/* Base Styles */
        :root {
            --primary-color: #2c3e50;
            --secondary-color: #e74c3c;
        }

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

        body {
            font-family: 'Segoe UI', system-ui, sans-serif;
            line-height: 1.6;
            min-height: 100vh;
            background: #f8f9fa;
        }

        /* Non-sticky Header */
        .header {
            background: var(--primary-color);
            color: white;
            padding: 1rem;
            display: flex;
            align-items: center;
            gap: 1rem;
        }

        .logo-link {
            display: flex;
            align-items: center;
            gap: 1rem;
            text-decoration: none;
            color: inherit;
        }

        .logo {
            width: 50px;
            height: 50px;
            background: url('https://go.topaisite.com/logo-512x512.png') center/cover;
            border-radius: 50%;
            border: 2px solid white;
        }

        /* Main Content Grid */
        .main {
            padding: 2rem;
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 1.5rem;
            max-width: 1280px;
            margin: 0 auto;
        }

        /* Tool Cards */
        .tool-card {
            background: white;
            border-radius: 12px;
            padding: 1.5rem;
            text-decoration: none;
            color: #333;
            transition: transform 0.2s, box-shadow 0.2s;
            display: flex;
            flex-direction: column;
            gap: 0.75rem;
            border: 1px solid #eee;
        }

        .tool-card:hover {
            transform: translateY(-3px);
            box-shadow: 0 4px 15px rgba(0,0,0,0.1);
        }

        .tool-emoji {
            font-size: 2rem;
            margin-bottom: 0.5rem;
        }

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

        .tool-desc {
            color: #666;
            font-size: 0.95rem;
            line-height: 1.4;
        }

        /* Footer */
        .footer {
            background: var(--primary-color);
            color: white;
            padding: 2rem;
            margin-top: 3rem;
            text-align: center;
        }

        .footer-links {
            display: flex;
            justify-content: center;
            gap: 2rem;
            flex-wrap: wrap;
            margin-bottom: 1.5rem;
        }

        .footer a {
            color: white;
            text-decoration: none;
            opacity: 0.9;
        }

        .footer a:hover {
            opacity: 1;
            text-decoration: underline;
        }

        /* Loading Animation */
        .loader {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: white;
            display: flex;
            justify-content: center;
            align-items: center;
            z-index: 1000;
            transition: opacity 0.3s;
        }

        .spinner {
            width: 40px;
            height: 40px;
            border: 4px solid #f3f3f3;
            border-top: 4px solid var(--primary-color);
            border-radius: 50%;
            animation: spin 1s linear infinite;
        }

        @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }

        /* Responsive Design */
        @media (max-width: 768px) {
            .main {
                padding: 1.5rem;
                grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            }

            .tool-card {
                padding: 1.25rem;
            }
        }

        @media (max-width: 480px) {
            .header {
                padding: 0.75rem;
            }

            .logo {
                width: 40px;
                height: 40px;
            }

            .main {
                padding: 1rem;
            }
        }