/* ==========================================================================
   飞鸟云 (feiniaoyun.cyou) - 主样式表
   主题：天蓝色渐变背景、飞鸟飞翔动画、天空渐变字、精致白云/飞鸟按钮
   ========================================================================== */

/* 导入 Google 字体 */
@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;500;600;700;800&family=Noto+Sans+SC:wght@300;400;500;700;900&display=swap');

:root {
    --primary-color: #0284c7;       /* 天空蓝 */
    --primary-hover: #0369a1;       /* 深天蓝 */
    --primary-light: #e0f2fe;       /* 极亮天蓝 */
    --accent-color: #38bdf8;        /* 亮天蓝 */
    --dark-sky: #0c4a6e;            /* 深海蓝/云海夜空 */
    --heading-color: #0f172a;       /* 暗灰石色 */
    --text-color: #475569;          /* 板岩灰 */
    --bg-white: #ffffff;
    --bg-light: #f0f9ff;            /* 云海微蓝 */
    --border-color: #e2e8f0;        /* 浅灰边界 */
    --shadow-sm: 0 4px 6px -1px rgba(2, 132, 199, 0.05);
    --shadow-md: 0 10px 15px -3px rgba(2, 132, 199, 0.08), 0 4px 6px -2px rgba(2, 132, 199, 0.03);
    --shadow-lg: 0 20px 25px -5px rgba(2, 132, 199, 0.12), 0 10px 10px -5px rgba(2, 132, 199, 0.04);
    --shadow-glow: 0 0 20px rgba(56, 189, 248, 0.4);
    --radius-sm: 8px;
    --radius-md: 16px;
    --radius-lg: 24px;
    --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
    font-family: 'Outfit', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
    background-color: var(--bg-white);
    color: var(--text-color);
    line-height: 1.7;
    overflow-x: hidden;
}

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

a:hover {
    color: var(--primary-hover);
}

ul, ol {
    list-style: none;
}

h1, h2, h3, h4, h5, h6 {
    color: var(--heading-color);
    font-weight: 700;
    line-height: 1.3;
}

/* 常用布局工具 */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.section {
    padding: 80px 0;
    position: relative;
    z-index: 1;
}

.section-bg-light {
    background-color: var(--bg-light);
}

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

.section-header {
    max-width: 700px;
    margin: 0 auto 50px auto;
}

.section-header h2 {
    font-size: 2.25rem;
    margin-bottom: 16px;
    position: relative;
    display: inline-block;
    background: linear-gradient(135deg, var(--dark-sky), var(--primary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.section-header h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-color), var(--primary-color));
    margin: 12px auto 0 auto;
    border-radius: 2px;
}

.section-header p {
    font-size: 1.125rem;
    color: var(--text-color);
}

/* 飞鸟天空背景动画 */
.sky-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: 0;
    pointer-events: none;
}

/* 独立的一只飞鸟容器 */
.bird-container {
    position: absolute;
    pointer-events: none;
    left: -100px;
    top: var(--bird-top, 20%);
    transform: scale(var(--bird-scale, 1));
    animation: fly-across var(--fly-duration, 25s) linear infinite;
    animation-delay: var(--fly-delay, 0s);
    opacity: 0.85;
}

.bird-svg {
    width: 80px;
    height: 80px;
}

/* 鸟的羽翼扇动动画 */
.left-wing {
    fill: var(--primary-color);
    transform-origin: 40px 38px;
    animation: flap-left 0.6s ease-in-out infinite;
}

.right-wing {
    fill: var(--primary-color);
    transform-origin: 40px 38px;
    animation: flap-right 0.6s ease-in-out infinite;
}

.bird-body {
    fill: var(--primary-hover);
}

@keyframes flap-left {
    0%, 100% {
        transform: rotate(0deg);
    }
    50% {
        transform: rotate(-35deg) skewX(-10deg);
    }
}

@keyframes flap-right {
    0%, 100% {
        transform: rotate(0deg);
    }
    50% {
        transform: rotate(35deg) skewX(10deg);
    }
}

@keyframes fly-across {
    0% {
        transform: translate3d(-100px, 0, 0) scale(var(--bird-scale, 1));
    }
    50% {
        transform: translate3d(50vw, var(--fly-bob, -25px), 0) scale(var(--bird-scale, 1));
    }
    100% {
        transform: translate3d(110vw, -10px, 0) scale(var(--bird-scale, 1));
    }
}

