:root {
    --bg: #e9f1f5;
    --bg2: #dbe8ee;
    --surface: #082225;
    --surface-light: #103238;
    --primary: #21d6d6;
    --accent: #7f8cff;
    --success: #30d184;
    --danger: #ff6f8d;
    --text: #f4fbff;
    --muted: #99afba;
    --border: rgba(151, 194, 203, 0.26);
    --radius-lg: 24px;
    --radius-md: 16px;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100dvh;
    font-family: 'Manrope', system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
    color: var(--text);
    background: radial-gradient(circle at 12% 18%, #f4fbff 0%, var(--bg) 35%, var(--bg2) 100%);
}

.app-bg {
    position: fixed;
    inset: 0;
    pointer-events: none;
    overflow: hidden;
}

.ambient {
    position: absolute;
    border-radius: 50%;
    filter: blur(64px);
    opacity: 0.24;
}

.ambient-1 {
    width: 260px;
    height: 260px;
    top: -70px;
    left: -90px;
    background: #28dcdd;
}

.ambient-2 {
    width: 220px;
    height: 220px;
    right: -70px;
    top: 16%;
    background: #7b7dff;
}

.ambient-3 {
    width: 280px;
    height: 280px;
    left: 40%;
    bottom: -120px;
    background: #23be87;
}

.player-shell {
    min-height: 100dvh;
    padding: 20px 14px 26px;
    display: grid;
    place-items: center;
}

.panel {
    width: 100%;
    max-width: 520px;
    background: linear-gradient(165deg, var(--surface-light) 0%, var(--surface) 62%);
    border-radius: var(--radius-lg);
    border: 1px solid rgba(190, 220, 227, 0.22);
    box-shadow: 0 20px 48px rgba(5, 16, 18, 0.3);
    padding: 20px;
}

.eyebrow {
    margin: 0;
    text-transform: uppercase;
    letter-spacing: 0.14em;
    font-size: 0.72rem;
    color: #b7d4dc;
    font-weight: 700;
}

.hero-title {
    margin: 10px 0 10px;
    font-size: clamp(2.1rem, 8vw, 3.2rem);
    line-height: 0.95;
    letter-spacing: -0.02em;
}

.hero-title span {
    color: var(--primary);
}

.hero-copy {
    margin: 0 0 20px;
    color: #c7dbe2;
    font-size: 0.95rem;
}

.meta-grid,
.stats-row {
    display: grid;
    gap: 12px;
    margin-bottom: 20px;
}

.meta-grid {
    grid-template-columns: repeat(3, 1fr);
}

.stats-row {
    grid-template-columns: repeat(2, 1fr);
    margin-bottom: 0;
}

.stats-3 {
    grid-template-columns: repeat(3, 1fr);
}

.meta-grid article,
.stats-row > div {
    padding: 12px;
    border-radius: 14px;
    background: rgba(157, 210, 219, 0.08);
    border: 1px solid var(--border);
}

.meta-grid span,
.stats-row span,
.quiz-footer span {
    color: var(--muted);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.meta-grid strong,
.stats-row strong {
    display: block;
    margin-top: 6px;
    font-size: 1rem;
}

.btn {
    border: 0;
    text-decoration: none;
    border-radius: 14px;
    padding: 14px;
    font-weight: 700;
    font-size: 0.98rem;
    text-align: center;
    transition: transform .2s ease, filter .2s ease;
    display: inline-block;
}

.btn:active {
    transform: scale(0.98);
}

.btn-primary {
    background: linear-gradient(140deg, #2be6dd, #4fbbff);
    color: #052125;
}

.btn-ghost {
    color: var(--text);
    border: 1px solid var(--border);
    background: rgba(156, 206, 213, 0.1);
}

.btn-lg {
    width: 100%;
    margin-bottom: 20px;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 10px;
}

.progress-copy {
    margin: 8px 0 0;
    font-size: 1.05rem;
    font-weight: 700;
}

.timer {
    position: relative;
    width: 72px;
    height: 72px;
    display: grid;
    place-items: center;
}

.timer-svg {
    position: absolute;
    width: 72px;
    height: 72px;
    transform: rotate(-90deg);
}

.timer-track,
.timer-ring {
    fill: none;
    stroke-width: 5;
}

.timer-track {
    stroke: rgba(188, 222, 230, 0.2);
}

.timer-ring {
    stroke: var(--primary);
    stroke-dasharray: 163.4;
    stroke-linecap: round;
    transition: stroke .2s ease;
}

.timer.warning .timer-ring { stroke: #ffd166; }
.timer.danger .timer-ring {
    stroke: var(--danger);
    filter: drop-shadow(0 0 5px rgba(255, 111, 141, 0.7));
}

