:root {
        --primary-color: #1d7c7c;
        --primary-light: #2d9c9c;
        --primary-dark: #0d5c5c;
        --secondary-color: #121b1a;
        --accent-color: #163c2a;
        --success-color: #2ECC71;
        --warning-color: #F39C12;
        --danger-color: #E74C3C;
        --text-primary: #2C3E50;
        --text-secondary: #7F8C8D;
        --text-muted: #95A5A6;
        --bg-primary: #FFFFFF;
        --bg-secondary: #F8F9FA;
        --bg-tertiary: #ECEFF1;
        --border-color: #E9ECEF;
        --shadow-light: rgba(78, 205, 196, 0.1);
        --shadow-medium: rgba(78, 205, 196, 0.2);
        --shadow-heavy: rgba(78, 205, 196, 0.3);
        --gradient-primary: linear-gradient(135deg, #5ecbc6 0%, #209382 100%);
        --gradient-secondary: linear-gradient(135deg, #2ed68a 0%, #2f9f89 100%);
        --light-grey: #f8f9fa;
        --dark-grey: #6c757d;
      }

      [data-theme="dark"] {
          --text-primary: #ECEFF1;
          --text-secondary: #B0BEC5;
          --text-muted: #90A4AE;
          --bg-primary: #1A1A1A;
          --bg-secondary: #2D2D2D;
          --bg-tertiary: #3A3A3A;
          --border-color: #404040;
          --shadow-light: rgba(0, 0, 0, 0.2);
          --shadow-medium: rgba(0, 0, 0, 0.3);
          --shadow-heavy: rgba(0, 0, 0, 0.4);
          --light-grey: #2D2D2D;
      }

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

      body {
          font-family: 'Cairo', 'Tajawal', sans-serif;
          background-color: var(--bg-primary);
          color: var(--text-primary);
          transition: all 0.3s ease;
          line-height: 1.7;
      }

      /* Theme Toggle */
      .theme-toggle {
          position: fixed;
          top: 20px;
          left: 20px;
          z-index: 1050;
          background: var(--primary-color);
          border: none;
          width: 50px;
          height: 50px;
          border-radius: 50%;
          color: white;
          font-size: 1.2rem;
          box-shadow: 0 4px 15px var(--shadow-medium);
          transition: all 0.3s ease;
          cursor: pointer;
      }

      .theme-toggle:hover {
          transform: scale(1.1);
          box-shadow: 0 6px 20px var(--shadow-heavy);
      }

      /* Navigation */
      .navbar {
          background: rgba(255, 255, 255, 0.95);
          backdrop-filter: blur(10px);
          padding: 1rem 0;
          transition: all 0.3s ease;
          box-shadow: 0 2px 20px var(--shadow-light);
      }

      [data-theme="dark"] .navbar {
          background: rgba(26, 26, 26, 0.95);
      }

      .navbar-brand {
          font-size: 2rem;
          font-weight: 700;
          color: var(--primary-color) !important;
          text-decoration: none;
      }

      [data-theme="dark"] .navbar-toggler-icon {
          filter: invert(1) grayscale(100%) brightness(200%);
      }

      .nav-link {
          color: var(--text-primary) !important;
          font-weight: 500;
          margin: 0 1rem;
          position: relative;
          transition: all 0.3s ease;
          text-decoration: none;
      }

      .nav-link:hover {
          color: var(--primary-color) !important;
          transform: translateY(-2px);
      }

      .nav-link::after {
          content: '';
          position: absolute;
          width: 0;
          height: 2px;
          bottom: -5px;
          right: 50%;
          background: var(--primary-color);
          transition: all 0.3s ease;
          transform: translateX(50%);
      }

      .nav-link:hover::after {
          width: 100%;
      }

      /* Hero Section - Playful & Dynamic */
      .hero-section {
          min-height: 100vh;
          background: var(--gradient-primary);
          position: relative;
          overflow: hidden;
          display: flex;
          align-items: center;
          padding: 100px 0 50px;
      }

      .shape-blob {
          position: absolute;
          opacity: 0.6;
          mix-blend-mode: screen;
          animation: blob-move 20s ease-in-out infinite alternate;
          transition: transform 0.2s ease-out;
      }

      .shape-blob.one {
          width: 400px;
          height: 400px;
          top: -50px;
          left: -100px;
          background: var(--accent-color);
          border-radius: 50% 60% 40% 70% / 60% 40% 70% 50%;
      }