/* 按钮样式 - 天空与白云微动效 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 28px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition-normal);
    border: 2px solid transparent;
    gap: 8px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    color: var(--bg-white);
    box-shadow: 0 4px 15px rgba(2, 132, 199, 0.25);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(2, 132, 199, 0.4);
    color: var(--bg-white);
}

.btn-secondary {
    background-color: var(--bg-white);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.btn-secondary:hover {
    background-color: var(--primary-light);
    transform: translateY(-2px);
}

/* 头部导航 */
header {
    background-color: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(2, 132, 199, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 14px 0;
    transition: var(--transition-fast);
}

.header-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.5rem;
    font-weight: 800;
}

.logo span {
    background: linear-gradient(135deg, var(--dark-sky), var(--primary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.logo-bird {
    width: 38px;
    height: 38px;
}

nav ul {
    display: flex;
    gap: 32px;
}

nav ul li a {
    color: var(--heading-color);
    font-weight: 500;
    position: relative;
    padding: 6px 0;
}

nav ul li a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: var(--transition-fast);
}

nav ul li a:hover {
    color: var(--primary-color);
}

nav ul li a:hover::after {
    width: 100%;
}

/* 巨幕区 Hero */
.hero {
    position: relative;
    padding: 140px 0 110px 0;
    text-align: center;
    background: radial-gradient(circle at 50% 30%, #e0f2fe 0%, #f0f9ff 50%, #ffffff 100%);
    overflow: hidden;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 3.75rem;
    letter-spacing: -1px;
    line-height: 1.2;
    margin-bottom: 24px;
    background: linear-gradient(135deg, var(--dark-sky) 0%, var(--primary-color) 50%, var(--accent-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-color);
    margin-bottom: 40px;
    font-weight: 400;
}

.hero-ctas {
    display: flex;
    gap: 16px;
    justify-content: center;
}

/* 服务优势 */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
    position: relative;
    z-index: 1;
}

.feature-card {
    background-color: var(--bg-white);
    border: 1px solid rgba(2, 132, 199, 0.1);
    border-radius: var(--radius-md);
    padding: 40px 32px;
    text-align: left;
    transition: var(--transition-normal);
    box-shadow: var(--shadow-sm);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-color);
}

.feature-icon {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-sm);
    background-color: var(--primary-light);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 24px;
    color: var(--primary-color);
}

.feature-icon svg {
    width: 32px;
    height: 32px;
    fill: currentColor;
}

.feature-card h3 {
    font-size: 1.35rem;
    margin-bottom: 12px;
    color: var(--dark-sky);
}

.feature-card p {
    font-size: 0.95rem;
    color: var(--text-color);
}

/* 订阅套餐 */
.pricing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 32px;
    position: relative;
    z-index: 1;
}

.pricing-card {
    background-color: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 40px 32px;
    text-align: center;
    position: relative;
    transition: var(--transition-normal);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
}

.pricing-card.popular {
    border: 2px solid var(--primary-color);
    box-shadow: var(--shadow-md);
    transform: scale(1.02);
}

.pricing-card.popular::before {
    content: '最受欢迎 / 推荐';
    position: absolute;
    top: -14px;
    left: 50%;
    transform: translateX(-50%);
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    color: var(--bg-white);
    padding: 4px 16px;
    font-size: 0.75rem;
    font-weight: 700;
    border-radius: 20px;
    letter-spacing: 1px;
}

.pricing-card:hover {
    transform: translateY(-4px) scale(1.04);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-color);
}

.pricing-name {
    font-size: 1.25rem;
    color: var(--dark-sky);
    margin-bottom: 12px;
}

.pricing-price {
    margin-bottom: 24px;
}

.price-currency {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.price-num {
    font-size: 3.5rem;
    font-weight: 800;
    color: var(--primary-color);
}

.price-period {
    font-size: 0.875rem;
    color: var(--text-color);
}

.pricing-features {
    text-align: left;
    margin-bottom: 32px;
    flex-grow: 1;
}

.pricing-features li {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 0.95rem;
    margin-bottom: 12px;
    color: var(--text-color);
}

.pricing-features li svg {
    width: 20px;
    height: 20px;
    fill: var(--primary-color);
    flex-shrink: 0;
}

/* 推荐文章区域 */
.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 32px;
    position: relative;
    z-index: 1;
}

.article-card {
    background-color: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: var(--transition-normal);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
}

.article-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-color);
}

.article-image-placeholder {
    height: 180px;
    background: linear-gradient(135deg, var(--primary-light), #bae6fd);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    position: relative;
}

