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

:root {
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --success: #16a34a;
    --error: #dc2626;
    --secondary: #6b7280;
    --background: #f9fafb;
    --surface: #ffffff;
    --border: #e5e7eb;
    --text: #111827;
    --text-light: #6b7280;
    --shadow: rgba(0, 0, 0, 0.08);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--background);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    padding: 20px;
}

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

header {
    background: var(--surface);
    padding: 30px;
    border-radius: 8px;
    border: 1px solid var(--border);
    box-shadow: 0 1px 3px var(--shadow);
    margin-bottom: 30px;
    text-align: center;
}

header h1 {
    font-size: 2rem;
    color: var(--text);
    margin-bottom: 10px;
    font-weight: 600;
}

header p {
    color: var(--text-light);
    font-size: 1rem;
}

/* Panel Layout */
.panel-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}

.panel {
    background: var(--surface);
    padding: 30px;
    border-radius: 8px;
    border: 1px solid var(--border);
    box-shadow: 0 1px 3px var(--shadow);
}

.panel h2 {
    font-size: 1.5rem;
    color: var(--text);
    margin-bottom: 15px;
    font-weight: 600;
}

.instructions {
    color: var(--text-light);
    margin-bottom: 20px;
    font-size: 0.95rem;
}

/* Grid Editor */
#grid-container {
    display: inline-grid;
    gap: 2px;
    padding: 20px;
    background: var(--background);
    border-radius: 4px;
    margin: 20px 0;
    border: 1px solid var(--border);
}

.grid-cell {
    width: 50px;
    height: 50px;
    background: white;
    border: 1px solid var(--border);
    cursor: pointer;
    transition: all 0.15s ease;
}

.grid-cell:hover {
    border-color: var(--primary);
    background: #eff6ff;
}

.grid-cell.filled {
    background: var(--primary);
    border-color: var(--primary-dark);
}

/* Buttons */
.button-group {
    display: flex;
    gap: 15px;
    margin-top: 20px;
}

.btn {
    padding: 10px 20px;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.15s ease;
    background: white;
    color: var(--text);
}

.btn:hover {
    border-color: var(--primary);
    background: #eff6ff;
}

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

.btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
    background: var(--background);
}

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

.btn-primary:hover:not(:disabled) {
    background: var(--primary-dark);
    border-color: var(--primary-dark);
}

.btn-success {
    background: var(--success);
    color: white;
    border-color: var(--success);
    width: 100%;
    padding: 12px;
    font-size: 1rem;
    margin-top: 20px;
}

.btn-success:hover:not(:disabled) {
    background: #15803d;
    border-color: #15803d;
}

.btn-secondary {
    background: white;
    color: var(--text);
    border-color: var(--border);
}

.btn-secondary:hover {
    background: var(--background);
}

/* Messages */
.message {
    margin-top: 20px;
    padding: 12px;
    border-radius: 4px;
    font-weight: 500;
    text-align: center;
    opacity: 0;
    transition: opacity 0.2s ease;
    font-size: 0.95rem;
}

.message.show {
    opacity: 1;
}

.message.success {
    background: #dcfce7;
    color: #15803d;
    border: 1px solid #86efac;
}

.message.error {
    background: #fee2e2;
    color: #991b1b;
    border: 1px solid #fca5a5;
}

/* Info Panel */
.info-content h3 {
    color: var(--text);
    font-size: 1.1rem;
    margin: 20px 0 10px;
    font-weight: 600;
}

.info-content p {
    color: var(--text-light);
    margin-bottom: 15px;
}

.info-content ul,
.info-content ol {
    color: var(--text-light);
    margin-left: 20px;
    margin-bottom: 15px;
}

.info-content li {
    margin-bottom: 8px;
}

.stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
    margin: 20px 0;
}

.stat {
    background: var(--background);
    padding: 15px;
    border-radius: 8px;
    text-align: center;
}

.stat-label {
    display: block;
    color: var(--text-light);
    font-size: 0.9rem;
    margin-bottom: 5px;
}

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
}

/* Visualization Mode */
.viz-header {
    background: var(--surface);
    padding: 20px 30px;
    border-radius: 8px;
    border: 1px solid var(--border);
    box-shadow: 0 1px 3px var(--shadow);
    margin-bottom: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.viz-header h2 {
    color: var(--text);
    font-size: 1.5rem;
    font-weight: 600;
}

.viz-container {
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: 20px;
}

#canvas-container {
    background: var(--surface);
    border-radius: 8px;
    border: 1px solid var(--border);
    box-shadow: 0 1px 3px var(--shadow);
    overflow: hidden;
    position: relative;
    min-height: 600px;
}

#viz-canvas {
    width: 100%;
    height: 100%;
    display: block;
}

.viz-controls {
    background: var(--surface);
    padding: 25px;
    border-radius: 8px;
    border: 1px solid var(--border);
    box-shadow: 0 1px 3px var(--shadow);
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.control-group label {
    font-weight: 600;
    color: var(--text);
    font-size: 0.9rem;
}

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

.control-group input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    background: var(--primary);
    border-radius: 50%;
    cursor: pointer;
    border: 2px solid white;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
}

.control-group input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    background: var(--primary);
    border-radius: 50%;
    cursor: pointer;
    border: 2px solid white;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
}

#speed-value {
    text-align: center;
    font-weight: 600;
    color: var(--primary);
}

.progress-bar {
    width: 100%;
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--primary);
    width: 0%;
    transition: width 0.2s ease;
}

.control-info {
    background: var(--background);
    padding: 15px;
    border-radius: 8px;
    margin-top: auto;
}

.control-info p {
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--text);
}

.control-info ul {
    list-style: none;
    color: var(--text-light);
    font-size: 0.9rem;
}

.control-info li {
    margin-bottom: 5px;
}

/* Responsive Design */
@media (max-width: 1200px) {
    .panel-container {
        grid-template-columns: 1fr;
    }

    .viz-container {
        grid-template-columns: 1fr;
    }

    .viz-controls {
        flex-direction: row;
        flex-wrap: wrap;
    }

    .control-group {
        flex: 1;
        min-width: 200px;
    }
}

@media (max-width: 768px) {
    header h1 {
        font-size: 1.8rem;
    }

    .grid-cell {
        width: 40px;
        height: 40px;
    }

    .button-group {
        flex-direction: column;
    }
}

/* Loading Animation */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.loading {
    animation: pulse 1.5s ease-in-out infinite;
}