:root {
    --bg-color: #0c1116;
    --container-bg: #141b22;
    --card-bg: #1b232c;
    --border-color: #2f3b47;
    --text-primary: #eef2f5;
    --text-secondary: #8b97a3;
    --accent-steel: #5eb1e0;
    --accent-yellow: #f2c94c;
    --accent-red: #e0524f;
    --accent-green: #4fbf83;
    --panel-sunken: rgba(0, 0, 0, 0.35);
    --font-header: 'Big Shoulders Display', sans-serif;
    --font-body: 'Barlow', sans-serif;
    --font-mono: 'Roboto Mono', monospace;
    --shadow-color: rgba(0, 0, 0, 0.6);

    /* Shared kit mapping (dark theme) */
    --kit-accent: var(--accent-yellow);
    --kit-accent-ink: #1f1600;
    --kit-accent-glow: rgba(242, 201, 76, 0.25);
    --kit-surface: var(--card-bg);
    --kit-border: var(--border-color);
    --kit-input-bg: var(--container-bg);
    --kit-error: var(--accent-red);
}

body.light-mode {
    --bg-color: #f6f7f5;
    --container-bg: #ffffff;
    --card-bg: #eef1ee;
    --border-color: #d3d8d1;
    --text-primary: #161a17;
    --text-secondary: #525b53;
    --accent-steel: #1c6fa0;
    --accent-yellow: #8a6d1a;
    --accent-red: #b0322f;
    --accent-green: #2f7d4f;
    --panel-sunken: rgba(0, 0, 0, 0.05);
    --shadow-color: rgba(0, 0, 0, 0.1);

    /* Shared kit mapping (light theme) */
    --kit-accent: var(--accent-yellow);
    --kit-accent-ink: #ffffff;
    --kit-accent-glow: rgba(138, 109, 26, 0.18);
    --kit-surface: var(--card-bg);
    --kit-border: var(--border-color);
    --kit-input-bg: var(--container-bg);
    --kit-error: var(--accent-red);
}

* {
    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(--font-body);
    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: 9px 16px;
    border-radius: 6px;
    font-family: var(--font-mono);
    font-weight: 700;
    font-size: 0.85rem;
    cursor: pointer;
    box-shadow: 0 4px 10px var(--shadow-color);
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

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

.bridge-container {
    width: 100%;
    max-width: 920px;
    background: var(--container-bg);
    border: 2px solid var(--border-color);
    border-top: 6px solid var(--accent-steel);
    border-radius: 8px;
    padding: 36px;
    box-shadow: 0 12px 30px var(--shadow-color);
    min-height: 600px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    position: relative;
}

.bridge-icon {
    font-size: 2.6rem;
    text-align: center;
    margin-bottom: 8px;
}

.bridge-title {
    font-family: var(--font-header);
    font-size: 2.3rem;
    color: var(--accent-steel);
    text-align: center;
    letter-spacing: 0.5px;
    margin-bottom: 4px;
    text-transform: uppercase;
}

.bridge-subtitle {
    font-family: var(--font-mono);
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.88rem;
    margin-bottom: 22px;
    letter-spacing: 0.3px;
}

/* HUD Status Bar */
.status-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 14px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 12px 20px;
    margin-bottom: 20px;
    font-family: var(--font-mono);
}

.status-item {
    display: flex;
    flex-direction: column;
    gap: 3px;
    align-items: center;
    font-size: 0.9rem;
    font-weight: 700;
}

.status-label {
    color: var(--text-secondary);
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.status-value {
    color: var(--accent-steel);
    font-size: 1.05rem;
}

.tension-gauge {
    position: relative;
    width: 120px;
    height: 12px;
    background: var(--border-color);
    border-radius: 6px;
    overflow: visible;
    margin-top: 2px;
}

.tension-fill {
    height: 100%;
    width: 100%;
    background: var(--accent-green);
    border-radius: 6px;
    overflow: hidden;
    transition: width 0.15s ease, background-color 0.15s ease;
}

.tension-target-marker {
    position: absolute;
    top: -3px;
    left: 62.5%;
    width: 2px;
    height: 18px;
    background: var(--text-primary);
    opacity: 0.55;
    z-index: 2;
}

/* Survey Layout */
.survey-grid {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 20px;
    align-items: start;
}

@media (max-width: 760px) {
    .survey-grid { grid-template-columns: 1fr; }
}

.bridge-stage {
    background: var(--panel-sunken);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 220px;
}

.bridge-stage svg {
    width: 100%;
    height: auto;
    display: block;
    overflow: visible;
}

.anchor-handle {
    cursor: grab;
    touch-action: none;
}

.anchor-handle:active {
    cursor: grabbing;
}

.anchor-handle:focus-visible {
    outline: 3px solid var(--accent-yellow);
    outline-offset: 2px;
}