.progress-bar {
    margin-top: 14px;
    height: 5px;
    border-radius: 999px;
    background: rgba(201, 229, 235, 0.18);
    overflow: hidden;
}

#progress-fill {
    display: block;
    width: 5%;
    height: 100%;
    background: linear-gradient(90deg, #3cd8de, #7d8bff);
    transition: width .3s ease;
}

.question-wrap {
    margin: 20px 0 16px;
    min-height: 112px;
    transition: opacity .25s ease, transform .25s ease;
}

.question-wrap.transition-out { opacity: 0; transform: translateY(6px); }
.question-wrap.transition-in { opacity: 1; transform: translateY(0); }

.question-label {
    margin: 0 0 8px;
    text-transform: uppercase;
    letter-spacing: .09em;
    color: #b8d6de;
    font-size: .78rem;
    font-weight: 700;
}

.question-text {
    margin: 0;
    font-size: clamp(1.26rem, 5.8vw, 1.74rem);
    line-height: 1.24;
}

.answer-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 10px;
}

.answer-btn {
    width: 100%;
    border: 1px solid rgba(173, 213, 221, 0.4);
    background: rgba(174, 224, 233, 0.07);
    color: var(--text);
    border-radius: var(--radius-md);
    min-height: 58px;
    padding: 14px 14px;
    display: grid;
    grid-template-columns: 34px 1fr auto;
    align-items: center;
    gap: 12px;
    text-align: left;
    font: inherit;
    transition: transform .16s ease, border-color .16s ease, background .16s ease;
}

.answer-btn:active { transform: scale(0.99); }
.answer-btn:hover { border-color: #56d7df; }

.answer-letter {
    width: 34px;
    height: 34px;
    border-radius: 10px;
    display: grid;
    place-items: center;
    font-weight: 800;
    background: rgba(44, 218, 220, 0.18);
}

.answer-text {
    font-weight: 600;
    line-height: 1.3;
}

.answer-icon { color: #9fcad4; }

.answer-btn.selected {
    border-color: #59dde2;
    background: rgba(44, 218, 220, 0.2);
}

.answer-btn.correct {
    border-color: #46dd8f;
    background: rgba(70, 221, 143, 0.22);
}

.answer-btn.incorrect {
    border-color: #ff8098;
    background: rgba(255, 128, 152, 0.2);
    animation: shake .36s ease;
}

.answer-btn.locked {
    cursor: default;
}

.feedback {
    margin-top: 14px;
    min-height: 45px;
    border-radius: 13px;
    padding: 10px 12px;
    border: 1px solid transparent;
    background: rgba(152, 198, 207, 0.08);
    color: #d8ecf1;
    font-size: .88rem;
}

.feedback.success { border-color: rgba(70, 221, 143, .58); }
.feedback.error { border-color: rgba(255, 128, 152, .58); }
.feedback.warning { border-color: rgba(255, 212, 102, .62); }

.quiz-footer {
    margin-top: 14px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

#score-value {
    display: block;
    font-size: 1.3rem;
    font-weight: 800;
}

.score-delta {
    color: #89f4c0;
    font-weight: 800;
    opacity: 0;
    transform: translateY(8px);
    transition: all .28s ease;
}

.score-delta.show {
    opacity: 1;
    transform: translateY(0);
}

.results-score {
    margin: 14px 0 4px;
    font-size: clamp(2.2rem, 13vw, 3.6rem);
    line-height: 1;
}

.results-score small {
    margin-left: 6px;
    font-size: 1.05rem;
    color: var(--muted);
}

.results-percent {
    margin: 0 0 14px;
    color: #8ec6ff;
    font-weight: 700;
}

.button-stack {
    display: grid;
    gap: 10px;
    margin-top: 18px;
}

.review-head h1 {
    margin: 8px 0 14px;
    font-size: 1.5rem;
}

.review-list {
    display: grid;
    gap: 10px;
    max-height: 58dvh;
    overflow: auto;
    padding-right: 2px;
}

.review-card {
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 12px;
    background: rgba(148, 201, 211, 0.08);
}

.review-card h3 {
    margin: 0 0 6px;
    font-size: 0.96rem;
}

.review-card p {
    margin: 4px 0;
    color: #d7e9ef;
    font-size: 0.87rem;
}

.review-state { font-weight: 800; }
.review-state.success { color: #89f4c0; }
.review-state.error { color: #ffa1b3; }
.review-state.warning { color: #ffd58f; }

.hidden {
    display: none;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-4px); }
    75% { transform: translateX(4px); }
}

@media (min-width: 768px) {
    .player-shell { padding: 28px; }
    .panel { padding: 28px; max-width: 620px; }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation: none !important;
        transition: none !important;
    }
}