/* HTML4编程网 - 2026 Design System */
:root{--primary:#6366f1;--primary-dark:#4f46e5;--secondary:#ec4899;--accent:#06b6d4;--bg:#fff;--bg-dark:#0f172a;--bg-card:#f8fafc;--text:#1e293b;--text-secondary:#64748b;--text-light:#94a3b8;--border:#e2e8f0;--border-dark:#334155;--shadow-sm:0 1px 2px 0 rgba(0,0,0,.05);--shadow:0 4px 6px -1px rgba(0,0,0,.07),0 2px 4px -2px rgba(0,0,0,.05);--shadow-lg:0 10px 15px -3px rgba(0,0,0,.08),0 4px 6px -4px rgba(0,0,0,.05);--shadow-xl:0 20px 25px -5px rgba(0,0,0,.08),0 8px 10px -6px rgba(0,0,0,.05);--radius:12px;--radius-lg:16px;--radius-full:9999px;--transition:all .2s cubic-bezier(.4,0,.2,1);--font-sans:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;--font-mono:"SF Mono","Fira Code",Menlo,Monaco,Consolas,monospace}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{font-family:var(--font-sans);font-size:16px;line-height:1.7;color:var(--text);background:var(--bg);-webkit-font-smoothing:antialiased}
a{color:var(--primary);text-decoration:none;transition:var(--transition)}
a:hover{color:var(--primary-dark)}
.container{max-width:1280px;margin:0 auto;padding:0 24px}
.header{position:sticky;top:0;z-index:1000;background:rgba(255,255,255,.85);backdrop-filter:blur(20px);-webkit-backdrop-filter:blur(20px);border-bottom:1px solid var(--border)}
.header-inner{display:flex;align-items:center;justify-content:space-between;height:72px;gap:24px}
.logo{display:flex;align-items:center;gap:10px;font-size:22px;font-weight:800;color:var(--text);white-space:nowrap}
.logo-icon{width:40px;height:40px;background:linear-gradient(135deg,var(--primary),var(--secondary));border-radius:var(--radius);display:flex;align-items:center;justify-content:center;color:#fff;font-weight:900;font-size:16px}
.nav{display:flex;align-items:center;gap:4px}
.nav a{padding:8px 14px;border-radius:var(--radius);color:var(--text-secondary);font-weight:500;font-size:15px;white-space:nowrap}
.nav a:hover,.nav a.active{color:var(--primary);background:rgba(99,102,241,.08)}
.search-box{position:relative;flex:1;max-width:480px}
.search-input{width:100%;height:44px;padding:0 20px 0 48px;border:2px solid var(--border);border-radius:var(--radius-full);font-size:15px;background:var(--bg-card);outline:none;transition:var(--transition)}
.search-input:focus{border-color:var(--primary);background:#fff;box-shadow:0 0 0 4px rgba(99,102,241,.1)}
.search-icon{position:absolute;left:18px;top:50%;transform:translateY(-50%);color:var(--text-light);font-size:18px}
.search-results{position:absolute;top:calc(100% + 8px);left:0;right:0;background:#fff;border-radius:var(--radius-lg);box-shadow:var(--shadow-xl);border:1px solid var(--border);max-height:480px;overflow-y:auto;display:none}
.search-results.active{display:block}
.search-result-item{padding:12px 20px;border-bottom:1px solid var(--border);cursor:pointer;transition:var(--transition);display:block}
.search-result-item:hover{background:var(--bg-card)}
.search-result-item:last-child{border-bottom:none}
.search-result-title{font-weight:600;color:var(--text);margin-bottom:4px}
.search-result-desc{font-size:13px;color:var(--text-secondary)}
.search-no-result{padding:24px;text-align:center;color:var(--text-light)}
.mobile-toggle{display:none;width:40px;height:40px;border:none;background:var(--bg-card);border-radius:var(--radius);font-size:20px;cursor:pointer}
.hero{padding:80px 0 60px;text-align:center;background:linear-gradient(180deg,rgba(99,102,241,.06) 0%,rgba(236,72,153,.03) 100%)}
.hero h1{font-size:48px;font-weight:900;margin-bottom:16px;background:linear-gradient(135deg,var(--primary),var(--secondary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;letter-spacing:-1px}
.hero p{font-size:18px;color:var(--text-secondary);max-width:640px;margin:0 auto}
.hero-search{max-width:640px;margin:32px auto 0;position:relative}
.hero-search .search-input{height:54px;font-size:16px;padding-left:54px}
.hero-search .search-icon{font-size:20px;left:20px}
.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:24px;margin:48px 0}
.stat-card{text-align:center;padding:24px;background:var(--bg-card);border-radius:var(--radius-lg);border:1px solid var(--border)}
.stat-num{font-size:32px;font-weight:900;color:var(--primary);margin-bottom:4px}
