* { margin: 0; padding: 0; box-sizing: border-box; }
        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
            background: linear-gradient(135deg, #0f0f23 0%, #1a1a3e 50%, #0f0f23 100%);
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            overflow: hidden;
            color: #fff;
            perspective: 1000px;
        }
        body.modal-open { overflow: hidden; }
        
        .title-section { text-align: center; margin-bottom: 30px; z-index: 10; }
        .title {
            font-size: 3em; font-weight: 700;
            background: linear-gradient(45deg, #667eea, #764ba2, #f093fb);
            background-size: 300% 300%;
            -webkit-background-clip: text; -webkit-text-fill-color: transparent;
            background-clip: text;
            animation: gradient 5s ease infinite;
        }
        .subtitle { font-size: 0.9em; color: rgba(255,255,255,0.6); letter-spacing: 3px; margin-top: 8px; }
        @keyframes gradient { 0%, 100% { background-position: 0% 50%; } 50% { background-position: 100% 50%; } }
        
        .carousel-container { width: 100%; height: 350px; position: relative; display: flex; justify-content: center; align-items: center; transform-style: preserve-3d; }
        .carousel { position: relative; width: 320px; height: 180px; transform-style: preserve-3d; transition: transform 0.8s cubic-bezier(0.175, 0.885, 0.32, 1.275); }
        .card {
            position: absolute; width: 300px; height: 160px; left: 10px; top: 10px;
            background: linear-gradient(135deg, rgba(255,255,255,0.1), rgba(255,255,255,0.05));
            border: 1px solid rgba(255,255,255,0.15); border-radius: 16px;
            backdrop-filter: blur(20px); display: flex; justify-content: center; align-items: center;
            cursor: pointer; transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
            backface-visibility: visible; box-shadow: 0 10px 40px rgba(0,0,0,0.3); overflow: hidden;
        }
        .card::before {
            content: ''; position: absolute; top: 0; left: 0; width: 100%; height: 100%;
            background-size: cover; background-position: center; opacity: 0.6;
            transition: opacity 0.4s ease; z-index: 0;
        }
        .card[data-index="0"]::before { background-image: linear-gradient(135deg, #667eea 0%, #764ba2 100%); }
        .card[data-index="1"]::before { background-image: linear-gradient(135deg, #f093fb 0%, #f5576c 100%); }
        .card[data-index="2"]::before { background-image: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%); }
        .card[data-index="3"]::before { background-image: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%); }
        .card:hover::before { opacity: 0.8; }
        @media (min-width: 601px) {
            .card:hover { transform: scale(1.15) translateZ(20px); border-color: rgba(255,255,255,0.5); box-shadow: 0 25px 70px rgba(102, 126, 234, 0.4); }
            .card:hover .icon { transform: scale(1.3) rotate(8deg); }
        }
        .card-content { position: relative; z-index: 1; text-align: center; display: flex; flex-direction: column; align-items: center; gap: 8px; }
        .card .icon { font-size: 2.8em; filter: drop-shadow(0 3px 10px rgba(0,0,0,0.4)); transition: transform 0.4s ease; }
        .card .label { font-size: 1.6em; font-weight: 700; color: #fff; text-shadow: 0 2px 10px rgba(0,0,0,0.5), 0 0 20px rgba(255,255,255,0.3); letter-spacing: 2px; }
        .card .desc { font-size: 0.75em; color: rgba(255,255,255,0.85); text-shadow: 0 1px 5px rgba(0,0,0,0.5); letter-spacing: 1px; white-space: nowrap; }
        
        .hint { position: fixed; bottom: 25px; left: 50%; transform: translateX(-50%); color: rgba(255,255,255,0.5); font-size: 0.85em; display: flex; align-items: center; gap: 10px; animation: bounce 2s infinite; }
        @keyframes bounce { 0%, 100% { transform: translateX(-50%); } 50% { transform: translateX(-50%) translateY(-5px); } }
        .status { position: fixed; top: 20px; right: 20px; padding: 10px 18px; background: rgba(255,255,255,0.05); border-radius: 20px; backdrop-filter: blur(10px); display: flex; align-items: center; gap: 8px; font-size: 0.8em; color: rgba(255,255,255,0.7); }
        .status-dot { width: 8px; height: 8px; background: #4ade80; border-radius: 50%; animation: pulse 2s infinite; }
        @keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.5; } }
        .bg-circle { position: fixed; border-radius: 50%; background: radial-gradient(circle, rgba(102,126,234,0.15) 0%, transparent 70%); pointer-events: none; }
        