.handle-outer {
    fill: var(--accent-yellow);
    stroke: var(--text-primary);
}

.handle-center {
    fill: var(--text-primary);
}

.anchor-state-success .handle-outer { fill: var(--accent-green); }
.anchor-state-slack .handle-outer { fill: var(--accent-steel); }
.anchor-state-overtension .handle-outer { fill: var(--accent-red); }

.cable-line {
    fill: none;
    stroke: var(--accent-steel);
    stroke-width: 5;
    stroke-linecap: round;
}

.cable-line.cable-success {
    stroke: var(--accent-green);
    stroke-width: 6;
    filter: drop-shadow(0 0 6px var(--accent-green));
    animation: cablePulse 0.55s ease-in-out 2;
}

.cable-line.cable-slack {
    stroke: var(--accent-steel);
    opacity: 0.65;
    stroke-dasharray: 3 5;
}

.cable-line.cable-overtension {
    stroke: var(--accent-red);
    stroke-width: 5;
    filter: drop-shadow(0 0 5px var(--accent-red));
    animation: cableShake 0.12s linear infinite;
}

@keyframes cablePulse {
    0%, 100% { filter: drop-shadow(0 0 6px var(--accent-green)); }
    50% { filter: drop-shadow(0 0 14px var(--accent-green)); }
}

@keyframes cableShake {
    0% { transform: translateX(0); }
    25% { transform: translateX(1.5px); }
    50% { transform: translateX(0); }
    75% { transform: translateX(-1.5px); }
    100% { transform: translateX(0); }
}

.spark-particle {
    fill: var(--accent-yellow);
    animation: sparkFlicker 0.35s ease-in-out infinite;
}

@keyframes sparkFlicker {
    0%, 100% { opacity: 0.15; transform: scale(0.6); }
    50% { opacity: 1; transform: scale(1.2); }
}

.question-panel {
    display: flex;
    flex-direction: column;
}

.control-panel {
    background: var(--panel-sunken);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 16px;
    margin-top: 4px;
}

.readout-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    margin-bottom: 14px;
}

@media (max-width: 560px) {
    .readout-grid { grid-template-columns: 1fr; }
}

.readout-box {
    display: flex;
    flex-direction: column;
    gap: 4px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 8px 10px;
    text-align: center;
}

.readout-label {
    font-family: var(--font-mono);
    font-size: 0.62rem;
    text-transform: uppercase;
    letter-spacing: 0.4px;
    color: var(--text-secondary);
}

.readout-value {
    font-family: var(--font-mono);
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--accent-steel);
}

.nudge-row {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 14px;
}

.nudge-label {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--text-secondary);
    margin-right: 2px;
}

.nudge-btn {
    background: var(--card-bg);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
    padding: 8px 12px;
    border-radius: 6px;
    font-family: var(--font-mono);
    font-weight: 700;
    font-size: 0.85rem;
    cursor: pointer;
}

.nudge-btn:hover {
    border-color: var(--accent-steel);
}

.nudge-btn:disabled,
.lock-btn:disabled {
    opacity: 0.5;
    cursor: default;
}

.lock-btn {
    width: 100%;
    margin-top: 0;
    font-size: 1.1rem;
    padding: 12px 20px;
}

.question-card {
    background: var(--panel-sunken);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--accent-steel);
    border-radius: 6px;
    padding: 20px 22px;
    margin-bottom: 16px;
}

.question-tag {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    text-transform: uppercase;
    color: var(--accent-steel);
    font-weight: 700;
    margin-bottom: 10px;
    letter-spacing: 1px;
}

.question-text {
    font-size: 1.05rem;
    line-height: 1.6;
    font-weight: 500;
}

/* Feedback */
.feedback-line {
    font-family: var(--font-mono);
    text-align: center;
    font-size: 0.92rem;
    font-weight: 700;
    min-height: 24px;
    margin-top: 14px;
}

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

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

.action-btn {
    background: var(--accent-steel);
    color: #061620;
    border: none;
    padding: 14px 36px;
    font-family: var(--font-header);
    font-size: 1.3rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    cursor: pointer;
    margin-top: 20px;
    border-radius: 6px;
    box-shadow: 0 4px 12px var(--shadow-color);
}

.action-btn:hover {
    opacity: 0.9;
}

.brief-box {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 20px 28px;
    text-align: left;
    margin: 20px 0;
    max-width: 680px;
    line-height: 1.7;
    font-size: 0.94rem;
}

.brief-box code {
    font-family: var(--font-mono);
    background: var(--panel-sunken);
    padding: 1px 6px;
    border-radius: 4px;
}

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

footer {
    margin-top: 24px;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-align: center;
    letter-spacing: 0.5px;
}