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

:root {
    --primary-blue: #007AFF;
    --secondary-blue: #5AC8FA;
    --background-light: rgba(255, 255, 255, 0.9);
    --background-dark: rgba(28, 28, 30, 0.9);
    --surface-light: rgba(255, 255, 255, 0.95);
    --surface-dark: rgba(58, 58, 60, 0.95);
    --text-primary: #1D1D1F;
    --text-secondary: #86868B;
    --accent-color: #FF3B30;
    --border-light: rgba(0, 0, 0, 0.1);
    --shadow-light: rgba(0, 0, 0, 0.1);
    --shadow-medium: rgba(0, 0, 0, 0.15);
    --radius-small: 12px;
    --radius-medium: 16px;
    --radius-large: 24px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'SF Pro Text', system-ui, sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    background-attachment: fixed;
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 头部导航 - Apple 风格 */
.header {
    background: rgba(255, 255, 255, 0.72);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid var(--border-light);
    padding: 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: all 0.3s ease;
}

.nav {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 24px;
    height: 44px;
}

.logo {
    font-size: 21px;
    font-weight: 600;
    color: var(--text-primary);
    text-decoration: none;
    letter-spacing: -0.5px;
    transition: opacity 0.3s ease;
}

.logo:hover {
    opacity: 0.8;
}

.nav-links {
    display: flex;
    gap: 32px;
    align-items: center;
}

.nav-links a {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 400;
    font-size: 17px;
    transition: opacity 0.3s ease;
    position: relative;
}

.nav-links a:hover {
    opacity: 0.8;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 2px;
    background: var(--primary-blue);
    transition: width 0.3s ease;
}

.nav-links a:hover::after {
    width: 100%;
}

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* 按钮样式 - Apple 风格 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    border: none;
    border-radius: var(--radius-large);
    cursor: pointer;
    text-decoration: none;
    font-weight: 400;
    font-size: 17px;
    transition: all 0.2s ease;
    min-height: 44px;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: inherit;
    padding: 1px;
    background: linear-gradient(135deg, rgba(255,255,255,0.2), rgba(0,0,0,0.1));
    mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    mask-composite: exclude;
    -webkit-mask-composite: xor;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-blue) 0%, var(--secondary-blue) 100%);
    color: white;
    box-shadow: 0 4px 16px rgba(0, 122, 255, 0.3);
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 8px 24px rgba(0, 122, 255, 0.4);
}

.btn-secondary {
    background: var(--surface-light);
    color: var(--text-primary);
    border: 1px solid var(--border-light);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 1);
    transform: translateY(-1px);
    box-shadow: 0 4px 16px var(--shadow-light);
}

/* 表单元素 - Apple 风格 */
.form-control {
    padding: 16px 20px;
    border: 1px solid var(--border-light);
    border-radius: var(--radius-medium);
    font-size: 17px;
    background: var(--surface-light);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    transition: all 0.3s ease;
    width: 100%;
    font-family: inherit;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 4px rgba(0, 122, 255, 0.1);
    background: rgba(255, 255, 255, 1);
}

.form-control::placeholder {
    color: var(--text-secondary);
}

/* 卡片样式 */
.card {
    background: var(--surface-light);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-radius: var(--radius-large);
    border: 1px solid var(--border-light);
    box-shadow: 0 8px 32px var(--shadow-light);
    transition: all 0.3s ease;
    overflow: hidden;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: 0 16px 48px var(--shadow-medium);
}

/* 加载状态 */
.loading {
    text-align: center;
    padding: 48px 24px;
    color: var(--text-secondary);
    font-size: 17px;
}

/* 页脚 */
.footer {
    background: var(--surface-light);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    text-align: center;
    padding: 48px 24px;
    margin-top: 80px;
    border-top: 1px solid var(--border-light);
    color: var(--text-secondary);
    font-size: 15px;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav {
        padding: 12px 16px;
        flex-direction: column;
        gap: 16px;
        height: auto;
    }
    
    .nav-links {
        gap: 24px;
    }
    
    .container {
        padding: 0 16px;
    }
    
    .btn {
        padding: 14px 20px;
        font-size: 15px;
    }
}

/* 工具类 */
.text-center { text-align: center; }
.text-secondary { color: var(--text-secondary); }
.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }
.mb-4 { margin-bottom: 32px; }
.mb-5 { margin-bottom: 48px; }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mt-4 { margin-top: 32px; }
.mt-5 { margin-top: 48px; }

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

.animate-fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}