@keyframes sparkRise {
    0% { transform: translate(0, 0) scale(.4); opacity: 0; }
    12% { opacity: 1; }
    100% { transform: translate(var(--spark-dx), var(--spark-dy)) scale(.15); opacity: 0; }
}

.quiz-page {
    height: 100vh;
    height: 100dvh;
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 14px;
    box-sizing: border-box;
    overflow: hidden;
    overscroll-behavior: none;
}

.quiz-shell {
    width: 100%;
    height: 100%;
    min-height: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.quiz-topbar {
    flex: none;
    width: 100%;
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 0 4px;
}

.quiz-topbar__progress {
    flex: 1;
    display: flex;
    align-items: center;
    gap: 12px;
    min-width: 0;
}

.quiz-topbar__counter {
    flex: none;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 15px;
    color: var(--color-text-strong);
    white-space: nowrap;
}

.quiz-topbar__counter-total {
    color: var(--color-text-subtle);
    font-weight: 500;
}

.quiz-progress-track {
    flex: 1;
    min-width: 0;
}

.quiz-progress-fill {
    transition: width .35s ease;
}

.quiz-pill {
    flex: none;
    gap: 6px;
    padding: 5px 11px;
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 12px;
    color: var(--color-text-strong);
    white-space: nowrap;
}

.quiz-pill__icon {
    flex: none;
    color: var(--color-accent);
}

.quiz-card-stack {
    width: 100%;
    flex: 1;
    min-height: 0;
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    grid-template-rows: minmax(0, 1fr);
}

.quiz-card-placeholder {
    grid-area: 1 / 1;
    border-radius: 30px;
    box-shadow: 0 10px 24px -18px rgba(0, 0, 0, .15);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    padding: 20px 22px;
    gap: 16px;
}

.quiz-skeleton-timer {
    flex: none;
    height: 6px;
    border-radius: 4px;
}

.quiz-skeleton-head {
    flex: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.quiz-skeleton-bar {
    height: 14px;
    border-radius: 7px;
}

.quiz-skeleton-bar--category {
    width: 35%;
    height: 10px;
}

.quiz-skeleton-bar--question {
    width: 92%;
    height: 18px;
}

.quiz-skeleton-bar--short {
    width: 58%;
}

.quiz-skeleton-options {
    flex: none;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.quiz-skeleton-option {
    height: 48px;
    border-radius: 14px;
}

.quiz-skeleton-timer,
.quiz-skeleton-bar,
.quiz-skeleton-option {
    background: linear-gradient(90deg, var(--color-border) 25%, var(--color-surface-2) 37%, var(--color-border) 63%);
    background-size: 400% 100%;
    animation: skeletonShimmer 1.6s ease-in-out infinite;
}

.quiz-card {
    grid-area: 1 / 1;
    width: 100%;
    border-radius: 30px;
    box-shadow: 0 20px 50px -20px rgba(0, 0, 0, .25);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    position: relative;
    touch-action: pan-y;
    will-change: transform, opacity;
    box-sizing: border-box;
}

.quiz-card--dragging {
    cursor: grabbing;
    animation: none;
}

.quiz-card--enter {
    animation: popIn .3s ease both;
}

/* Scrolls independently so long questions/explanations never push the footer
   buttons out of view or let content scroll on top of them. */
.quiz-card__scroll {
    flex: 1;
    min-height: 0;
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    overflow-x: hidden;
    -webkit-overflow-scrolling: touch;
    overscroll-behavior: contain;
    touch-action: pan-y;
}

.quiz-timer-track {
    position: sticky;
    top: 0;
    z-index: 2;
    width: 100%;
    height: 6px;
    background: var(--color-border);
    border-radius: 4px;
    overflow: hidden;
    flex: none;
}

.quiz-timer-fill {
    height: 100%;
    width: 100%;
    background: var(--color-accent);
    transition: width .1s linear, background .3s;
}

.quiz-timer-fill--urgent {
    background: var(--color-wrong-border);
}

.quiz-card__head {
    flex: none;
    padding: 18px 22px 4px;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.quiz-card__category {
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 11px;
    letter-spacing: .12em;
    text-transform: uppercase;
    color: var(--color-accent);
}

.quiz-card__question {
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: clamp(19px, 5.5vw, 23px);
    line-height: 1.25;
    color: var(--color-text-strong);
}

.quiz-card__options {
    flex: none;
    padding: 8px 20px 0;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: 10px;
    width: 100%;
    min-height: 48px;
    text-align: left;
    padding: 11px 16px;
    border-radius: 16px;
    border: 1.5px solid var(--color-border);
    background: var(--color-surface-2);
    color: var(--color-text-strong);
    font-family: var(--font-body);
    font-weight: 500;
    font-size: 14.5px;
    line-height: 1.3;
    cursor: pointer;
    transition: background-color .2s, border-color .2s, color .2s;
    box-sizing: border-box;
}

