@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --color-bg: #020617;
        --color-bg-alt: #0f172a;
        --color-bg-dark: #1e293b;
        --color-text: #f8fafc;
        --color-text-muted: #94a3b8;
        --color-text-light: #64748b;
        --color-border: #1e293b;
        --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
        --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4);
        --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.5);
    }
}
body, .header, .service-block, .sector-card, .method-card { transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease; }