:root {
            --bg-1: #0f1c2e;
            --bg-2: #1b3a4b;
            --ink: #f5f1e8;
            --muted: #b6c2c9;
            --accent: #f5a623;
            --accent-2: #58c4dd;
            --good: #4dd49a;
            --bad: #ff6b6b;
            --card: rgba(18, 28, 39, 0.85);
            --glass: rgba(255, 255, 255, 0.06);
            --shadow: 0 20px 60px rgba(0, 0, 0, 0.35);
            --radius: 18px;
        }

        * {
            box-sizing: border-box;
        }

        html,
        body {
            height: 100%;
        }

        body {
            margin: 0;
            font-family: "Palatino Linotype", "Book Antiqua", Palatino, serif;
            color: var(--ink);
            background: radial-gradient(1200px 600px at 20% 10%, #223c52 0%, transparent 60%),
                radial-gradient(1000px 700px at 90% 20%, #163145 0%, transparent 60%),
                linear-gradient(160deg, var(--bg-1), var(--bg-2));
            display: grid;
            place-items: center;
            padding: clamp(12px, 2.2vw, 22px);
            overflow-x: hidden;
        }

        .stage {
            width: min(860px, 100%);
            position: relative;
            padding: clamp(16px, 2.6vw, 26px);
            border-radius: clamp(16px, 2.4vw, 22px);
            background: linear-gradient(120deg, rgba(255, 255, 255, 0.04), rgba(255, 255, 255, 0.02));
            box-shadow: var(--shadow);
            overflow: hidden;
        }

        .stage::before,
        .stage::after {
            content: "";
            position: absolute;
            border-radius: 50%;
            opacity: 0.25;
            z-index: 0;
        }

        .stage::before {
            width: 260px;
            height: 260px;
            background: radial-gradient(circle, var(--accent), transparent 70%);
            top: -120px;
            left: -120px;
            animation: float 10s ease-in-out infinite;
        }

        .stage::after {
            width: 320px;
            height: 320px;
            background: radial-gradient(circle, var(--accent-2), transparent 70%);
            bottom: -180px;
            right: -140px;
            animation: float 12s ease-in-out infinite reverse;
        }

        .content {
            position: relative;
            z-index: 1;
            display: grid;
            gap: clamp(16px, 2.6vw, 22px);
        }

        header {
            display: flex;
            align-items: flex-start;
            justify-content: space-between;
            gap: 16px;
            flex-wrap: wrap;
        }

        .brand h1 {
            margin: 0;
            font-size: clamp(1.7rem, 2.4vw, 2.2rem);
            letter-spacing: 0.5px;
        }

        .brand p {
            margin: 6px 0 0;
            color: var(--muted);
            font-size: clamp(0.88rem, 1.8vw, 0.95rem);
            font-family: "Trebuchet MS", "Lucida Sans", "Lucida Grande", sans-serif;
        }

        .stats {
            text-align: right;
            font-family: "Trebuchet MS", "Lucida Sans", "Lucida Grande", sans-serif;
            color: var(--muted);
        }

        .stats strong {
            display: block;
            color: var(--ink);
            font-size: clamp(0.95rem, 2vw, 1.05rem);
        }

.card {
    background: var(--card);
    border-radius: var(--radius);
    padding: clamp(14px, 2.4vw, 22px);
    border: 1px solid rgba(255, 255, 255, 0.08);
    backdrop-filter: blur(6px);
    animation: rise 0.6s ease;
}

#quiz-card {
    max-height: 80vh;
    overflow: auto;
}

.question {
    font-size: clamp(1.05rem, 2.1vw, 1.35rem);
    line-height: 1.5;
    margin: 0 0 clamp(12px, 2vw, 16px);
}

.question.rich {
    display: grid;
    gap: 12px;
}

.code-card {
    background: rgba(0, 0, 0, 0.35);
    border-radius: 14px;
    padding: 12px 14px;
    border: 1px solid rgba(255, 255, 255, 0.08);
    font-family: "Cascadia Code", "Fira Code", "Consolas", "Courier New", monospace;
    font-size: 0.95rem;
    width: 100%;
    overflow: auto;
}

.code-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    color: var(--muted);
    font-size: 0.82rem;
    margin-bottom: 10px;
}

.code-header .code-lang {
    text-transform: lowercase;
    letter-spacing: 0.6px;
}

.copy-btn {
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.18);
    color: var(--ink);
    border-radius: 999px;
    padding: 6px 10px;
    font-size: 0.78rem;
    font-family: "Trebuchet MS", "Lucida Sans", "Lucida Grande", sans-serif;
}

.code-block {
    margin: 0;
    white-space: pre;
    color: #f3f3f3;
}

        .options {
            display: grid;
            gap: clamp(8px, 1.8vw, 12px);
        }

        .option {
            display: flex;
            align-items: center;
            gap: 10px;
            padding: clamp(10px, 2vw, 12px) clamp(12px, 2.4vw, 14px);
            background: var(--glass);
            color: var(--ink);
            border: 1px solid transparent;
            border-radius: 12px;
            cursor: pointer;
            transition: transform 0.2s ease, border-color 0.2s ease, background 0.2s ease;
            font-family: "Trebuchet MS", "Lucida Sans", "Lucida Grande", sans-serif;
        }

        .option:hover {
            transform: translateY(-2px);
            border-color: rgba(255, 255, 255, 0.3);
        }

        .option.selected {
            border-color: var(--accent);
            background: rgba(245, 166, 35, 0.12);
        }

        .option.correct {
            border-color: var(--good);
            background: rgba(77, 212, 154, 0.15);
        }

        .option.wrong {
            border-color: var(--bad);
            background: rgba(255, 107, 107, 0.12);
        }

