:root {
            --bg-color: #0d1610;
            --container-bg: #13201a;
            --panel-bg: #182a20;
            --border-color: #2a4535;
            --panel-sunken: rgba(0, 0, 0, 0.3);
            --text-primary: #dff5e6;
            --text-secondary: #7fa88f;
            --accent-lime: #84cc16;
            --accent-amber: #f59e0b;
            --accent-red: #ef4444;
            --accent-green: #4ade80;
            --display-font: 'Big Shoulders Display', sans-serif;
            --mono-font: 'Public Sans', sans-serif;
            --shadow-color: rgba(0, 0, 0, 0.6);

            /* Shared kit mapping */
            --kit-accent: var(--accent-lime);
            --kit-accent-ink: #101b0a;
            --kit-accent-glow: rgba(132, 204, 22, 0.25);
            --kit-surface: var(--panel-bg);
            --kit-border: var(--border-color);
            --kit-input-bg: var(--container-bg);
            --kit-error: var(--accent-red);

            /* Number-line / drag mechanic (dark) */
            --rail-bg: var(--panel-sunken);
            --rail-border: var(--border-color);
            --tick-color: var(--text-secondary);
            --tick-major-color: var(--text-primary);
            --token-bg: var(--panel-bg);
            --token-border: var(--accent-lime);
            --token-text: var(--text-primary);
            --token-placed-bg: rgba(132, 204, 22, 0.18);
            --pin-shadow: rgba(0, 0, 0, 0.55);
            --marker-color: var(--accent-green);
        }

        body.light-mode {
            --bg-color: #f7f8f2;
            --container-bg: #ffffff;
            --panel-bg: #eef3e6;
            --border-color: #d3ddc4;
            --panel-sunken: rgba(0, 0, 0, 0.045);
            --text-primary: #1c2a1a;
            --text-secondary: #55684f;
            --accent-lime: #4d7c0f;
            --accent-amber: #b45309;
            --accent-red: #b91c1c;
            --accent-green: #15803d;
            --shadow-color: rgba(28, 42, 26, 0.1);

            /* Shared kit mapping (light theme) */
            --kit-accent: var(--accent-lime);
            --kit-accent-ink: #f5faf0;
            --kit-accent-glow: rgba(77, 124, 15, 0.15);
            --kit-surface: var(--panel-bg);
            --kit-border: var(--border-color);
            --kit-input-bg: var(--container-bg);
            --kit-error: var(--accent-red);

            /* Number-line / drag mechanic (light) */
            --rail-bg: var(--panel-sunken);
            --rail-border: var(--border-color);
            --tick-color: var(--text-secondary);
            --tick-major-color: var(--text-primary);
            --token-bg: var(--panel-bg);
            --token-border: var(--accent-lime);
            --token-text: var(--text-primary);
            --token-placed-bg: rgba(77, 124, 15, 0.15);
            --pin-shadow: rgba(28, 42, 26, 0.3);
            --marker-color: var(--accent-green);
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
            transition: background-color 0.25s ease, color 0.25s ease, border-color 0.25s ease;
        }

        body {
            background-color: var(--bg-color);
            color: var(--text-primary);
            font-family: var(--mono-font);
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            padding: 20px;
        }

        .top-controls {
            position: fixed;
            top: 20px;
            right: 24px;
            z-index: 1000;
        }

        .theme-toggle-btn {
            background: var(--container-bg);
            color: var(--text-primary);
            border: 2px solid var(--border-color);
            padding: 8px 16px;
            border-radius: 6px;
            font-family: var(--mono-font);
            font-weight: 600;
            font-size: 0.85rem;
            cursor: pointer;
            box-shadow: 0 4px 10px var(--shadow-color);
        }

        .theme-toggle-btn:hover {
            border-color: var(--accent-lime);
        }

        .field-container {
            width: 100%;
            max-width: 860px;
            background: var(--container-bg);
            border: 2px solid var(--border-color);
            border-top: 6px solid var(--accent-lime);
            border-radius: 10px;
            padding: 32px;
            box-shadow: 0 12px 30px var(--shadow-color);
            min-height: 600px;
            display: flex;
            flex-direction: column;
            justify-content: space-between;
        }

        .hero-icon {
            font-size: 3rem;
            margin-bottom: 8px;
        }

