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

:root {
    --primary-color: #0891b2;
    --secondary-color: #7c3aed;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --info-color: #0ea5e9;
    --dark-color: #0f172a;
    --light-color: #f0f9ff;
    --border-color: #e2e8f0;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --bg-gradient: linear-gradient(135deg, #0891b2 0%, #0ea5e9 50%, #7c3aed 100%);
    --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --hover-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

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

.stm-container {
    max-width: 1400px;
    margin: 0 auto;
    background: white;
    border-radius: 16px;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    overflow: hidden;
}

header {
    background: var(--bg-gradient);
    color: white;
    padding: 40px;
    text-align: center;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

header .subtitle {
    font-size: 1.1rem;
    opacity: 0.95;
    font-weight: 300;
}

main {
    padding: 40px;
}

.visualization-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    margin-bottom: 40px;
}

@media (max-width: 1024px) {
    .visualization-layout {
        grid-template-columns: 1fr;
    }
}

.setup-panel,
.imaging-panel {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.setup-display,
.tunneling-display,
.scan-display,
.image-display {
    background: var(--light-color);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--card-shadow);
    transition: box-shadow 0.3s ease;
}

.setup-display:hover,
.tunneling-display:hover,
.scan-display:hover,
.image-display:hover {
    box-shadow: var(--hover-shadow);
}

.setup-display h3,
.tunneling-display h3,
.scan-display h3,
.image-display h3 {
    color: var(--primary-color);
    font-size: 1.2rem;
    margin-bottom: 15px;
    font-weight: 600;
}

canvas {
    width: 100%;
    border-radius: 8px;
    background: white;
    box-shadow: inset 0 2px 4px 0 rgba(0, 0, 0, 0.06);
}

#setupCanvas {
    height: 300px;
}

#tunnelingCanvas {
    height: 250px;
}

#scanCanvas {
    height: 280px;
}

#imageCanvas {
    height: 350px;
}

.setup-info,
.tunneling-info,
.scan-legend {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-top: 15px;
    padding: 12px;
    background: white;
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

.info-item {
    flex: 1;
    min-width: 150px;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.info-item span:first-child {
    font-weight: 600;
    color: var(--text-primary);
}

.info-item span:nth-child(2) {
    color: var(--info-color);
    font-weight: 700;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.legend-color {
    width: 20px;
    height: 20px;
    border-radius: 4px;
    flex-shrink: 0;
}

.image-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 15px;
}

.image-btn {
    flex: 1;
    min-width: 100px;
    padding: 8px 12px;
    border: 2px solid var(--primary-color);
    border-radius: 6px;
    background: white;
    color: var(--primary-color);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.image-btn:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(8, 145, 178, 0.3);
}

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

.controls-panel {
    background: var(--light-color);
    border-radius: 12px;
    padding: 30px;
    margin-bottom: 40px;
    box-shadow: var(--card-shadow);
}

.controls-panel h3 {
    color: var(--primary-color);
    font-size: 1.5rem;
    margin-bottom: 25px;
    font-weight: 600;
}

.controls-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
    margin-bottom: 25px;
}

.control-group {
    background: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
}

.control-group h4 {
    color: var(--secondary-color);
    font-size: 1rem;
    margin-bottom: 15px;
    font-weight: 600;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 8px;
}

.control-group label {
    display: block;
    margin-bottom: 12px;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.control-group label span:first-child {
    font-weight: 500;
}

.control-group input[type="range"] {
    width: 100%;
    margin-bottom: 15px;
    height: 6px;
    border-radius: 3px;
    background: var(--border-color);
    outline: none;
    -webkit-appearance: none;
}

.control-group input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
    transition: all 0.2s ease;
}

.control-group input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
    box-shadow: 0 3px 6px rgba(0, 0, 0, 0.3);
}

.control-group input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
    transition: all 0.2s ease;
}

.control-group input[type="range"]::-moz-range-thumb:hover {
    transform: scale(1.2);
    box-shadow: 0 3px 6px rgba(0, 0, 0, 0.3);
}

.control-group select {
    width: 100%;
    padding: 10px;
    margin-bottom: 15px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.9rem;
    background: white;
    cursor: pointer;
}

.checkbox-input {
    margin-right: 10px;
    width: 18px;
    height: 18px;
    cursor: pointer;
}

.control-group label:has(input[type="checkbox"]) {
    display: flex;
    align-items: center;
    margin-bottom: 10px;
    cursor: pointer;
}

.preset-btn {
    width: 100%;
    padding: 10px;
    margin-bottom: 10px;
    border: 2px solid var(--primary-color);
    border-radius: 6px;
    background: white;
    color: var(--primary-color);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.preset-btn:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(8, 145, 178, 0.3);
}

.button-group {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-bottom: 30px;
}

.control-button {
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.control-button.start {
    background: var(--success-color);
    color: white;
}

.control-button.start:hover {
    background: #059669;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(16, 185, 129, 0.3);
}

.control-button.pause {
    background: var(--warning-color);
    color: white;
}

.control-button.pause:hover {
    background: #d97706;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(245, 158, 11, 0.3);
}

.control-button.reset {
    background: var(--danger-color);
    color: white;
}

.control-button.reset:hover {
    background: #dc2626;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(239, 68, 68, 0.3);
}

.formulas-section {
    background: white;
    border-radius: 8px;
    padding: 25px;
    box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
}

.formulas-section h3 {
    color: var(--primary-color);
    font-size: 1.3rem;
    margin-bottom: 20px;
    font-weight: 600;
}

.formula-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 15px;
}

.formula-item {
    display: flex;
    flex-direction: column;
    gap: 5px;
    padding: 12px;
    background: var(--light-color);
    border-radius: 6px;
    border-left: 4px solid var(--secondary-color);
}

.formula-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.formula {
    font-family: 'Courier New', monospace;
    font-size: 1rem;
    color: var(--text-primary);
    font-weight: 600;
}

.explanation {
    background: white;
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--card-shadow);
}

.explanation h2 {
    color: var(--primary-color);
    font-size: 1.8rem;
    margin-bottom: 20px;
    font-weight: 600;
}

.explanation h3 {
    color: var(--secondary-color);
    font-size: 1.3rem;
    margin-top: 25px;
    margin-bottom: 15px;
    font-weight: 600;
}

.explanation p {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.8;
    margin-bottom: 15px;
}

.explanation strong {
    color: var(--text-primary);
    font-weight: 600;
}

@media (max-width: 768px) {
    body {
        padding: 10px;
    }

    header {
        padding: 20px;
    }

    header h1 {
        font-size: 1.8rem;
    }

    header .subtitle {
        font-size: 0.95rem;
    }

    main {
        padding: 20px;
    }

    .controls-grid {
        grid-template-columns: 1fr;
    }

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

    .formula-list {
        grid-template-columns: 1fr;
    }

    .explanation h2 {
        font-size: 1.5rem;
    }

    .explanation h3 {
        font-size: 1.1rem;
    }
}