:root {
    /* 谷歌风格主色调 */
    --google-blue: #4285f4;
    --google-red: #ea4335;
    --google-yellow: #fbbc05;
    --google-green: #34a853;
    
    /* 中性色 */
    --google-text-primary: #202124;
    --google-text-secondary: #5f6368;
    --google-text-tertiary: #80868b;
    --google-border: #dadce0;
    --google-background: #ffffff;
    --google-surface: #f8f9fa;
    --google-surface-hover: #f1f3f4;
    
    /* 设计系统参数 */
    --google-border-radius: 8px;
    --google-border-radius-small: 4px;
    --google-shadow-sm: 0 1px 2px 0 rgba(60,64,67,0.3), 0 1px 3px 1px rgba(60,64,67,0.15);
    --google-shadow-md: 0 1px 3px 0 rgba(60,64,67,0.3), 0 4px 8px 3px rgba(60,64,67,0.15);
    --google-transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 全局样式重置 */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Google Sans', 'Roboto', -apple-system, BlinkMacSystemFont, 'Segoe UI', Arial, sans-serif;
    background-color: var(--google-background);
    color: var(--google-text-primary);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 认证页面容器 */
.auth-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    background-color: var(--google-background);
}

/* 主卡片 */
.auth-card {
    background-color: var(--google-background);
    border-radius: var(--google-border-radius);
    box-shadow: var(--google-shadow-md);
    border: 1px solid var(--google-border);
    width: 100%;
    max-width: 450px;
    overflow: hidden;
    animation: authSlideIn 0.5s ease-out;
}

/* 卡片头部 */
.auth-card-header {
    padding: 2rem;
    text-align: center;
}

/* Logo样式 */
.auth-logo {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
}

.auth-logo-icon {
    font-size: 2.5rem;
    color: var(--google-blue);
}

/* 标题样式 */
.auth-card-title {
    font-size: 1.75rem;
    font-weight: 500;
    color: var(--google-text-primary);
    margin-bottom: 0.5rem;
}

.auth-card-subtitle {
    font-size: 1rem;
    color: var(--google-text-secondary);
}

/* 卡片主体 */
.auth-card-body {
    padding: 0 2rem 2rem;
}

/* 表单样式 */
.auth-form {
    width: 100%;
}

.auth-form-group {
    margin-bottom: 1.25rem;
}

.auth-form-label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--google-text-primary);
    margin-bottom: 0.375rem;
}

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

.auth-input-icon {
    position: absolute;
    left: 0.75rem;
    color: var(--google-text-secondary);
    font-size: 1rem;
    z-index: 1;
}

.auth-form-control {
    width: 100%;
    padding: 0.75rem 1rem 0.75rem 2.5rem;
    font-size: 1rem;
    font-weight: 400;
    line-height: 1.5;
    color: var(--google-text-primary);
    background-color: var(--google-background);
    border: 1px solid var(--google-border);
    border-radius: var(--google-border-radius-small);
    transition: var(--google-transition);
    font-family: inherit;
}

.auth-form-control:focus {
    outline: none;
    border-color: var(--google-blue);
    box-shadow: 0 0 0 2px rgba(66, 133, 244, 0.2);
}

.auth-form-control::placeholder {
    color: var(--google-text-tertiary);
}

/* 密码切换按钮 */
.auth-toggle-password {
    position: absolute;
    right: 0.75rem;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: var(--google-text-secondary);
    cursor: pointer;
    font-size: 1.25rem;
    padding: 0.25rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--google-transition);
    z-index: 2;
}

.auth-toggle-password:hover {
    color: var(--google-blue);
}

/* 帮助文本 */
.auth-form-text {
    margin-top: 0.25rem;
    font-size: 0.875rem;
    color: var(--google-text-tertiary);
}

/* 复选框 */
.auth-form-check {
    display: flex;
    align-items: center;
    margin-bottom: 1.5rem;
}

