:root {
    --bg-app: #f4f4f4;
    --bg-panel: #ffffff;
    --bg-elevated: #e8e8e8;
    --bg-canvas: #fafafa;
    --bg-input: #ffffff;
    --border-color: #1a1a1a;
    --accent-color: #0a7a2a;
    --accent-warm: #cc1f1f;
    --accent-vector: #b8860b;
    --text-main: #1a1a1a;
    --text-muted: #555;
    --text-inverse: #ffffff;
    --highlight: #1f6feb;
    --streamline: rgba(31, 111, 235, 0.35);
    --pipe-wall: #1a1a1a;
    --manometer-bg: rgba(0, 0, 0, 0.05);
    --manometer-tube: rgba(0, 0, 0, 0.08);
    --result-divider: #cccccc;
    --font-mono: 'Fira Code', 'Courier New', monospace;
    --font-ui: 'Inter', sans-serif;
    --grid-gap: 15px;
}

:root[data-theme="dark"] {
    --bg-app: #111;
    --bg-panel: #1a1a1a;
    --bg-elevated: #222;
    --bg-canvas: #000;
    --bg-input: #111;
    --border-color: #444;
    --accent-color: #0f0;
    --accent-warm: #ff3333;
    --accent-vector: #ffcc00;
    --text-main: #eee;
    --text-muted: #888;
    --text-inverse: #000;
    --highlight: #58a6ff;
    --streamline: rgba(0, 255, 255, 0.2);
    --pipe-wall: #444;
    --manometer-bg: rgba(255, 255, 255, 0.1);
    --manometer-tube: rgba(0, 0, 0, 0.5);
    --result-divider: #333;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    background-color: var(--bg-app);
    color: var(--text-main);
    font-family: var(--font-ui);
    height: 100vh;
    overflow: hidden;
}

body, .panel, .panel-header, .panel-header-small,
.canvas-container, .dynamic-equation-box,
.mono-value, .mono-select, .theme-toggle,
.manometer, .manometer .label, .manometer .tube {
    transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

/* --- LAYOUT --- */
.app-layout {
    display: grid;
    grid-template-areas:
        "header header"
        "viewport data"
        "theory data";
    grid-template-columns: 2fr 1fr;
    grid-template-rows: auto 2fr 1fr;
    gap: var(--grid-gap);
    height: 100vh;
    padding: var(--grid-gap);
}

@media (max-width: 900px) {
    .app-layout {
        grid-template-areas:
            "header"
            "viewport"
            "data"
            "theory";
        grid-template-columns: 1fr;
        grid-template-rows: auto 400px auto auto;
        overflow-y: auto;
        display: block;
    }

    .app-layout>* {
        margin-bottom: 20px;
    }
}

/* --- HEADER --- */
.app-header {
    grid-area: header;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 2px solid var(--text-main);
    padding-bottom: 10px;
    gap: 15px;
}

.brand h1 {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    margin: 0;
    letter-spacing: -1px;
}

.brand .highlight {
    color: var(--accent-color);
}

.meta {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: 12px;
}

.status-indicator {
    color: var(--accent-color);
    animation: blink 2s infinite;
}

@keyframes blink {
    50% {
        opacity: 0.5;
    }
}

/* --- THEME TOGGLE --- */
.theme-toggle {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    background: var(--bg-elevated);
    color: var(--text-main);
    border: 1px solid var(--border-color);
    padding: 6px 12px;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.theme-toggle:hover {
    background: var(--accent-color);
    color: var(--text-inverse);
    border-color: var(--accent-color);
}

.theme-toggle:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

/* --- PANELS --- */
.panel {
    background: var(--bg-panel);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    position: relative;
}

.panel-header {
    background: var(--bg-elevated);
    color: var(--text-muted);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    padding: 8px 12px;
    border-bottom: 1px solid var(--border-color);
    text-transform: uppercase;
    letter-spacing: 1px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* --- VIEWPORT --- */
.viewport-panel {
    grid-area: viewport;
    min-height: 300px;
}

