:root {
    --primary-color: #0984e3;
    /* インテリジェントブルー */
    --secondary-color: #6c5ce7;
    /* 未来的なパープル */
    --accent-color: #00cec9;
    /* 爽やかなシアン */
    --bg-color: #dfe6e9;
    /* クールなグレー */
    --text-color: #2d3436;
    --card-bg: #ffffff;
}

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

body {
    font-family: 'Zen Maru Gothic', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    background-image:
        linear-gradient(rgba(255, 255, 255, 0.5) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.5) 1px, transparent 1px);
    background-size: 40px 40px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 800px;
    margin: 40px auto;
    padding: 20px;
    width: 100%;
}

.screen {
    display: none;
    background: var(--card-bg);
    padding: 50px;
    border-radius: 12px;
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.1);
    text-align: center;
    border-top: 6px solid var(--primary-color);
    position: relative;
}

.screen.active {
    display: block;
    animation: fadeIn 0.5s ease-out;
}

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

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

h1 {
    color: var(--secondary-color);
    font-size: 2.5rem;
    margin-bottom: 25px;
    letter-spacing: 2px;
    border-bottom: 2px solid #eee;
    padding-bottom: 15px;
}

.icon {
    font-size: 4rem;
    margin: 20px 0;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.btn {
    display: inline-block;
    padding: 16px 45px;
    font-size: 1.2rem;
    font-weight: bold;
    color: white;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
    margin: 15px;
    box-shadow: 0 4px 15px rgba(108, 92, 231, 0.3);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(108, 92, 231, 0.4);
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 30px;
    font-size: 1.2rem;
    color: #636e72;
    border-bottom: 1px solid #eee;
    padding-bottom: 10px;
}

.question-box {
    background: #f1f2f6;
    padding: 35px;
    border-radius: 8px;
    margin-bottom: 30px;
    font-size: 1.5rem;
    color: var(--text-color);
    border-left: 5px solid var(--primary-color);
    text-align: left;
}

.choices-container {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.choice-btn {
    padding: 20px;
    font-size: 1.2rem;
    background: white;
    border: 2px solid #dfe6e9;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    text-align: left;
    padding-left: 30px;
    position: relative;
    color: var(--text-color);
}

.choice-btn:hover {
    border-color: var(--primary-color);
    background: #f4faff;
}

.choice-btn::before {
    content: '';
    position: absolute;
    left: 10px;
    top: 50%;
    transform: translateY(-50%);
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: #dfe6e9;
    transition: 0.2s;
}

.choice-btn:hover::before {
    background: var(--primary-color);
}

.choice-btn.correct {
    background-color: #dff9fb;
    border-color: #00cec9;
    color: #006266;
}

.choice-btn.incorrect {
    background-color: #ffeaa7;
    border-color: #ffeaa7;
    color: #d35400;
}

.feedback-area {
    margin-top: 30px;
    padding: 25px;
    border-radius: 8px;
    background: white;
    border: 2px solid var(--primary-color);
}

.progress-bar-container {
    width: 100%;
    height: 8px;
    background: #e0e0e0;
    margin-bottom: 0;
    position: fixed;
    top: 0;
    left: 0;
    z-index: 100;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    width: 0%;
    transition: width 0.4s;
}

.back-link {
    display: block;
    margin-top: 25px;
    color: #636e72;
    text-decoration: none;
    font-size: 0.9rem;
}

footer {
    text-align: center;
    padding: 30px;
    color: #b2bec3;
    font-size: 0.9rem;
}