:root {
    --bg-primary: #0a0e27;
    --bg-secondary: #1a1f3a;
    --bg-tertiary: #252b4a;
    --text-primary: #e8eaed;
    --text-secondary: #a8b2d1;
    --text-muted: #6a7192;
    --accent-primary: #7c3aed;
    --accent-secondary: #a78bfa;
    --accent-hover: #8b5cf6;
    --success: #22c55e;
    --warning: #f59e0b;
    --danger: #ef4444;
    --border-color: #2d3561;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, var(--bg-primary) 0%, #1a1f3a 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 30px;
    padding: 30px 20px;
    background: var(--bg-secondary);
    border-radius: 12px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

header h1 {
    font-size: 3rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--accent-secondary) 0%, var(--accent-primary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 10px;
}

header h2 {
    font-size: 1.5rem;
    color: var(--text-secondary);
    font-weight: 500;
    margin-bottom: 10px;
}

.subtitle {
    color: var(--text-muted);
    font-size: 0.95rem;
    max-width: 700px;
    margin: 0 auto;
}

/* Main Content */
.main-content {
    display: grid;
    grid-template-columns: 1fr 380px;
    gap: 20px;
    margin-bottom: 30px;
}

@media (max-width: 1100px) {
    .main-content {
        grid-template-columns: 1fr;
    }
}

/* Canvas Section */
.canvas-section {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.canvas-container {
    position: relative;
    margin-bottom: 20px;
}

#laplaceCanvas {
    display: block;
    width: 100%;
    max-width: 600px;
    height: auto;
    margin: 0 auto;
    border-radius: 8px;
    cursor: crosshair;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
}

.canvas-info {
    display: flex;
    justify-content: space-around;
    margin-top: 15px;
    padding: 12px;
    background: var(--bg-tertiary);
    border-radius: 8px;
    font-size: 0.9rem;
}

.canvas-info span {
    color: var(--text-secondary);
}

.canvas-info span:nth-child(2) {
    color: var(--accent-secondary);
    font-weight: 600;
}

/* Mode Selector */
.mode-selector {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

.mode-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 12px 8px;
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 0.85rem;
    font-weight: 500;
}

.mode-btn:hover {
    background: var(--bg-secondary);
    border-color: var(--accent-primary);
    color: var(--text-primary);
}

.mode-btn.active {
    background: var(--accent-primary);
    border-color: var(--accent-primary);
    color: white;
}

.mode-icon {
    font-size: 1.5rem;
    font-weight: 700;
}

/* Controls Section */
.controls-section {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    max-height: calc(100vh - 100px);
    overflow-y: auto;
}

.control-group {
    margin-bottom: 25px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
}

.control-group:last-child {
    border-bottom: none;
    margin-bottom: 0;
}

.control-group h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.control-group h3::before {
    content: '▸';
    color: var(--accent-primary);
}

select {
    width: 100%;
    padding: 10px 12px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: border-color 0.2s;
}

select:hover,
select:focus {
    outline: none;
    border-color: var(--accent-primary);
}

/* Sliders */
.slider-group {
    margin-bottom: 15px;
}

.slider-group label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-bottom: 8px;
}

.slider-group small {
    display: block;
    color: var(--text-muted);
    font-size: 0.75rem;
    margin-top: 4px;
}

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

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

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

input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    background: var(--accent-primary);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    transition: background 0.2s;
}

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

/* Checkboxes */
.checkbox-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.checkbox-group label {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    font-size: 0.9rem;
    cursor: pointer;
    padding: 6px 8px;
    border-radius: 6px;
    transition: background 0.2s;
}

.checkbox-group label:hover {
    background: var(--bg-tertiary);
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    font-size: 0.9rem;
    cursor: pointer;
    padding: 8px 12px;
    background: var(--bg-tertiary);
    border-radius: 6px;
    transition: background 0.2s;
}

.checkbox-label:hover {
    background: var(--bg-secondary);
}

input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
    accent-color: var(--accent-primary);
}

/* Buttons */
.preset-buttons {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
}

.preset-btn {
    padding: 10px 12px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-secondary);
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.2s;
}

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

.action-buttons {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 10px;
}

.action-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 16px;
    border: none;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-icon {
    font-size: 1.1rem;
}

.action-btn.primary {
    background: var(--accent-primary);
    color: white;
    grid-column: span 2;
}

.action-btn.primary:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(124, 58, 237, 0.4);
}

.action-btn.secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.action-btn.secondary:hover {
    background: var(--bg-secondary);
    border-color: var(--accent-primary);
}

.action-btn.danger {
    background: var(--danger);
    color: white;
    grid-column: span 2;
}

.action-btn.danger:hover {
    background: #dc2626;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.4);
}

/* Convergence Info */
.convergence-info {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    margin-bottom: 15px;
}

.info-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 10px;
    background: var(--bg-tertiary);
    border-radius: 6px;
}

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

.info-value {
    font-size: 0.9rem;
    color: var(--accent-secondary);
    font-weight: 600;
    font-family: 'Courier New', monospace;
}

/* Info Panel */
.info-panel {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: 25px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    margin-bottom: 20px;
}

.info-panel h3 {
    font-size: 1.3rem;
    margin-bottom: 15px;
    color: var(--text-primary);
}

.info-panel p {
    color: var(--text-secondary);
    margin-bottom: 20px;
    line-height: 1.7;
}

.info-sections {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
}

.info-section h4 {
    font-size: 1rem;
    color: var(--accent-secondary);
    margin-bottom: 10px;
}

.info-section ul {
    list-style: none;
    padding-left: 0;
}

.info-section li {
    color: var(--text-secondary);
    padding: 4px 0;
    padding-left: 20px;
    position: relative;
}

.info-section li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--accent-primary);
}

.info-section strong {
    color: var(--text-primary);
}

/* Footer */
footer {
    text-align: center;
    padding: 20px;
    color: var(--text-muted);
    font-size: 0.85rem;
}

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

.controls-section::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
    border-radius: 4px;
}

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

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

/* Animations */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.7;
    }
}

.mode-btn.active .mode-icon {
    animation: pulse 2s ease-in-out infinite;
}

/* Responsive */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    header h2 {
        font-size: 1.2rem;
    }

    .mode-selector {
        grid-template-columns: repeat(2, 1fr);
    }

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

    .convergence-info {
        grid-template-columns: 1fr;
    }

    .info-sections {
        grid-template-columns: 1fr;
    }
}