:root {
    --primary-color: #3a86ff;
    /* ブルー */
    --secondary-color: #fb5607;
    /* オレンジ */
    --accent-color: #ffbe0b;
    /* イエロー */
    --bg-color: #f8f9fa;
    --text-color: #212529;
    --card-bg: #ffffff;
    --btn-hover: #4361ee;
}

* {
    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;
    overflow-x: hidden;
    background-image:
        linear-gradient(135deg, rgba(58, 134, 255, 0.05) 0%, transparent 100%),
        radial-gradient(circle at 80% 20%, rgba(251, 86, 7, 0.05) 0%, transparent 20%);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 900px;
    margin: 40px auto;
    padding: 20px;
    width: 100%;
    flex-grow: 1;
}

.screen {
    display: none;
    background: var(--card-bg);
    padding: 50px;
    border-radius: 20px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
    text-align: center;
    animation: slideIn 0.5s ease-out;
    border-top: 8px solid var(--primary-color);
}

.screen.active {
    display: block;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(30px);
    }

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

h1 {
    color: var(--primary-color);
    font-size: 2.8rem;
    margin-bottom: 20px;
}

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

.btn {
    display: inline-block;
    padding: 15px 45px;
    font-size: 1.2rem;
    font-weight: bold;
    color: white;
    background-color: var(--primary-color);
    border: none;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s;
    box-shadow: 0 4px 6px rgba(58, 134, 255, 0.2);
    margin: 10px;
}

.btn:hover {
    background-color: var(--btn-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(58, 134, 255, 0.3);
}

.btn.next {
    background-color: var(--secondary-color);
    box-shadow: 0 4px 6px rgba(251, 86, 7, 0.2);
}

.btn.next:hover {
    background-color: #e34c06;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 30px;
    font-size: 1.1rem;
    border-bottom: 2px solid #f0f0f0;
    padding-bottom: 10px;
}

.question-box {
    background: #fdfdfd;
    padding: 40px;
    border-radius: 15px;
    margin-bottom: 30px;
    border: 2px solid #eee;
    font-size: 1.5rem;
}

.choices-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}

.choice-btn {
    padding: 25px;
    font-size: 1.3rem;
    font-weight: bold;
    background: white;
    border: 2px solid #ddd;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.2s;
}

.choice-btn:hover {
    border-color: var(--primary-color);
    background: #f0f7ff;
}

.choice-btn.correct {
    background-color: #e7f3ef;
    border-color: #2ecc71;
    color: #27ae60;
}

.choice-btn.incorrect {
    background-color: #fdeaea;
    border-color: #e74c3c;
    color: #c0392b;
}

.feedback-area {
    margin-top: 30px;
    padding: 25px;
    border-radius: 12px;
    background: #fff8e1;
    text-align: left;
}

.explanation-box {
    margin: 15px 0;
}

.hidden {
    display: none;
}

.progress-bar-container {
    width: 100%;
    height: 12px;
    background: #e9ecef;
    border-radius: 6px;
    margin-bottom: 30px;
    overflow: hidden;
}

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

footer {
    text-align: center;
    padding: 30px;
    color: #adb5bd;
}

.result-stamp {
    font-size: 6rem;
    margin: 30px 0;
    display: block;
}