/**
 * N-Body Gravity Simulator Styles
 * Dark space theme with modern UI controls
 */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --bg-primary: #0a0a14;
    --bg-secondary: #12121f;
    --bg-tertiary: #1a1a2e;
    --text-primary: #e0e0e0;
    --text-secondary: #a0a0b0;
    --accent: #4a9eff;
    --accent-hover: #6ab3ff;
    --border: #2a2a40;
    --success: #4ade80;
    --warning: #fbbf24;
    --danger: #f87171;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow: hidden;
}

.container {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

header {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    padding: 1rem 2rem;
    text-align: center;
}

header h1 {
    font-size: 1.8rem;
    font-weight: 600;
    color: var(--accent);
    margin-bottom: 0.25rem;
}

.subtitle {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.main-content {
    display: flex;
    flex: 1;
    overflow: hidden;
}

.controls-panel {
    width: 320px;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border);
    padding: 1.5rem;
    overflow-y: auto;
    flex-shrink: 0;
}

.control-group {
    margin-bottom: 2rem;
}

.control-group h3 {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    border-bottom: 2px solid var(--border);
    padding-bottom: 0.5rem;
}

.preset-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.5rem;
}

.preset-btn {
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    color: var(--text-primary);
    padding: 0.6rem 0.8rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.8rem;
    transition: all 0.2s ease;
}

.preset-btn:hover {
    background: var(--accent);
    border-color: var(--accent);
    color: white;
    transform: translateY(-1px);
}

.control-item {
    margin-bottom: 1rem;
}

.control-item label {
    display: block;
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 0.4rem;
}

.control-item input[type="range"] {
    width: 100%;
    height: 6px;
    -webkit-appearance: none;
    appearance: none;
    background: var(--bg-tertiary);
    border-radius: 3px;
    outline: none;
}

.control-item input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    background: var(--accent);
    border-radius: 50%;
    cursor: pointer;
    transition: background 0.2s ease;
}

.control-item input[type="range"]::-webkit-slider-thumb:hover {
    background: var(--accent-hover);
}

.control-item input[type="range"]::-moz-range-thumb {
    width: 16px;
    height: 16px;
    background: var(--accent);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    transition: background 0.2s ease;
}

.control-item input[type="range"]::-moz-range-thumb:hover {
    background: var(--accent-hover);
}

.control-item span {
    display: inline-block;
    font-size: 0.85rem;
    color: var(--accent);
    margin-left: 0.5rem;
    min-width: 40px;
    text-align: right;
}

.toggle-group {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.toggle {
    display: flex;
    align-items: center;
    cursor: pointer;
    font-size: 0.85rem;
    color: var(--text-primary);
}

.toggle input[type="checkbox"] {
    display: none;
}

.toggle span {
    position: relative;
    padding-left: 2rem;
}

.toggle span::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 36px;
    height: 20px;
    background: var(--bg-tertiary);
    border-radius: 10px;
    border: 1px solid var(--border);
    transition: all 0.2s ease;
}

.toggle span::after {
    content: '';
    position: absolute;
    left: 2px;
    top: 50%;
    transform: translateY(-50%);
    width: 16px;
    height: 16px;
    background: var(--text-secondary);
    border-radius: 50%;
    transition: all 0.2s ease;
}

.toggle input[type="checkbox"]:checked + span::before {
    background: var(--accent);
    border-color: var(--accent);
}

.toggle input[type="checkbox"]:checked + span::after {
    left: 20px;
    background: white;
}

.sim-buttons {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.control-btn {
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    color: var(--text-primary);
    padding: 0.7rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s ease;
}

.control-btn:hover {
    background: var(--accent);
    border-color: var(--accent);
    color: white;
}

.control-btn:active {
    transform: scale(0.98);
}

.add-body-controls {
    color: var(--text-secondary);
}

.hint {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-top: 0.5rem;
    font-style: italic;
}

.simulation-area {
    flex: 1;
    position: relative;
    background: var(--bg-primary);
    overflow: hidden;
}

#simCanvas {
    display: block;
    width: 100%;
    height: 100%;
    cursor: crosshair;
}

.canvas-overlay {
    position: absolute;
    top: 1rem;
    right: 1rem;
    pointer-events: none;
}

.stats-panel {
    background: rgba(18, 18, 31, 0.9);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1rem;
    min-width: 200px;
}

.stat-item {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
    font-size: 0.85rem;
}

.stat-item:last-child {
    margin-bottom: 0;
}

.stat-label {
    color: var(--text-secondary);
}

.stat-value {
    color: var(--accent);
    font-family: 'Courier New', monospace;
    font-weight: 600;
}

footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border);
    padding: 0.75rem 2rem;
    text-align: center;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Scrollbar styling */
.controls-panel::-webkit-scrollbar {
    width: 8px;
}

.controls-panel::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

.controls-panel::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 4px;
}

.controls-panel::-webkit-scrollbar-thumb:hover {
    background: var(--accent);
}

/* Responsive design */
@media (max-width: 768px) {
    .main-content {
        flex-direction: column;
    }

    .controls-panel {
        width: 100%;
        height: 40%;
        border-right: none;
        border-bottom: 1px solid var(--border);
    }

    .simulation-area {
        height: 60%;
    }

    header h1 {
        font-size: 1.4rem;
    }

    .preset-buttons {
        grid-template-columns: 1fr;
    }
}