:root {
            --primary: #2563eb;
            --primary-light: #3b82f6;
            --primary-dark: #1d4ed8;
            --accent: #7c3aed;
            --success: #22c55e;
            --danger: #ef4444;
            --warning: #f59e0b;

            --dark-900: #111827;
            --dark-800: #1f2937;
            --dark-700: #374151;
            --gray-600: #4b5563;
            --gray-500: #6b7280;
            --gray-400: #9ca3af;
            --gray-300: #d1d5db;
            --gray-200: #e5e7eb;
            --gray-100: #f3f4f6;
            --gray-50: #f9fafb;
            --white: #ffffff;

            --radius-sm: 6px;
            --radius-md: 12px;
            --radius-lg: 16px;
            --radius-xl: 20px;
            --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
            --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
            --shadow-lg: 0 8px 24px rgba(0,0,0,0.12);
            --shadow-card: 0 4px 20px rgba(37,99,235,0.08);
        }

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

        /* 强制使用电脑排版：固定最小宽度，所有设备都使用桌面布局 */
        html {
            width: 100%;
            overflow-x: hidden;
        }

        body {
            width: 100%;
            min-width: 1200px;
            margin: 0;
            overflow-x: hidden;
            font-family: 'Microsoft YaHei', 'PingFang SC', -apple-system, sans-serif;
            background: #f0f2f5;
            color: var(--dark-900);
            min-height: 100vh;
            line-height: 1.6;
            display: flex;
            flex-direction: column;
        }

        /* ========== 导航栏 ========== */
        .nav-bar {
            background: var(--white);
            box-shadow: 0 1px 4px rgba(0,0,0,0.06);
            border-bottom: 1px solid var(--gray-200);
            position: sticky;
            top: 0;
            z-index: 100;
            width: 100%;
        }

        .nav-inner {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            align-items: center;
            justify-content: space-between;
            height: 60px;
            padding: 0 24px;
        }

        .nav-logo {
            width: 140px;
            height: 42px;
            background: url(http://www.1698.win/static/images/icon_logo.png) no-repeat center;
            background-size: contain;
            display: block;
        }

        .nav-links {
            display: flex;
            gap: 28px;
            align-items: center;
        }

        .nav-links a {
            color: var(--gray-600);
            text-decoration: none;
            font-size: 14px;
            font-weight: 500;
            transition: color 0.2s;
        }

        .nav-links a:hover {
            color: var(--primary);
        }

        .nav-links a.active {
            color: var(--primary);
            font-weight: 600;
        }

        /* ========== 主体区域 ========== */
        .main-area {
            flex: 1;
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 40px 16px;
            position: relative;
            background:
                radial-gradient(ellipse at 20% 50%, rgba(37,99,235,0.04) 0%, transparent 50%),
                radial-gradient(ellipse at 80% 20%, rgba(124,58,237,0.03) 0%, transparent 50%),
                linear-gradient(180deg, #f0f2f5 0%, #e8eaef 100%);
        }

        /* 装饰元素 */
        .deco-circle {
            position: absolute;
            border-radius: 50%;
            opacity: 0.07;
            pointer-events: none;
        }

        .deco-1 {
            width: 300px;
            height: 300px;
            background: var(--primary);
            top: -80px;
            right: -60px;
        }

        .deco-2 {
            width: 200px;
            height: 200px;
            background: var(--accent);
            bottom: -40px;
            left: -40px;
        }

        .deco-3 {
            width: 120px;
            height: 120px;
            background: var(--success);
            top: 30%;
            left: 8%;
        }

        /* ========== 登录卡片 ========== */
        .login-card {
            width: 100%;
            max-width: 420px;
            background: var(--white);
            border-radius: var(--radius-xl);
            box-shadow: var(--shadow-card);
            overflow: hidden;
            position: relative;
            z-index: 10;
            border: 1px solid var(--gray-200);
        }

        /* 卡片顶部装饰条 */
        .login-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 4px;
            background: linear-gradient(90deg, var(--primary), var(--accent));
        }

        /* 卡片头部 */
        .card-header {
            padding: 36px 32px 20px;
            text-align: center;
            position: relative;
        }

        .card-header::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 50%;
            transform: translateX(-50%);
            width: 40px;
            height: 3px;
            background: linear-gradient(90deg, var(--primary), var(--accent));
            border-radius: 2px;
        }

        .card-icon {
            width: 56px;
            height: 56px;
            margin: 0 auto 16px;
            background: linear-gradient(135deg, rgba(37,99,235,0.1), rgba(124,58,237,0.1));
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            color: var(--primary);
            font-size: 24px;
        }

        .card-title {
            font-size: 24px;
            font-weight: 700;
            color: var(--dark-900);
            margin-bottom: 4px;
        }