        .field-title {
            font-family: var(--display-font);
            font-size: 2rem;
            font-weight: 700;
            color: var(--accent-lime);
            text-align: center;
            letter-spacing: 0.5px;
            margin-bottom: 8px;
            text-transform: uppercase;
        }

        .field-subtitle {
            font-family: var(--mono-font);
            text-align: center;
            color: var(--text-secondary);
            font-size: 0.94rem;
            margin-bottom: 20px;
            letter-spacing: 0.3px;
        }

        .screen-center {
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            text-align: center;
            padding: 10px 0;
        }

        .brief-box {
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 20px 28px;
            text-align: left;
            margin: 16px 0;
            max-width: 680px;
            line-height: 1.7;
            font-size: 0.93rem;
        }

        .brief-box ul { padding-left: 20px; }
        .brief-box li { margin-bottom: 8px; }

        .action-btn {
            background: var(--accent-lime);
            color: #101b0a;
            border: none;
            padding: 14px 36px;
            font-family: var(--display-font);
            font-size: 1.05rem;
            font-weight: 700;
            text-transform: uppercase;
            letter-spacing: 1px;
            cursor: pointer;
            margin-top: 18px;
            border-radius: 8px;
            box-shadow: 0 4px 12px var(--shadow-color);
        }

        .action-btn:hover { opacity: 0.92; }

        /* HUD Bar */
        .hud-bar {
            display: flex;
            justify-content: space-between;
            align-items: center;
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            padding: 12px 20px;
            margin-bottom: 18px;
            border-radius: 8px;
            gap: 12px;
            flex-wrap: wrap;
        }

        .hud-item {
            display: flex;
            flex-direction: column;
        }

        .hud-label {
            font-size: 0.72rem;
            color: var(--text-secondary);
            text-transform: uppercase;
            letter-spacing: 0.5px;
        }

        .hud-value {
            font-family: var(--display-font);
            font-weight: 700;
            font-size: 1.1rem;
            color: var(--accent-lime);
        }

        /* Trail Camera Frame */
        .camera-frame {
            border: 2px solid var(--accent-lime);
            border-radius: 8px;
            padding: 4px;
            margin-bottom: 18px;
            position: relative;
        }

        .camera-topbar {
            display: flex;
            align-items: center;
            gap: 6px;
            font-family: var(--mono-font);
            font-size: 0.7rem;
            font-weight: 700;
            color: var(--accent-red);
            letter-spacing: 1px;
            padding: 6px 10px;
        }

        .rec-dot {
            width: 8px;
            height: 8px;
            border-radius: 50%;
            background: var(--accent-red);
            display: inline-block;
            animation: blink 1.4s infinite;
        }

        @keyframes blink {
            0%, 100% { opacity: 1; }
            50% { opacity: 0.2; }
        }

        .cam-timestamp {
            margin-left: auto;
            color: var(--text-secondary);
            font-weight: 600;
        }

        .data-card {
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            border-left: 4px solid var(--accent-lime);
            border-radius: 6px;
            padding: 18px 22px;
        }

        .data-tag {
            font-family: var(--display-font);
            font-size: 0.85rem;
            text-transform: uppercase;
            color: var(--accent-lime);
            font-weight: 700;
            margin-bottom: 8px;
            letter-spacing: 1px;
        }

        .data-text {
            font-size: 1.02rem;
            line-height: 1.6;
            margin-bottom: 10px;
        }

        .question-text {
            font-size: 1.1rem;
            font-weight: 700;
            color: var(--accent-amber);
        }

        /* ---------- Pin-Drop Data Mechanic ---------- */

        .phase-label {
            font-family: var(--display-font);
            font-size: 0.95rem;
            font-weight: 800;
            letter-spacing: 0.5px;
            text-transform: uppercase;
            color: var(--accent-amber);
            margin-bottom: 4px;
        }

        .phase-hint {
            font-size: 0.85rem;
            color: var(--text-secondary);
            margin-bottom: 12px;
            line-height: 1.5;
        }

        /* Token tray: scattered numbered tags waiting to be sorted */
        .token-tray {
            display: flex;
            flex-wrap: wrap;
            gap: 14px;
            align-items: flex-end;
            min-height: 74px;
            padding: 10px 6px 22px;
            margin-bottom: 4px;
        }

