/* ========================================
   17c一起草 - 全站样式表
   品牌色: #1E6FD9 (品牌蓝)
   辅助色: #0A1628 (深蓝黑)
   强调色: #FF6B35 (活力橙)
   背景色: #F5F7FA (浅灰白)
   ======================================== */

/* Reset & Base */
*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;color:#2D3748;background:#F5F7FA;line-height:1.7;overflow-x:hidden}
a{color:#1E6FD9;text-decoration:none;transition:color .3s}
a:hover{color:#FF6B35}
img{max-width:100%;height:auto;display:block}
ul,ol{list-style:none}
h1,h2,h3,h4,h5,h6{font-weight:700;line-height:1.3;color:#0A1628}

/* Container */
.container{max-width:1200px;margin:0 auto;padding:0 20px}
.section{padding:60px 0}
.section-title{text-align:center;margin-bottom:40px}
.section-title h2{font-size:28px;margin-bottom:10px;position:relative;display:inline-block}
.section-title h2::after{content:'';display:block;width:60px;height:3px;background:linear-gradient(90deg,#1E6FD9,#FF6B35);margin:10px auto 0}
.section-title p{color:#718096;font-size:15px;max-width:600px;margin:0 auto}

/* Header & Navigation */
.site-header{background:#0A1628;position:sticky;top:0;z-index:1000;box-shadow:0 2px 10px rgba(0,0,0,.3)}
.header-inner{display:flex;align-items:center;justify-content:space-between;padding:0 20px;max-width:1200px;margin:0 auto;height:64px}
.site-logo{display:flex;align-items:center;gap:10px}
.site-logo img{height:40px;width:auto;max-width:140px;object-fit:contain}
.site-logo span{color:#fff;font-size:20px;font-weight:700}
.main-nav{display:flex;align-items:center;gap:0}
.main-nav a{color:#ccc;padding:20px 16px;font-size:14px;transition:all .3s;position:relative}
.main-nav a:hover,.main-nav a.active{color:#fff;background:rgba(30,111,217,.2)}
.main-nav a::after{content:'';position:absolute;bottom:0;left:50%;transform:translateX(-50%);width:0;height:2px;background:#FF6B35;transition:width .3s}
.main-nav a:hover::after,.main-nav a.active::after{width:60%}
.mobile-menu-btn{display:none;background:none;border:none;color:#fff;font-size:24px;cursor:pointer}

/* Search Bar */
.search-bar{background:linear-gradient(135deg,#1E6FD9,#0A1628);padding:16px 0}
.search-bar .container{display:flex;justify-content:center}
.search-form{display:flex;max-width:600px;width:100%;background:#fff;border-radius:30px;overflow:hidden;box-shadow:0 4px 15px rgba(0,0,0,.15)}
.search-form input{flex:1;border:none;padding:12px 24px;font-size:15px;outline:none;color:#2D3748}
.search-form input::placeholder{color:#a0aec0}
.search-form button{background:#FF6B35;color:#fff;border:none;padding:12px 28px;font-size:14px;cursor:pointer;transition:background .3s;font-weight:600}
.search-form button:hover{background:#e55a25}

/* Hero Section */
.hero{position:relative;background:url('../images/hero-bg.jpg') center/cover no-repeat;min-height:480px;display:flex;align-items:center;overflow:hidden}
.hero::before{content:'';position:absolute;inset:0;background:linear-gradient(135deg,rgba(10,22,40,.85),rgba(30,111,217,.6))}
.hero-content{position:relative;z-index:2;text-align:center;width:100%;padding:60px 20px}
.hero h1{font-size:42px;color:#fff;margin-bottom:16px;text-shadow:0 2px 8px rgba(0,0,0,.3)}
.hero h1 span{color:#FF6B35}
.hero p{color:rgba(255,255,255,.9);font-size:18px;max-width:700px;margin:0 auto 30px;line-height:1.8}
.hero-tags{display:flex;flex-wrap:wrap;justify-content:center;gap:10px;margin-bottom:30px}
.hero-tags span{background:rgba(255,255,255,.15);color:#fff;padding:6px 18px;border-radius:20px;font-size:13px;backdrop-filter:blur(5px)}
.hero-btns{display:flex;justify-content:center;gap:16px;flex-wrap:wrap}
.btn{display:inline-flex;align-items:center;gap:8px;padding:12px 32px;border-radius:30px;font-size:15px;font-weight:600;transition:all .3s;cursor:pointer;border:none}
.btn-primary{background:#FF6B35;color:#fff;box-shadow:0 4px 15px rgba(255,107,53,.4)}
.btn-primary:hover{background:#e55a25;transform:translateY(-2px);color:#fff}
.btn-outline{background:transparent;color:#fff;border:2px solid rgba(255,255,255,.5)}
.btn-outline:hover{background:rgba(255,255,255,.15);color:#fff}

