:root {
            --dt-blue: #1e3a5f;
            --dt-mid: #2c5364;
            --dt-accent: #6ec6ff;
            --dt-red: #e57373;
            --dt-bg: #0f2744;
            --dt-card: #ffffff;
            --dt-muted: #6b7785;
            --dt-line: #e5ebf3;
        }
        body.dt-body {
            margin: 0;
            min-height: 100vh;
            font-family: 'Calibri', 'Helvetica Neue', Arial, sans-serif;
            color: #2c3e50;
            background:
                radial-gradient(900px 480px at 8% -8%, rgba(110, 198, 255, 0.22), transparent 55%),
                radial-gradient(800px 420px at 100% 0%, rgba(255, 138, 128, 0.14), transparent 50%),
                linear-gradient(165deg, #0f2744 0%, #1e3a5f 45%, #2c5364 100%);
        }
        .dt-shell {
            max-width: 760px;
            margin: 0 auto;
            padding: 28px 16px 48px;
            box-sizing: border-box;
        }
        .dt-brand {
            text-align: center;
            margin-bottom: 18px;
        }
        .dt-brand img {
            height: 48px;
            width: auto;
            filter: drop-shadow(0 6px 14px rgba(0,0,0,0.22));
        }
        .dt-screen { display: none; animation: dtIn 0.38s cubic-bezier(0.22, 1, 0.36, 1); }
        .dt-screen.active { display: block; }
        @keyframes dtIn {
            from { opacity: 0; transform: translateY(12px); }
            to { opacity: 1; transform: none; }
        }
        @media (prefers-reduced-motion: reduce) {
            .dt-screen, .dt-pop { animation: none !important; }
        }
        .dt-card {
            background: rgba(255,255,255,0.98);
            border-radius: 22px;
            box-shadow: 0 28px 70px rgba(0,0,0,0.28);
            border: 1px solid rgba(255,255,255,0.35);
            overflow: hidden;
        }
        .dt-card-inner { padding: 32px 30px 28px; }
        @media (max-width: 560px) {
            .dt-card-inner { padding: 24px 18px 22px; }
        }
        .dt-card h1 {
            margin: 0 0 8px;
            font-size: 1.65rem;
            color: var(--dt-blue);
            letter-spacing: -0.02em;
            text-align: center;
        }
        .dt-lead {
            text-align: center;
            color: var(--dt-muted);
            font-size: 1rem;
            line-height: 1.55;
            margin: 0 0 22px;
        }
        .dt-meta-grid {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 10px;
            margin-bottom: 22px;
        }
        @media (max-width: 480px) {
            .dt-meta-grid { grid-template-columns: 1fr; }
        }
        .dt-meta {
            background: #f6f9fc;
            border: 1px solid var(--dt-line);
            border-radius: 14px;
            padding: 12px 14px;
            font-size: 0.92rem;
            color: #445;
        }
        .dt-meta strong {
            display: block;
            color: var(--dt-blue);
            font-size: 0.78rem;
            letter-spacing: 0.04em;
            text-transform: uppercase;
            margin-bottom: 4px;
        }
        .dt-sections {
            display: flex;
            flex-wrap: wrap;
            gap: 8px;
            justify-content: center;
            margin: 0 0 22px;
        }
        .dt-chip {
            font-size: 0.8rem;
            font-weight: 700;
            color: #fff;
            padding: 6px 12px;
            border-radius: 999px;
            letter-spacing: 0.02em;
        }
        .dt-field { margin-bottom: 14px; }
        .dt-field label {
            display: block;
            font-weight: 700;
            font-size: 0.9rem;
            color: #334;
            margin-bottom: 6px;
        }
        .dt-field input {
            width: 100%;
            box-sizing: border-box;
            padding: 13px 14px;
            border: 1.5px solid #d5dce6;
            border-radius: 12px;
            font-size: 1rem;
            font-family: inherit;
            outline: none;
            transition: border-color 0.2s, box-shadow 0.2s;
        }
        .dt-field input:focus {
            border-color: var(--dt-accent);
            box-shadow: 0 0 0 4px rgba(110, 198, 255, 0.22);
        }
        .dt-btn {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
            border: none;
            border-radius: 12px;
            padding: 14px 22px;
            font-size: 1.02rem;
            font-weight: 700;
            font-family: inherit;
            cursor: pointer;
            transition: transform 0.15s, box-shadow 0.2s, background 0.2s, opacity 0.2s;
        }
        .dt-btn:active { transform: scale(0.98); }
        .dt-btn:disabled { opacity: 0.5; cursor: not-allowed; transform: none; }
        .dt-btn-primary {
            width: 100%;
            background: linear-gradient(135deg, #c62828, #b71c1c);
            color: #fff;
            box-shadow: 0 10px 22px rgba(183, 28, 28, 0.28);