      .shape-blob.two {
          width: 300px;
          height: 300px;
          bottom: -80px;
          right: -80px;
          background: var(--secondary-color);
          border-radius: 70% 40% 60% 50% / 50% 70% 40% 60%;
          animation-duration: 15s;
          animation-direction: alternate-reverse;
      }

      .hero-content h1 {
          font-size: 4.2rem;
          font-weight: 800;
          color: #fff;
          margin-bottom: 1.5rem;
          text-shadow: 2px 2px 10px rgba(0,0,0,0.15);
          animation: popIn 1s ease-out;
      }

      .hero-content p {
          font-size: 1.5rem;
          color: rgba(255, 255, 255, 0.95);
          margin-bottom: 2.5rem;
          line-height: 1.8;
          animation: popIn 1s ease-out 0.2s both;
      }

      .btn-hero {
          background: #fff;
          border: none;
          padding: 18px 45px;
          border-radius: 50px;
          color: var(--primary-color);
          font-weight: 700;
          font-size: 1.2rem;
          box-shadow: 0 10px 30px rgba(0,0,0,0.1);
          transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
          text-decoration: none;
          display: inline-block;
          animation: popIn 1s ease-out 0.4s both;
      }

      .btn-hero:hover {
          transform: translateY(-5px) scale(1.05);
          box-shadow: 0 15px 40px rgba(0,0,0,0.15);
          color: var(--secondary-color);
      }

      .hero-image {
          animation: popIn 1s ease-out 0.3s both;
          margin-top:40px;
          perspective: 1500px;
      }

      .hero-mockup {
          width: 100%;
          max-width: 420px;
          height: 520px;
          background: rgba(255, 255, 255, 0.2);
          backdrop-filter: blur(20px);
          border-radius: 35px;
          box-shadow: 0 25px 70px rgba(0,0,0,0.1);
          position: relative;
          overflow: hidden;
          margin: 0 auto;
          border: 1.5px solid rgba(255, 255, 255, 0.3);
          transition: transform 0.4s cubic-bezier(0.25, 0.8, 0.25, 1);
      }

      @keyframes blob-move {
          from {
              transform: rotate(0deg) scale(1);
          }
          to {
              transform: rotate(360deg) scale(1.2);
          }
      }

      @keyframes popIn {
          from { opacity: 0; transform: scale(0.8); }
          to { opacity: 1; transform: scale(1); }
      }

      /* Section Styles */
      .section {
          padding: 80px 0;
          position: relative;
      }

      .section-title {
          font-size: 2.5rem;
          font-weight: 700;
          color: var(--text-primary);
          text-align: center;
          margin-bottom: 1rem;
      }

      .section-subtitle {
          font-size: 1.2rem;
          color: var(--text-secondary);
          text-align: center;
          margin-bottom: 4rem;
          max-width: 600px;
          margin-left: auto;
          margin-right: auto;
      }

      /* Feature Cards */
      .feature-card {
          background: var(--bg-primary);
          border-radius: 20px;
          padding: 2.5rem;
          box-shadow: 0 10px 30px var(--shadow-light);
          transition: all 0.3s ease;
          border: 1px solid var(--border-color);
          height: 100%;
          text-align: center;
      }

      .feature-card:hover {
          transform: translateY(-10px);
          box-shadow: 0 20px 50px var(--shadow-medium);
      }

      .feature-icon {
          width: 80px;
          height: 80px;
          background: var(--gradient-primary);
          border-radius: 50%;
          display: flex;
          align-items: center;
          justify-content: center;
          margin: 0 auto 1.5rem;
          font-size: 2rem;
          color: white;
      }

      .feature-card h3 {
          font-size: 1.5rem;
          font-weight: 600;
          color: var(--text-primary);
          margin-bottom: 1rem;
      }

      .feature-card p {
          color: var(--text-secondary);
          line-height: 1.7;
      }

      /* How it Works */
      .step-card {
          background: var(--bg-primary);
          border-radius: 20px;
          padding: 2rem;
          box-shadow: 0 10px 30px var(--shadow-light);
          border: 1px solid var(--border-color);
          position: relative;
          text-align: center;
          transition: all 0.3s ease;
      }

      .step-card:hover {
          transform: translateY(-5px);
          box-shadow: 0 15px 40px var(--shadow-medium);
      }

