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

:root {
    --primary-color: #2c3e50;
    --accent-color: #3498db;
    --light-accent: #5dade2;
    --dark-accent: #2874a6;
    --success-color: #27ae60;
    --warning-color: #f39c12;
    --danger-color: #e74c3c;
    --light-bg: #ecf0f1;
    --medium-bg: #bdc3c7;
    --dark-bg: #2c3e50;
    --text-color: #2c3e50;
    --light-text: #ecf0f1;
    --border-radius: 8px;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.tyndall-container {
    max-width: 1400px;
    margin: 0 auto;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

/* Header */
header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 40px 30px;
    text-align: center;
}

header h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
    font-weight: 300;
    letter-spacing: 1px;
}

header .subtitle {
    font-size: 1.1em;
    opacity: 0.9;
    max-width: 800px;
    margin: 0 auto;
}

/* Main Content */
main {
    padding: 30px;
}

/* Mode Selector */
.mode-selector {
    background: var(--light-bg);
    padding: 20px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.mode-selector h3 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.mode-options {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.mode-btn {
    padding: 12px 24px;
    border: 2px solid var(--accent-color);
    background: white;
    color: var(--accent-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1em;
    flex: 1;
    min-width: 150px;
}

.mode-btn:hover {
    background: var(--accent-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.mode-btn.active {
    background: var(--accent-color);
    color: white;
    font-weight: 600;
}

/* Canvas Wrapper */
.canvas-wrapper {
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: 20px;
    margin-bottom: 30px;
}

.canvas-container {
    background: #1a1a2e;
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow);
    min-height: 500px;
}

#tyndallCanvas {
    width: 100%;
    height: 500px;
    background: radial-gradient(ellipse at center, #1a1a2e 0%, #0f0f1e 100%);
    border-radius: var(--border-radius);
}

/* Stats Panel */
.stats-panel {
    background: var(--light-bg);
    padding: 20px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.stats-panel h4 {
    margin-bottom: 15px;
    color: var(--primary-color);
    font-size: 1.1em;
}

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

.stat-item {
    background: white;
    padding: 12px;
    border-radius: var(--border-radius);
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
}

.stat-label {
    display: block;
    font-size: 0.85em;
    color: var(--dark-accent);
    margin-bottom: 5px;
}

.stat-value {
    display: block;
    font-size: 1.5em;
    font-weight: 600;
    color: var(--accent-color);
}

.stat-unit {
    font-size: 0.9em;
    color: var(--medium-bg);
    margin-left: 5px;
}

.color-preview {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 20px;
    color: white;
    font-size: 0.9em;
}

/* Formula Display */
.formula-display {
    background: white;
    padding: 15px;
    border-radius: var(--border-radius);
    border-left: 4px solid var(--accent-color);
}

.formula-main {
    font-size: 1.3em;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
}

.formula-text {
    color: var(--primary-color);
}

.formula-fraction {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    margin: 0 5px;
}

.numerator {
    border-bottom: 2px solid var(--primary-color);
    padding: 2px 8px;
    text-align: center;
}

.denominator {
    padding: 2px 8px;
    text-align: center;
}

.formula-calculation {
    font-size: 0.9em;
    color: var(--dark-accent);
    font-style: italic;
}

/* Solution Properties Panel */
.solution-panel {
    background: var(--light-bg);
    padding: 20px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.solution-panel h3 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.properties-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
}

.property-item {
    background: white;
    padding: 15px;
    border-radius: var(--border-radius);
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.property-label {
    font-size: 0.9em;
    color: var(--dark-accent);
}

.property-value {
    font-size: 1.1em;
    font-weight: 600;
    color: var(--accent-color);
}

/* Controls Panel */
.controls-panel {
    background: var(--light-bg);
    padding: 25px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.controls-panel h3 {
    margin-bottom: 20px;
    color: var(--primary-color);
}

.controls-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    margin-bottom: 25px;
}

.control-group {
    background: white;
    padding: 15px;
    border-radius: var(--border-radius);
}

.control-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.control-group select {
    width: 100%;
    padding: 10px;
    border: 2px solid var(--medium-bg);
    border-radius: var(--border-radius);
    font-size: 1em;
    background: white;
    cursor: pointer;
    transition: border-color 0.3s ease;
}

.control-group select:focus {
    outline: none;
    border-color: var(--accent-color);
}

.control-group input[type="range"] {
    width: 100%;
    margin: 10px 0;
    cursor: pointer;
}

.range-info {
    font-size: 0.85em;
    color: var(--dark-accent);
    margin-top: 5px;
}

