:root {
    --primary-color: #ff9f1c;
    /* オレンジ */
    --secondary-color: #2ec4b6;
    /* ミントグリーン */
    --accent-color: #ffbf69;
    /* やさしい黄色 */
    --bg-color: #cbf3f0;
    /* うすい水色 */
    --text-color: #333;
    --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: 1.5;
    background-image:
        radial-gradient(#fff 20%, transparent 20%),
        radial-gradient(#fff 20%, transparent 20%);
    background-position: 0 0, 25px 25px;
    background-size: 50px 50px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 600px;
    margin: 20px auto;
    padding: 15px;
    width: 100%;
    flex: 1;
}

.screen {
    display: none;
    background: var(--card-bg);
    padding: 30px 20px;
    border-radius: 30px;
    box-shadow: 0 10px 0 rgba(0, 0, 0, 0.1);
    text-align: center;
    border: 8px solid #fff;
}

.screen.active {
    display: block;
    animation: bounceIn 0.6s;
}

@keyframes bounceIn {
    0% {
        transform: scale(0.3);
        opacity: 0;
    }

    50% {
        transform: scale(1.05);
    }

    70% {
        transform: scale(0.9);
    }

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

h1 {
    color: var(--primary-color);
    font-size: 2.5rem;
    margin-bottom: 20px;
    text-shadow: 2px 2px 0 #fff;
    line-height: 1.3;
}

.icon {
    font-size: 6rem;
    margin: 20px 0;
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0% {
        transform: translateY(0px);
    }

    50% {
        transform: translateY(-15px);
    }

    100% {
        transform: translateY(0px);
    }
}

.btn {
    display: block;
    width: 100%;
    padding: 25px;
    font-size: 2rem;
    font-weight: bold;
    color: white;
    background-color: var(--primary-color);
    border: none;
    border-radius: 50px;
    cursor: pointer;
    box-shadow: 0 8px 0 #e88d0c;
    margin: 20px 0;
    transition: transform 0.1s;
    text-decoration: none;
}

.btn:active {
    transform: translateY(4px);
    box-shadow: 0 4px 0 #e88d0c;
}

.question-box {
    background: #fff;
    padding: 20px;
    border-radius: 20px;
    margin-bottom: 20px;
}

.question-text {
    font-size: 2.5rem;
    font-weight: bold;
    color: var(--text-color);
}

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

.choice-btn {
    padding: 20px;
    font-size: 2rem;
    background: #fff;
    border: 4px solid var(--secondary-color);
    border-radius: 20px;
    cursor: pointer;
    color: var(--text-color);
    font-weight: bold;
    transition: all 0.2s;
}

.choice-btn:active {
    background-color: var(--secondary-color);
    color: #fff;
}

.choice-btn.correct {
    background-color: #ff9f1c;
    border-color: #ff9f1c;
    color: white;
    animation: pulse 0.5s;
}

.choice-btn.incorrect {
    background-color: #ccc;
    border-color: #999;
    color: #666;
}

.feedback-area {
    margin-top: 20px;
    padding: 20px;
    border-radius: 20px;
    background: #fffbe6;
    border: 4px solid var(--accent-color);
}

.big-mark {
    font-size: 8rem;
    display: block;
    margin: 10px 0;
}

.back-link {
    display: inline-block;
    margin-top: 30px;
    color: #888;
    text-decoration: none;
    font-size: 1.2rem;
    padding: 10px 20px;
    background: #f0f0f0;
    border-radius: 30px;
}

footer {
    text-align: center;
    padding: 20px;
    color: #666;
    font-size: 0.9rem;
}