      .step-number {
          position: absolute;
          top: -20px;
          right: 50%;
          transform: translateX(50%);
          width: 40px;
          height: 40px;
          background: var(--primary-color);
          border-radius: 50%;
          display: flex;
          align-items: center;
          justify-content: center;
          color: white;
          font-weight: 700;
          font-size: 1.2rem;
      }

      .step-icon {
          font-size: 3rem;
          color: var(--primary-color);
          margin-bottom: 1rem;
      }

      /* FAQ Section */
      .faq-item {
          background: var(--bg-primary);
          border-radius: 15px;
          margin-bottom: 1rem;
          box-shadow: 0 5px 15px var(--shadow-light);
          border: 1px solid var(--border-color);
          overflow: hidden;
      }

      .faq-question {
          padding: 1.5rem;
          background: none;
          border: none;
          width: 100%;
          text-align: right;
          font-size: 1.1rem;
          font-weight: 600;
          color: var(--text-primary);
          cursor: pointer;
          display: flex;
          justify-content: space-between;
          align-items: center;
          transition: all 0.3s ease;
      }

      .faq-question:hover {
          background: var(--bg-secondary);
      }

      .faq-answer {
          padding: 0 1.5rem;
          max-height: 0;
          overflow: hidden;
          transition: all 0.3s ease;
          color: var(--text-secondary);
          line-height: 1.7;
      }

      .faq-answer.active {
          padding: 1.5rem;
          max-height: 200px;
      }

      .faq-icon {
          transition: transform 0.3s ease;
      }

      .faq-question.active .faq-icon {
          transform: rotate(180deg);
      }

      /* Contact Section */
      .contact-section {
          background: var(--gradient-primary);
          color: white;
          text-align: center;
      }

      .contact-btn {
          background: white;
          color: var(--primary-color);
          border: none;
          padding: 15px 30px;
          border-radius: 50px;
          font-weight: 600;
          font-size: 1.1rem;
          margin: 0 10px;
          transition: all 0.3s ease;
          text-decoration: none;
          display: inline-block;
      }

      .contact-btn:hover {
          transform: translateY(-3px);
          box-shadow: 0 10px 25px rgba(255, 255, 255, 0.3);
          color: var(--primary-color);
      }

      /* Footer */
      .footer {
          background: var(--bg-secondary);
          padding: 2rem 0;
          text-align: center;
          border-top: 1px solid var(--border-color);
      }

      /* Animations */
      .animate-on-scroll {
          opacity: 0;
          transform: translateY(30px);
          transition: all 0.8s ease;
      }

      .animate-on-scroll.animate {
          opacity: 1;
          transform: translateY(0);
      }

      /* Responsive Design */
      @media (max-width: 768px) {
          .hero-content h1 {
              font-size: 2.5rem;
          }
          
          .section-title {
              font-size: 2rem;
          }
          
          .feature-card,
          .step-card {
              margin-bottom: 2rem;
          }
          
          .theme-toggle {
              width: 45px;
              height: 45px;
              font-size: 1rem;
          }
          
          .hero-mockup {
              max-width: 300px;
              height: 400px;
          }
      }

      @media (max-width: 576px) {
          .hero-content h1 {
              font-size: 2rem;
          }
          
          .hero-content p {
              font-size: 1.1rem;
          }
          
          .section {
              padding: 60px 0;
          }
          
          .feature-card,
          .step-card {
              padding: 2rem 1.5rem;
          }
      }

      /* Background Decorations */
      .bg-decoration {
          position: absolute;
          opacity: 0.1;
          pointer-events: none;
      }

      .bg-decoration-1 {
          top: 10%;
          right: 10%;
          font-size: 8rem;
          color: var(--primary-color);
          animation: float 6s ease-in-out infinite;
      }

      .bg-decoration-2 {
          bottom: 10%;
          left: 10%;
          font-size: 6rem;
          color: var(--secondary-color);
          animation: float 8s ease-in-out infinite reverse;
      }



/* ________________________________ */


/* course detail */

      .hero-section {
        background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
        color: white;
        padding: 60px 0;
        position: relative;
        overflow: hidden;
        margin-top: 76px; /* Adjust for fixed navbar */
      }
      
      .hero-section::before {
        content: '';
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: url('https://images.pexels.com/photos/5212317/pexels-photo-5212317.jpeg?auto=compress&cs=tinysrgb&w=800') center/cover;
        opacity: 0.1;
        z-index: 1;
      }
      
