:root {
    --primary-color: #27ae60;
    /* 公園や大地のグリーン */
    --secondary-color: #2980b9;
    /* 空や海のブルー */
    --accent-color: #e67e22;
    /* 建物や道路のオレンジ */
    --bg-color: #eafaf1;
    --text-color: #2c3e50;
    --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(39, 174, 96, 0.1) 1px, transparent 1px),
        linear-gradient(90deg, rgba(39, 174, 96, 0.1) 1px, transparent 1px);
    background-size: 20px 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 800px;
    margin: 40px auto;
    padding: 20px;
    width: 100%;
    flex: 1;
}

.screen {
    display: none;
    background: var(--card-bg);
    padding: 50px;
    border-radius: 20px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    text-align: center;
    border-bottom: 8px solid var(--primary-color);
    position: relative;
    overflow: hidden;
}

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

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

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

h1 {
    color: var(--secondary-color);
    font-size: 2.8rem;
    margin-bottom: 25px;
}

.icon {
    font-size: 5rem;
    margin: 20px 0;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.1);
    }

    100% {
        transform: scale(1);
    }
}

.btn {
    display: inline-block;
    padding: 18px 50px;
    font-size: 1.4rem;
    font-weight: bold;
    color: white;
    background-color: var(--primary-color);
    border: none;
    border-radius: 50px;
    cursor: pointer;
    transition: all 0.3s;
    margin: 15px;
    box-shadow: 0 5px 0 #1e8449;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 7px 0 #1e8449;
    background-color: #2ecc71;
}

.btn:active {
    transform: translateY(4px);
    box-shadow: 0 2px 0 #1e8449;
}

.btn.next {
    background-color: var(--secondary-color);
    box-shadow: 0 5px 0 #1f618d;
}

.btn.next:hover {
    background-color: #3498db;
    box-shadow: 0 7px 0 #1f618d;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 30px;
    font-size: 1.3rem;
    font-weight: bold;
    color: #7f8c8d;
    background: #f7f9f9;
    padding: 10px 20px;
    border-radius: 50px;
}

.question-box {
    background: #fff8e1;
    /* うすい黄色 */
    padding: 40px;
    border-radius: 15px;
    margin-bottom: 30px;
    font-size: 1.6rem;
    border-left: 6px solid var(--accent-color);
    text-align: left;
}

.choices-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.choice-btn {
    padding: 20px;
    font-size: 1.3rem;
    background: white;
    border: 2px solid #bdc3c7;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.2s;
    font-weight: bold;
    color: var(--text-color);
}

.choice-btn:hover {
    border-color: var(--secondary-color);
    background: #ebf5fb;
}

.choice-btn.correct {
    background-color: #d5f5e3;
    border-color: #2ecc71;
    color: #186a3b;
}

.choice-btn.incorrect {
    background-color: #fadbd8;
    border-color: #e74c3c;
    color: #922b21;
}

.feedback-area {
    margin-top: 30px;
    padding: 25px;
    border-radius: 15px;
    background: #fff;
    border: 3px solid var(--secondary-color);
}

.progress-bar-container {
    width: 100%;
    height: 15px;
    background: #d5dbdb;
    border-radius: 10px;
    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;
}

.back-link {
    display: block;
    margin-top: 25px;
    color: #95a5a6;
    text-decoration: none;
    font-size: 1rem;
    transition: color 0.3s;
}

.back-link:hover {
    color: var(--primary-color);
}

footer {
    text-align: center;
    padding: 30px;
    color: #7f8c8d;
}