/* 喝水计算器 - 主样式文件 */

/* CSS变量定义 */
:root {
    /* 颜色变量 */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --accent-color: #4ecdc4;
    --warning-color: #ff9a9e;
    --success-color: #7ed321;
    --error-color: #e74c3c;
    
    /* 背景颜色 */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-gradient: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    
    /* 文字颜色 */
    --text-primary: #2c3e50;
    --text-secondary: #7f8c8d;
    --text-light: #bdc3c7;
    --text-white: #ffffff;
    
    /* 边框颜色 */
    --border-color: #e1e8ed;
    --border-focus: #667eea;
    --border-error: #e74c3c;
    
    /* 阴影 */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 16px 32px rgba(0, 0, 0, 0.2);
    
    /* 间距 */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-xxl: 48px;
    
    /* 字体大小 */
    --font-xs: 12px;
    --font-sm: 14px;
    --font-md: 16px;
    --font-lg: 18px;
    --font-xl: 24px;
    --font-xxl: 32px;
    --font-xxxl: 48px;
    
    /* 圆角 */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-xxl: 24px;
    
    /* 过渡动画 */
    --transition-fast: 0.2s ease-out;
    --transition-normal: 0.3s ease-out;
    --transition-slow: 0.5s ease-out;
    --transition-bounce: 0.6s cubic-bezier(0.68, -0.55, 0.265, 1.55);
    --transition-elastic: 0.8s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* 动画缓动函数 */
    --ease-in-out-cubic: cubic-bezier(0.4, 0, 0.2, 1);
    --ease-out-back: cubic-bezier(0.34, 1.56, 0.64, 1);
    --ease-in-out-quart: cubic-bezier(0.76, 0, 0.24, 1);
}

/* 重置样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-gradient);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
    position: relative;
}

/* 动态背景装饰 */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 80%, rgba(102, 126, 234, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(118, 75, 162, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 40% 40%, rgba(78, 205, 196, 0.05) 0%, transparent 50%);
    pointer-events: none;
    z-index: -1;
    animation: gradientShift 20s ease infinite;
}

/* 主容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-md);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* 欢迎页面 */
.welcome-page {
    width: 100%;
    max-width: 600px;
    background: var(--bg-primary);
    border-radius: var(--radius-xxl);
    box-shadow: var(--shadow-xl);
    overflow: hidden;
    animation: slideInUp 0.6s var(--ease-out-back);
    position: relative;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

/* 玻璃拟态效果 */
.welcome-page::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.4), transparent);
}

.welcome-content {
    padding: var(--spacing-xxl);
}

/* 标题区域 */
.welcome-header {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
}

.welcome-title {
    font-size: var(--font-xxxl);
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-md);
    line-height: 1.2;
}

.welcome-subtitle {
    font-size: var(--font-lg);
    color: var(--text-secondary);
    font-weight: 400;
    line-height: 1.5;
}

/* 表单容器 */
.form-container {
    width: 100%;
}

.form-section {
    margin-bottom: var(--spacing-xl);
}

.section-title {
    font-size: var(--font-lg);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--border-color);
}

/* 表单组 */
.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-label {
    display: block;
    font-size: var(--font-sm);
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.form-input {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-lg);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    font-size: var(--font-md);
    font-family: inherit;
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: all var(--transition-normal);
}

.form-input:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.form-input::placeholder {
    color: var(--text-light);
}

.form-input:invalid {
    border-color: var(--border-error);
}

/* 单选按钮组 */
.radio-group {
    display: flex;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
}

.radio-label {
    display: flex;
    align-items: center;
    cursor: pointer;
    font-size: var(--font-md);
    color: var(--text-primary);
    transition: color var(--transition-fast);
}

.radio-label:hover {
    color: var(--primary-color);
}

.radio-input {
    display: none;
}

.radio-custom {
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-radius: 50%;
    margin-right: var(--spacing-sm);
    position: relative;
    transition: all var(--transition-normal);
}

.radio-input:checked + .radio-custom {
    border-color: var(--primary-color);
    background: var(--primary-color);
}