      .hero-content {
        position: relative;
        z-index: 2;
      }
      
      .stats-badge {
        background: rgba(255, 255, 255, 0.2);
        backdrop-filter: blur(10px);
        border-radius: 20px;
        padding: 8px 16px;
        margin-left: 10px;
        margin-bottom: 10px;
        display: inline-block;
        border: 1px solid rgba(255, 255, 255, 0.3);
      }
      
      .instructor-img {
        width: 300px;
        height: 350px;
        object-fit: cover;
        border-radius: 15px;
        box-shadow: 0 20px 40px rgba(0,0,0,0.1);
      }
      
      .nav-tabs .nav-link {
        color: #666;
        border: none;
        padding: 12px 24px;
        font-weight: 500;
        border-radius: 25px;
        margin-left: 10px;
        transition: all 0.3s ease;
      }
      
      .nav-tabs .nav-link.active {
        background: var(--primary-color);
        color: white;
        box-shadow: 0 4px 15px rgba(29, 124, 124, 0.3);
      }
      
      .nav-tabs .nav-link:hover {
        background: var(--primary-light);
        color: white;
        transform: translateY(-2px);
      }
      
      .content-card {
        background: var(--bg-primary);
        border-radius: 15px;
        padding: 30px;
        margin-bottom: 30px;
        box-shadow: 0 5px 20px rgba(0,0,0,0.08);
        border: 1px solid var(--border-color);
        transition: transform 0.3s ease, box-shadow 0.3s ease;
      }
      
      .content-card:hover {
        transform: translateY(-5px);
        box-shadow: 0 15px 35px rgba(0,0,0,0.1);
      }
      
      .section-title {
        color: var(--text-primary);
        font-size: 28px;
        font-weight: 700;
        margin-bottom: 25px;
        position: relative;
        padding-right: 20px;
      }
      
      .section-title::before {
        content: '';
        position: absolute;
        right: 0;
        top: 50%;
        transform: translateY(-50%);
        width: 4px;
        height: 30px;
        background: var(--primary-color);
        border-radius: 2px;
      }
      
      .learning-item {
        display: flex;
        align-items: flex-start;
        margin-bottom: 15px;
        padding: 12px 0;
        border-bottom: 1px solid var(--border-color);
      }
      
      .learning-item:last-child {
        border-bottom: none;
      }
      
      .learning-item i {
        color: var(--primary-color);
        margin-left: 15px;
        margin-top: 2px;
        font-size: 14px;
      }
      
      .course-module {
        border: 1px solid var(--border-color);
        border-radius: 10px;
        margin-bottom: 15px;
        overflow: hidden;
        transition: all 0.3s ease;
      }
      
      .course-module:hover {
        box-shadow: 0 5px 15px rgba(0,0,0,0.1);
        border-color: var(--primary-color);
      }
      
      .module-header {
        background: var(--bg-secondary);
        padding: 20px;
        cursor: pointer;
        transition: background 0.3s ease;
        border-bottom: 1px solid var(--border-color);
      }
      
      .module-header:hover {
        background: #e9ecef;
      }
      
      .module-header.active {
        background: var(--primary-color);
        color: white;
      }
      
      .module-content {
        padding: 15px 20px;
        background: var(--bg-primary);
      }
      
      .lesson-item {
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 10px 0;
        border-bottom: 1px solid var(--border-color);
      }
      
      .lesson-item:last-child {
        border-bottom: none;
      }
      
      .lesson-duration {
        color: var(--dark-grey);
        font-size: 14px;
      }
      
      .instructor-card {
        background: var(--bg-primary);
        border-radius: 20px;
        padding: 30px;
        text-align: center;
        box-shadow: 0 10px 30px rgba(0,0,0,0.1);
        margin-top: 30px;
      }
      
      .instructor-avatar {
        width: 100px;
        height: 100px;
        border-radius: 50%;
        object-fit: cover;
        border: 4px solid var(--primary-color);
        margin-bottom: 20px;
      }
      
      .rating-stars {
        color: #ffc107;
        margin-bottom: 15px;
      }
      
      .btn-primary {
        background: var(--primary-color);
        border-color: var(--primary-color);
        padding: 12px 30px;
        border-radius: 25px;
        font-weight: 600;
        transition: all 0.3s ease;
      }
      
      .btn-primary:hover {
        background: var(--primary-dark);
        border-color: var(--primary-dark);
        transform: translateY(-2px);
        box-shadow: 0 8px 20px rgba(29, 124, 124, 0.3);
      }
      