.auth-form-check-input {
    width: 1.25rem;
    height: 1.25rem;
    margin-right: 0.5rem;
    background-color: var(--google-background);
    border: 1px solid var(--google-border);
    border-radius: var(--google-border-radius-small);
    transition: var(--google-transition);
    cursor: pointer;
}

.auth-form-check-input:checked {
    background-color: var(--google-blue);
    border-color: var(--google-blue);
}

.auth-form-check-label {
    font-size: 0.875rem;
    color: var(--google-text-secondary);
    cursor: pointer;
}

/* 按钮样式 */
.auth-btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 500;
    text-align: center;
    text-decoration: none;
    white-space: nowrap;
    vertical-align: middle;
    cursor: pointer;
    border: none;
    border-radius: var(--google-border-radius-small);
    transition: var(--google-transition);
    font-family: inherit;
}

.auth-btn-primary {
    background-color: var(--google-blue);
    color: white;
}

.auth-btn-primary:hover {
    background-color: #3367d6;
    box-shadow: 0 1px 2px 0 rgba(66, 133, 244, 0.45);
}

.auth-btn-primary:active {
    background-color: #2557d6;
}

.auth-btn-block {
    width: 100%;
}

/* 警告信息 */
.auth-alert {
    padding: 1rem;
    margin-bottom: 1.5rem;
    border-radius: var(--google-border-radius-small);
    display: flex;
    align-items: flex-start;
}

.auth-alert-danger {
    background-color: rgba(234, 67, 53, 0.1);
    color: var(--google-red);
    border-left: 4px solid var(--google-red);
}

.auth-alert-warning {
    background-color: rgba(251, 188, 5, 0.1);
    color: var(--google-text-primary);
    border-left: 4px solid var(--google-yellow);
}

.auth-alert i {
    font-size: 1.25rem;
    margin-right: 0.75rem;
    margin-top: 0.125rem;
}

/* 链接样式 */
.auth-link {
    color: var(--google-blue);
    text-decoration: none;
    font-weight: 500;
    transition: var(--google-transition);
}

.auth-link:hover {
    text-decoration: underline;
}

/* 卡片页脚 */
.auth-card-footer {
    padding: 1.5rem 2rem;
    text-align: center;
    background-color: var(--google-surface);
    border-top: 1px solid var(--google-border);
}

.auth-card-footer p {
    margin-bottom: 0.5rem;
    color: var(--google-text-secondary);
}

/* 徽章 */
.auth-badge {
    display: inline-block;
    padding: 0.25rem 0.5rem;
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: 1rem;
}

.auth-badge-warning {
    background-color: var(--google-yellow);
    color: white;
}

/* 尝试次数警告 */
.auth-attempts-warning {
    display: flex;
    align-items: center;
    margin-bottom: 1.5rem;
    color: var(--google-text-secondary);
    font-size: 0.875rem;
}

.auth-attempts-warning i {
    margin-right: 0.5rem;
}

/* 动画效果 */
@keyframes authSlideIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 响应式设计 */
@media (max-width: 480px) {
    .auth-container {
        padding: 0.5rem;
    }
    
    .auth-card {
        box-shadow: var(--google-shadow-sm);
    }
    
    .auth-card-header,
    .auth-card-body,
    .auth-card-footer {
        padding: 1.5rem;
    }
    
    .auth-card-title {
        font-size: 1.5rem;
    }
    
    .auth-btn {
        padding: 0.625rem 1.25rem;
    }
}

/* 工具类 */
.text-center {
    text-align: center;
}

.mb-0 {
    margin-bottom: 0 !important;
}

.mb-1 {
    margin-bottom: 0.5rem !important;
}

.mb-2 {
    margin-bottom: 1rem !important;
}

.mb-3 {
    margin-bottom: 1.5rem !important;
}

.mb-4 {
    margin-bottom: 2rem !important;
}

.mt-2 {
    margin-top: 1rem !important;
}

.mt-4 {
    margin-top: 2rem !important;
}