.container {
        max-width: 1200px;
        margin: 0 auto;
        padding: 0 1rem;
      }

      .main-content {
        min-height: 100vh;
        padding: 2rem 0;
      }

      .card {
        background: white;
        border-radius: var(--border-radius);
        padding: 2rem;
        margin-bottom: 2rem;
        box-shadow: var(--shadow);
        border-left: 5px solid var(--primary-color);
        transition: var(--transition);
        opacity: 0;
        transform: translateY(20px);
        animation: fadeInUp 0.6s ease forwards;
      }


      .card:hover {
        transform: translateY(-2px);
        box-shadow: var(--shadow-lg);
      }

      .hero-section {
        background: linear-gradient(
          135deg,
          var(--primary-color) 0%,
          var(--secondary-color) 100%
        );
        color: white;
        padding: 5rem 0;
        text-align: center;
        position: relative;
        overflow: hidden;
        margin-bottom: 2rem;
      }

      .hero-section::before {
        content: "";
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><polygon points="0,100 100,0 100,100" fill="rgba(255,255,255,0.1)"/></svg>');
      }




      .stats {
        display: flex;
        justify-content: center;
        gap: 2rem;
        flex-wrap: wrap;
        margin-top: 2rem;
      }

      .stat {
        text-align: center;
        background: rgba(255, 255, 255, 0.1);
        padding: 1rem 1.5rem;
        border-radius: 10px;
        backdrop-filter: blur(10px);
      }



      .quick-nav {
        background: white;
        padding: 1.5rem;
        border-radius: var(--border-radius);
        box-shadow: var(--shadow);
        margin-bottom: 2rem;
        text-align: center;
      }

      .quick-nav-title {
        font-weight: bold;
        margin-bottom: 1rem;
        color: var(--text-primary);
        font-size: 1.1rem;
      }

      .quick-nav-links {
        display: flex;
        gap: 0.75rem;
        flex-wrap: wrap;
        justify-content: center;
      }



      .category-header {
        background: linear-gradient(
          135deg,
          var(--primary-color) 0%,
          var(--secondary-color) 100%
        );
        color: white;
        padding: 2.5rem;
        border-radius: var(--border-radius);
        text-align: center;
        margin: 3rem 0 2rem 0;
        position: relative;
        overflow: hidden;
      }

      .category-header > * {
        position: relative;
        z-index: 1;
      }

      .category-title {
        font-size: 2.2rem;
        font-weight: bold;
        margin-bottom: 0.5rem;
      }

      .card-title {
        color: var(--primary-color);
        font-size: 1.8rem;
        font-weight: bold;
        margin-bottom: 1rem;
      }

      .badge {
        background: var(--primary-color);
        color: white;
        padding: 0.35rem 0.85rem;
        border-radius: 20px;
        font-size: 0.8rem;
        font-weight: bold;
        display: inline-block;
        margin-left: 1rem;
      }

      .badge.beginner {
        background: var(--success-color);
      }

      .badge.intermediate {
        background: var(--warning-color);
      }

      .badge.advanced {
        background: var(--danger-color);
      }

      .comparison-table {
        width: 100%;
        border-collapse: collapse;
        background: white;
        border-radius: 8px;
        overflow: hidden;
        margin: 1.5rem 0;
        box-shadow: var(--shadow);
      }

      .comparison-table th {
        background: linear-gradient(
          135deg,
          var(--primary-color),
          var(--secondary-color)
        );
        color: white;
        padding: 1rem;
        text-align: left;
        font-weight: bold;
      }

      .comparison-table td {
        padding: 1rem;
        border-bottom: 1px solid #e2e8f0;
      }

      .comparison-table tr:hover {
        background: var(--bg-light);
      }

      .example-box {
        background: white;
        padding: 1.25rem;
        border-radius: 8px;
        margin: 1rem 0;
        border: 2px solid var(--primary-color);
        box-shadow: var(--shadow);
      }

      .example-title {
        font-weight: bold;
        color: var(--text-primary);
        margin-bottom: 0.75rem;
        font-size: 0.95rem;
      }

      .highlight-prep {
        background: #fed7aa;
        color: #92400e;
        padding: 0.2rem 0.4rem;
        border-radius: 3px;
        font-weight: bold;
      }

      .highlight-at {
        background: #dcfce7;
        color: #166534;
        padding: 0.2rem 0.4rem;
        border-radius: 3px;
        font-weight: bold;
      }

      .highlight-in {
        background: #dbeafe;
        color: #1e40af;
        padding: 0.2rem 0.4rem;
        border-radius: 3px;
        font-weight: bold;
      }

      .highlight-on {
        background: #fce7f3;
        color: #9f1239;
        padding: 0.2rem 0.4rem;
        border-radius: 3px;
        font-weight: bold;
      }

      .text-large {
        font-size: 1.05rem;
        line-height: 1.8;
        margin-bottom: 1rem;
      }

      .rule-box {
        background: #fff5cd;
        border: 2px solid var(--warning-color);
        border-radius: 8px;
        padding: 1rem;
        margin: 1.5rem 0;
      }

      .rule-title {
        color: #92400e;
        font-weight: bold;
        margin-bottom: 0.5rem;
        font-size: 1rem;
      }

      .rule-content {
        color: var(--text-primary);
        font-size: 0.95rem;
        line-height: 1.6;
      }