      .progress-custom {
        height: 8px;
        background: #f0f0f0;
        border-radius: 4px;
        overflow: hidden;
      }
      
      .progress-custom .progress-bar {
        background: var(--primary-color);
        transition: width 0.3s ease;
      }
      
      .feature-badge {
        background: var(--primary-color);
        color: white;
        padding: 6px 12px;
        border-radius: 20px;
        font-size: 12px;
        font-weight: 600;
        margin-left: 8px;
        margin-bottom: 8px;
        display: inline-block;
      }
      
      .hero-title {
        font-size: 48px;
        font-weight: 800;
        margin-bottom: 20px;
        line-height: 1.2;
      }
      
      @media (max-width: 768px) {
        .hero-title {
          font-size: 32px;
        }
        
        .instructor-img {
          width: 100%;
          height: 250px;
        }
      }


/* _________ quizzes */

      .quiz-main-container {
        display: flex;
      }
      .quiz-sidebar {
        width: 280px;
        background-color: var(--bg-primary);
        border-left: 1px solid var(--border-color);
        padding: 15px;
        height: calc(100vh - 80px);
        position: fixed;
        right: 0;
        top: 80px;
        overflow-y: auto;
        transition: transform 0.3s ease-in-out;
        z-index: 1000;
      }
      .quiz-content-area {
        flex-grow: 1;
        padding: 20px;
        margin-right: 280px;
        transition: margin-right 0.3s ease-in-out;
      }
      .quiz-header {
        background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
        color: white;
        padding: 30px 0;
        text-align: center;
      }
      .quiz-container {
        max-width: 800px;
        margin: 20px auto;
        background: var(--bg-primary);
        border-radius: 10px;
        box-shadow: 0 5px 20px rgba(0,0,0,0.08);
        padding: 20px;
        border: 1px solid var(--border-color);
      }
      .progress-container {
        margin-bottom: 20px;
      }
      .progress-bar-custom {
        height: 8px;
        background-color: #e9ecef;
        border-radius: 4px;
        overflow: hidden;
      }
      .progress-bar-custom .progress {
        background-color: var(--primary-color);
        height: 100%;
        width: 0%;
        transition: width 0.4s ease;
      }
      .question-title {
        font-size: 20px;
        font-weight: 600;
        margin-bottom: 15px;
        color: var(--text-primary);
      }
      .answers-container .answer {
        display: block;
        background: var(--light-grey);
        border: 1px solid var(--border-color);
        padding: 12px;
        margin-bottom: 8px;
        border-radius: 8px;
        cursor: pointer;
        transition: all 0.3s ease;
        color: var(--text-primary);
      }
      .answers-container .answer:hover {
        background: #e2e6ea;
        border-color: var(--dark-grey);
      }
      .answers-container .answer.selected {
        background: var(--primary-light);
        color: white;
        border-color: var(--primary-color);
      }
      .btn-submit {
        background: var(--primary-color);
        border-color: var(--primary-color);
        padding: 10px 25px;
        border-radius: 20px;
        font-weight: 500;
        transition: all 0.3s ease;
        color: white;
      }
      .btn-submit:hover {
        background: var(--primary-dark);
        border-color: var(--primary-dark);
      }
      .quiz-footer {
        display: flex;
        justify-content: space-between;
        align-items: center;
        margin-top: 20px;
      }
      .timer {
        font-size: 20px;
        font-weight: 600;
        color: var(--primary-color);
        text-align: center;
        margin-bottom: 15px;
      }

        .sidebar-info {
            margin-bottom: 15px;
        }
        .info-item {
            display: flex;
            justify-content: space-between;
            margin-bottom: 8px;
            font-size: 14px;
        }
        .question-nav {
            list-style: none;
            padding: 0;
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(35px, 1fr));
            gap: 8px;
        }
        .question-nav-item {
            width: 35px;
            height: 35px;
            border-radius: 50%;
            background-color: var(--light-grey);
            border: 1px solid var(--border-color);
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            transition: all 0.3s ease;
            font-size: 14px;
        }
        .question-nav-item:hover {
            background-color: #e2e6ea;
        }
        .question-nav-item.active {
            background-color: var(--primary-color);
            color: white;
            border-color: var(--primary-color);
        }
        .question-nav-item.answered {
            background-color: var(--primary-light);
            color: white;
        }
        .question-nav-item.flagged {
            border-color: var(--warning-color);
            color: var(--warning-color);
        }
        .btn-flag {
            background: none;
            border: 1px solid var(--dark-grey);
            color: var(--dark-grey);
            padding: 4px 8px;
            border-radius: 15px;
            cursor: pointer;
            font-size: 12px;
        }
        .btn-flag.flagged {
            background-color: var(--warning-color);
            color: white;
            border-color: var(--warning-color);
        }
        .sidebar-toggle-btn {
            display: none;
        }

