:root {
    --primary-color: #4a6fa5;
    --primary-light: #6a8cc9;
    --primary-dark: #345284;
    --accent-color: #ff9800;
    --accent-light: #ffb74d;
    --accent-dark: #f57c00;
    --text-dark: #333;
    --text-light: #f8f9fa;
    --bg-light: #f8f9fa;
    --bg-dark: #212529;
    --gray-100: #f8f9fa;
    --gray-200: #e9ecef;
    --gray-300: #dee2e6;
    --gray-400: #ced4da;
    --gray-500: #adb5bd;
    --gray-600: #6c757d;
    --gray-700: #495057;
    --gray-800: #343a40;
    --gray-900: #212529;
    --border-radius: 8px;
    --box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
    }

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

    body {
    font-family: 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
    color: var(--text-dark);
    line-height: 1.6;
    background-color: var(--bg-light);
}

    a {
    text-decoration: none;
    color: var(--primary-color);
    transition: var(--transition);
    }

    a:hover {
    color: var(--primary-dark);
    }

    .container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    }

    /* === Page Header === */
    .page-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 3rem 0;
    margin-bottom: 2rem;
    }
    .page-header h1 {
    color: white;
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    }
    .page-header p {
    font-size: 1.1rem;
    opacity: 0.9;
    max-width: 600px;
    }

    /* Main Content */
    .main-content {
    padding: 2rem 0;
    }

    /* Card Design */
    .card {
    background-color: #fff;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    margin-bottom: 1.5rem;
    overflow: hidden;
    }

    .card-header {
    background-color: var(--primary-color);
    color: var(--text-light);
    padding: 1rem 1.5rem;
    font-weight: 600;
    display: flex;
    justify-content: space-between;
    align-items: center;
    }

    .card-body {
    padding: 1.5rem;
    }

    /* Form Elements */
    .form-group {
    margin-bottom: 1.2rem;
    }

    .form-row {
    display: flex;
    flex-wrap: wrap;
    margin: 0 -0.5rem;
    }

    .form-col {
    flex: 1;
    padding: 0 0.5rem;
    min-width: 200px;
    }

    label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--gray-700);
    }

    .input-group {
    display: flex;
    align-items: center;
    }

    .input-group label {
    margin-bottom: 0;
    margin-right: 0.5rem;
    }

    .form-control {
    width: 100%;
    padding: 0.6rem 0.8rem;
    border: 1px solid var(--gray-300);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
    }

    .form-control:focus {
    border-color: var(--primary-color);
    outline: none;
    box-shadow: 0 0 0 3px rgba(74, 111, 165, 0.1);
    }

    select.form-control {
    cursor: pointer;
    background-color: white;
    }

    /* Buttons */
    .btn {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    padding: 0.7rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
    }

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

    .btn-outline {
    background-color: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    }

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

    .btn-accent {
    background-color: var(--accent-color);
    }

    .btn-accent:hover {
    background-color: var(--accent-dark);
    }

    /* Toggle Switch */
    .switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 24px;
    margin: 0 10px;
    }

    .switch input {
    opacity: 0;
    width: 0;
    height: 0;
    }

    .slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--gray-300);
    transition: .4s;
    border-radius: 24px;
    }

    .slider:before {
    position: absolute;
    content: "";
    height: 16px;
    width: 16px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
    }

    input:checked + .slider {
    background-color: var(--primary-color);
    }

    input:focus + .slider {
    box-shadow: 0 0 1px var(--primary-color);
    }

    input:checked + .slider:before {
    transform: translateX(26px);
    }

    /* Results Section */
    .result-section {
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--gray-200);
    }

    .result-box {
    background-color: var(--gray-100);
    border-radius: var(--border-radius);
    padding: 1rem;
    margin-bottom: 1rem;
    }

    .result-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    }

    .result-explanation {
    font-size: 0.95rem;
    color: var(--gray-700);
    }

    /* Chart container */
    .chart-container {
    position: relative;
    height: 300px;
    margin: 1.5rem 0;
    }

