/* Reset & Variables */
:root {
    --primary-color: #0071e3; /* Apple Blue */
    --primary-hover: #0077ed;
    --bg-color: #fbfbfd; /* Apple Light Gray Background */
    --alt-bg: #ffffff;   /* Pure White for alternating sections */
    --text-main: #1d1d1f; /* Apple Dark Text */
    --text-light: #86868b; /* Apple Gray Text */
    --border-color: #d2d2d7;
    --font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

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

body {
    font-family: var(--font-family);
    color: var(--text-main);
    line-height: 1.47059;
    letter-spacing: -0.022em;
    background-color: var(--bg-color);
    -webkit-font-smoothing: antialiased;
    scroll-behavior: smooth;
}

a {
    text-decoration: none;
    color: var(--primary-color);
}

/* 椭圆形悬浮导航栏 */
header {
    position: fixed;
    top: 20px;
    left: 0;
    width: 100%;
    z-index: 1000;
    display: flex;
    justify-content: center;
    pointer-events: none; /* 让空白处可以被点击透过 */
}

.nav-container {
    pointer-events: auto; /* 恢复导航栏本体的点击 */
    background: rgba(255, 255, 255, 0.75);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid rgba(0, 0, 0, 0.05);
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
    border-radius: 50px;
    padding: 10px 20px;
    width: 90%;
    max-width: 1000px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 20px;
    font-weight: 700;
    color: var(--text-main);
    padding-left: 10px;
}

.nav-menu {
    display: none;
}

@media (min-width: 768px) {
    .nav-menu {
        display: flex;
        gap: 30px;
    }
    .nav-menu a {
        color: var(--text-main);
        font-size: 14px;
        font-weight: 500;
        opacity: 0.8;
        transition: opacity 0.2s;
    }
    .nav-menu a:hover {
        opacity: 1;
    }
}

/* 按钮样式 */
.cta-btn {
    display: inline-block;
    background-color: var(--primary-color);
    color: #fff !important;
    padding: 10px 24px;
    border-radius: 30px;
    font-weight: 600;
    font-size: 14px;
    text-align: center;
    border: 1px solid transparent;
    transition: all 0.3s ease;
}

.cta-btn:hover {
    background-color: var(--primary-hover);
    transform: scale(1.02);
}

.secondary-btn {
    display: inline-block;
    background-color: transparent;
    color: var(--text-main);
    padding: 10px 24px;
    border-radius: 30px;
    font-weight: 600;
    font-size: 14px;
    text-align: center;
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
}

.secondary-btn:hover {
    background-color: #f5f5f7;
}

/* 极简主视觉区 */
section.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding-top: 80px !important;
    padding-bottom: 60px !important;
    text-align: center;
    max-width: 850px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 3.8rem;
    font-weight: 700;
    letter-spacing: -0.015em;
    line-height: 1.15;
    margin-bottom: 30px;
    color: var(--text-main);
}

.hero p {
    font-size: 1.3rem;
    color: var(--text-light);
    margin-bottom: 50px;
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    gap: 15px;
    justify-content: center;
}

/* 章节通用样式 */
.section-padding {
    padding: 100px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.alternate-bg {
    background-color: var(--alt-bg);
    max-width: 100%;
}

.alternate-bg > div, .alternate-bg > h2 {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.section-title {
    text-align: center;
    margin-bottom: 60px;
}

.section-title h2 {
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: -0.015em;
    margin-bottom: 15px;
}

.section-title p.subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
}

/* 卡片网格 (无图片设计) */
.card-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 24px;
}

@media (min-width: 768px) {
    .card-grid { grid-template-columns: repeat(3, 1fr); }
    .two-cols { grid-template-columns: repeat(2, 1fr); gap: 30px; }
    .three-cols { grid-template-columns: repeat(3, 1fr); }
}

/* 高级质感卡片 */
.card, .article-card, .pricing-card {
    background-color: #ffffff;
    border-radius: 24px;
    padding: 40px;
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.03);
    border: none;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    text-align: left;
}
.alternate-bg .card, .alternate-bg .article-card {
    background-color: #fbfbfd;
}

.card:hover, .article-card:hover {
    transform: translateY(-4px) scale(1.01);
    box-shadow: 0 12px 32px rgba(0, 0, 0, 0.08);
}

.card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text-main);
}

.card p {
    font-size: 1.05rem;
    color: var(--text-light);
    line-height: 1.6;
}

/* SEO 文章专用卡片 */
.article-card {
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    padding: 35px 30px;
}

.article-card .tag {
    font-size: 12px;
    font-weight: 600;
    color: var(--primary-color);
    letter-spacing: 0.5px;
    margin-bottom: 12px;
    text-transform: uppercase;
}

.article-card h3 {
    font-size: 1.25rem;
    line-height: 1.3;
    margin-bottom: 12px;
}

.article-card p {
    font-size: 0.95rem;
    margin: 0;
}

.inline-link {
    color: var(--primary-color);
    font-weight: 500;
}

/* 定价表 */
.pricing-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 30px;
}
@media (min-width: 768px) {
    .pricing-grid { grid-template-columns: repeat(3, 1fr); }
}

.pricing-card {
    position: relative;
    padding: 50px 30px;
    display: flex;
    flex-direction: column;
    background: #ffffff;
}

.pricing-card.popular {
    border: 2px solid var(--primary-color);
}

.badge {
    position: absolute;
    top: -14px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--primary-color);
    color: #fff;
    padding: 4px 16px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.pricing-card h3 {
    font-size: 1.3rem;
    text-align: center;
    margin-bottom: 10px;
}

.price {
    font-size: 3rem;
    font-weight: 700;
    color: var(--text-main);
    text-align: center;
    margin-bottom: 30px;
    letter-spacing: -0.02em;
}

.price span {
    font-size: 1.1rem;
    color: var(--text-light);
    font-weight: 500;
}

.pricing-card ul {
    list-style: none;
    margin-bottom: 40px;
    flex-grow: 1;
}

.pricing-card ul li {
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-light);
    font-size: 1rem;
    text-align: center;
}

.pricing-card ul li:last-child {
    border-bottom: none;
}

.plan-btn {
    width: 100%;
    padding: 14px 0;
    font-size: 1.1rem;
}

/* FAQ */
.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    margin-bottom: 30px;
    padding-bottom: 30px;
    border-bottom: 1px solid var(--border-color);
}
.faq-item:last-child { border-bottom: none; }

.faq-item h3 {
    font-size: 1.3rem;
    margin-bottom: 12px;
    color: var(--text-main);
}

.faq-item p {
    font-size: 1.05rem;
    color: var(--text-light);
    line-height: 1.6;
}

/* 页脚 */
footer {
    background-color: #f5f5f7;
    padding: 60px 20px;
    border-top: 1px solid var(--border-color);
    text-align: center;
}

.footer-inner {
    max-width: 1000px;
    margin: 0 auto;
}

.footer-links a {
    margin: 0 15px;
    color: var(--text-main);
    font-size: 0.9rem;
    display: inline-block;
    margin-bottom: 20px;
}

.pbn-links {
    margin: 20px 0;
    font-size: 0.85rem;
    color: var(--text-light);
}

.pbn-links a {
    color: var(--text-light);
    margin: 0 8px;
    text-decoration: underline;
}

.pbn-links a:hover {
    color: var(--text-main);
}

.copyright {
    font-size: 0.8rem;
    color: #a1a1a6;
    margin-top: 30px;
}