        }
        .dt-btn-primary:hover:not(:disabled) {
            background: linear-gradient(135deg, #d32f2f, #c62828);
        }
        .dt-btn-ghost {
            background: #f1f5f9;
            color: var(--dt-blue);
        }
        .dt-btn-ghost:hover:not(:disabled) { background: #e2e8f0; }
        .dt-btn-next {
            background: linear-gradient(135deg, var(--dt-blue), var(--dt-mid));
            color: #fff;
            min-width: 120px;
            box-shadow: 0 8px 18px rgba(30, 58, 95, 0.25);
        }
        .dt-error {
            color: #c62828;
            font-weight: 600;
            font-size: 0.9rem;
            text-align: center;
            min-height: 1.3em;
            margin: 10px 0 0;
        }
        .dt-note {
            margin-top: 14px;
            font-size: 0.75rem;
            color: #8a96a3;
            text-align: center;
            line-height: 1.45;
        }
        .dt-note a { color: #5f6b7a; font-weight: 600; }

        /* ===== Test chrome ===== */
        .dt-topbar {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            justify-content: space-between;
            gap: 10px;
            margin-bottom: 14px;
            color: #fff;
        }
        .dt-student {
            font-weight: 700;
            font-size: 0.95rem;
            opacity: 0.95;
        }
        .dt-timer {
            font-variant-numeric: tabular-nums;
            font-weight: 800;
            font-size: 1.15rem;
            background: rgba(255,255,255,0.12);
            border: 1px solid rgba(255,255,255,0.2);
            padding: 8px 14px;
            border-radius: 999px;
            letter-spacing: 0.04em;
        }
        .dt-timer.warn { background: rgba(255, 183, 77, 0.25); color: #ffe0b2; }
        .dt-timer.critical {
            background: rgba(198, 40, 40, 0.45);
            color: #fff;
            animation: dtPulse 1s ease infinite;
        }
        @keyframes dtPulse {
            0%, 100% { transform: scale(1); }
            50% { transform: scale(1.04); }
        }
        .dt-progress-wrap { margin-bottom: 12px; }
        .dt-progress-label {
            color: rgba(255,255,255,0.85);
            font-size: 0.82rem;
            margin-bottom: 6px;
            display: flex;
            justify-content: space-between;
        }
        .dt-progress-track {
            height: 8px;
            background: rgba(255,255,255,0.15);
            border-radius: 999px;
            overflow: hidden;
        }
        .dt-progress-bar {
            height: 100%;
            width: 0%;
            background: linear-gradient(90deg, var(--dt-accent), #81c784);
            border-radius: 999px;
            transition: width 0.35s ease;
        }
        .dt-q-head {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            justify-content: space-between;
            gap: 10px;
            margin-bottom: 14px;
        }
        .dt-q-num {
            font-weight: 800;
            color: var(--dt-blue);
            font-size: 0.95rem;
        }
        .dt-badge {
            display: inline-block;
            color: #fff;
            font-size: 0.75rem;
            font-weight: 800;
            letter-spacing: 0.04em;
            text-transform: uppercase;
            padding: 6px 12px;
            border-radius: 999px;
        }
        .dt-prompt {
            font-size: 1.05rem;
            font-weight: 600;
            color: #334;
            margin: 0 0 12px;
            line-height: 1.45;
        }
        .dt-stem {
            background: #f6f9fc;
            border: 1px solid var(--dt-line);
            border-left: 4px solid var(--dt-accent);
            border-radius: 12px;
            padding: 14px 16px;
            font-size: 1.08rem;
            color: #1a2332;
            line-height: 1.55;
            margin: 0 0 16px;
        }
        .dt-stem u { font-weight: 800; color: var(--dt-blue); text-decoration-color: var(--dt-red); }
        .dt-hint {
            font-size: 0.88rem;
            color: var(--dt-muted);
            margin: 0 0 14px;
            font-style: italic;
        }
        .dt-options { display: flex; flex-direction: column; gap: 10px; }
        .dt-option {
            display: flex;
            align-items: flex-start;
            gap: 12px;
            padding: 13px 14px;
            border: 1.5px solid #d5dce6;
            border-radius: 14px;
            cursor: pointer;
            transition: border-color 0.2s, background 0.2s, box-shadow 0.2s;
            background: #fff;
        }
        .dt-option:hover {
            border-color: var(--dt-accent);
            background: #f8fcff;
        }
        .dt-option:has(input:checked),
        .dt-option.is-selected {
            border-color: var(--dt-blue);
            background: #eef5ff;
            box-shadow: 0 0 0 3px rgba(30, 58, 95, 0.12);