.option span {
    width: clamp(24px, 5.6vw, 28px);
    height: clamp(24px, 5.6vw, 28px);
    border-radius: 50%;
    display: grid;
    place-items: center;
    background: rgba(255, 255, 255, 0.1);
    font-weight: 700;
}

.option-code {
    flex-direction: column;
    align-items: stretch;
    gap: 10px;
}

.option-code .option-letter {
    width: auto;
    height: auto;
    border-radius: 8px;
    padding: 2px 8px;
    background: rgba(255, 255, 255, 0.12);
    align-self: flex-start;
    font-size: 0.82rem;
}

.option-code .option-code-card {
    margin: 0;
}

        .actions {
            display: flex;
            flex-wrap: wrap;
            gap: 10px;
            align-items: center;
            margin-top: clamp(10px, 2.2vw, 14px);
        }

        button {
            border: none;
            border-radius: 999px;
            padding: clamp(9px, 2.2vw, 11px) clamp(14px, 3vw, 18px);
            font-size: clamp(0.85rem, 2.4vw, 0.98rem);
            cursor: pointer;
            font-family: "Trebuchet MS", "Lucida Sans", "Lucida Grande", sans-serif;
            transition: transform 0.2s ease, box-shadow 0.2s ease;
        }

        button:disabled {
            opacity: 0.6;
            cursor: not-allowed;
            transform: none;
            box-shadow: none;
        }

        .primary {
            background: linear-gradient(130deg, var(--accent), #f08c2e);
            color: #2b1b0c;
            box-shadow: 0 10px 20px rgba(245, 166, 35, 0.3);
        }

        .ghost {
            background: transparent;
            border: 1px solid rgba(255, 255, 255, 0.3);
            color: var(--ink);
        }

        button:hover:not(:disabled) {
            transform: translateY(-2px);
        }

        .explanation {
            margin-top: clamp(10px, 2.2vw, 14px);
            padding: clamp(12px, 2.4vw, 16px) clamp(14px, 2.6vw, 18px);
            border-radius: 12px;
            background: rgba(255, 255, 255, 0.06);
            border: 1px solid rgba(255, 255, 255, 0.08);
            color: var(--muted);
            font-family: "Trebuchet MS", "Lucida Sans", "Lucida Grande", sans-serif;
            animation: fadeIn 0.4s ease;
        }

        .progress {
            height: 6px;
            border-radius: 999px;
            background: rgba(255, 255, 255, 0.12);
            overflow: hidden;
            margin-top: clamp(10px, 2.2vw, 14px);
        }

        .bar {
            height: 100%;
            background: linear-gradient(90deg, var(--accent-2), var(--accent));
            border-radius: inherit;
            transition: width 0.4s ease;
        }

        .indicator {
            display: flex;
            flex-wrap: wrap;
            gap: 6px;
            margin-top: clamp(10px, 2.2vw, 12px);
        }

        .indicator-item {
            width: clamp(24px, 6vw, 30px);
            height: clamp(24px, 6vw, 30px);
            border-radius: 999px;
            display: grid;
            place-items: center;
            font-size: clamp(0.68rem, 2.2vw, 0.8rem);
            font-weight: 700;
            background: rgba(255, 255, 255, 0.08);
            color: var(--muted);
            border: 1px solid rgba(255, 255, 255, 0.12);
        }

        .indicator-item.current {
            border-color: var(--accent);
            color: var(--ink);
        }

        .indicator-item.correct {
            background: rgba(77, 212, 154, 0.2);
            border-color: var(--good);
            color: var(--good);
        }

        .indicator-item.wrong {
            background: rgba(255, 107, 107, 0.2);
            border-color: var(--bad);
            color: var(--bad);
        }

        .finish {
            text-align: center;
            display: none;
        }

        .summary {
            display: grid;
            gap: 12px;
            margin: 20px 0;
            color: var(--muted);
            font-family: "Trebuchet MS", "Lucida Sans", "Lucida Grande", sans-serif;
        }

        .review {
            text-align: left;
            margin-top: 18px;
            display: grid;
            gap: 14px;
        }

        .review-item {
            padding: 14px 16px;
            border-radius: 12px;
            background: rgba(255, 255, 255, 0.04);
            border: 1px solid rgba(255, 255, 255, 0.08);
        }

        .review-item h3 {
            margin: 0 0 8px;
            font-size: 1.05rem;
        }

        .review-item p {
            margin: 6px 0;
            color: var(--muted);
            font-family: "Trebuchet MS", "Lucida Sans", "Lucida Grande", sans-serif;
        }

        .tag {
            display: inline-block;
            padding: 2px 10px;
            border-radius: 999px;
            font-size: 0.85rem;
            margin-left: 6px;
        }

        .tag.good {
            background: rgba(77, 212, 154, 0.2);
            color: var(--good);
        }

        .tag.bad {
            background: rgba(255, 107, 107, 0.2);
            color: var(--bad);
        }

        @keyframes rise {
            from {
                transform: translateY(18px);
                opacity: 0;
            }

            to {
                transform: translateY(0);
                opacity: 1;
            }
        }

        @keyframes float {

            0%,
            100% {
                transform: translate(0, 0);
            }

            50% {
                transform: translate(10px, -12px);
            }
        }

        @keyframes fadeIn {
            from {
                opacity: 0;
                transform: translateY(8px);
            }

            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        @media (max-width: 720px) {
            header {
                flex-direction: column;
                align-items: flex-start;
            }

            .stats {
                text-align: left;
                width: 100%;
            }
        }

        @media (max-width: 520px) {
            .indicator {
                gap: 6px;
            }

            .option {
                align-items: flex-start;
            }
        }