:root {
            --primary: #4361ee;
            --secondary: #3a0ca3;
            --accent: #4cc9f0;
            --dna-a: #e63946;
            --dna-t: #2a9d8f;
            --dna-g: #e9c46a;
            --dna-c: #f4a261;
            --rna-u: #9d4edd;
            --success: #06d6a0;
            --light: #f8f9fa;
            --dark: #212529;
            --gray: #6c757d;
            --light-gray: #e9ecef;
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }

        body {
            background: linear-gradient(135deg, #f5f7fa 0%, #e4edf5 100%);
            color: var(--dark);
            line-height: 1.6;
            min-height: 100vh;
            padding: 20px;
        }

        html{
            scroll-behavior: smooth;

        }

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

        header {
            text-align: center;
            margin-bottom: 40px;
            padding: 30px 20px;
            background: white;
            border-radius: 16px;
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
            position: relative;
            overflow: hidden;
        }

        h1 {
            color: var(--secondary);
            margin-bottom: 15px;
            font-size: 2.5rem;
            font-weight: 700;
        }

        .subtitle {
            color: var(--gray);
            font-size: 1.1rem;
            max-width: 800px;
            margin: 0 auto;
        }

        .process-flow {
            display: flex;
            justify-content: center;
            align-items: center;
            margin: 30px 0;
            flex-wrap: wrap;
            gap: 20px;
        }

        .process-step {
            display: flex;
            flex-direction: column;
            align-items: center;
            text-align: center;
            width: 150px;
        }

        .process-step a{
text-decoration: none;
        }
        .step-icon {
            width: 70px;
            height: 70px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            background: white;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
            margin-bottom: 15px;
            font-size: 1.8rem;
            color: var(--primary);
            transition: transform 0.3s;
        }

        .process-step.active:hover .step-icon{
            transform: scale(1.4);
            box-shadow: 0 8px 70px rgba(238, 67, 67, 0.3);

        }

        .process-step.active .step-icon {
            transform: scale(1.1);
            box-shadow: 0 8px 20px rgba(67, 97, 238, 0.3);
        }

        .step-label {
            font-weight: 600;
            color: var(--dark);
            margin-bottom: 5px;
        }

        .step-desc {
            font-size: 0.85rem;
            color: var(--gray);
        }

        .arrow {
            font-size: 1.5rem;
            color: var(--primary);
            margin: 0 10px;
        }

.card {
    background: white;
    border-radius: 16px;
    padding: 30px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
    margin-bottom: 30px;
    transition: transform 0.3s, box-shadow 0.3s;
    position: relative;
    overflow: hidden; 
}




        .card:hover {
            transform: translateY(-5px);
            box-shadow: 0 15px 35px rgba(0, 0, 0, 0.12);
        }

        .card-header {
            display: flex;
            align-items: center;
            margin-bottom: 25px;
            padding-bottom: 15px;
            border-bottom: 2px solid var(--light-gray);
        }

        .card-icon {
            width: 50px;
            height: 50px;
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
            background: var(--primary);
            color: white;
            font-size: 1.5rem;
            margin-right: 15px;
        }

        .card-title {
            font-size: 1.5rem;
            color: var(--secondary);
            font-weight: 600;
        }

        .input-group {
            display: flex;
            gap: 15px;
            margin-bottom: 20px;
        }

        #dna-input {
            flex: 1;
            padding: 15px 20px;
            border: 2px solid var(--light-gray);
            border-radius: 12px;
            font-size: 1rem;
            transition: all 0.3s;
            box-shadow: 0 3px 10px rgba(0, 0, 0, 0.05);
        }

        #dna-input:focus {
            border-color: var(--primary);
            outline: none;
            box-shadow: 0 5px 15px rgba(67, 97, 238, 0.15);
        }

        .btn {
            padding: 15px 30px;
            border: none;
            border-radius: 12px;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .btn-primary {
            background: var(--primary);
            color: white;
            box-shadow: 0 5px 15px rgba(67, 97, 238, 0.3);
        }

        .btn-primary:hover {
            background: var(--secondary);
            transform: translateY(-3px);
            box-shadow: 0 8px 20px rgba(67, 97, 238, 0.4);
        }

        .btn-secondary {
            background: var(--light-gray);
            color: var(--dark);
        }

        .btn-secondary:hover {
            background: #dde1e7;
        }

        .example {
            color: var(--gray);
            font-style: italic;
            margin-top: 10px;
            font-size: 0.9rem;
        }