.article-image-placeholder svg {
    width: 60px;
    height: 60px;
    fill: currentColor;
    opacity: 0.8;
}

.article-content {
    padding: 24px;
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.article-meta {
    display: flex;
    gap: 16px;
    font-size: 0.8rem;
    color: var(--text-color);
    margin-bottom: 12px;
}

.article-title {
    font-size: 1.15rem;
    margin-bottom: 12px;
    line-height: 1.4;
}

.article-title a {
    color: var(--heading-color);
}

.article-title a:hover {
    color: var(--primary-color);
}

.article-excerpt {
    font-size: 0.9rem;
    color: var(--text-color);
    margin-bottom: 20px;
    flex-grow: 1;
}

.article-readmore {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-weight: 600;
    font-size: 0.9rem;
}

.article-readmore svg {
    width: 16px;
    height: 16px;
    fill: currentColor;
    transition: var(--transition-fast);
}

.article-readmore:hover svg {
    transform: translateX(4px);
}

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

.faq-item {
    background-color: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    margin-bottom: 16px;
    overflow: hidden;
    transition: var(--transition-normal);
}

.faq-question {
    padding: 20px 24px;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--dark-sky);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
    user-select: none;
}

.faq-question svg {
    width: 24px;
    height: 24px;
    fill: var(--text-color);
    transition: var(--transition-normal);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out;
    padding: 0 24px;
}

.faq-answer p {
    padding-bottom: 20px;
    color: var(--text-color);
    font-size: 0.95rem;
}

/* 激活状态 */
.faq-item.active {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-sm);
}

.faq-item.active .faq-question svg {
    transform: rotate(180deg);
    fill: var(--primary-color);
}

.faq-item.active .faq-answer {
    max-height: 500px; /* 足够容纳展开内容的值 */
}

/* 用户评价 */
.reviews-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
}

.review-card {
    background-color: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 32px;
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    transition: var(--transition-normal);
}

.review-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-color);
}

.review-stars {
    display: flex;
    gap: 4px;
    margin-bottom: 16px;
}

.review-stars svg {
    width: 20px;
    height: 20px;
    fill: #f59e0b; /* 琥珀色星级 */
}

.review-text {
    font-style: italic;
    font-size: 0.95rem;
    color: var(--text-color);
    margin-bottom: 24px;
    flex-grow: 1;
}

.review-user {
    display: flex;
    align-items: center;
    gap: 12px;
}

.review-avatar {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background-color: var(--primary-light);
    color: var(--primary-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.25rem;
}

.review-user-info h4 {
    font-size: 1rem;
    color: var(--heading-color);
}

.review-user-info span {
    font-size: 0.8rem;
    color: var(--text-color);
}

/* CTA 横幅 */
.cta-banner {
    position: relative;
    padding: 80px 0;
    text-align: center;
    background: linear-gradient(135deg, var(--dark-sky), var(--primary-color));
    color: var(--bg-white);
    overflow: hidden;
}

.cta-banner h2 {
    color: var(--bg-white);
    font-size: 2.25rem;
    margin-bottom: 16px;
}

.cta-banner p {
    font-size: 1.125rem;
    margin-bottom: 32px;
    opacity: 0.9;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* 文章页详情样式 */
.article-page {
    max-width: 800px;
    padding-top: 40px;
    padding-bottom: 80px;
}

.article-breadcrumb {
    font-size: 0.9rem;
    color: var(--text-color);
    margin-bottom: 24px;
}

.article-breadcrumb a {
    color: var(--text-color);
}

.article-breadcrumb a:hover {
    color: var(--primary-color);
}

.article-header {
    margin-bottom: 40px;
    text-align: center;
}

.article-header h1 {
    font-size: 2.5rem;
    margin-bottom: 16px;
    color: var(--dark-sky);
    line-height: 1.3;
}

.article-meta {
    display: flex;
    justify-content: center;
    gap: 24px;
    font-size: 0.9rem;
    color: var(--text-color);
}

.article-body {
    font-size: 1.05rem;
    line-height: 1.85;
    color: var(--heading-color);
}

.article-body p {
    margin-bottom: 24px;
}

.article-body h2 {
    font-size: 1.75rem;
    margin-top: 40px;
    margin-bottom: 20px;
    color: var(--dark-sky);
}

.article-body h3 {
    font-size: 1.35rem;
    margin-top: 30px;
    margin-bottom: 16px;
    color: var(--primary-hover);
}