        @media (max-width: 992px) {
            .quiz-sidebar {
                transform: translateX(100%);
            }
            .quiz-sidebar.open {
                transform: translateX(0);
            }
            .quiz-content-area {
                margin-right: 0;
            }
            .sidebar-toggle-btn {
                display: block;
                position: fixed;
                top: 95px;
                right: 15px;
                z-index: 1050;
                background: var(--primary-color);
                color: white;
                border: none;
                width: 45px;
                height: 45px;
                border-radius: 50%;
                font-size: 1.2rem;
            }
        }

        @media (max-width: 576px) {
            .quiz-header h1 {
                font-size: 24px;
            }
            .quiz-container {
                padding: 15px;
            }
            .quiz-footer {
                flex-direction: column;
                gap: 10px;
            }
        }



    /* _____________ lesson-detail */

      .video-container {
        background: #000;
        border-radius: 15px;
        overflow: hidden;
        position: relative;
        box-shadow: 0 10px 30px rgba(0,0,0,0.2);
      }
      
      .video-player {
        width: 100%;
        height: 500px;
        background: linear-gradient(45deg, #1a1a1a, #2a2a2a);
        display: flex;
        align-items: center;
        justify-content: center;
        color: white;
        font-size: 48px;
        position: relative;
      }
      
      .play-button {
        background: var(--primary-color);
        border: none;
        border-radius: 50%;
        width: 80px;
        height: 80px;
        display: flex;
        align-items: center;
        justify-content: center;
        color: white;
        font-size: 24px;
        cursor: pointer;
        transition: all 0.3s ease;
        box-shadow: 0 5px 20px rgba(29, 124, 124, 0.4);
      }
      
      .play-button:hover {
        transform: scale(1.1);
        background: var(--primary-light);
      }
      
      .video-controls {
        position: absolute;
        bottom: 0;
        left: 0;
        right: 0;
        background: linear-gradient(transparent, rgba(0,0,0,0.8));
        padding: 20px;
        color: white;
      }
      
      .progress-bar-video {
        height: 6px;
        background: rgba(255,255,255,0.3);
        border-radius: 3px;
        margin-bottom: 15px;
        overflow: hidden;
      }
      
      .progress-bar-video .progress {
        height: 100%;
        background: var(--primary-color);
        width: 35%;
        border-radius: 3px;
      }
      
      .lesson-header {
        background: white;
        border-radius: 15px;
        padding: 30px;
        margin-bottom: 30px;
        box-shadow: 0 5px 20px rgba(0,0,0,0.08);
      }
      
      .lesson-title {
        color: #333;
        font-size: 32px;
        font-weight: 700;
        margin-bottom: 15px;
      }
      
      .lesson-meta {
        display: flex;
        flex-wrap: wrap;
        gap: 20px;
        color: #666;
        margin-bottom: 20px;
      }
      
      .meta-item {
        display: flex;
        align-items: center;
        gap: 8px;
      }
      
      .lesson-nav {
        background: white;
        border-radius: 15px;
        padding: 25px;
        box-shadow: 0 5px 20px rgba(0,0,0,0.08);
      }
      
      .nav-button {
        background: var(--primary-color);
        border: none;
        color: white;
        padding: 12px 24px;
        border-radius: 25px;
        font-weight: 600;
        transition: all 0.3s ease;
        text-decoration: none;
        display: inline-flex;
        align-items: center;
        gap: 10px;
      }
      
      .nav-button:hover {
        background: var(--primary-dark);
        transform: translateY(-2px);
        box-shadow: 0 8px 20px rgba(29, 124, 124, 0.3);
        color: white;
      }
      
      .nav-button.secondary {
        background: #6c757d;
      }
      
      .nav-button.secondary:hover {
        background: #5a6268;
      }
      
      .comments-section {
        background: white;
        border-radius: 15px;
        padding: 30px;
        box-shadow: 0 5px 20px rgba(0,0,0,0.08);
      }
      
      .section-title {
        color: #333;
        font-size: 24px;
        font-weight: 700;
        margin-bottom: 25px;
        position: relative;
        padding-right: 20px;
      }
      
