:root {
            --bg: #0f172a;
            --bg-light: #111827;
            --card-bg: #1f2937;
            --accent: #3b82f6;
            --accent-soft: rgba(59, 130, 246, 0.15);
            --accent-strong: #2563eb;
            --text: #e5e7eb;
            --muted: #9ca3af;
            --danger: #ef4444;
            --success: #22c55e;
            --border: #374151;
            --radius-lg: 16px;
            --radius-md: 10px;
            --shadow-soft: 0 14px 30px rgba(0, 0, 0, 0.35);
        }

        * {
            box-sizing: border-box;
        }

        body {
            margin: 0;
            min-height: 100vh;
            font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
            background: radial-gradient(circle at top, #1e293b 0, #020617 55%, #000 100%);
            color: var(--text);
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 16px;
        }

        #app {
            width: 100%;
            max-width: 980px;
        }

        .page {
            background: linear-gradient(145deg, var(--bg-light), #020617);
            border-radius: 20px;
            border: 1px solid rgba(148, 163, 184, 0.25);
            box-shadow: var(--shadow-soft);
            padding: 24px;
            display: none;
        }

        .page.active {
            display: block;
        }

        h1, h2, h3 {
            margin: 0 0 12px 0;
            font-weight: 700;
            letter-spacing: 0.02em;
            color: #f9fafb;
        }

        h1 {
            font-size: 1.75rem;
        }

        h2 {
            font-size: 1.3rem;
        }

        p {
            margin: 4px 0 10px;
            color: var(--muted);
        }

        .subtext {
            font-size: 0.9rem;
            color: var(--muted);
        }

        .badge {
            display: inline-flex;
            align-items: center;
            gap: 6px;
            padding: 4px 10px;
            font-size: 0.8rem;
            border-radius: 999px;
            background: rgba(15, 118, 110, 0.15);
            border: 1px solid rgba(34, 197, 94, 0.4);
            color: #6ee7b7;
            margin-bottom: 12px;
        }

        .badge span.icon {
            font-size: 0.85rem;
        }

        .row {
            display: flex;
            flex-wrap: wrap;
            gap: 16px;
            margin-top: 16px;
        }

        .card {
            background: rgba(15, 23, 42, 0.92);
            border-radius: var(--radius-lg);
            border: 1px solid var(--border);
            padding: 16px;
        }

        .card-half {
            flex: 1 1 260px;
        }

        label {
            font-size: 0.9rem;
            color: var(--muted);
            display: block;
            margin-bottom: 4px;
        }

        select {
            width: 100%;
            padding: 8px 10px;
            border-radius: 999px;
            border: 1px solid var(--border);
            background: rgba(15, 23, 42, 0.9);
            color: var(--text);
            outline: none;
            font-size: 0.9rem;
        }

        select:focus {
            border-color: var(--accent);
            box-shadow: 0 0 0 1px rgba(59, 130, 246, 0.4);
        }

        button {
            border-radius: 999px;
            border: none;
            padding: 10px 18px;
            font-size: 0.95rem;
            font-weight: 600;
            cursor: pointer;
            transition: transform 0.05s ease, box-shadow 0.1s ease, background 0.15s ease;
        }

        button.primary {
            background: linear-gradient(135deg, var(--accent), var(--accent-strong));
            color: white;
            box-shadow: 0 10px 25px rgba(37, 99, 235, 0.45);
        }

        button.primary:hover {
            transform: translateY(-1px);
            box-shadow: 0 14px 30px rgba(37, 99, 235, 0.6);
        }

        button.secondary {
            background: rgba(15, 23, 42, 1);
            color: var(--text);
            border: 1px solid var(--border);
        }

        button.secondary:hover {
            background: rgba(30, 64, 175, 0.45);
        }

        button:disabled {
            opacity: 0.5;
            cursor: default;
            transform: none;
            box-shadow: none;
        }

        .button-row {
            display: flex;
            justify-content: flex-end;
            gap: 10px;
            margin-top: 18px;
        }

        .center-row {
            display: flex;
            justify-content: center;
            margin-top: 24px;
        }

        .hidden {
            display: none !important;
        }

        /* Timer + Progress */

        #timer {
            font-size: 0.95rem;
            padding: 6px 12px;
            border-radius: 999px;
            background: rgba(15, 23, 42, 0.9);
            border: 1px solid rgba(148, 163, 184, 0.4);
            display: inline-flex;
            align-items: center;
            gap: 8px;
            color: var(--muted);
            margin-bottom: 10px;
        }

        #timer span.time {
            font-weight: 600;
            color: var(--accent);
        }

