:root {
    /* Dark Theme (Default) */
    --bg-color: #1a1a2e;
    --container-bg: #16213e;
    --panel-bg: #1f2833;
    --input-bg: rgba(15, 52, 96, 0.5);
    --text-color: #e0e0e0;
    --secondary-text: #a0a0a0;
    --accent-color: #e94560;
    --primary-color: #0f3460;
    --border-color: rgba(255,255,255,0.05);
    --shadow-color: rgba(0, 0, 0, 0.5);
    --canvas-bg-grad-start: #1f2833;
    --canvas-bg-grad-end: #16213e;
    --grid-color: rgba(255, 255, 255, 0.05);
    --ground-color: #2a3b55;
    --joint-color: #1a1a2e;
}

[data-theme="light"] {
    /* Light Theme Overrides */
    --bg-color: #f0f2f5;
    --container-bg: #ffffff;
    --panel-bg: #f8f9fa;
    --input-bg: #e9ecef;
    --text-color: #2c3e50;
    --secondary-text: #6c757d;
    --accent-color: #ff4757;
    --primary-color: #3498db;
    --border-color: #dee2e6;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --canvas-bg-grad-start: #ffffff;
    --canvas-bg-grad-end: #f0f2f5;
    --grid-color: rgba(0, 0, 0, 0.05);
    --ground-color: #bdc3c7;
    --joint-color: #ffffff;
}

body {
    font-family: 'Roboto', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    box-sizing: border-box;
    transition: background-color 0.3s, color 0.3s;
}

.theme-toggle {
    position: absolute;
    top: 20px;
    right: 20px;
    background: var(--container-bg);
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 10px;
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 10px var(--shadow-color);
    font-size: 1.2rem;
    transition: all 0.3s ease;
    z-index: 100;
}

.theme-toggle:hover {
    transform: scale(1.1);
    color: var(--accent-color);
}

.container {
    width: 100%;
    max-width: 1400px;
    background: var(--container-bg);
    padding: 30px;
    border-radius: 20px;
    box-shadow: 0 10px 30px var(--shadow-color);
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: 30px;
    align-items: start;
    transition: background-color 0.3s, box-shadow 0.3s;
    position: relative;
}

header {
    grid-column: 1 / -1;
    text-align: center;
    margin-bottom: 10px;
}

header h1 {
    color: var(--text-color);
    font-weight: 700;
    letter-spacing: 1px;
    margin: 0;
    text-transform: uppercase;
}

header p {
    color: var(--secondary-text);
    font-size: 0.9rem;
    margin-top: 5px;
}

/* Simulation Area (Canvas) */
.simulation-area {
    width: 100%;
    height: 600px;
    background: radial-gradient(circle at center, var(--canvas-bg-grad-start) 0%, var(--canvas-bg-grad-end) 100%);
    border-radius: 15px;
    position: relative;
    overflow: hidden;
    grid-column: 1 / 2;
    border: 1px solid var(--border-color);
    transition: background 0.3s, border-color 0.3s;
}

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

/* Controls Panel */
.controls {
    grid-column: 2 / 3;
    display: flex;
    flex-direction: column;
    gap: 20px;
    background: var(--panel-bg);
    padding: 25px;
    border-radius: 15px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    transition: background-color 0.3s;
}

.control-group {
    background: var(--input-bg);
    padding: 15px;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    transition: transform 0.2s ease, background-color 0.3s, border-color 0.3s;
}

.control-group:hover {
    transform: translateY(-2px);
    border-color: var(--accent-color);
}

.control-group label {
    display: flex;
    justify-content: space-between;
    font-weight: 500;
    margin-bottom: 10px;
    color: var(--text-color);
    font-size: 0.9rem;
}

.control-group label span {
    color: var(--accent-color);
    font-family: monospace;
    font-size: 1rem;
}

/* Inputs */
input[type="range"] {
    -webkit-appearance: none;
    width: 100%;
    height: 6px;
    background: var(--primary-color);
    border-radius: 5px;
    outline: none;
    margin: 15px 0;
    opacity: 0.8;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--accent-color);
    cursor: pointer;
    box-shadow: 0 0 5px rgba(0,0,0,0.2);
    transition: transform 0.1s;
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.input-row {
    display: flex;
    gap: 10px;
    align-items: center;
}

input[type="number"] {
    background: var(--container-bg);
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 8px;
    border-radius: 5px;
    width: 60px;
    text-align: center;
    font-family: monospace;
    font-weight: bold;
    transition: background-color 0.3s, color 0.3s, border-color 0.3s;
}

/* Info Panel */
.info-panel {
    margin-top: auto;
    background: var(--input-bg);
    padding: 20px;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    text-align: center;
    transition: background-color 0.3s, border-color 0.3s;
}

.info-panel h3 {
    margin: 0 0 15px 0;
    font-size: 1rem;
    color: var(--secondary-text);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.info-data {
    display: flex;
    justify-content: space-around;
}

.coordinate {
    display: flex;
    flex-direction: column;
}

.coordinate .label {
    font-size: 0.8rem;
    color: var(--secondary-text);
}

.coordinate .value {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--accent-color);
    font-family: monospace;
}

/* Responsive Design */
@media (max-width: 968px) {
    .container {
        grid-template-columns: 1fr;
        padding: 20px;
    }

    .simulation-area {
        height: 500px;
    }

    .controls {
        grid-column: 1 / -1;
        flex-direction: row;
        flex-wrap: wrap;
    }

    .control-group {
        flex: 1 1 250px;
    }
}

@media (max-width: 600px) {
    body {
        padding: 10px;
    }

    .container {
        padding: 15px;
    }

    .simulation-area {
        height: 350px;
    }

    header h1 {
        font-size: 1.5rem;
    }
    
    .theme-toggle {
        top: 10px;
        right: 10px;
    }
}