* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Hiragino Kaku Gothic Pro', 'Meiryo', sans-serif;
}

body {
    background-color: #f5f5f5;
    color: #333;
    line-height: 1.6;
    background-image: url('/bicycles.png');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    position: relative;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    position: relative;
    z-index: 1;
}

header {
    text-align: center;
    margin-bottom: 30px;
    padding: 20px;
    background-color: #3498db;
    color: white;
    border-radius: 8px;
}

h1 {
    margin-bottom: 10px;
}

.quiz-container {
    background-color: white;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    margin-bottom: 20px;
    position: relative;
    z-index: 1;
}

#question {
    font-size: 1.4rem;
    margin-bottom: 20px;
    color: #2c3e50;
}

#options-container {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 20px;
}

.option {
    padding: 15px;
    background-color: #f1f1f1;
    border: 2px solid #ddd;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
}

.option:hover {
    background-color: #e8e8e8;
}

.option.correct {
    background-color: #d4edda;
    border-color: #c3e6cb;
    color: #155724;
}

.option.incorrect {
    background-color: #f8d7da;
    border-color: #f5c6cb;
    color: #721c24;
}

.option.selected {
    border-color: #3498db;
}

.option.hallucination {
    background-color: #e2e3e5;
    border-color: #d6d8db;
    color: #383d41;
}

.warning {
    font-size: 0.9rem;
    padding: 10px;
    margin-top: 15px;
    background-color: #fff3cd;
    color: #856404;
    border: 1px solid #ffeeba;
    border-radius: 4px;
    text-align: center;
}

#controls {
    display: flex;
    justify-content: center;
    margin-top: 20px;
}

button {
    padding: 12px 24px;
    background-color: #3498db;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #2980b9;
}

#next-btn {
    display: none;
}

.alert {
    padding: 12px;
    border-radius: 4px;
    margin-top: 10px;
}

.alert-warning {
    background-color: #fff3cd;
    color: #856404;
    border: 1px solid #ffeeba;
}

#result-container {
    text-align: center;
}

#score-display {
    font-size: 1.2rem;
    margin-bottom: 15px;
}

#feedback {
    margin-bottom: 20px;
}

.hidden {
    display: none;
}

footer {
    text-align: center;
    font-size: 0.8rem;
    color: #666;
    margin-top: 20px;
}

.reference-button {
    display: block;
    margin: 10px auto 20px;
    padding: 12px 25px;
    background-color: #2ecc71;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.3s;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}

.reference-button:hover {
    background-color: #27ae60;
    transform: scale(1.03);
}

.modal {
    display: none;
    position: fixed;
    z-index: 100;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0, 0, 0, 0.7);
}

.modal-content {
    background-color: #fefefe;
    margin: 10% auto;
    padding: 20px;
    border: 1px solid #888;
    width: 80%;
    max-width: 600px;
    border-radius: 8px;
}

.close {
    color: #aaa;
    float: right;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
}

.close:hover,
.close:focus {
    color: black;
    text-decoration: none;
}

.reference-links {
    list-style-type: none;
    padding: 0;
}

.reference-links li {
    margin-bottom: 15px;
}
.reference-links a {
    color: #3498db;
    text-decoration: none;
    font-size: 1.1rem;
    transition: color 0.3s;
}

.reference-links a:hover {
    color: #2980b9;
    text-decoration: underline;
}