.article-body ul, .article-body ol {
    margin-bottom: 24px;
    padding-left: 20px;
}

.article-body ul {
    list-style: disc;
}

.article-body ol {
    list-style: decimal;
}

.article-body li {
    margin-bottom: 10px;
}

.article-body blockquote {
    border-left: 4px solid var(--accent-color);
    background-color: var(--bg-light);
    padding: 20px 24px;
    margin-bottom: 24px;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.article-body blockquote p {
    margin-bottom: 0;
    font-style: italic;
    color: var(--text-color);
}

.article-body strong {
    color: var(--primary-color);
}

.article-navigation {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    border-top: 1px solid var(--border-color);
    margin-top: 60px;
    padding-top: 30px;
}

.nav-link-card {
    background-color: var(--bg-light);
    padding: 20px;
    border-radius: var(--radius-sm);
    display: flex;
    flex-direction: column;
    gap: 8px;
    border: 1px solid transparent;
    transition: var(--transition-fast);
}

.nav-link-card:hover {
    border-color: var(--accent-color);
    background-color: var(--bg-white);
}

.nav-link-card span {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-color);
}

.nav-link-card a {
    font-weight: 600;
    color: var(--dark-sky);
    font-size: 0.95rem;
}

.nav-link-card a:hover {
    color: var(--primary-color);
}

/* 页脚 */
footer {
    background-color: #0f172a;
    color: #94a3b8;
    padding: 80px 0 40px 0;
    border-top: 1px solid #1e293b;
    position: relative;
    z-index: 1;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 60px;
    margin-bottom: 60px;
}

.footer-col h3 {
    color: var(--bg-white);
    font-size: 1.15rem;
    margin-bottom: 24px;
    position: relative;
}

.footer-col h3::after {
    content: '';
    display: block;
    width: 30px;
    height: 2px;
    background-color: var(--primary-color);
    margin-top: 8px;
}

.footer-col p {
    font-size: 0.9rem;
    line-height: 1.8;
}

.footer-col ul li {
    margin-bottom: 12px;
}

.footer-col ul li a {
    color: #94a3b8;
    font-size: 0.9rem;
}

.footer-col ul li a:hover {
    color: var(--bg-white);
    padding-left: 4px;
}

.footer-bottom {
    border-top: 1px solid #1e293b;
    padding-top: 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    flex-wrap: wrap;
    gap: 20px;
}

.footer-bottom-links {
    display: flex;
    gap: 24px;
}

.footer-bottom-links a {
    color: #94a3b8;
}

.footer-bottom-links a:hover {
    color: var(--bg-white);
}

/* ==========================================================================
   移动端与媒体查询适配 (Responsive Design)
   ========================================================================== */

@media (max-width: 1024px) {
    html {
        font-size: 15px;
    }
    
    .hero h1 {
        font-size: 3.25rem;
    }
}

@media (max-width: 768px) {
    .section {
        padding: 60px 0;
    }

    /* 移动端菜单变为折叠或隐藏（此模板使用自适应隐藏/简单布局） */
    header {
        padding: 10px 0;
    }

    .header-container {
        flex-direction: column;
        gap: 12px;
    }

    nav ul {
        gap: 16px;
        flex-wrap: wrap;
        justify-content: center;
    }

    #header-cta {
        display: none; /* 移动端在导航收起时隐藏，可通过Hero区域注册 */
    }

    .hero {
        padding: 100px 0 70px 0;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero p {
        font-size: 1.1rem;
        margin-bottom: 30px;
    }

    .hero-ctas {
        flex-direction: column;
        gap: 12px;
        width: 100%;
        max-width: 300px;
        margin: 0 auto;
    }

    .hero-ctas .btn {
        width: 100%;
    }

    .features-grid, .pricing-grid, .articles-grid, .reviews-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .pricing-card.popular {
        transform: none;
    }

    .pricing-card:hover {
        transform: translateY(-4px);
    }

    .faq-question {
        padding: 16px 20px;
        font-size: 1rem;
    }

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .footer-bottom {
        flex-direction: column;
        text-align: center;
        gap: 16px;
    }
    
    .article-header h1 {
        font-size: 2rem;
    }
    
    .article-navigation {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 14px;
    }

    .hero h1 {
        font-size: 2.15rem;
    }

    .section-header h2 {
        font-size: 1.85rem;
    }
    
    .article-header h1 {
        font-size: 1.75rem;
    }
}