      .section-title::before {
        content: '';
        position: absolute;
        right: 0;
        top: 50%;
        transform: translateY(-50%);
        width: 4px;
        height: 24px;
        background: var(--primary-color);
        border-radius: 2px;
      }
      
      .comment-form {
        background: #f8f9fa;
        border-radius: 12px;
        padding: 25px;
        margin-bottom: 30px;
        border: 1px solid #e9ecef;
      }
      
      .comment-item {
        border-bottom: 1px solid #f0f0f0;
        padding: 25px 0;
        display: flex;
        gap: 15px;
      }
      
      .comment-item:last-child {
        border-bottom: none;
      }
      
      .comment-avatar {
        width: 50px;
        height: 50px;
        border-radius: 50%;
        object-fit: cover;
        border: 2px solid var(--primary-color);
      }
      
      .comment-content {
        flex: 1;
      }
      
      .comment-author {
        font-weight: 600;
        color: #333;
        margin-bottom: 5px;
      }
      
      .comment-time {
        color: #666;
        font-size: 14px;
        margin-bottom: 10px;
      }
      
      .comment-text {
        color: #555;
        line-height: 1.6;
        margin-bottom: 15px;
      }
      
      .comment-actions {
        display: flex;
        gap: 15px;
      }
      
      .comment-action {
        background: none;
        border: none;
        color: #666;
        font-size: 14px;
        cursor: pointer;
        display: flex;
        align-items: center;
        gap: 5px;
        transition: color 0.3s ease;
      }
      
      .comment-action:hover {
        color: var(--primary-color);
      }
      
      .comment-action.liked {
        color: var(--primary-color);
      }
      
      .form-control:focus {
        border-color: var(--primary-color);
        box-shadow: 0 0 0 0.2rem rgba(29, 124, 124, 0.25);
      }
      
      .btn-primary {
        background: var(--primary-color);
        border-color: var(--primary-color);
        padding: 12px 30px;
        border-radius: 25px;
        font-weight: 600;
        transition: all 0.3s ease;
      }
      
      .btn-primary:hover {
        background: var(--primary-dark);
        border-color: var(--primary-dark);
        transform: translateY(-2px);
        box-shadow: 0 8px 20px rgba(29, 124, 124, 0.3);
      }
      
      .lesson-playlist {
        background: white;
        border-radius: 15px;
        padding: 25px;
        box-shadow: 0 5px 20px rgba(0,0,0,0.08);
        max-height: 600px;
        overflow-y: auto;
      }
      
      .playlist-item {
        display: flex;
        align-items: center;
        padding: 15px;
        border-radius: 10px;
        margin-bottom: 10px;
        cursor: pointer;
        transition: all 0.3s ease;
        border: 1px solid transparent;
      }
      
      .playlist-item:hover {
        background: #f8f9fa;
        border-color: var(--primary-color);
      }
      
      .playlist-item.active {
        background: var(--primary-color);
        color: white;
      }
      
      .playlist-item.active .lesson-duration {
        color: rgba(255,255,255,0.8);
      }
      
      .playlist-thumbnail {
        width: 60px;
        height: 40px;
        background: #ddd;
        border-radius: 6px;
        margin-left: 15px;
        display: flex;
        align-items: center;
        justify-content: center;
        color: #666;
      }
      
      .playlist-item.active .playlist-thumbnail {
        background: rgba(255,255,255,0.2);
        color: white;
      }
      
      .lesson-info h6 {
        margin-bottom: 5px;
        font-weight: 600;
      }
      
      .lesson-duration {
        font-size: 12px;
        color: #666;
      }
      
      @media (max-width: 992px) {
        .col-lg-8, .col-lg-4 {
          flex: 0 0 100%;
          max-width: 100%;
        }
        .lesson-playlist {
          margin-top: 30px;
        }
      }

      @media (max-width: 768px) {
        .video-player {
          height: 300px;
        }
        
        .lesson-title {
          font-size: 24px;
        }
        
        .lesson-meta {
          flex-direction: column;
          gap: 10px;
        }

        .nav-button {
          padding: 10px 18px;
          font-size: 14px;
        }

        .comment-item {
          flex-direction: column;
          align-items: flex-start;
        }

        .comment-avatar {
          margin-bottom: 15px;
        }
      }

      @media (max-width: 576px) {
        .lesson-header, .comments-section, .lesson-playlist, .comment-form {
          padding: 20px;
        }

