:root {
    --bg-color: #0a0e14;
    --card-bg: rgba(20, 25, 35, 0.8);
    --accent-blue: #00d2ff;
    --accent-purple: #9d50bb;
    --text-primary: #e0e6ed;
    --text-secondary: #94a3b8;
    --neon-shadow: 0 0 15px rgba(0, 210, 255, 0.5);
    --glass-border: rgba(255, 255, 255, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    overflow: hidden;
    height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    padding: 1.5rem 2rem;
    background: linear-gradient(to right, rgba(10, 14, 20, 0.9), rgba(20, 25, 35, 0.5));
    border-bottom: 1px solid var(--glass-border);
    backdrop-filter: blur(10px);
    z-index: 10;
}

header h1 {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(to right, var(--accent-blue), var(--accent-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.5px;
}

header p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

main {
    flex: 1;
    display: flex;
    position: relative;
    overflow: hidden;
    background: radial-gradient(circle at 50% 50%, #171f2d 0%, #0a0e14 100%);
}

#canvas-container {
    flex: 1;
    position: relative;
    background: radial-gradient(circle at 50% 50%, #1e293b 0%, #0a0e14 100%);
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

canvas {
    display: block;
    box-shadow: 0 30px 100px rgba(0, 0, 0, 0.5);
    background: transparent;
}

.drag-hint {
    position: absolute;
    top: 2rem;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0, 210, 255, 0.1);
    border: 1px solid rgba(0, 210, 255, 0.3);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.8rem;
    color: var(--accent-blue);
    pointer-events: none;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% { opacity: 0.6; }
    50% { opacity: 1; }
    100% { opacity: 0.6; }
}

#ui-panel {
    width: 350px;
    background: var(--card-bg);
    backdrop-filter: blur(20px);
    border-left: 1px solid var(--glass-border);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
    z-index: 20;
    box-shadow: -10px 0 30px rgba(0, 0, 0, 0.5);
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.control-label {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.control-label span:first-child {
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.value-display {
    font-family: 'JetBrains Mono', 'Courier New', monospace;
    font-size: 1.1rem;
    color: var(--accent-blue);
    font-weight: 700;
}

input[type="range"] {
    -webkit-appearance: none;
    width: 100%;
    height: 6px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 3px;
    outline: none;
}

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

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

.metrics-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.metric-card {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--glass-border);
    padding: 1rem;
    border-radius: 12px;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.metric-card span:first-child {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.metric-card span:last-child {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

.formula-box {
    margin-top: auto;
    background: rgba(0, 210, 255, 0.05);
    border: 1px solid rgba(0, 210, 255, 0.2);
    padding: 1rem;
    border-radius: 12px;
    font-size: 0.85rem;
    line-height: 1.6;
    color: var(--text-secondary);
}

.formula-box code {
    color: var(--accent-blue);
    font-weight: 600;
}

.btn-reset {
    background: linear-gradient(45deg, var(--accent-blue), var(--accent-purple));
    border: none;
    color: white;
    padding: 0.75rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s;
}

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

/* Tooltip for vector explanation */
.overlay-info {
    position: absolute;
    bottom: 2rem;
    left: 2rem;
    background: rgba(0, 0, 0, 0.6);
    padding: 0.75rem 1rem;
    border-radius: 8px;
    font-size: 0.8rem;
    color: var(--text-secondary);
    pointer-events: none;
    border: 1px solid var(--glass-border);
}

.vector-legend {
    display: flex;
    gap: 1.5rem;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
}

.dot.v { background: #ff4757; }
.dot.a { background: #2ed573; }
.dot.r { background: var(--accent-blue); }