.spectrum-bar {
    position: relative;
    height: 20px;
    margin-top: 10px;
    border-radius: 10px;
    overflow: hidden;
}

.spectrum-gradient {
    width: 100%;
    height: 100%;
    background: linear-gradient(to right,
        #8b00ff 0%,
        #0000ff 15%,
        #00ff00 50%,
        #ffff00 70%,
        #ffa500 85%,
        #ff0000 100%
    );
}

.wavelength-marker {
    position: absolute;
    top: 0;
    bottom: 0;
    width: 3px;
    background: white;
    border: 1px solid black;
    transform: translateX(-50%);
    left: 50%;
}

/* Button Group */
.button-group {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 25px;
}

.control-button {
    padding: 12px 20px;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 1em;
    transition: all 0.3s ease;
    font-weight: 500;
}

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

.control-button.reset:hover {
    background: #c0392b;
}

.control-button.toggle {
    background: var(--medium-bg);
    color: var(--primary-color);
}

.control-button.toggle:hover {
    background: var(--dark-accent);
    color: white;
}

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

/* Presets Panel */
.presets-panel {
    background: white;
    padding: 20px;
    border-radius: var(--border-radius);
}

.presets-panel h4 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.preset-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.preset-btn {
    padding: 10px 18px;
    border: 2px solid var(--accent-color);
    background: white;
    color: var(--accent-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.95em;
}

.preset-btn:hover {
    background: var(--accent-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

/* Spectrum Panel */
.spectrum-panel {
    background: var(--light-bg);
    padding: 25px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.spectrum-panel h3 {
    margin-bottom: 20px;
    color: var(--primary-color);
}

.spectrum-comparison {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}

.wavelength-option {
    background: white;
    padding: 20px;
    border-radius: var(--border-radius);
    text-align: center;
}

.color-box {
    width: 60px;
    height: 60px;
    margin: 0 auto 15px;
    border-radius: 50%;
    box-shadow: var(--shadow);
}

.red-box {
    background: #e74c3c;
}

.green-box {
    background: #27ae60;
}

.blue-box {
    background: #3498db;
}

.wavelength-option h4 {
    margin-bottom: 10px;
    color: var(--primary-color);
}

.scattering-level {
    font-size: 0.9em;
    color: var(--dark-accent);
    margin-bottom: 10px;
}

.scattering-bar {
    width: 100%;
    height: 20px;
    background: var(--medium-bg);
    border-radius: 10px;
    overflow: hidden;
}

.scattering-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-color), var(--light-accent));
    transition: width 0.5s ease;
}

.spectrum-explanation {
    background: white;
    padding: 15px;
    border-radius: var(--border-radius);
    border-left: 4px solid var(--accent-color);
}

.spectrum-explanation p {
    color: var(--primary-color);
    font-style: italic;
}

/* Applications Panel */
.applications-panel {
    background: var(--light-bg);
    padding: 25px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.applications-panel h3 {
    margin-bottom: 20px;
    color: var(--primary-color);
}

.applications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.application-card {
    background: white;
    padding: 20px;
    border-radius: var(--border-radius);
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.application-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.15);
}

.application-icon {
    font-size: 2.5em;
    margin-bottom: 15px;
}

.application-card h4 {
    margin-bottom: 10px;
    color: var(--primary-color);
}

.application-card p {
    font-size: 0.9em;
    color: var(--dark-accent);
    line-height: 1.5;
}

/* Explanation Section */
.explanation {
    background: var(--light-bg);
    padding: 30px;
    border-radius: var(--border-radius);
}

.explanation h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
    border-bottom: 3px solid var(--accent-color);
    padding-bottom: 10px;
}

.explanation h3 {
    color: var(--dark-accent);
    margin-top: 25px;
    margin-bottom: 15px;
}

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

.explanation strong {
    color: var(--accent-color);
}

/* Responsive Design */
@media (max-width: 1024px) {
    .canvas-wrapper {
        grid-template-columns: 1fr;
    }

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

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

    header .subtitle {
        font-size: 1em;
    }

    .mode-options {
        flex-direction: column;
    }

    .mode-btn {
        min-width: 100%;
    }

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

    .control-button {
        width: 100%;
    }

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

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

    .spectrum-comparison {
        grid-template-columns: 1fr;
    }
}

/* Animation for particles */
@keyframes twinkle {
    0%, 100% {
        opacity: 0.3;
    }
    50% {
        opacity: 1;
    }
}

/* Loading state */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}