        .card-subtitle {
            font-size: 13px;
            color: var(--gray-500);
        }

        /* 表单区域 */
        .card-form {
            padding: 28px 32px 32px;
        }

        /* 输入组 */
        .input-group {
            margin-bottom: 20px;
            position: relative;
        }

        .input-wrap {
            position: relative;
        }

        .input-wrap .icon {
            position: absolute;
            left: 14px;
            top: 50%;
            transform: translateY(-50%);
            color: var(--gray-400);
            font-size: 15px;
            transition: color 0.2s;
            z-index: 2;
        }

        .form-input {
            width: 100%;
            padding: 12px 14px 12px 42px;
            background: var(--gray-50);
            border: 1.5px solid var(--gray-200);
            border-radius: var(--radius-md);
            font-size: 14px;
            color: var(--dark-900);
            transition: all 0.2s;
            outline: none;
        }

        .form-input::placeholder {
            color: var(--gray-400);
        }

        .form-input:focus {
            border-color: var(--primary);
            background: var(--white);
            box-shadow: 0 0 0 3px rgba(37,99,235,0.1);
        }

        .form-input:focus ~ .icon,
        .input-wrap:hover .icon {
            color: var(--primary);
        }

        /* 密码切换 */
        .pwd-toggle {
            position: absolute;
            right: 14px;
            top: 50%;
            transform: translateY(-50%);
            color: var(--gray-400);
            cursor: pointer;
            font-size: 15px;
            transition: color 0.2s;
            z-index: 2;
            background: none;
            border: none;
        }

        .pwd-toggle:hover {
            color: var(--primary);
        }

        /* 验证码行 */
        .captcha-row {
            display: flex;
            gap: 12px;
            align-items: stretch;
        }

        .captcha-row .form-input {
            flex: 1;
        }

        .captcha-code {
            display: flex;
            align-items: center;
            padding: 0 18px;
            background: linear-gradient(135deg, #eef2ff, #f0e7ff);
            border: 1.5px solid var(--gray-200);
            border-radius: var(--radius-md);
            font-size: 20px;
            font-weight: 700;
            font-family: 'Courier New', monospace;
            letter-spacing: 4px;
            color: var(--primary);
            user-select: none;
            cursor: pointer;
            min-width: 110px;
            justify-content: center;
            position: relative;
        }

        .captcha-code::before {
            content: '';
            position: absolute;
            inset: 4px;
            background: repeating-linear-gradient(
                45deg,
                transparent,
                transparent 4px,
                rgba(37,99,235,0.03) 4px,
                rgba(37,99,235,0.03) 8px
            );
        }

        .captcha-code span {
            position: relative;
            z-index: 1;
        }

        /* 提交按钮 */
        .submit-btn {
            width: 100%;
            padding: 13px;
            background: linear-gradient(135deg, var(--primary), var(--primary-light));
            color: var(--white);
            font-size: 15px;
            font-weight: 600;
            border: none;
            border-radius: var(--radius-md);
            cursor: pointer;
            transition: all 0.3s;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
            position: relative;
            overflow: hidden;
            margin-top: 4px;
        }

        .submit-btn:hover {
            background: linear-gradient(135deg, var(--primary-dark), var(--primary));
            box-shadow: 0 4px 14px rgba(37,99,235,0.3);
            transform: translateY(-1px);
        }

        .submit-btn:active {
            transform: translateY(0);
        }

        .submit-btn::before {
            content: '';
            position: absolute;
            top: 0;
            left: -100%;
            width: 100%;
            height: 100%;
            background: linear-gradient(90deg, transparent, rgba(255,255,255,0.15), transparent);
            transition: left 0.5s ease;
        }

        .submit-btn:hover::before {
            left: 100%;
        }

        /* 底部链接 */
        .form-footer {
            display: flex;
            justify-content: center;
            align-items: center;
            gap: 12px;
            margin-top: 20px;
        }

        .form-link {
            color: var(--primary);
            text-decoration: none;
            font-size: 13px;
            font-weight: 500;
            transition: color 0.2s;
            position: relative;
            display: flex;
            align-items: center;
            gap: 4px;
        }

        .form-link:hover {
            color: var(--primary-dark);
        }

        .form-link::after {
            content: '';
            position: absolute;
            bottom: -2px;
            left: 0;
            width: 0;
            height: 1.5px;
            background: var(--primary);
            transition: width 0.3s;
        }

        .form-link:hover::after {
            width: 100%;
        }

        .divider-dot {
            width: 4px;
            height: 4px;
            background: var(--gray-300);
            border-radius: 50%;
        }

        /* ========== 底部信息 ========== */
        .page-footer {
            text-align: center;
            padding: 20px;
            font-size: 12px;
            color: var(--gray-400);
            background: var(--white);
            border-top: 1px solid var(--gray-200);
            width: 100%;
        }