:root {
    color-scheme: light;
    --app-bg: #f5f5f5;
    --card-bg: #ffffffcc;
    --primary: #2b6cb0;
    --primary-dark: #1b4f82;
    --accent: #f6ad55;
    --text-main: #1a202c;
    --correct: #38a169;
    --incorrect: #e53e3e;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: "Hiragino Sans", "Noto Sans JP", "Segoe UI", sans-serif;
    background: var(--app-bg);
    color: var(--text-main);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left);
}

main.app {
    width: min(960px, 100%);
    padding: 24px;
}

.screen {
    display: none;
}

.screen.screen--active {
    display: block;
}

.screen__inner {
    background: var(--card-bg);
    border-radius: 18px;
    padding: 28px 24px 36px;
    box-shadow: 0 18px 50px rgba(27, 45, 94, 0.18);
}

.app__title {
    font-size: clamp(28px, 5vw, 42px);
    margin: 0 0 12px;
    text-align: center;
}

.app__intro {
    text-align: center;
    margin: 0 0 32px;
    font-size: 18px;
}

.btn {
    border: none;
    cursor: pointer;
    border-radius: 12px;
    font-size: 18px;
    padding: 16px 24px;
    transition: transform 0.15s ease, background 0.15s ease;
    width: min(280px, 90%);
    margin: 0 auto;
    display: block;
}

.btn:focus-visible {
    outline: 3px solid var(--accent);
    outline-offset: 3px;
}

.btn--primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff;
}

.btn--primary:active {
    transform: scale(0.97);
}

.btn--secondary {
    background: #fff;
    border: 2px solid var(--primary);
    color: var(--primary);
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    margin-bottom: 20px;
    font-size: 18px;
}

.quiz-card__question {
    margin: 0 0 24px;
    font-size: clamp(22px, 4vw, 28px);
    text-align: center;
    line-height: 1.5;
}

.quiz-card__choices {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
}

.choice-card {
    border: 3px solid transparent;
    border-radius: 16px;
    overflow: hidden;
    background: #fff;
    display: flex;
    flex-direction: column;
    cursor: pointer;
    transition: transform 0.18s ease, border-color 0.18s ease, box-shadow 0.18s ease;
    min-height: 260px;
}

.choice-card:focus-visible {
    outline: none;
    border-color: var(--accent);
}

.choice-card__image {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.choice-card__label {
    font-size: 22px;
    text-align: center;
    padding: 16px 12px;
}

.choice-card.is-correct {
    border-color: var(--correct);
    box-shadow: 0 0 0 4px rgba(56, 161, 105, 0.2);
}

.choice-card.is-incorrect {
    border-color: var(--incorrect);
    box-shadow: 0 0 0 4px rgba(229, 62, 62, 0.18);
}

.feedback-card {
    display: flex;
    flex-direction: column;
    gap: 16px;
    align-items: center;
    text-align: center;
    padding: 8px 12px 0;
}

.feedback-card__title {
    font-size: clamp(26px, 5vw, 34px);
    margin: 8px 0 4px;
}

.feedback-card__selection,
.feedback-card__answer {
    font-size: 20px;
    margin: 0;
}

.feedback-card__selection {
    color: #4a5568;
}

.feedback-card__answer {
    font-weight: 600;
}

.feedback-card__explanation {
    margin: 0;
    font-size: 18px;
    line-height: 1.6;
    color: #2d3748;
    max-width: 640px;
}

.feedback-card__media {
    margin: 12px 0;
    max-width: min(520px, 90%);
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.feedback-card__media img {
    width: 100%;
    height: clamp(180px, 28vh, 280px);
    object-fit: cover;
    border-radius: 16px;
    box-shadow: 0 10px 28px rgba(26, 32, 44, 0.22);
    border: 3px solid rgba(255, 255, 255, 0.85);
    background: #f8fafc;
}

.feedback-card__media figcaption {
    font-size: 16px;
    color: #4a5568;
    text-align: center;
    line-height: 1.4;
}

.feedback-card--correct .feedback-card__title {
    color: var(--correct);
}

.feedback-card--incorrect .feedback-card__title {
    color: var(--incorrect);
}

.feedback-card__reaction {
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    font-size: 20px;
    font-weight: 600;
    color: #2c5282;
    margin: 8px 0;
    text-align: center;
}

.feedback-card__reaction span {
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.feedback-card__reaction--encourage {
    color: #dd6b20;
    animation: reaction-bounce 800ms ease;
}

.feedback-card__burst {
    position: relative;
    width: 100%;
    display: flex;
    justify-content: center;
}

@keyframes reaction-bounce {
    0%,
    100% {
        transform: translateY(0);
    }
    30% {
        transform: translateY(-10px);
    }
    60% {
        transform: translateY(4px);
    }
}

.confetti-container {
    pointer-events: none;
    position: fixed;
    overflow: visible;
    z-index: 30;
}

.confetti-piece {
    position: absolute;
    width: 12px;
    height: 18px;
    background: var(--confetti-color, #f6ad55);
    border-radius: 3px;
    opacity: 0;
    will-change: transform, opacity;
}

.result__score {
    font-size: clamp(26px, 5vw, 34px);
    text-align: center;
    margin: 24px 0 12px;
}

.result__note {
    text-align: center;
    margin: 0 0 32px;
    font-size: 18px;
}

@media (max-width: 820px) {
    main.app {
        padding: 12px;
    }

    .screen__inner {
        padding: 24px 18px 28px;
        border-radius: 14px;
    }

    .quiz-card__choices {
        grid-template-columns: 1fr;
    }

    .choice-card__image {
        height: 180px;
    }

    .btn {
        width: 100%;
    }

    .feedback-card__selection,
    .feedback-card__answer {
        font-size: 18px;
    }

    .feedback-card__explanation {
        font-size: 17px;
    }

    .feedback-card__reaction {
        font-size: 18px;
        min-height: 40px;
    }

    .feedback-card__media img {
        height: clamp(160px, 32vh, 240px);
    }

    .feedback-card__media figcaption {
        font-size: 15px;
    }
}