.stat-label{font-size:14px;color:var(--text-secondary)}
.section{padding:48px 0}
.section-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:28px}
.section-title{font-size:28px;font-weight:800;letter-spacing:-.5px}
.section-more{color:var(--primary);font-weight:600;font-size:15px}
.category-grid{display:grid;grid-template-columns:repeat(6,1fr);gap:16px}
.category-card{padding:24px 16px;background:var(--bg-card);border-radius:var(--radius-lg);border:1px solid var(--border);text-align:center;transition:var(--transition);cursor:pointer}
.category-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg);border-color:var(--primary)}
.category-icon{width:48px;height:48px;margin:0 auto 12px;border-radius:var(--radius);display:flex;align-items:center;justify-content:center;font-weight:800;font-size:14px;color:#fff}
.category-name{font-weight:700;font-size:15px;margin-bottom:4px;color:var(--text)}
.category-count{font-size:13px;color:var(--text-light)}
.article-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:20px}
.article-card{padding:24px;background:var(--bg-card);border-radius:var(--radius-lg);border:1px solid var(--border);transition:var(--transition)}
.article-card:hover{box-shadow:var(--shadow);border-color:var(--primary)}
.article-tag{display:inline-block;padding:3px 10px;background:rgba(99,102,241,.1);color:var(--primary);border-radius:var(--radius-full);font-size:12px;font-weight:600;margin-bottom:12px}
.article-title{font-size:18px;font-weight:700;margin-bottom:8px;line-height:1.5}
.article-title a{color:var(--text)}
.article-title a:hover{color:var(--primary)}
.article-desc{font-size:14px;color:var(--text-secondary);line-height:1.7;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
.article-meta{margin-top:16px;display:flex;gap:16px;font-size:13px;color:var(--text-light)}
.hot-list{display:grid;gap:12px}
.hot-item{display:flex;gap:16px;padding:16px;background:var(--bg-card);border-radius:var(--radius);border:1px solid var(--border);align-items:center;transition:var(--transition)}
.hot-item:hover{border-color:var(--primary)}
.hot-num{width:28px;height:28px;border-radius:8px;display:flex;align-items:center;justify-content:center;font-weight:800;font-size:13px;flex-shrink:0;background:var(--border);color:var(--text-secondary)}
.hot-item:nth-child(1) .hot-num{background:#ef4444;color:#fff}
.hot-item:nth-child(2) .hot-num{background:#f97316;color:#fff}
.hot-item:nth-child(3) .hot-num{background:#eab308;color:#fff}
.hot-title{font-weight:600;font-size:15px;color:var(--text);flex:1}
.hot-title a{color:var(--text)}
.hot-title a:hover{color:var(--primary)}
.footer{background:var(--bg-dark);color:var(--text-light);padding:48px 0 24px;margin-top:64px}
.footer-grid{display:grid;grid-template-columns:2fr repeat(3,1fr);gap:40px;margin-bottom:40px}
.footer-col h4{color:#fff;font-size:16px;font-weight:700;margin-bottom:16px}
.footer-col a{display:block;color:var(--text-light);padding:4px 0;font-size:14px}
.footer-col a:hover{color:#fff}
.footer-bottom{border-top:1px solid var(--border-dark);padding-top:24px;text-align:center;font-size:13px}
.footer-bottom a{color:var(--text-light)}
.breadcrumb{padding:24px 0;font-size:14px;color:var(--text-secondary)}
.breadcrumb a{color:var(--text-secondary)}
.breadcrumb a:hover{color:var(--primary)}
.breadcrumb span{margin:0 8px}
.article-layout{display:grid;grid-template-columns:1fr 320px;gap:32px;padding:24px 0 48px}
.article-main{background:#fff;border-radius:var(--radius-lg);border:1px solid var(--border);padding:40px}
.article-header{margin-bottom:32px;padding-bottom:24px;border-bottom:1px solid var(--border)}
.article-header h1{font-size:32px;font-weight:900;line-height:1.4;margin-bottom:16px;letter-spacing:-.5px}
.article-content h2{font-size:24px;font-weight:800;margin:32px 0 16px;padding-left:12px;border-left:4px solid var(--primary)}
.article-content h3{font-size:19px;font-weight:700;margin:24px 0 12px}
.article-content p{margin-bottom:16px;font-size:16px;line-height:1.9;color:#334155}
.article-content ul,.article-content ol{margin:16px 0;padding-left:24px}
.article-content li{margin-bottom:8px;line-height:1.8}
.article-content pre{background:var(--bg-dark);color:#e2e8f0;padding:20px;border-radius:var(--radius);overflow-x:auto;margin:20px 0;font-family:var(--font-mono);font-size:14px;line-height:1.7}