        /* 独立遮罩层（物理屏障，强虚化马赛克效果） */
        .modal-backdrop {
            position: fixed; top: 0; left: 0; width: 100%; height: 100%;
            background: rgba(0,0,0,0.3);
            backdrop-filter: blur(20px) saturate(200%) contrast(120%);
            -webkit-backdrop-filter: blur(20px) saturate(200%) contrast(120%);
            /* 兼容旧浏览器：使用纯色背景作为 fallback */
            background: rgba(0,0,0,0.5);
            z-index: 1000;
            opacity: 0;
            /* 使用 display 控制，兼容性更好 */
            display: none;
            cursor: pointer;
            pointer-events: none;
        }
        .modal-backdrop.active {
            opacity: 1;
            display: block;
            pointer-events: auto;
        }
        
        /* 弹窗容器（在遮罩层上面） */
        .modal-overlay {
            position: fixed; top: 0; left: 0; width: 100%; height: 100%;
            display: flex; justify-content: center; align-items: center;
            z-index: 1001;
            pointer-events: none;
            opacity: 0; visibility: hidden;
            transition: opacity 0.3s cubic-bezier(0.4, 0, 0.2, 1), visibility 0.3s;
        }
        .modal-overlay.active {
            opacity: 1; visibility: visible;
            pointer-events: auto;
        }
        .modal {
            background: linear-gradient(135deg, rgba(20,20,40,0.95), rgba(30,30,60,0.95));
            border: 1px solid rgba(102,126,234,0.3); border-radius: 24px; padding: 40px;
            max-width: 420px; width: 90%; position: relative;
            transform: scale(0.8) translateY(20px);
            transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
            box-shadow: 0 30px 80px rgba(0,0,0,0.5), 0 0 100px rgba(102,126,234,0.2);
        }
        .modal-overlay.active .modal { transform: scale(1) translateY(0); }
        .modal-overlay.active .modal * { pointer-events: auto; }
        
        .modal-close {
            position: absolute; top: 15px; right: 15px;
            width: 32px; height: 32px;
            background: rgba(255,255,255,0.1);
            border: none; border-radius: 50%;
            color: rgba(255,255,255,0.6);
            font-size: 24px; line-height: 1;
            cursor: pointer;
            transition: all 0.3s ease;
            display: flex; align-items: center; justify-content: center;
            padding: 0;
        }
        .modal-close:hover {
            background: rgba(255,255,255,0.2);
            color: #fff;
            transform: rotate(90deg);
        }
        .modal-title { text-align: center; margin-bottom: 25px; }
        .modal-title-cn {
            display: block; font-size: 1.6em; font-weight: 600; margin-bottom: 8px;
            background: linear-gradient(135deg, #667eea 0%, #f093fb 50%, #667eea 100%);
            background-size: 200% 200%;
            -webkit-background-clip: text; -webkit-text-fill-color: transparent;
            background-clip: text;
            animation: gradient 3s ease infinite;
            letter-spacing: 3px;
        }
        .modal-title-en {
            display: block; font-size: 0.85em; color: rgba(255,255,255,0.4);
            letter-spacing: 4px; text-transform: uppercase; font-weight: 400;
        }
        
        .login-tabs { display: flex; background: rgba(255,255,255,0.05); border-radius: 12px; padding: 4px; margin-bottom: 25px; }
        .login-tab { flex: 1; padding: 10px; text-align: center; border-radius: 10px; cursor: pointer; font-size: 0.9em; color: rgba(255,255,255,0.6); transition: all 0.3s ease; white-space: nowrap; }
        .login-tab.active { background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; font-weight: 600; }
        .login-tab:hover:not(.active) { background: rgba(255,255,255,0.1); color: rgba(255,255,255,0.8); }
        
        .login-content { display: none; }
        .login-content.active { display: block; }
        
        .form-group { margin-bottom: 20px; }
        .form-input { width: 100%; padding: 14px 18px; background: rgba(255,255,255,0.05); border: 1px solid rgba(255,255,255,0.1); border-radius: 12px; color: #fff; font-size: 1em; transition: all 0.3s ease; outline: none; }
        .form-input:focus { border-color: rgba(102,126,234,0.5); background: rgba(255,255,255,0.08); box-shadow: 0 0 20px rgba(102,126,234,0.2); }
        .form-input::placeholder { color: rgba(255,255,255,0.4); }
        