        .d-flex.gap-3 {
          flex-direction: column;
          align-items: stretch;
        }

        .nav-button {
          width: 100%;
          justify-content: center;
        }

        .text-start {
          text-align: center !important;
        }
      }


    /* ___________ exam intro */

      .intro-container {
        max-width: 800px;
        margin: 80px auto 40px auto;
        background: var(--bg-primary);
        border-radius: 15px;
        box-shadow: 0 10px 30px rgba(0,0,0,0.1);
        padding: 40px;
        border: 1px solid var(--border-color);
        text-align: center;
      }
      .intro-container h1 {
        color: var(--primary-color);
        font-size: 36px;
        margin-bottom: 20px;
      }
      .intro-container p {
        font-size: 18px;
        color: var(--text-secondary);
        margin-bottom: 30px;
      }
      .intro-details {
        text-align: right;
        margin-bottom: 40px;
      }
      .intro-details div {
        margin-bottom: 10px;
        font-size: 16px;
        color: var(--text-primary);
      }
      .intro-details div i {
        color: var(--primary-color);
        margin-left: 10px;
      }
      .btn-start-exam {
        background: var(--primary-color);
        border-color: var(--primary-color);
        padding: 15px 40px;
        border-radius: 30px;
        font-weight: 600;
        font-size: 20px;
        transition: all 0.3s ease;
        color: white;
        text-decoration: none;
      }
      .btn-start-exam:hover {
        background: var(--primary-dark);
        border-color: var(--primary-dark);
        transform: translateY(-3px);
        box-shadow: 0 8px 20px rgba(29, 124, 124, 0.3);
      }

.page-content {
    padding-top: 20px; /* Adjust this value as needed to clear your navbar */
    /* You might also want some padding-bottom if your footer is fixed or very short */
    padding-bottom: 0px;
}

/* Media query for smaller screens if navbar height changes */
@media (max-width: 768px) {
    .page-content {
        padding-top: 0px; /* Adjust for smaller navbar on mobile */
    }
}

/* Course Manage Detail Page Styles */
.unit-details {
    border: 1px solid var(--border-color);
    border-radius: 10px;
    margin-bottom: 1.5rem;
    transition: all 0.4s cubic-bezier(0.25, 0.8, 0.25, 1);
    box-shadow: 0 5px 15px var(--shadow-light);
}

.unit-details[open] {
    border-color: var(--primary-color);
    box-shadow: 0 10px 30px var(--shadow-medium);
}

.unit-summary {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.2rem 1.5rem;
    cursor: pointer;
    background-color: var(--bg-primary);
    border-radius: 10px;
    transition: background-color 0.3s ease;
    position: relative;
}

.unit-summary:hover {
    background-color: var(--bg-secondary);
}

.unit-summary h5 {
    margin: 0;
    color: var(--text-primary);
    font-weight: 700;
    font-size: 1.2rem;
}

.unit-summary::after {
    content: '\25BC';
    font-size: 1rem;
    color: var(--primary-color);
    transition: transform 0.3s ease;
}

.unit-details[open] .unit-summary::after {
    transform: rotate(180deg);
}

.unit-content {
    padding: 1.5rem;
    border-top: 1px solid var(--border-color);
    animation: fadeIn 0.6s ease;
    background-color: var(--bg-secondary);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.list-group-item {
    background-color: var(--bg-primary);
    border-color: var(--border-color);
    transition: all 0.3s ease;
}

.list-group-item:hover {
    background-color: var(--bg-secondary);
    transform: translateX(5px);
}

.btn-sm {
    padding: 0.4rem 0.8rem;
    font-size: 0.875rem;
    border-radius: 20px;
    transition: all 0.3s ease;
}

.btn-outline-secondary {
    color: var(--text-secondary);
    border-color: var(--text-secondary);
}

.btn-outline-secondary:hover {
    color: white;
    background-color: var(--text-secondary);
}

.btn-outline-danger {
    color: var(--danger-color);
    border-color: var(--danger-color);
}

.btn-outline-danger:hover {
    color: white;
    background-color: var(--danger-color);
}

@media (max-width: 768px) {
    .unit-summary {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.8rem;
    }

    .unit-summary div {
        display: flex;
        flex-wrap: wrap;
        gap: 0.5rem;
    }

    .btn {
        width: auto;
        margin-bottom: 0;
    }
}
.question-actions {
    display: flex;
    justify-content: flex-end;
    width: 100%;
}