        .strand-container {
            position: relative;
            margin: 25px 0;
            padding: 20px;
            background: var(--light);
            border-radius: 12px;
            overflow-x: auto;
            box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.05);
        }

        .strand {
            display: flex;
            gap: 5px;
            min-width: max-content;
            justify-content: center;
        }

        .nucleotide {
            width: 50px;
            height: 50px;
            display: flex;
            align-items: center;
            justify-content: center;
            border-radius: 10px;
            font-weight: bold;
            color: white;
            transition: all 0.3s;
            box-shadow: 0 3px 8px rgba(0, 0, 0, 0.1);
        }

        .dna-a { background-color: var(--dna-a); }
        .dna-t { background-color: var(--dna-t); }
        .dna-g { background-color: var(--dna-g); }
        .dna-c { background-color: var(--dna-c); }

        .rna-a { background-color: var(--dna-a); }
        .rna-u { background-color: var(--rna-u); }
        .rna-g { background-color: var(--dna-g); }
        .rna-c { background-color: var(--dna-c); }

        .amino-acid {
            padding: 12px 20px;
            border-radius: 10px;
            background: var(--secondary);
            color: white;
            font-weight: bold;
            text-align: center;
            min-width: 100px;
            box-shadow: 0 3px 8px rgba(0, 0, 0, 0.1);
            transition: all 0.3s;
        }

        .amino-acid.highlight {
            transform: scale(1.1);
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
        }

        .process-info {
            margin-top: 20px;
            padding: 20px;
            background: #e8f4fc;
            border-radius: 12px;
            border-left: 5px solid var(--primary);
        }

        .animation-container {
            position: relative;
            height: 120px;
            margin: 30px 0;
            border: 2px dashed var(--light-gray);
            border-radius: 12px;
            overflow: hidden;
            background: var(--light);
        }

        #ribosome {
            position: absolute;
            width: 70px;
            height: 50px;
            background: var(--primary);
            border-radius: 10px;
            top: 50%;
            transform: translateY(-50%);
            left: 0;
            transition: left 2s linear;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-weight: bold;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
            z-index: 10;
        }

        #rna-strand-animation {
            position: absolute;
            top: 50%;
            transform: translateY(-50%);
            left: 0;
            right: 0;
            height: 25px;
            background: repeating-linear-gradient(
                90deg,
                transparent,
                transparent 49px,
                var(--gray) 49px,
                var(--gray) 51px
            );
        }

        .controls {
            display: flex;
            gap: 15px;
            margin-top: 25px;
        }

        .legend {
            display: flex;
            gap: 20px;
            flex-wrap: wrap;
            margin-top: 20px;
        }

        .legend-item {
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .legend-color {
            width: 25px;
            height: 25px;
            border-radius: 5px;
            box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
        }

        .hidden {
            display: none;
        }

        .highlight {
            animation: highlight 1s ease;
            box-shadow: 0 0 15px rgba(67, 97, 238, 0.7);
        }

        @keyframes highlight {
            0% { transform: scale(1); }
            50% { transform: scale(1.15); }
            100% { transform: scale(1); }
        }

        .fade-in {
            animation: fadeIn 0.8s ease;
        }

        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        .progress-bar {
            height: 8px;
            background: var(--light-gray);
            border-radius: 4px;
            margin: 20px 0;
            overflow: hidden;
        }

        .progress {
            height: 100%;
            background: linear-gradient(90deg, var(--primary), var(--accent));
            border-radius: 4px;
            width: 0%;
            transition: width 0.5s;
        }

/* === BACK BUTTON === */
.back-btn {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background: linear-gradient(135deg, #2b3a55, #4a6fa5);
  border: none;
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.2s, box-shadow 0.3s;
  z-index: 9999;
}

.back-btn:hover {
  transform: translateY(-5px) scale(1.05);
  box-shadow: 0 12px 35px rgba(0, 0, 0, 0.3);
}

.back-btn:active {
  transform: scale(0.95);
}

.back-btn svg {
  width: 28px;
  height: 28px;
  fill: #fff;
}        

        @media (max-width: 768px) {
            .input-group {
                flex-direction: column;
            }
            
            .process-flow {
                flex-direction: column;
            }
            
            .arrow {
                transform: rotate(90deg);
            }
            
            .strand {
                justify-content: flex-start;
            }
        }