:root {
            --bg: #f0f2f5;
            --card-bg: #ffffff;
            --text: #1a1a2e;
            --text-secondary: #6b7280;
            --input-bg: #f9fafb;
            --input-border: #e5e7eb;
            --input-focus-border: #6366f1;
            --input-focus-shadow: rgba(99, 102, 241, 0.12);
            --btn-bg: #4f46e5;
            --btn-hover-bg: #4338ca;
            --btn-text: #ffffff;
            --link-color: #6366f1;
            --divider: #e5e7eb;
            --radius: 12px;
            --input-radius: 10px;
            --transition: 0.2s ease;
        }

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

        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
            background-color: var(--bg);
            display: flex;
            align-items: center;
            justify-content: center;
            min-height: 100vh;
            margin: 0;
            padding: 20px;
            -webkit-font-smoothing: antialiased;
            -moz-osx-font-smoothing: grayscale;
        }

        /* 背景装饰 */
        body::before {
            content: '';
            position: fixed;
            top: -40%;
            right: -20%;
            width: 600px;
            height: 600px;
            border-radius: 50%;
            background: radial-gradient(circle, rgba(99, 102, 241, 0.06) 0%, transparent 70%);
            pointer-events: none;
            z-index: 0;
        }

        body::after {
            content: '';
            position: fixed;
            bottom: -30%;
            left: -15%;
            width: 500px;
            height: 500px;
            border-radius: 50%;
            background: radial-gradient(circle, rgba(139, 92, 246, 0.05) 0%, transparent 70%);
            pointer-events: none;
            z-index: 0;
        }

        .login-card {
            position: relative;
            z-index: 1;
            background: var(--card-bg);
            border-radius: 20px;
            padding: 44px 36px 36px;
            width: 100%;
            max-width: 420px;
            box-shadow:
                0 1px 3px rgba(0, 0, 0, 0.04),
                0 6px 24px rgba(0, 0, 0, 0.06),
                0 20px 50px rgba(0, 0, 0, 0.04);
            animation: fadeInUp 0.55s ease-out;
        }

        @keyframes fadeInUp {
            from {
                opacity: 0;
                transform: translateY(24px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        .login-header {
            text-align: center;
            margin-bottom: 36px;
        }

        .login-icon {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            width: 52px;
            height: 52px;
            border-radius: 14px;
            background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
            margin-bottom: 20px;
            box-shadow: 0 4px 14px rgba(99, 102, 241, 0.3);
        }

        .login-icon svg {
            width: 24px;
            height: 24px;
            stroke: #ffffff;
            fill: none;
            stroke-width: 2;
            stroke-linecap: round;
            stroke-linejoin: round;
        }

        .login-header h1 {
            font-size: 26px;
            font-weight: 700;
            color: var(--text);
            letter-spacing: -0.3px;
            margin-bottom: 6px;
        }

        .login-header p {
            font-size: 15px;
            color: var(--text-secondary);
            font-weight: 400;
            line-height: 1.5;
        }

        .form-group {
            margin-bottom: 20px;
        }

        .form-group label {
            display: block;
            font-size: 13.5px;
            font-weight: 600;
            color: var(--text);
            margin-bottom: 7px;
            letter-spacing: 0.01em;
        }

        .input-wrapper {
            position: relative;
            display: flex;
            align-items: center;
        }

        .input-wrapper .input-icon {
            position: absolute;
            left: 14px;
            pointer-events: none;
            display: flex;
            align-items: center;
        }

        .input-wrapper .input-icon svg {
            width: 18px;
            height: 18px;
            stroke: #9ca3af;
            fill: none;
            stroke-width: 1.8;
            stroke-linecap: round;
            stroke-linejoin: round;
            transition: stroke var(--transition);
        }

        .input-wrapper input {
            width: 100%;
            padding: 13px 14px 13px 44px;
            font-size: 15px;
            font-family: inherit;
            color: var(--text);
            background: var(--input-bg);
            border: 1.5px solid var(--input-border);
            border-radius: var(--input-radius);
            outline: none;
            transition:
                border-color var(--transition),
                box-shadow var(--transition),
                background var(--transition);
            letter-spacing: 0.01em;
        }

        .input-wrapper input::placeholder {
            color: #c4c7cc;
            font-size: 14.5px;
        }