    /* Tooltips */
    .tooltip-icon {
    display: inline-block;
    width: 18px;
    height: 18px;
    background-color: var(--gray-500);
    color: white;
    border-radius: 50%;
    text-align: center;
    line-height: 18px;
    font-size: 12px;
    margin-left: 5px;
    cursor: help;
    position: relative;
    }

    .tooltip-content {
    position: absolute;
    z-index: 10;
    width: 200px;
    background-color: var(--gray-800);
    color: white;
    padding: 10px;
    border-radius: var(--border-radius);
    font-size: 0.85rem;
    visibility: hidden;
    opacity: 0;
    transition: opacity 0.3s;
    bottom: 125%;
    left: 50%;
    transform: translateX(-50%);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
    }

    .tooltip-icon:hover .tooltip-content {
    visibility: visible;
    opacity: 1;
    }

    .tooltip-content:after {
    content: "";
    position: absolute;
    top: 100%;
    left: 50%;
    margin-left: -5px;
    border-width: 5px;
    border-style: solid;
    border-color: var(--gray-800) transparent transparent transparent;
    }

    /* Comparison section */
    .comparison-section {
    margin-top: 2rem;
    padding: 1.5rem;
    background-color: rgba(74, 111, 165, 0.05);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary-color);
    }

    .comparison-title {
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--primary-dark);
    }

    .comparison-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    }

    .stat-card {
    background: white;
    padding: 1rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    }

    .stat-label {
    font-size: 0.9rem;
    color: var(--gray-600);
    margin-bottom: 0.3rem;
    }

    .stat-value {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--primary-color);
    }

    /* Learning resources */
    .learning-resources {
    margin-top: 2rem;
    }

    .resource-cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 1rem;
    margin-top: 1rem;
    }

    .resource-card {
    border: 1px solid var(--gray-200);
    border-radius: var(--border-radius);
    padding: 1rem;
    transition: var(--transition);
    }

    .resource-card:hover {
    border-color: var(--primary-color);
    transform: translateY(-2px);
    }

    .resource-title {
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
    }

    .resource-source {
    font-size: 0.85rem;
    color: var(--gray-600);
    }

    /* Formula display */
    .formula-display {
    background-color: white;
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin: 1rem 0;
    box-shadow: var(--box-shadow);
    overflow-x: auto;
    }

    /* Media Queries */
    @media (max-width: 992px) {
    nav ul {
        flex-wrap: wrap;
    }
    nav li {
        margin-left: 1rem;
    }
    }

    @media (max-width: 768px) {
    .comparison-grid {
        grid-template-columns: 1fr;
    }
    }

    @media (max-width: 576px) {
    header .container {
        flex-direction: column;
        text-align: center;
    }
    nav {
        margin-top: 1rem;
    }
    nav ul {
        justify-content: center;
    }
    nav li {
        margin: 0 0.5rem;
    }
    }

    /* Toggle buttons for chart display */
    .chart-toggle {
    display: flex;
    justify-content: center;
    margin: 1rem 0;
    }

    .chart-toggle button {
    background-color: var(--gray-200);
    border: none;
    padding: 0.5rem 1rem;
    cursor: pointer;
    font-weight: 500;
    transition: var(--transition);
    }

    .chart-toggle button:first-child {
    border-radius: var(--border-radius) 0 0 var(--border-radius);
    }

    .chart-toggle button:last-child {
    border-radius: 0 var(--border-radius) var(--border-radius) 0;
    }

    .chart-toggle button.active {
    background-color: var(--primary-color);
    color: white;
    }

    .calculation-steps {
    background-color: var(--gray-100);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary-color);
    padding: 1rem;
    margin: 1rem 0;
    font-size: 0.95rem;
    }

    /* Make the math formulas look better */
    .katex-display {
    overflow-x: auto;
    overflow-y: hidden;
    margin: 1rem 0;
    }