/* Video Card Grid */
.video-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:20px}
.video-card{background:#fff;border-radius:12px;overflow:hidden;box-shadow:0 2px 12px rgba(0,0,0,.08);transition:all .3s;position:relative}
.video-card:hover{transform:translateY(-5px);box-shadow:0 8px 25px rgba(0,0,0,.15)}
.video-thumb{position:relative;padding-top:56.25%;overflow:hidden;background:#0A1628}
.video-thumb img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;transition:transform .5s}
.video-card:hover .video-thumb img{transform:scale(1.05)}
.video-play-btn{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;opacity:0;transition:opacity .3s;background:rgba(0,0,0,.35)}
.video-card:hover .video-play-btn{opacity:1}
.video-play-btn span{width:56px;height:56px;background:rgba(255,107,53,.9);border-radius:50%;display:flex;align-items:center;justify-content:center;box-shadow:0 4px 15px rgba(0,0,0,.3)}
.video-play-btn span::after{content:'';display:block;width:0;height:0;border-style:solid;border-width:10px 0 10px 18px;border-color:transparent transparent transparent #fff;margin-left:3px}
.video-duration{position:absolute;bottom:8px;right:8px;background:rgba(0,0,0,.75);color:#fff;padding:2px 8px;border-radius:4px;font-size:12px}
.video-info{padding:14px}
.video-info h3{font-size:14px;margin-bottom:6px;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden;line-height:1.5}
.video-meta{display:flex;align-items:center;justify-content:space-between;color:#718096;font-size:12px}
.video-meta .views{display:flex;align-items:center;gap:4px}
.video-tag{display:inline-block;background:#EBF5FF;color:#1E6FD9;padding:2px 8px;border-radius:4px;font-size:11px;margin-top:6px}

/* Category Tabs */
.category-tabs{display:flex;justify-content:center;gap:8px;margin-bottom:30px;flex-wrap:wrap}
.category-tabs .tab{padding:8px 22px;border-radius:20px;font-size:14px;cursor:pointer;transition:all .3s;background:#fff;color:#718096;border:1px solid #e2e8f0}
.category-tabs .tab:hover,.category-tabs .tab.active{background:#1E6FD9;color:#fff;border-color:#1E6FD9}

/* Feature Cards */
.feature-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.feature-card{background:#fff;border-radius:12px;padding:30px;text-align:center;box-shadow:0 2px 12px rgba(0,0,0,.06);transition:all .3s;border:1px solid #e2e8f0}
.feature-card:hover{border-color:#1E6FD9;box-shadow:0 8px 25px rgba(30,111,217,.12)}
.feature-icon{width:64px;height:64px;margin:0 auto 16px;background:linear-gradient(135deg,#1E6FD9,#4A90E2);border-radius:16px;display:flex;align-items:center;justify-content:center;font-size:28px;color:#fff}
.feature-card h3{font-size:18px;margin-bottom:8px}
.feature-card p{color:#718096;font-size:14px;line-height:1.6}

/* Expert Section */
.expert-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:24px}
.expert-card{background:#fff;border-radius:12px;overflow:hidden;box-shadow:0 2px 12px rgba(0,0,0,.06);text-align:center;transition:all .3s}
.expert-card:hover{transform:translateY(-5px);box-shadow:0 8px 25px rgba(0,0,0,.12)}
.expert-avatar{width:100px;height:100px;border-radius:50%;margin:24px auto 12px;overflow:hidden;border:3px solid #1E6FD9}
.expert-avatar img{width:100%;height:100%;object-fit:cover}
.expert-card h4{font-size:16px;margin-bottom:4px}
.expert-card .role{color:#1E6FD9;font-size:13px;margin-bottom:8px}
.expert-card .desc{color:#718096;font-size:13px;padding:0 16px;line-height:1.5}
.expert-card .expert-btns{display:flex;gap:8px;justify-content:center;padding:16px}
.expert-card .expert-btns a{padding:6px 16px;border-radius:20px;font-size:12px;transition:all .3s}
.expert-card .expert-btns .btn-contact{background:#1E6FD9;color:#fff}
.expert-card .expert-btns .btn-contact:hover{background:#1558b0}
.expert-card .expert-btns .btn-work{background:#EBF5FF;color:#1E6FD9}
.expert-card .expert-btns .btn-work:hover{background:#d6eaff}

