/*******************************************************************************
MCQ CARD STYLES
多选一题卡片样式（现代简约，兼容 Tufte 风格）
*******************************************************************************/

:root {
    --mcq-bg: #ffffff;
    --mcq-border: #d9d9d4;
    --mcq-shadow: 0 2px 10px rgba(20, 20, 20, 0.06);
    --mcq-shadow-hover: 0 8px 20px rgba(20, 20, 20, 0.1);
    --mcq-text: #1f1f1f;
    --mcq-muted: #666;
    --mcq-option-bg: #fbfbf8;
    --mcq-option-border: #dfdfd8;
    --mcq-option-hover-bg: #f2f2ec;
    --mcq-option-hover-border: #c6c6bc;
    --mcq-focus-ring: rgba(62, 113, 169, 0.28);
    --mcq-correct-bg: #ebf6ee;
    --mcq-correct-border: #7ebc8a;
    --mcq-correct-text: #1f6b37;
    --mcq-wrong-bg: #fff0f0;
    --mcq-wrong-border: #d99898;
    --mcq-wrong-text: #9c2f2f;
    --mcq-feedback-bg: #f8f8f3;
}

html[data-theme="dark"] {
    --mcq-bg: #222;
    --mcq-border: #3f3f3f;
    --mcq-shadow: 0 2px 12px rgba(0, 0, 0, 0.28);
    --mcq-shadow-hover: 0 8px 24px rgba(0, 0, 0, 0.36);
    --mcq-text: #e7e7e7;
    --mcq-muted: #b6b6b6;
    --mcq-option-bg: #2a2a2a;
    --mcq-option-border: #474747;
    --mcq-option-hover-bg: #333;
    --mcq-option-hover-border: #5a5a5a;
    --mcq-focus-ring: rgba(113, 173, 233, 0.35);
    --mcq-correct-bg: #1f3426;
    --mcq-correct-border: #4e8c5b;
    --mcq-correct-text: #93d6a2;
    --mcq-wrong-bg: #3a2626;
    --mcq-wrong-border: #915a5a;
    --mcq-wrong-text: #f0b3b3;
    --mcq-feedback-bg: #272727;
}

.mcq-card {
    width: 55%;
    max-width: 55%;
    margin: 1.5em 0;
    border: 1px solid var(--mcq-border);
    border-radius: 10px;
    background: var(--mcq-bg);
    box-shadow: var(--mcq-shadow);
    overflow: hidden;
    transition: box-shadow 240ms ease, transform 240ms ease;
}

.mcq-card:hover {
    box-shadow: var(--mcq-shadow-hover);
    transform: translateY(-1px);
}

.mcq-card__question {
    padding: 16px 18px 12px;
    font-weight: 600;
    color: var(--mcq-text);
}

.mcq-card__options {
    counter-reset: mcq-option;
    display: grid;
    gap: 10px;
    padding: 0 14px 14px;
}

.mcq-card__option {
    counter-increment: mcq-option;
    width: 100%;
    border: 1px solid var(--mcq-option-border);
    background: var(--mcq-option-bg);
    color: var(--mcq-text);
    border-radius: 8px;
    text-align: left;
    padding: 10px 14px 10px 46px;
    font: inherit;
    line-height: 1.5;
    cursor: pointer;
    position: relative;
    transition:
        background-color 220ms ease,
        border-color 220ms ease,
        transform 220ms ease,
        box-shadow 220ms ease,
        opacity 220ms ease;
}

.mcq-card__option::before {
    content: counter(mcq-option, upper-alpha);
    position: absolute;
    top: 50%;
    left: 12px;
    transform: translateY(-50%);
    width: 22px;
    height: 22px;
    border-radius: 999px;
    border: 1px solid var(--mcq-option-border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.76em;
    font-weight: 700;
    letter-spacing: 0.02em;
    color: var(--mcq-muted);
    background: transparent;
    transition: all 220ms ease;
}

.mcq-card__option:hover {
    background: var(--mcq-option-hover-bg);
    border-color: var(--mcq-option-hover-border);
    transform: translateX(2px);
}

.mcq-card__option:focus-visible {
    outline: none;
    box-shadow: 0 0 0 3px var(--mcq-focus-ring);
}