        .code-input-group { display: flex; gap: 10px; }
        .code-input-group .form-input { flex: 1; }
        .code-btn { width: auto; padding: 14px 20px; background: linear-gradient(135deg, #667eea, #764ba2); border: none; border-radius: 12px; color: #fff; font-size: 0.9em; font-weight: 600; cursor: pointer; transition: all 0.3s ease; white-space: nowrap; }
        .code-btn:hover { transform: translateY(-2px); box-shadow: 0 10px 30px rgba(102,126,234,0.4); }
        
        .submit-btn { width: 100%; padding: 14px; background: linear-gradient(135deg, #667eea, #764ba2); border: none; border-radius: 12px; color: #fff; font-size: 1.1em; font-weight: 600; cursor: pointer; transition: all 0.3s ease; margin-top: 10px; }
        .submit-btn:hover { transform: translateY(-2px); box-shadow: 0 10px 30px rgba(102,126,234,0.4); }
        
        .qr-login { text-align: center; padding: 20px 0; }
        .qr-code { width: 180px; height: 180px; background: rgba(255,255,255,0.95); margin: 20px auto; border-radius: 12px; display: flex; align-items: center; justify-content: center; box-shadow: 0 10px 40px rgba(0,0,0,0.3); }
        .qr-code-placeholder { font-size: 3em; color: #667eea; }
        .qr-tip { color: rgba(255,255,255,0.6); font-size: 0.9em; margin-top: 15px; }
        .qr-tip strong { color: rgba(255,255,255,0.9); }
        
        .social-login { margin-top: 25px; text-align: center; }
        .social-text { color: rgba(255,255,255,0.5); font-size: 0.85em; margin-bottom: 15px; }
        .social-icons { display: flex; justify-content: center; gap: 20px; }
        .social-icon { width: 50px; height: 50px; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 1.5em; background: rgba(255,255,255,0.05); cursor: not-allowed; opacity: 0.4; transition: all 0.3s ease; position: relative; }
        .social-icon.coming-soon:hover { opacity: 0.7; }
        .social-icon svg { display: block; }
        .social-icon.qq { background: #12B7F5 !important; }
        .social-icon.wechat { background: #07C160 !important; }
        .social-icon.alipay { background: #1677FF !important; }
        .social-icon .tooltip {
            position: absolute; bottom: 100%; left: 50%; transform: translateX(-50%) translateY(-5px);
            background: rgba(0,0,0,0.9); color: #fff; padding: 8px 12px; border-radius: 8px;
            font-size: 0.75em; white-space: nowrap; opacity: 0; visibility: hidden;
            transition: all 0.3s ease; pointer-events: none; box-shadow: 0 5px 20px rgba(0,0,0,0.3);
        }
        .social-icon .tooltip::before {
            content: ''; position: absolute; top: 100%; left: 50%; transform: translateX(-50%);
            border-left: 5px solid transparent; border-right: 5px solid transparent; border-top: 5px solid rgba(0,0,0,0.9);
        }
        .social-icon:hover .tooltip { opacity: 1; visibility: visible; transform: translateX(-50%) translateY(-8px); }
        
        .switch-link { text-align: center; margin-top: 20px; color: rgba(255,255,255,0.6); font-size: 0.9em; }
        .switch-link a { color: #667eea; text-decoration: none; cursor: pointer; transition: color 0.3s ease; display: inline-block; padding: 5px 10px; }
        .switch-link a:hover { color: #f093fb; }
        
        .about-content { text-align: center; line-height: 1.8; }
        .about-text { color: rgba(255,255,255,0.8); margin-bottom: 20px; font-size: 1em; }
        .about-highlight { background: linear-gradient(135deg, #667eea, #f093fb); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; font-weight: 600; }
        
        @media (max-width: 600px) {
            .title { font-size: 2.2em; }
            .carousel { width: 260px; height: 150px; }
            .card { width: 240px; height: 130px; }
            .card .icon { font-size: 2.2em; }
            .card .label { font-size: 1.3em; }
            .modal { padding: 30px 20px; }
            .modal-title-cn { font-size: 1.4em; }
            .modal-title-en { font-size: 0.75em; }
            .login-tabs { font-size: 0.8em; }
            .login-tab { padding: 8px 5px; }
            .qr-code { width: 150px; height: 150px; }
            .qr-code-placeholder { font-size: 2.5em; }
        }