        .input-wrapper input:focus {
            border-color: var(--input-focus-border);
            background: #ffffff;
            box-shadow: 0 0 0 4px var(--input-focus-shadow);
        }

        .input-wrapper input:focus~.input-icon svg,
        .input-wrapper input:focus+.input-icon svg {
            stroke: var(--input-focus-border);
        }

        /* 让兄弟元素也能响应焦点（图标在input前面） */
        .input-wrapper:focus-within .input-icon svg {
            stroke: var(--input-focus-border);
        }

        .options-row {
            display: flex;
            align-items: center;
            justify-content: space-between;
            margin-bottom: 26px;
            font-size: 13.5px;
        }

        .remember-me {
            display: flex;
            align-items: center;
            gap: 7px;
            cursor: pointer;
            color: var(--text-secondary);
            user-select: none;
            font-size: 13.5px;
            transition: color var(--transition);
        }

        .remember-me input[type="checkbox"] {
            appearance: none;
            -webkit-appearance: none;
            width: 17px;
            height: 17px;
            border: 1.5px solid #d1d5db;
            border-radius: 5px;
            background: #ffffff;
            cursor: pointer;
            position: relative;
            flex-shrink: 0;
            transition: all var(--transition);
        }

        .remember-me input[type="checkbox"]:checked {
            background: #6366f1;
            border-color: #6366f1;
        }

        .remember-me input[type="checkbox"]:checked::after {
            content: '';
            position: absolute;
            left: 4.5px;
            top: 1.5px;
            width: 5px;
            height: 9px;
            border: solid #ffffff;
            border-width: 0 2px 2px 0;
            transform: rotate(45deg);
        }

        .remember-me:hover {
            color: var(--text);
        }

        .forgot-link {
            color: var(--link-color);
            text-decoration: none;
            font-weight: 600;
            font-size: 13.5px;
            transition: color var(--transition);
            letter-spacing: 0.01em;
        }

        .forgot-link:hover {
            color: #4338ca;
            text-decoration: underline;
            text-underline-offset: 3px;
        }

        .btn-login {
            display: block;
            width: 100%;
            padding: 14px;
            font-size: 15.5px;
            font-weight: 600;
            font-family: inherit;
            color: var(--btn-text);
            background: var(--btn-bg);
            border: none;
            border-radius: var(--input-radius);
            cursor: pointer;
            letter-spacing: 0.02em;
            transition:
                background var(--transition),
                transform 0.15s ease,
                box-shadow var(--transition);
            box-shadow: 0 2px 8px rgba(79, 70, 229, 0.25);
            position: relative;
            overflow: hidden;
        }

        .btn-login:hover {
            background: var(--btn-hover-bg);
            box-shadow: 0 4px 16px rgba(79, 70, 229, 0.35);
            transform: translateY(-1px);
        }

        .btn-login:active {
            transform: translateY(0);
            box-shadow: 0 2px 6px rgba(79, 70, 229, 0.3);
            transition: transform 0.05s ease;
        }

        .signup-prompt {
            text-align: center;
            margin-top: 28px;
            font-size: 14px;
            color: var(--text-secondary);
        }

        .signup-prompt a {
            color: var(--link-color);
            text-decoration: none;
            font-weight: 600;
            transition: color var(--transition);
            margin-left: 2px;
        }

        .signup-prompt a:hover {
            color: #4338ca;
            text-decoration: underline;
            text-underline-offset: 3px;
        }

        .divider-line {
            display: flex;
            align-items: center;
            gap: 16px;
            margin: 28px 0 24px;
            color: #c4c7cc;
            font-size: 12.5px;
            letter-spacing: 0.03em;
        }

        .divider-line::before,
        .divider-line::after {
            content: '';
            flex: 1;
            height: 1px;
            background: var(--divider);
        }

        /* 响应式 */
        @media (max-width: 480px) {
            .login-card {
                padding: 32px 24px 28px;
                border-radius: 16px;
            }

            .login-header h1 {
                font-size: 23px;
            }

            .input-wrapper input {
                padding: 12px 12px 12px 40px;
                font-size: 14.5px;
            }

            .btn-login {
                padding: 13px;
                font-size: 15px;
            }
        }