/* CSS Document */

        /* --- 全局变量与重置 --- */
        :root {
            --primary-color: #4facfe;
            --secondary-color: #00f2fe;
            --text-dark: #333;
            --text-light: #666;
            --bg-color: #f4f7f6;
            --card-bg: #ffffff;
            --shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
            --transition: all 0.3s ease;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
        }

        body {
            background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
            color: var(--text-dark);
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            overflow-x: hidden;
        }

        a {
            text-decoration: none;
            color: inherit;
        }

        /* ==============================
           登录遮罩层样式 (新增部分)
           ============================== */
        #login-overlay {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            z-index: 9999; /* 确保在最顶层 */
            display: flex;
            justify-content: center;
            align-items: center;
            transition: opacity 0.5s ease, visibility 0.5s ease;
        }

        .login-box {
            background: rgba(255, 255, 255, 0.15);
            backdrop-filter: blur(15px);
            border-radius: 20px;
            padding: 40px;
            width: 350px;
            box-shadow: 0 15px 35px rgba(0, 0, 0, 0.2);
            border: 1px solid rgba(255, 255, 255, 0.2);
            text-align: center;
            color: white;
        }

        .login-box h2 {
            margin-bottom: 30px;
            font-weight: 600;
            letter-spacing: 1px;
        }

        .input-group {
            position: relative;
            margin-bottom: 20px;
        }

        .input-group i {
            position: absolute;
            left: 15px;
            top: 50%;
            transform: translateY(-50%);
            color: rgba(255, 255, 255, 0.8);
        }

        .input-group input {
            width: 100%;
            padding: 12px 15px 12px 45px;
            background: rgba(255, 255, 255, 0.2);
            border: none;
            border-radius: 30px;
            color: white;
            font-size: 1rem;
            outline: none;
            transition: var(--transition);
        }

        .input-group input::placeholder {
            color: rgba(255, 255, 255, 0.6);
        }

        .input-group input:focus {
            background: rgba(255, 255, 255, 0.3);
            box-shadow: 0 0 10px rgba(255, 255, 255, 0.1);
        }

        .login-btn {
            width: 100%;
            padding: 12px;
            border: none;
            border-radius: 30px;
            background: white;
            color: #764ba2;
            font-size: 1rem;
            font-weight: bold;
            cursor: pointer;
            transition: var(--transition);
            margin-top: 10px;
        }

        .login-btn:hover {
            background: #f0f0f0;
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(0,0,0,0.2);
        }

        .error-msg {
            color: #ff6b6b;
            font-size: 0.9rem;
            margin-top: 15px;
            height: 20px;
            opacity: 0;
            transition: opacity 0.3s;
        }

        /* 错误时的抖动动画 */
        @keyframes shake {
            0%, 100% { transform: translateX(0); }
            10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
            20%, 40%, 60%, 80% { transform: translateX(5px); }
        }

        .shake-animation {
            animation: shake 0.5s;
        }

        /* 网站主内容容器 (初始隐藏) */
        #app-content {
            display: none; /* 登录前隐藏 */
            flex-direction: column;
            min-height: 100vh;
            opacity: 0;
            transition: opacity 0.8s ease;
        }

        /* ==============================
           原有样式保持不变
           ============================== */
        header {
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(10px);
            position: sticky;
            top: 0;
            z-index: 100;
            box-shadow: 0 2px 15px rgba(0,0,0,0.05);
            padding: 1rem 5%;
        }

        .nav-container {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .logo {
            font-size: 1.5rem;
            font-weight: 700;
            background: linear-gradient(to right, var(--primary-color), var(--secondary-color));
            -webkit-background-clip: text;
            color: transparent;
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .search-bar {
            display: none;
            background: #f0f2f5;
            padding: 8px 15px;
            border-radius: 20px;
            width: 300px;
            visibility: hidden;
        }
        
        .search-bar input {
            border: none;
            background: transparent;
            width: 100%;
            outline: none;
            color: var(--text-dark);
        }

        main {
            flex: 1;
            max-width: 1200px;
            margin: 2rem auto;
            padding: 0 20px;
            width: 100%;
        }

        .hero-section {
            text-align: center;
            margin-bottom: 3rem;
            animation: fadeInDown 0.8s ease;
        }

        .hero-section h1 {
            font-size: 2.5rem;
            margin-bottom: 10px;
            color: #2c3e50;
        }

        .hero-section p {
            color: var(--text-light);
            font-size: 1.1rem;
        }

        .tools-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
            gap: 25px;
            padding-bottom: 40px;
        }

        .card {
            background: var(--card-bg);
            border-radius: 16px;
            padding: 25px;
            box-shadow: var(--shadow);
            transition: var(--transition);
            border: 1px solid rgba(255,255,255,0.5);
            display: flex;
            flex-direction: column;
            align-items: flex-start;
            position: relative;
            overflow: hidden;
            cursor: pointer;
            opacity: 0;
            transform: translateY(20px);
            animation: fadeInUp 0.6s forwards;
        }

        .card:hover {
            transform: translateY(-10px);
            box-shadow: 0 20px 40px rgba(79, 172, 254, 0.2);
        }

        .card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 4px;
            height: 100%;
            background: linear-gradient(to bottom, var(--primary-color), var(--secondary-color));
            opacity: 0;
            transition: var(--transition);
        }

        .card:hover::before {
            opacity: 1;
        }

        .card-icon {
            width: 50px;
            height: 50px;
            background: rgba(79, 172, 254, 0.1);
            border-radius: 12px;
            display: flex;
            justify-content: center;
            align-items: center;
            font-size: 1.5rem;
            color: var(--primary-color);
            margin-bottom: 15px;
            transition: var(--transition);
        }

        .card:hover .card-icon {
            background: var(--primary-color);
            color: #fff;
            transform: rotate(10deg);
        }

        .card h3 {
            font-size: 1.2rem;
            margin-bottom: 10px;
            color: #2c3e50;
        }

        .card p {
            font-size: 0.9rem;
            color: var(--text-light);
            line-height: 1.5;
            margin-bottom: 20px;
            flex: 1;
        }

        .card-btn {
            display: inline-block;
            padding: 8px 20px;
            background: #f0f2f5;
            color: var(--text-dark);
            border-radius: 20px;
            font-size: 0.85rem;
            font-weight: 600;
            transition: var(--transition);
        }

        .card:hover .card-btn {
            background: linear-gradient(to right, var(--primary-color), var(--secondary-color));
            color: white;
            box-shadow: 0 5px 15px rgba(79, 172, 254, 0.4);
        }

        footer {
            background: white;
            padding: 2rem 0;
            text-align: center;
            color: var(--text-light);
            border-top: 1px solid #eee;
            margin-top: auto;
        }

        @keyframes fadeInUp {
            to { opacity: 1; transform: translateY(0); }
        }

        @keyframes fadeInDown {
            from { opacity: 0; transform: translateY(-20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        @media (min-width: 768px) {
            .search-bar { display: block; }
        }

        @media (max-width: 480px) {
            .hero-section h1 { font-size: 1.8rem; }
            .tools-grid { grid-template-columns: 1fr; }
            .login-box { width: 90%; padding: 30px 20px; }
        }