        .token-chip {
            width: 52px;
            height: 52px;
            border-radius: 50%;
            background: var(--token-bg);
            border: 2px solid var(--token-border);
            color: var(--token-text);
            display: flex;
            align-items: center;
            justify-content: center;
            font-family: var(--display-font);
            font-weight: 700;
            font-size: 1.1rem;
            cursor: grab;
            box-shadow: 0 3px 8px var(--shadow-color);
            user-select: none;
            touch-action: none;
            flex-shrink: 0;
        }

        .token-chip.dragging {
            cursor: grabbing;
            box-shadow: 0 10px 20px var(--shadow-color);
            opacity: 0.95;
        }

        .token-chip.token-placed {
            cursor: default;
            background: var(--token-placed-bg);
            border-color: var(--accent-green);
        }

        @keyframes shakeReject {
            0%, 100% { transform: translateX(0); }
            25% { transform: translateX(-6px); }
            75% { transform: translateX(6px); }
        }
        .token-chip.shake-reject { animation: shakeReject 0.35s ease; }

        /* Number line / field log rail */
        .line-wrap {
            padding: 32px 10px 44px;
            margin-bottom: 4px;
        }

        .number-line {
            position: relative;
        }

        .line-rail {
            position: relative;
            height: 6px;
            background: var(--rail-bg);
            border: 1px solid var(--rail-border);
            border-radius: 4px;
            margin: 0 12px;
        }

        .tick {
            position: absolute;
            top: 0;
            width: 2px;
            background: var(--tick-color);
            transform: translateX(-50%);
            pointer-events: none;
        }
        .tick-minor { height: 6px; opacity: 0.55; }
        .tick-major { height: 14px; top: -4px; background: var(--tick-major-color); }

        .tick-label {
            position: absolute;
            top: 16px;
            transform: translateX(-50%);
            font-size: 0.72rem;
            font-weight: 700;
            color: var(--tick-major-color);
            font-family: var(--mono-font);
            pointer-events: none;
        }

        .correct-marker {
            position: absolute;
            top: -28px;
            transform: translateX(-50%);
            color: var(--marker-color);
            font-weight: 800;
            font-size: 0.85rem;
            white-space: nowrap;
            pointer-events: none;
        }

        /* Measuring pin */
        .pin-zone {
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 10px;
            margin-top: 4px;
            margin-bottom: 14px;
        }

        .pin-caddy {
            display: flex;
            align-items: center;
            justify-content: center;
            min-height: 56px;
        }

        .measuring-pin {
            font-size: 2.1rem;
            line-height: 1;
            cursor: grab;
            user-select: none;
            touch-action: none;
            filter: drop-shadow(0 4px 6px var(--pin-shadow));
        }
        .measuring-pin.dragging { cursor: grabbing; }
        .measuring-pin.pin-correct { filter: drop-shadow(0 0 10px var(--accent-green)); }
        .measuring-pin.pin-wrong { filter: drop-shadow(0 0 10px var(--accent-red)); }

        .pin-readout {
            font-family: var(--display-font);
            font-weight: 700;
            font-size: 1.05rem;
            color: var(--accent-amber);
        }

        .lock-btn:disabled {
            opacity: 0.4;
            cursor: not-allowed;
            box-shadow: none;
        }

        @media (max-width: 480px) {
            .token-chip { width: 44px; height: 44px; font-size: 0.95rem; }
            .line-wrap { padding: 26px 4px 38px; }
            .measuring-pin { font-size: 1.8rem; }
        }

        .feedback-line {
            font-family: var(--mono-font);
            text-align: center;
            font-size: 0.98rem;
            font-weight: 700;
            min-height: 24px;
        }

        .text-success { color: var(--accent-green); }
        .text-error { color: var(--accent-red); }

        .score-readout {
            font-family: var(--display-font);
            font-size: 1.3rem;
            background: var(--panel-bg);
            padding: 10px 22px;
            border: 1px solid var(--border-color);
            border-radius: 8px;
            margin-bottom: 12px;
            color: var(--accent-lime);
        }

        footer {
            margin-top: 20px;
            font-family: var(--mono-font);
            font-size: 0.8rem;
            color: var(--text-secondary);
            text-align: center;
        }

        @media (max-width: 640px) {
            .hud-bar { flex-direction: column; align-items: flex-start; }
        }