.canvas-container {
    flex: 1;
    position: relative;
    background: var(--bg-canvas);
    overflow: hidden;
}

canvas {
    display: block;
    width: 100%;
    height: 100%;
}

.view-controls {
    display: flex;
    gap: 15px;
}

.view-controls label {
    font-size: 0.7rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 5px;
    color: var(--text-muted);
}

/* --- MANOMETERS OVERLAY --- */
.manometer {
    position: absolute;
    bottom: 0;
    width: 40px;
    height: 150px;
    background: var(--manometer-bg);
    border: 1px solid var(--border-color);
    border-bottom: none;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    align-items: center;
}

.manometer .tube {
    width: 100%;
    height: 100%;
    position: relative;
    background: var(--manometer-tube);
}

.manometer .liquid {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 50%;
    background: var(--accent-color);
    opacity: 0.8;
    transition: height 0.2s ease-out, background-color 0.2s ease;
}

.manometer .label {
    position: absolute;
    top: -25px;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-main);
    background: var(--bg-elevated);
    padding: 2px 5px;
    border: 1px solid var(--border-color);
}

.manometer .value {
    position: absolute;
    bottom: 5px;
    font-family: var(--font-mono);
    font-size: 0.6rem;
    color: var(--text-main);
    z-index: 2;
    text-shadow: 0 0 2px var(--bg-canvas);
    width: 100%;
    text-align: center;
}

.alert-overlay {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--accent-warm);
    color: var(--text-inverse);
    padding: 20px;
    font-family: var(--font-mono);
    font-weight: bold;
    border: 2px solid var(--text-inverse);
    z-index: 10;
    pointer-events: none;
}

.alert-overlay.hidden {
    display: none;
}

/* --- DATA PANEL --- */
.data-panel {
    grid-area: data;
    overflow-y: auto;
}

.control-group {
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.input-row {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.input-row label {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.mono-value,
.mono-select {
    font-family: var(--font-mono);
    color: var(--accent-color);
    font-size: 0.9rem;
    text-align: right;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    padding: 5px;
}

/* Custom Range Slider */
input[type=range] {
    -webkit-appearance: none;
    width: 100%;
    background: transparent;
}

input[type=range]::-webkit-slider-thumb {
    -webkit-appearance: none;
    height: 16px;
    width: 16px;
    background: var(--accent-color);
    border-radius: 0;
    cursor: pointer;
    margin-top: -6px;
}

input[type=range]::-webkit-slider-runnable-track {
    width: 100%;
    height: 4px;
    background: var(--border-color);
}

.separator {
    height: 1px;
    background: var(--border-color);
    margin: 0 20px;
}

.results-grid {
    padding: 20px;
    display: grid;
    grid-template-columns: 1fr;
    gap: 15px;
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px dashed var(--result-divider);
    padding-bottom: 5px;
}

.result-item .label {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.result-item .value-large {
    font-family: var(--font-mono);
    font-size: 1.1rem;
    font-weight: bold;
    color: var(--text-main);
}

.highlight {
    color: var(--highlight);
}

/* --- DYNAMIC EQUATION --- */
.dynamic-equation-box {
    margin: 20px;
    border: 1px solid var(--border-color);
    background: var(--bg-elevated);
}

.panel-header-small {
    background: var(--bg-elevated);
    padding: 5px 10px;
    font-size: 0.7rem;
    color: var(--text-muted);
    border-bottom: 1px solid var(--border-color);
}

.math-display {
    padding: 15px;
    font-size: 0.9rem;
    color: var(--text-main);
    overflow-x: auto;
}

/* --- THEORY PANEL --- */
.theory-panel {
    grid-area: theory;
    min-height: 200px;
    overflow-y: auto;
}

details summary {
    cursor: pointer;
    list-style: none;
}

details summary::-webkit-details-marker {
    display: none;
}

.theory-content {
    padding: 20px;
    font-size: 0.9rem;
    line-height: 1.6;
    color: var(--text-main);
}

.theory-content hr {
    border: 0;
    border-top: 1px solid var(--border-color);
    margin: 15px 0;
}