.mcq-card.is-answered .mcq-card__option {
    pointer-events: none;
}

.mcq-card.is-answered .mcq-card__option:not(.is-selected):not(.is-correct) {
    opacity: 0.72;
}

.mcq-card__option.is-selected {
    transform: scale(0.995);
}

.mcq-card__option.is-correct {
    border-color: var(--mcq-correct-border);
    background: var(--mcq-correct-bg);
    color: var(--mcq-correct-text);
}

.mcq-card__option.is-correct::before {
    content: "✓";
    border-color: var(--mcq-correct-border);
    background: var(--mcq-correct-bg);
    color: var(--mcq-correct-text);
}

.mcq-card__option.is-wrong {
    border-color: var(--mcq-wrong-border);
    background: var(--mcq-wrong-bg);
    color: var(--mcq-wrong-text);
}

.mcq-card__option.is-wrong::before {
    content: "✕";
    border-color: var(--mcq-wrong-border);
    color: var(--mcq-wrong-text);
}

.mcq-card__feedback {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transform: translateY(-8px);
    padding: 0 18px;
    border-top: 1px solid transparent;
    background: var(--mcq-feedback-bg);
    transition:
        max-height 420ms cubic-bezier(0.22, 1, 0.36, 1),
        opacity 300ms ease,
        transform 300ms ease,
        padding 300ms ease,
        border-color 300ms ease;
}

.mcq-card.is-answered .mcq-card__feedback {
    opacity: 1;
    transform: translateY(0);
    padding: 14px 18px 16px;
    border-top-color: var(--mcq-border);
}

.mcq-card__result {
    font-weight: 700;
    margin-bottom: 8px;
}

.mcq-card.is-correct .mcq-card__result {
    color: var(--mcq-correct-text);
}

.mcq-card.is-correct .mcq-card__result::before {
    content: "✓ ";
}

.mcq-card.is-incorrect .mcq-card__result {
    color: var(--mcq-wrong-text);
}

.mcq-card.is-incorrect .mcq-card__result::before {
    content: "✕ ";
}

.mcq-card__answer {
    display: flex;
    flex-wrap: wrap;
    gap: 8px 12px;
    margin-bottom: 6px;
    line-height: 1.5;
}

.mcq-card__answer-label {
    color: var(--mcq-muted);
}

.mcq-card__answer-value {
    font-weight: 600;
}

.mcq-card__your-answer {
    color: var(--mcq-muted);
    font-size: 0.94em;
}

.mcq-card__explanation {
    margin-top: 4px;
    color: var(--mcq-text);
    line-height: 1.65;
}

.mcq-card__explanation.is-empty {
    display: none;
}

.mcq-card__retry {
    margin-top: 12px;
    border: 1px solid var(--mcq-option-border);
    background: var(--mcq-option-bg);
    color: var(--mcq-text);
    border-radius: 7px;
    padding: 6px 12px;
    font: inherit;
    font-size: 0.94em;
    cursor: pointer;
    opacity: 0;
    transform: translateY(4px);
    pointer-events: none;
    transition:
        opacity 220ms ease,
        transform 220ms ease,
        background-color 220ms ease,
        border-color 220ms ease;
}

.mcq-card__retry:hover {
    background: var(--mcq-option-hover-bg);
    border-color: var(--mcq-option-hover-border);
}

.mcq-card__retry:focus-visible {
    outline: none;
    box-shadow: 0 0 0 3px var(--mcq-focus-ring);
}

.mcq-card.is-answered .mcq-card__retry {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

@media (max-width: 760px) {
    .mcq-card {
        width: 100%;
        max-width: 100%;
        margin-left: 0;
        margin-right: 0;
        border-left: 1px solid var(--mcq-border);
        border-right: 1px solid var(--mcq-border);
        border-radius: 10px;
        box-sizing: border-box;
    }

    .mcq-card__question {
        padding: 14px 12px 10px;
    }

    .mcq-card__options {
        padding: 0 12px 12px;
    }

    .mcq-card__feedback {
        padding: 0 12px;
    }

    .mcq-card.is-answered .mcq-card__feedback {
        padding: 12px;
    }
}

@media (prefers-reduced-motion: reduce) {
    .mcq-card,
    .mcq-card__option,
    .mcq-card__feedback {
        transition: none !important;
        animation: none !important;
    }
}