@media (hover: hover) and (pointer: fine) {
    .quiz-option:not([aria-disabled="true"]):hover {
        border-color: var(--color-accent);
    }
}

.quiz-option__text {
    flex: 1;
}

.quiz-option[aria-disabled="true"] {
    cursor: default;
}

.quiz-option--correct {
    background: var(--color-correct-bg);
    border-color: var(--color-correct-border);
    color: var(--color-correct-text);
    font-weight: 600;
}

.quiz-option--wrong {
    background: var(--color-wrong-bg);
    border-color: var(--color-wrong-border);
    color: var(--color-wrong-text);
    font-weight: 600;
    animation: shakeX .45s ease;
}

.quiz-option--dim {
    background: transparent;
    border-color: var(--color-border);
    color: var(--color-text-subtle);
}

.quiz-option__icon {
    flex: none;
}

.quiz-option__icon--correct {
    color: var(--color-correct-text);
}

.quiz-option__icon--wrong {
    color: var(--color-wrong-text);
}

.quiz-fact {
    flex: none;
    margin: 12px 20px 16px;
    padding: 14px 16px;
    border-radius: 20px;
    background: var(--color-explain-bg);
    border: 1px solid var(--color-explain-border);
    display: none;
    flex-direction: column;
    gap: 8px;
    box-sizing: border-box;
    scroll-margin: 16px;
}

.quiz-fact--visible {
    display: flex;
    animation: popIn .35s ease both;
}

.quiz-fact__head {
    display: flex;
    align-items: center;
    gap: 10px;
}

.quiz-fact__icon {
    flex: none;
}

.quiz-fact__label {
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 16px;
    color: var(--color-explain-text);
}

.quiz-fact__body {
    margin: 0;
    font-size: 14px;
    line-height: 1.5;
    color: var(--color-text-strong);
}

.quiz-footer {
    flex: none;
    display: none;
    align-items: center;
    gap: 10px;
    margin: 4px 20px 18px;
}

.quiz-footer--visible {
    display: flex;
}

.quiz-back {
    flex: none;
    width: 48px;
    height: 48px;
    border-radius: 15px;
    border: 1.5px solid var(--color-border);
    background: var(--color-surface-2);
    color: var(--color-text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-sizing: border-box;
    transition: border-color .15s ease;
}

.quiz-back:hover {
    border-color: var(--color-accent);
}

.quiz-next {
    flex: 1;
    min-width: 0;
    height: 48px;
    border-radius: 15px;
    box-shadow: 0 6px 14px -6px color-mix(in oklab, var(--color-accent) 25%, transparent);
    gap: 10px;
}

.quiz-next span:first-child {
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 16px;
    color: var(--color-on-accent);
}

.quiz-next__chevron {
    animation: chevronSway 1.4s ease-in-out infinite;
    color: var(--color-on-accent);
}

.quiz-sparks {
    position: absolute;
    inset: 0;
    overflow: hidden;
    pointer-events: none;
}

.quiz-sparks__dot {
    position: absolute;
    border-radius: 50%;
    background: var(--color-accent);
    box-shadow: 0 0 8px 1px var(--color-halo);
    animation: sparkRise both ease-out;
}

@media (min-width: 481px) {
    .quiz-card-placeholder,
    .quiz-card {
        max-height: 640px;
    }
}

@media (min-width: 1024px) {
    .quiz-page {
        height: calc(100vh - var(--nav-bar-height));
        height: calc(100dvh - var(--nav-bar-height));
        padding: 32px;
    }

    .quiz-shell {
        max-width: 800px;
        gap: 26px;
    }

    .quiz-card-placeholder,
    .quiz-card {
        max-height: 720px;
    }

    .quiz-card__head {
        padding: 28px 32px 6px;
        gap: 10px;
    }

    .quiz-card__question {
        font-size: clamp(23px, 2.4vw, 30px);
    }

    .quiz-card__options,
    .quiz-skeleton-options {
        gap: 12px;
    }

    .quiz-card__options {
        padding: 14px 30px 0;
    }

    .quiz-option {
        min-height: 60px;
        padding: 16px 22px;
        font-size: 16px;
    }

    .quiz-skeleton-option {
        height: 60px;
    }

    .quiz-fact {
        margin: 14px 30px 20px;
    }

    .quiz-footer {
        margin: 6px 30px 24px;
    }

    .quiz-back,
    .quiz-next {
        height: 54px;
    }
}