        }
        .dt-option input { margin-top: 3px; accent-color: var(--dt-blue); flex-shrink: 0; }
        .dt-option-letter {
            flex-shrink: 0;
            width: 28px;
            height: 28px;
            border-radius: 8px;
            background: #eef2f7;
            color: var(--dt-blue);
            font-weight: 800;
            font-size: 0.85rem;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        .dt-option:has(input:checked) .dt-option-letter,
        .dt-option.is-selected .dt-option-letter {
            background: var(--dt-blue);
            color: #fff;
        }
        .dt-option-text { flex: 1; line-height: 1.45; color: #2c3e50; padding-top: 3px; }
        .dt-fill-wrap { margin-top: 4px; }
        .dt-fill {
            width: 100%;
            box-sizing: border-box;
            padding: 14px 16px;
            border: 1.5px solid #d5dce6;
            border-radius: 14px;
            font-size: 1.08rem;
            font-family: inherit;
            outline: none;
        }
        .dt-fill:focus {
            border-color: var(--dt-accent);
            box-shadow: 0 0 0 4px rgba(110, 198, 255, 0.22);
        }
        .dt-answered-flag {
            font-size: 0.82rem;
            color: var(--dt-muted);
            font-weight: 600;
        }
        .dt-answered-flag.ok { color: #2e7d32; }
        .dt-nav {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            justify-content: space-between;
            gap: 12px;
            margin-top: 22px;
            padding-top: 16px;
            border-top: 1px solid var(--dt-line);
        }
        .dt-nav-right { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
        .dt-pop { animation: dtPop 0.32s cubic-bezier(0.22, 1, 0.36, 1); }
        @keyframes dtPop {
            from { opacity: 0; transform: translateX(14px); }
            to { opacity: 1; transform: none; }
        }
        .dt-spinner {
            display: inline-block;
            width: 16px;
            height: 16px;
            border: 2px solid rgba(255,255,255,0.35);
            border-top-color: #fff;
            border-radius: 50%;
            animation: dtSpin 0.7s linear infinite;
        }
        @keyframes dtSpin { to { transform: rotate(360deg); } }

        /* Results */
        .dt-result-hero {
            text-align: center;
            padding: 8px 0 6px;
        }
        .dt-level-pill {
            display: inline-block;
            background: linear-gradient(135deg, var(--dt-blue), var(--dt-mid));
            color: #fff;
            font-weight: 800;
            font-size: 1.25rem;
            padding: 12px 22px;
            border-radius: 999px;
            margin: 10px 0 8px;
            box-shadow: 0 12px 28px rgba(30, 58, 95, 0.3);
        }
        .dt-score-big {
            font-size: 2.4rem;
            font-weight: 900;
            color: var(--dt-blue);
            letter-spacing: -0.03em;
            margin: 6px 0 0;
        }
        .dt-score-sub { color: var(--dt-muted); font-weight: 600; margin: 4px 0 12px; }
        .dt-sec-row { margin-bottom: 14px; }
        .dt-sec-top {
            display: flex;
            justify-content: space-between;
            font-size: 0.9rem;
            font-weight: 700;
            color: #334;
            margin-bottom: 6px;
        }
        .dt-sec-track {
            height: 10px;
            background: #eef2f7;
            border-radius: 999px;
            overflow: hidden;
        }
        .dt-sec-fill {
            height: 100%;
            border-radius: 999px;
            transition: width 0.6s ease;
        }
        .dt-timeout {
            background: #fff3e0;
            border-left: 4px solid #ffb74d;
            padding: 10px 12px;
            border-radius: 0 10px 10px 0;
            color: #6d4c1b;
            font-size: 0.9rem;
            margin-bottom: 14px;
        }
        .dt-actions {
            display: flex;
            flex-wrap: wrap;
            gap: 10px;
            justify-content: center;
            margin-top: 18px;
        }
        .dt-actions .dt-btn { min-width: 160px; }
        .dt-back {
            text-align: center;
            margin-top: 16px;
        }
        .dt-back a {
            color: rgba(255,255,255,0.9);
            font-weight: 700;
            text-decoration: none;
            border-bottom: 1px solid rgba(255,255,255,0.35);
        }

/* Multi-form suite badges */
.dt-form-badge {
  text-align: center;
  margin: 0 0 10px;
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: #1e3a5f;
  background: #eef5ff;
  border: 1px solid #d0e4ff;
  display: inline-block;
  width: auto;
  padding: 6px 14px;
  border-radius: 999px;
  position: relative;
  left: 50%;
  transform: translateX(-50%);
}
.dt-form-focus {
  text-align: center;
  color: #5f6b7a;
  font-size: 0.95rem;
  font-weight: 600;
  margin: 0 0 12px;
}