox-input-area {
    background: #f8fafc !important;
    border-top: 1px solid #e2e8f0 !important;
  }

  body.light-mode .zetrox-input-area input {
    background: #ffffff !important;
    border-color: #cbd5e1 !important;
    color: #0f172a !important;
  }
}

/* Extra small screens (iPhone SE, Galaxy S, 320px - 400px) */
@media (max-width: 420px) {
  .chat-bubble {
    max-width: 90% !important;
    padding: 8px 11px !important;
    font-size: 0.88rem !important;
  }

  .user-communication-section .chat-app-header {
    padding: 6px 10px !important;
    margin-bottom: 6px !important;
  }

  .chat-app-title h2 {
    font-size: 0.98rem !important;
  }

  .chat-toggle-buttons .toggle-btn {
    padding: 6px 8px !important;
    font-size: 0.78rem !important;
  }
  /* Maximize character reading canvas on compact phone screens */
  .main-content {
    padding-left: 4px !important;
    padding-right: 4px !important;
  }

  .course-main-content {
    padding: 10px 3px !important;
  }

  #java-concept-content,
  #python-concept-content,
  #sql-concept-content {
    padding: 14px 8px !important;
  }

  #java-concept-content p,
  #python-concept-content p,
  #sql-concept-content p,
  .course-main-content p {
    font-size: 0.95rem !important;
    line-height: 1.62 !important;
  }

  .hero-title {
    font-size: 1.8rem !important;
  }

  .navbar-brand {
    font-size: 0.95rem !important;
  }

  .auth-card-face {
    padding: 18px 14px !important;
  }

  .auth-face-title {
    font-size: 1.2rem !important;
  }

  form[id="registerFormElement"] > div[style*="display:grid"] {
    grid-template-columns: 1fr !important;
    gap: 12px !important;
  }

  .btn-send-otp {
    padding: 0 10px !important;
    font-size: 0.75rem !important;
  }
}

/* Desktop styles: Hide mobile-only elements */
@media (min-width: 901px) {
  .mobile-nav-toggle,
  .mobile-nav-backdrop {
    display: none !important;
  }
}