.radio-input:checked + .radio-custom::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 8px;
    height: 8px;
    background: var(--text-white);
    border-radius: 50%;
}

.radio-text {
    font-weight: 500;
}

/* 选择框 */
.select-group {
    position: relative;
}

.form-select {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-lg);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    font-size: var(--font-md);
    font-family: inherit;
    background: var(--bg-primary);
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-normal);
    appearance: none;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 20 20'%3e%3cpath stroke='%236b7280' stroke-linecap='round' stroke-linejoin='round' stroke-width='1.5' d='m6 8 4 4 4-4'/%3e%3c/svg%3e");
    background-position: right var(--spacing-md) center;
    background-repeat: no-repeat;
    background-size: 1.5em 1.5em;
    padding-right: var(--spacing-xxl);
}

.form-select:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

/* 按钮样式 */
.form-actions {
    margin-top: var(--spacing-xxl);
    text-align: center;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xxl);
    border: none;
    border-radius: var(--radius-lg);
    font-size: var(--font-md);
    font-weight: 600;
    font-family: inherit;
    cursor: pointer;
    transition: all var(--transition-normal);
    text-decoration: none;
    min-height: 48px;
    min-width: 120px;
    position: relative;
    overflow: hidden;
    will-change: transform;
}

/* 按钮波纹效果 */
.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    background: rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
    pointer-events: none;
}

.btn:active::before {
    width: 300px;
    height: 300px;
}

.btn-primary {
    background: var(--primary-gradient);
    color: var(--text-white);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-3px) scale(1.02);
    box-shadow: 0 15px 35px rgba(102, 126, 234, 0.3);
}

.btn-primary:active {
    transform: translateY(-1px) scale(0.98);
    box-shadow: var(--shadow-md);
}

.btn-primary:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.3);
}

.btn-text {
    transition: transform var(--transition-fast);
}

.btn-icon {
    font-size: var(--font-lg);
    transition: transform var(--transition-fast);
}

.btn:hover .btn-icon {
    transform: translateX(4px);
}

/* 错误消息 */
.error-message {
    display: block;
    color: var(--error-color);
    font-size: var(--font-xs);
    margin-top: var(--spacing-xs);
    min-height: 16px;
    opacity: 0;
    transition: opacity var(--transition-fast);
}

.error-message.show {
    opacity: 1;
}

/* 主页面 */
.main-page {
    width: 100%;
    max-width: 800px;
    background: var(--bg-primary);
    border-radius: var(--radius-xxl);
    box-shadow: var(--shadow-xl);
    padding: var(--spacing-xxl);
}

.main-content {
    text-align: center;
}

/* 工具类 */
.hidden {
    display: none !important;
}

/* 动画 */
@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: var(--spacing-sm);
    }
    
    .welcome-content {
        padding: var(--spacing-xl);
    }
    
    .welcome-title {
        font-size: var(--font-xxl);
    }
    
    .welcome-subtitle {
        font-size: var(--font-md);
    }
    
    .radio-group {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .btn {
        width: 100%;
    }
}

@media (max-width: 480px) {
    .welcome-content {
        padding: var(--spacing-lg);
    }
    
    .welcome-title {
        font-size: var(--font-xl);
    }
    
    .section-title {
        font-size: var(--font-md);
    }
}

/* 免责声明样式 */
.disclaimer {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    border-top: 1px solid #dee2e6;
    padding: 20px 0;
    margin-top: 40px;
}

.disclaimer-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
    text-align: center;
}

.disclaimer-text {
    font-size: 1.1rem;
    font-weight: 600;
    color: #6c757d;
    margin: 0 0 8px 0;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.disclaimer-subtext {
    font-size: 0.9rem;
    color: #868e96;
    margin: 0;
    line-height: 1.5;
    max-width: 600px;
    margin: 0 auto;
}

/* 免责声明响应式 */
@media (max-width: 768px) {
    .disclaimer {
        padding: 15px 0;
        margin-top: 30px;
    }
    
    .disclaimer-content {
        padding: 0 15px;
    }
    
    .disclaimer-text {
        font-size: 1rem;
    }
    
    .disclaimer-subtext {
        font-size: 0.85rem;
    }
}