      .tip-box {
        background: #dcfce7;
        border: 2px solid var(--success-color);
        border-radius: 8px;
        padding: 1rem;
        margin: 1.5rem 0;
      }

      .tip-title {
        color: #166534;
        font-weight: bold;
        margin-bottom: 0.5rem;
        font-size: 1rem;
      }

      .tip-content {
        color: var(--text-primary);
        font-size: 0.95rem;
        line-height: 1.6;
      }

      .grid-2 {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
        gap: 1.5rem;
        margin: 1.5rem 0;
      }

      .grid-3 {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 1rem;
        margin: 1.5rem 0;
      }

      .feature-box {
        background: white;
        padding: 1.5rem;
        border-radius: 8px;
        border: 2px solid var(--primary-color);
        box-shadow: var(--shadow);
      }

      .feature-title {
        color: var(--primary-color);
        font-weight: bold;
        margin-bottom: 1rem;
        font-size: 1.1rem;
      }

      .feature-content {
        color: var(--text-secondary);
        font-size: 0.95rem;
        line-height: 1.6;
      }

      .prep-list {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
        gap: 0.75rem;
        margin: 1rem 0;
      }

      .prep-item {
        background: var(--bg-light);
        padding: 0.75rem;
        border-radius: 6px;
        border-left: 3px solid var(--primary-color);
        font-weight: 600;
        font-size: 0.9rem;
        text-align: center;
      }

      .visual-box {
        background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
        padding: 1.5rem;
        border-radius: 8px;
        margin: 1.5rem 0;
        border: 2px solid var(--primary-color);
        text-align: center;
      }

      .visual-title {
        color: var(--primary-color);
        font-weight: bold;
        margin-bottom: 1rem;
        font-size: 1.1rem;
      }

      .correct-example {
        background: #dcfce7;
        padding: 1rem;
        border-radius: 6px;
        margin: 0.5rem 0;
        border-left: 4px solid var(--success-color);
      }

      .incorrect-example {
        background: #fee2e2;
        padding: 1rem;
        border-radius: 6px;
        margin: 0.5rem 0;
        border-left: 4px solid var(--danger-color);
      }

      .label-correct {
        color: var(--success-color);
        font-weight: bold;
        font-size: 0.85rem;
        margin-bottom: 0.5rem;
      }

      .label-incorrect {
        color: var(--danger-color);
        font-weight: bold;
        font-size: 0.85rem;
        margin-bottom: 0.5rem;
      }

      @media (max-width: 768px) {
        .hero-title {
          font-size: 2rem;
        }

        .category-title {
          font-size: 1.5rem;
        }

        .card {
          padding: 1.5rem;
        }

        .stats {
          gap: 1rem;
        }

        .quick-nav-links {
          flex-direction: column;
        }

        .nav-link {
          width: 100%;
          text-align: center;
        }

        .grid-2,
        .grid-3 {
          grid-template-columns: 1fr;
        }

        .badge {
          display: block;
          margin-left: 0;
          margin-top: 0.5rem;
        }

        .comparison-table th,
        .comparison-table td {
          padding: 0.75rem;
          font-size: 0.9rem;
        }
      }

      /* Ensure mobile dropdowns work properly */
      @media (max-width: 768px) {
        /* FORCE mobile menu to display full width */
        .nav-links,
        #navLinks,
        ul.nav-links {
          display: flex !important;
          position: fixed !important;
          top: 70px !important;
          left: 0 !important;
          right: 0 !important;
          bottom: 0 !important;
          width: 100vw !important;
          height: auto !important;
          min-height: calc(100vh - 70px) !important;
        }

        .nav-links.active,
        #navLinks.active,
        ul.nav-links.active {
          display: flex !important;
          max-height: calc(100vh - 70px) !important;
          height: auto !important;
        }

        /* Make sure nav links with dropdowns are clearly tappable */
        .nav-item .nav-link {
          position: relative;
          user-select: none;
          -webkit-user-select: none;
          -webkit-tap-highlight-color: rgba(70, 187, 229, 0.2);
          cursor: pointer;
        }

        /* Ensure chevron is visible and clickable */
        .nav-link .fa-chevron-down {
          transition: transform 0.3s ease !important;
          opacity: 1 !important;
          pointer-events: none; /* Let clicks go through to parent link */
        }

        /* Visual feedback when dropdown is open */
        .nav-item.mobile-open > .nav-link,
        .nav-item.mobile-dropdown-open > .nav-link {
          background: rgba(70, 187, 229, 0.15) !important;
          border-color: var(--primary-color, #46bbe5) !important;
        }

        /* Make dropdowns smoother */
        .dropdown {
          transition: max-height 0.4s cubic-bezier(0.4, 0, 0.2, 1),
            padding 0.4s cubic-bezier(0.4, 0, 0.2, 1) !important;
        }

        /* Ensure dropdown items are visible when parent is open */
        .nav-item.mobile-open .dropdown,
        .nav-item.mobile-dropdown-open .dropdown {
          display: block !important;
          visibility: visible !important;
          opacity: 1 !important;
          pointer-events: auto !important;
        }

        /* Ensure dropdown items are clickable */
        .dropdown-item,
        .dropdown > a {
          pointer-events: auto !important;
          touch-action: manipulation !important;
          user-select: none;
          -webkit-user-select: none;
        }
      }