:root {
            color-scheme: light;
            --bg-color: #f8f9fa;
            --toolbar-bg: white;
            --toolbar-border: #e1e5e9;
            --toolbar-shadow: rgba(0, 0, 0, 0.1);
            --text-color: #374151;
            --btn-bg: transparent;
            --btn-border: #e1e5e9;
            --btn-hover-bg: #f3f4f6;
            --btn-hover-border: #d1d5db;
            --btn-active-bg: #3b82f6;
            --btn-active-border: #3b82f6;
            --btn-active-color: white;
            --canvas-bg: white;
            --modal-bg: #fefefe;
            --modal-border: #888;
            --modal-close-color: #aaa;
            --export-btn-bg: #f0f0f0;
            --export-btn-border: #ccc;
            --export-btn-hover-bg: #e0e0e0;
            --toast-bg: #1f2937;
            --toast-color: #ffffff;
            --toast-error-bg: #b91c1c;
            --focus-ring: #3b82f6;
        }

        body.dark-mode {
            color-scheme: dark;
            --bg-color: #1a1a1a;
            --toolbar-bg: #2c2c2c;
            --toolbar-border: #3a3a3a;
            --toolbar-shadow: rgba(0, 0, 0, 0.3);
            --text-color: #e0e0e0;
            --btn-bg: #3a3a3a;
            --btn-border: #4a4a4a;
            --btn-hover-bg: #4a4a4a;
            --btn-hover-border: #5a5a5a;
            --btn-active-bg: #3b82f6;
            --btn-active-border: #3b82f6;
            --btn-active-color: white;
            --canvas-bg: #2c2c2c;
            --modal-bg: #2c2c2c;
            --modal-border: #4a4a4a;
            --modal-close-color: #b0b0b0;
            --export-btn-bg: #3a3a3a;
            --export-btn-border: #4a4a4a;
            --export-btn-hover-bg: #4a4a4a;
            --toast-bg: #e5e7eb;
            --toast-color: #111827;
            --toast-error-bg: #dc2626;
        }

        [hidden] {
            display: none !important;
        }

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

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: var(--bg-color);
            overflow: hidden;
            color: var(--text-color);
            transition: background-color 0.3s ease, color 0.3s ease;
        }

        .container {
            height: 100vh;
            display: flex;
            flex-direction: column;
            position: relative;
        }

        .close-btn:hover,
        .close-btn:focus-visible {
            color: var(--text-color);
            text-decoration: none;
        }

        /* Keyboard focus indicator for all interactive controls */
        .tool-btn:focus-visible,
        .action-btn:focus-visible,
        .export-btn:focus-visible,
        .choice-btn:focus-visible,
        .close-btn:focus-visible,
        input:focus-visible,
        select:focus-visible {
            outline: 2px solid var(--focus-ring);
            outline-offset: 2px;
        }

        /* Animations */
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(-10px); }
            to { opacity: 1; transform: translateY(0); }
        }

        @media (prefers-reduced-motion: reduce) {
            * {
                animation-duration: 0.01ms !important;
                transition-duration: 0.01ms !important;
            }
        }