/* Partner Logos */
.partner-wall{display:flex;flex-wrap:wrap;justify-content:center;gap:30px;align-items:center}
.partner-wall .partner-item{width:140px;height:60px;background:#fff;border-radius:8px;display:flex;align-items:center;justify-content:center;box-shadow:0 2px 8px rgba(0,0,0,.06);padding:10px;filter:grayscale(1);opacity:.6;transition:all .3s;font-weight:700;color:#718096;font-size:14px}
.partner-wall .partner-item:hover{filter:grayscale(0);opacity:1}

/* FAQ Section */
.faq-list{max-width:800px;margin:0 auto}
.faq-item{background:#fff;border-radius:10px;margin-bottom:12px;overflow:hidden;box-shadow:0 2px 8px rgba(0,0,0,.04)}
.faq-item .faq-q{padding:18px 24px;font-weight:600;cursor:pointer;display:flex;justify-content:space-between;align-items:center;transition:background .3s;font-size:15px}
.faq-item .faq-q:hover{background:#f7fafc}
.faq-item .faq-q::after{content:'+';font-size:20px;color:#1E6FD9;transition:transform .3s;font-weight:400}
.faq-item.open .faq-q::after{transform:rotate(45deg)}
.faq-item .faq-a{padding:0 24px;max-height:0;overflow:hidden;transition:all .3s;color:#718096;font-size:14px;line-height:1.8}
.faq-item.open .faq-a{padding:0 24px 18px;max-height:300px}

/* Reviews */
.review-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:20px}
.review-card{background:#fff;border-radius:12px;padding:24px;box-shadow:0 2px 12px rgba(0,0,0,.06)}
.review-header{display:flex;align-items:center;gap:12px;margin-bottom:12px}
.review-avatar{width:48px;height:48px;border-radius:50%;background:linear-gradient(135deg,#1E6FD9,#FF6B35);display:flex;align-items:center;justify-content:center;color:#fff;font-weight:700;font-size:18px}
.review-name{font-weight:600;font-size:15px}
.review-date{color:#a0aec0;font-size:12px}
.review-stars{color:#FF6B35;font-size:14px;margin-bottom:8px}
.review-text{color:#4a5568;font-size:14px;line-height:1.7}

/* Contact Section */
.contact-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:30px}
.contact-info{background:#fff;border-radius:12px;padding:30px;box-shadow:0 2px 12px rgba(0,0,0,.06)}
.contact-info h3{font-size:20px;margin-bottom:16px;color:#0A1628}
.contact-item{display:flex;align-items:flex-start;gap:12px;margin-bottom:16px;font-size:14px;color:#4a5568}
.contact-item .icon{width:36px;height:36px;background:#EBF5FF;border-radius:8px;display:flex;align-items:center;justify-content:center;color:#1E6FD9;font-size:16px;flex-shrink:0}
.qrcode-group{display:flex;gap:24px;justify-content:center;margin-top:20px}
.qrcode-item{text-align:center}
.qrcode-item img{width:140px;height:140px;border-radius:8px}
.qrcode-item p{margin-top:8px;font-size:13px;color:#718096}

/* How-To Guide */
.howto-steps{display:grid;grid-template-columns:repeat(4,1fr);gap:20px;margin-top:30px}
.howto-step{text-align:center;position:relative}
.howto-step .step-num{width:48px;height:48px;background:linear-gradient(135deg,#1E6FD9,#4A90E2);color:#fff;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:20px;font-weight:700;margin:0 auto 12px}
.howto-step h4{font-size:15px;margin-bottom:6px}
.howto-step p{color:#718096;font-size:13px}

/* Footer */
.site-footer{background:#0A1628;color:#a0aec0;padding:40px 0 0}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:30px;padding-bottom:30px;border-bottom:1px solid rgba(255,255,255,.1)}
.footer-brand .footer-logo{display:flex;align-items:center;gap:10px;margin-bottom:12px}
.footer-brand .footer-logo img{height:36px;width:auto;max-width:130px;object-fit:contain}
.footer-brand .footer-logo span{color:#fff;font-size:18px;font-weight:700}
.footer-brand p{font-size:13px;line-height:1.7;margin-bottom:16px}
.footer-col h4{color:#fff;font-size:15px;margin-bottom:16px;position:relative;padding-bottom:10px}
.footer-col h4::after{content:'';position:absolute;bottom:0;left:0;width:30px;height:2px;background:#FF6B35}
.footer-col a{display:block;color:#a0aec0;font-size:13px;padding:4px 0;transition:color .3s}
.footer-col a:hover{color:#FF6B35}
.footer-bottom{text-align:center;padding:20px 0;font-size:13px;border-top:1px solid rgba(255,255,255,.08)}
.footer-bottom .update-time{color:#718096;margin-top:4px;font-size:12px}

