/* Central Dogma Study Guide - Simplified Version */
body {
    font-family: 'Roboto', Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    margin: 0;
    padding: 0;
    background-color: #f5f5f5;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    background-color: #fff;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

header {
    background-color: #2c3e50;
    color: #fff;
    padding: 20px;
    text-align: center;
}

h1, h2, h3, h4 {
    font-family: 'Montserrat', sans-serif;
    margin-top: 30px;
}

h1 {
    font-size: 2.5em;
    margin-bottom: 20px;
}

h2 {
    font-size: 2em;
    color: #2c3e50;
    border-bottom: 2px solid #3498db;
    padding-bottom: 10px;
}

h3 {
    font-size: 1.5em;
    color: #2980b9;
}

p {
    margin-bottom: 20px;
    font-size: 1.1em;
}

.nav-container {
    background-color: #34495e;
    position: sticky;
    top: 0;
    z-index: 100;
}

.main-nav {
    display: flex;
    justify-content: center;
    padding: 0;
    margin: 0;
    list-style: none;
}

.main-nav li {
    margin: 0;
    padding: 0;
}

.main-nav a {
    display: block;
    color: white;
    text-decoration: none;
    padding: 15px 20px;
    font-weight: 500;
    transition: background-color 0.3s;
}

.main-nav a:hover {
    background-color: #2c3e50;
}

.section {
    margin-bottom: 40px;
    padding: 20px;
    background-color: #fff;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.image-container {
    text-align: center;
    margin: 20px 0;
}

.image-container img {
    max-width: 100%;
    height: auto;
    border: 1px solid #ddd;
    border-radius: 4px;
    padding: 5px;
}

.caption {
    font-style: italic;
    color: #666;
    margin-top: 10px;
    font-size: 0.9em;
}

.checkpoint {
    background-color: #f8f9fa;
    border-left: 5px solid #3498db;
    padding: 15px;
    margin: 20px 0;
}

.checkpoint h3 {
    color: #3498db;
    margin-top: 0;
}

.quiz-container {
    margin: 20px 0;
}

.quiz-question {
    margin-bottom: 20px;
    background-color: #f1f8fe;
    padding: 15px;
    border-radius: 5px;
}

.quiz-options {
    list-style-type: none;
    padding: 0;
}

.quiz-options li {
    margin: 10px 0;
    padding: 10px;
    background-color: #fff;
    border: 1px solid #ddd;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s;
}

.quiz-options li:hover {
    background-color: #e3f2fd;
}

.quiz-options li.selected {
    background-color: #bbdefb;
    border-color: #64b5f6;
}

.quiz-options li.correct {
    background-color: #c8e6c9;
    border-color: #81c784;
}

.quiz-options li.incorrect {
    background-color: #ffcdd2;
    border-color: #e57373;
}

.matching-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    margin: 20px 0;
}

.matching-item {
    width: 48%;
    margin-bottom: 10px;
    padding: 10px;
    background-color: #fff;
    border: 1px solid #ddd;
    border-radius: 4px;
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    background-color: #3498db;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1em;
    transition: background-color 0.3s;
}

.btn:hover {
    background-color: #2980b9;
}

.btn-check {
    margin-top: 10px;
}

.feedback {
    margin-top: 10px;
    padding: 10px;
    border-radius: 4px;
    display: none;
}

.feedback.correct {
    background-color: #dff0d8;
    color: #3c763d;
    display: block;
}

.feedback.incorrect {
    background-color: #f2dede;
    color: #a94442;
    display: block;
}

.highlight-box {
    background-color: #e8f4f8;
    border: 1px solid #b8daff;
    padding: 15px;
    margin: 20px 0;
    border-radius: 5px;
}

.mutation-comparison {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    margin: 20px 0;
}

.mutation-column {
    width: 48%;
    padding: 15px;
    background-color: #f8f9fa;
    border-radius: 5px;
}

.normal {
    border-left: 5px solid #2ecc71;
}

.mutated {
    border-left: 5px solid #e74c3c;
}

footer {
    background-color: #2c3e50;
    color: #fff;
    text-align: center;
    padding: 20px;
    margin-top: 40px;
}

/* Responsive design */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    h1 {
        font-size: 2em;
    }
    
    h2 {
        font-size: 1.7em;
    }
    
    h3 {
        font-size: 1.3em;
    }
    
    .main-nav {
        flex-direction: column;
    }
    
    .matching-container {
        flex-direction: column;
    }
    
    .matching-item {
        width: 100%;
    }
    
    .mutation-comparison {
        flex-direction: column;
    }
    
    .mutation-column {
        width: 100%;
        margin-bottom: 15px;
    }
}