        #progress {
            font-size: 0.9rem;
            color: var(--muted);
            margin-bottom: 10px;
        }

        /* Question / Options */

        #question-container {
            margin-top: 8px;
        }

        .question-card {
            border-radius: var(--radius-lg);
            padding: 16px;
            background: radial-gradient(circle at top left, rgba(59, 130, 246, 0.24), rgba(15, 23, 42, 0.95));
            border: 1px solid rgba(148, 163, 184, 0.4);
        }

        .question-text {
            font-size: 1rem;
            margin-bottom: 12px;
        }

        .question-meta {
            font-size: 0.8rem;
            color: var(--muted);
            margin-bottom: 10px;
        }

        .question-type-badge {
            display: inline-flex;
            padding: 2px 8px;
            border-radius: 999px;
            border: 1px solid rgba(148, 163, 184, 0.5);
            font-size: 0.7rem;
            text-transform: uppercase;
            letter-spacing: 0.07em;
            color: var(--muted);
        }

        .options-list {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        .option {
            display: flex;
            align-items: flex-start;
            gap: 10px;
            padding: 10px 12px;
            margin-bottom: 8px;
            border-radius: var(--radius-md);
            border: 1px solid rgba(148, 163, 184, 0.45);
            background: rgba(15, 23, 42, 0.85);
            cursor: pointer;
            transition: background 0.12s ease, border-color 0.12s ease, transform 0.05s ease;
        }

        .option:hover {
            background: rgba(30, 64, 175, 0.3);
            border-color: var(--accent);
        }

        .option input {
            margin-top: 2px;
        }

        .option-label {
            font-size: 0.95rem;
        }

        .option.selected {
            border-color: var(--accent);
            background: var(--accent-soft);
        }

        /* Result coloring */

        .option.correct {
            border-color: rgba(34, 197, 94, 0.8);
            background: rgba(22, 163, 74, 0.12);
        }

        .option.incorrect {
            border-color: rgba(239, 68, 68, 0.85);
            background: rgba(127, 29, 29, 0.25);
        }

        .option.correct.user-choice {
            box-shadow: 0 0 0 1px rgba(34, 197, 94, 0.7);
        }

        .option.incorrect.user-choice {
            box-shadow: 0 0 0 1px rgba(239, 68, 68, 0.75);
        }

        /* Results Page */

        #resultsSummary {
            margin-top: 10px;
        }

        .summary-stats {
            display: flex;
            flex-wrap: wrap;
            gap: 12px;
            margin-bottom: 16px;
        }

        .stat-pill {
            padding: 8px 12px;
            border-radius: 999px;
            border: 1px solid var(--border);
            background: rgba(15, 23, 42, 0.95);
            font-size: 0.85rem;
            color: var(--muted);
        }

        .stat-pill strong {
            color: var(--text);
        }

        .results-list {
            max-height: 360px;
            overflow-y: auto;
            margin-top: 10px;
            padding-right: 8px;
        }

        .result-item {
            border-radius: var(--radius-md);
            border: 1px solid var(--border);
            padding: 10px 12px;
            margin-bottom: 8px;
            background: rgba(15, 23, 42, 0.95);
            font-size: 0.9rem;
        }

        .result-item.correct {
            border-color: rgba(34, 197, 94, 0.7);
        }

        .result-item.incorrect {
            border-color: rgba(239, 68, 68, 0.8);
        }

        .result-q {
            font-weight: 600;
        }

        .result-line {
            margin-top: 4px;
            font-size: 0.85rem;
        }

        .result-line span.label {
            color: var(--muted);
        }

        /* Previous attempts */

        #previousResults {
            margin-top: 8px;
            font-size: 0.9rem;
        }

        .attempt-list {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        .attempt-item {
            padding: 6px 8px;
            border-radius: 999px;
            border: 1px solid var(--border);
            background: rgba(15, 23, 42, 0.92);
            margin-bottom: 6px;
            font-size: 0.8rem;
            display: flex;
            justify-content: space-between;
            gap: 6px;
        }

        .attempt-item span.score {
            color: var(--accent);
            font-weight: 600;
        }

        .attempt-item span.meta {
            color: var(--muted);
        }

        /* Utility */

        .mt-1 { margin-top: 4px; }
        .mt-2 { margin-top: 8px; }
        .mt-3 { margin-top: 12px; }
        .mt-4 { margin-top: 16px; }

        @media (max-width: 640px) {
            .page {
                padding: 16px;
            }

            .button-row {
                flex-direction: column-reverse;
                align-items: stretch;
            }

            button {
                width: 100%;
                justify-content: center;
            }
        }