:root {
            --color-white: #ffffff;
            --color-dark-text: #1a202c;
            --color-medium-text: #4a5568;
            --color-light-border: #e2e8f0;
            --color-error: #c53030;
        }
        /* --- File Upload Section --- */
        .upload-card {
            max-width: 42rem;
            margin-left: auto;
            margin-right: auto;
            text-align: center;
        }
        #file-name {
            margin-top: 1rem;
            color: var(--color-medium-text);
            font-size: 0.875rem;
        }

        /* --- Buttons --- */
        .btn {
            cursor: pointer;
            padding: 0.75rem 1.5rem;
            border-radius: 0.5rem;
            color: var(--color-white);
            font-weight: 600;
            transition: background-color 0.2s;
            display: inline-flex;
            align-items: center;
            gap: 0.5rem;
            border: none;
            font-size: 1rem;
            box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
        }
        .btn:focus-visible {
            outline: 3px solid var(--secondary-color);
            outline-offset: 1px;
        }
        .btn-primary {
            background-color: var(--main-color);
        }
        .btn-primary:hover, .btn-primary:focus {
            background-color: var(--secondary-color);
        }
        .btn-sm {
            padding: 0.25rem 0.75rem;
            font-size: 0.875rem;
            font-weight: bold;
            background-color: #6b7280;
        }
        .btn-sm:hover, .btn-sm:focus {
            background-color: #4b5563;
        }
        
        .help-icon {
            border: none;
            background-color: #cbd5e0;
            color: var(--color-dark-text);
            width: 1rem;
            height: 1rem;
            border-radius: 50%;
            padding: 0;
            font-size: 0.75rem;
            line-height: 1rem;
            cursor: pointer;
            margin-left: 0.5rem;
            font-weight: bold;
            transition: background-color 0.2s, color 0.2s;
        }
        .help-icon:hover, .help-icon:focus {
            background-color: var(--secondary-color);
            color: var(--color-white);
            outline: none;
        }

        /* --- Results Section --- */
        #results-container {
            margin-top: 3rem;
        }
        #placeholder {
            text-align: center;
            color: var(--color-medium-text);
        }
        .download-section {
            text-align: center;
            margin-bottom: 2rem;
        }
        .download-section .tip {
            color: var(--color-medium-text);
            font-size: 0.875rem;
            margin-top: 0.5rem;
        }
        .results-grid {
            display: grid;
            grid-template-columns: 1fr;
            gap: 1.5rem;
        }
        @media (min-width: 768px) {
            .results-grid { grid-template-columns: repeat(2, 1fr); }
        }
        @media (min-width: 1024px) {
            .results-grid { grid-template-columns: repeat(3, 1fr); }
        }
        @media (min-width: 1280px) {
            .results-grid { grid-template-columns: repeat(4, 1fr); }
        }

        /* --- Stats Card Styling --- */
        .stats-card {
            display: flex;
            flex-direction: column;
            padding: 1.5rem;
        }
        .stats-card .card-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 0.25rem;
        }
        .stats-card h3 {
            font-size: 1.25rem;
            font-weight: bold;
            margin: 0;
        }
        .stats-card .card-subheader {
            font-size: 0.875rem;
            font-weight: 600;
            margin-bottom: 1rem;
        }
        .type-numeric {
            color: var(--main-color);
        }
        .type-categorical {
            color: #38a169; /* Green color for categorical */
        }
        .stats-card ul {
            list-style: none;
            padding: 0;
            margin: 0;
            font-size: 0.9rem;
        }
        .stats-card li {
            display: flex;
            justify-content: space-between;
            align-items: center;
            border-bottom: 1px solid var(--color-light-border);
            padding: 0.5rem 0;
        }
        .stats-card li:last-child {
            border-bottom: none;
        }
        .stats-card .stat-name {
            font-weight: 600;
            color: var(--color-medium-text);
        }
        .stats-card .stat-value {
            font-weight: bold;
            color: var(--color-dark-text);
        }

        /* --- Error Message --- */
        .error-message {
            background-color: #fed7d7;
            border: 1px solid #f56565;
            color: var(--color-error);
            padding: 1rem;
            border-radius: 0.5rem;
            text-align: center;
            font-weight: bold;
        }

        /* --- Modals --- */
        .modal {
            display: none;
            position: fixed;
            z-index: 1000;
            left: 0; top: 0;
            width: 100%; height: 100%;
            overflow: auto;
            background-color: rgba(0,0,0,0.6);
            align-items: center;
            justify-content: center;
        }
        .modal-content {
            position: relative;
            background-color: var(--color-white);
            margin: auto;
            padding: 2rem;
            border: 1px solid var(--color-light-border);
            width: 90%;
            max-width: 500px;
            border-radius: 0.5rem;
            animation: fadeIn 0.3s;
            color: var(--color-dark-text);
        }
        @keyframes fadeIn {
            from { opacity: 0; transform: scale(0.95); }
            to { opacity: 1; transform: scale(1); }
        }
        .modal-content h3 {
            font-size: 1.5rem;
            font-weight: bold;
            margin-top: 0;
            margin-bottom: 1rem;
        }
        .modal-content p {
            color: var(--color-medium-text);
            line-height: 1.6;
        }
        .modal-content .calculation-box {
            font-size: 0.875rem;
            color: var(--color-medium-text);
            background-color: var(--secondary-background);
            padding: 0.75rem;
            border-radius: 0.25rem;
            margin-top: 1rem;
            border: 1px solid var(--color-light-border);
        }
        .modal-content .calculation-box h4 {
            font-weight: 600;
            color: var(--color-dark-text);
            margin-top: 0;
            margin-bottom: 0.5rem;
        }
        .close-button {
            position: absolute;
            top: 1rem;
            right: 1rem;
            color: #a0aec0;
            font-size: 1.5rem;
            font-weight: bold;
            cursor: pointer;
            line-height: 1;
            background: none;
            border: none;
            padding: 0;
        }
        .close-button:hover, .close-button:focus {
            color: var(--color-dark-text);
            outline: none;
        }
        #distribution-svg-container {
            background-color: var(--secondary-background);
            padding: 1rem;
            border-radius: 0.5rem;
            margin-bottom: 1rem;
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 120px;
        }
        #distribution-svg-container path {
            stroke: var(--main-color);
        }