/* Social Share */
.share-bar{display:flex;gap:10px;justify-content:center;margin-top:20px}
.share-btn{width:40px;height:40px;border-radius:50%;display:flex;align-items:center;justify-content:center;color:#fff;font-size:16px;transition:all .3s;cursor:pointer}
.share-btn:hover{transform:translateY(-3px)}
.share-btn.wechat{background:#07C160}
.share-btn.weibo{background:#E6162D}
.share-btn.douyin{background:#000}
.share-btn.bilibili{background:#FB7299}

/* Breadcrumb */
.breadcrumb{padding:12px 0;font-size:13px;color:#718096}
.breadcrumb a{color:#1E6FD9}
.breadcrumb span{margin:0 6px}

/* AI Section */
.ai-features{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.ai-card{background:linear-gradient(135deg,#0A1628,#1a2a4a);border-radius:12px;padding:28px;color:#fff;transition:all .3s;border:1px solid rgba(30,111,217,.3)}
.ai-card:hover{border-color:#1E6FD9;box-shadow:0 8px 25px rgba(30,111,217,.2)}
.ai-card h4{font-size:17px;margin-bottom:8px;color:#fff}
.ai-card p{color:rgba(255,255,255,.7);font-size:13px;line-height:1.6}
.ai-card .ai-icon{font-size:32px;margin-bottom:12px}

/* Community Section */
.community-features{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.community-card{background:#fff;border-radius:12px;padding:24px;text-align:center;box-shadow:0 2px 12px rgba(0,0,0,.06);transition:all .3s;border-bottom:3px solid transparent}
.community-card:hover{border-bottom-color:#FF6B35;transform:translateY(-3px)}
.community-card .comm-icon{font-size:36px;margin-bottom:12px}
.community-card h4{font-size:16px;margin-bottom:6px}
.community-card p{color:#718096;font-size:13px}

/* Stats Bar */
.stats-bar{background:linear-gradient(135deg,#1E6FD9,#0A1628);padding:40px 0;color:#fff}
.stats-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:20px;text-align:center}
.stat-item .stat-num{font-size:36px;font-weight:700;margin-bottom:4px}
.stat-item .stat-label{font-size:14px;opacity:.8}

/* Responsive */
@media(max-width:1024px){
.video-grid{grid-template-columns:repeat(3,1fr)}
.feature-grid,.ai-features,.community-features{grid-template-columns:repeat(2,1fr)}
.expert-grid{grid-template-columns:repeat(2,1fr)}
.footer-grid{grid-template-columns:repeat(2,1fr)}
.howto-steps{grid-template-columns:repeat(2,1fr)}
}
@media(max-width:768px){
.header-inner{height:56px}
.main-nav{display:none;position:absolute;top:56px;left:0;right:0;background:#0A1628;flex-direction:column;padding:10px 0;box-shadow:0 4px 15px rgba(0,0,0,.3)}
.main-nav.open{display:flex}
.main-nav a{padding:14px 24px;border-bottom:1px solid rgba(255,255,255,.05)}
.mobile-menu-btn{display:block}
.hero h1{font-size:28px}
.hero p{font-size:15px}
.video-grid{grid-template-columns:repeat(2,1fr)}
.feature-grid,.ai-features,.community-features{grid-template-columns:1fr}
.expert-grid{grid-template-columns:repeat(2,1fr)}
.review-grid{grid-template-columns:1fr}
.contact-grid{grid-template-columns:1fr}
.footer-grid{grid-template-columns:1fr}
.stats-grid{grid-template-columns:repeat(2,1fr)}
.howto-steps{grid-template-columns:1fr}
.section{padding:40px 0}
.section-title h2{font-size:22px}
}
@media(max-width:480px){
.video-grid{grid-template-columns:1fr}
.expert-grid{grid-template-columns:1fr}
.hero h1{font-size:24px}
.stats-grid{grid-template-columns:repeat(2,1fr)}
.search-form{flex-direction:column;border-radius:12px}
.search-form button{border-radius:0 0 12px 12px}
}

/* Lazy Load */
img[loading="lazy"]{opacity:0;transition:opacity .5s}
img[loading="lazy"].loaded,img[loading="lazy"][src]{opacity:1}

/* Animation */
.fade-in{opacity:0;transform:translateY(20px);transition:all .6s ease}
.fade-in.visible{opacity:1;transform:translateY(0)}