.article-content code{background:rgba(99,102,241,.1);color:var(--primary);padding:2px 8px;border-radius:6px;font-family:var(--font-mono);font-size:.9em}
.article-content pre code{background:none;color:inherit;padding:0}
.article-content strong{font-weight:700;color:var(--text)}
.article-content blockquote{border-left:4px solid var(--accent);padding:16px 20px;background:rgba(6,182,212,.05);border-radius:0 var(--radius) var(--radius) 0;margin:20px 0;color:var(--text-secondary)}
.sidebar{display:flex;flex-direction:column;gap:24px}
.sidebar-card{background:#fff;border-radius:var(--radius-lg);border:1px solid var(--border);padding:24px}
.sidebar-card h3{font-size:18px;font-weight:700;margin-bottom:16px}
.sidebar-list{display:grid;gap:10px}
.sidebar-list a{display:block;padding:10px 12px;border-radius:var(--radius);font-size:14px;color:var(--text-secondary);line-height:1.5}
.sidebar-list a:hover{background:var(--bg-card);color:var(--primary)}
.pagination{display:flex;justify-content:center;align-items:center;gap:8px;margin:40px 0;flex-wrap:wrap}
.pagination a,.pagination span{min-width:40px;height:40px;display:inline-flex;align-items:center;justify-content:center;padding:0 12px;border-radius:var(--radius);font-weight:600;font-size:14px;border:1px solid var(--border);color:var(--text-secondary);background:#fff}
.pagination a:hover{border-color:var(--primary);color:var(--primary)}
.pagination .active{background:var(--primary);color:#fff;border-color:var(--primary)}
.pagination .disabled{color:var(--text-light);cursor:not-allowed;background:var(--bg-card)}
.link-grid{display:grid;grid-template-columns:repeat(6,1fr);gap:12px}
.link-item{padding:12px;text-align:center;border:1px solid var(--border);border-radius:var(--radius);font-size:14px;color:var(--text-secondary);transition:var(--transition)}
.link-item:hover{border-color:var(--primary);color:var(--primary)}
.cat-header{background:linear-gradient(135deg,rgba(99,102,241,.08),rgba(236,72,153,.05));padding:40px 0;border-radius:var(--radius-lg);margin-bottom:32px;text-align:center}
.cat-header h1{font-size:36px;font-weight:900;margin-bottom:8px}
.cat-header p{color:var(--text-secondary);font-size:16px}
.friend-links{padding:48px 0;border-top:1px solid var(--border)}
@media(max-width:1024px){.category-grid{grid-template-columns:repeat(4,1fr)}.footer-grid{grid-template-columns:repeat(2,1fr)}.article-layout{grid-template-columns:1fr}.sidebar{display:none}.link-grid{grid-template-columns:repeat(4,1fr)}}
@media(max-width:768px){.container{padding:0 16px}.header-inner{height:60px;gap:12px}.nav{display:none;position:absolute;top:100%;left:0;right:0;background:#fff;flex-direction:column;padding:12px;border-bottom:1px solid var(--border);gap:4px;align-items:stretch}.nav.open{display:flex}.nav a{padding:12px 16px;border-radius:var(--radius)}.mobile-toggle{display:block}.search-box{display:none}.hero{padding:48px 0 32px}.hero h1{font-size:28px}.hero p{font-size:15px}.stats{grid-template-columns:repeat(2,1fr);gap:12px}.stat-card{padding:16px}.stat-num{font-size:24px}.category-grid{grid-template-columns:repeat(3,1fr);gap:10px}.category-card{padding:16px 8px}.article-grid{grid-template-columns:1fr}.footer-grid{grid-template-columns:1fr;gap:24px}.link-grid{grid-template-columns:repeat(2,1fr)}.article-main{padding:24px 20px}.article-header h1{font-size:22px}.article-content h2{font-size:20px}.cat-header h1{font-size:24px}.section-title{font-size:22px}}
::-webkit-scrollbar{width:8px;height:8px}
::-webkit-scrollbar-track{background:var(--bg-card)}
::-webkit-scrollbar-thumb{background:var(--border);border-radius:4px}
::-webkit-scrollbar-thumb:hover{background:var(--text-light)}
.tag-html{background:rgba(228,77,38,.1)!important;color:#e44d26!important}
.tag-css{background:rgba(38,77,228,.1)!important;color:#264de4!important}
.tag-js{background:rgba(247,223,30,.15)!important;color:#b8a410!important}
.tag-vue{background:rgba(65,184,131,.1)!important;color:#41b883!important}
.tag-react{background:rgba(97,218,251,.1)!important;color:#00bcd4!important}
.tag-java{background:rgba(248,152,32,.1)!important;color:#f89820!important}
.tag-python{background:rgba(55,118,171,.1)!important;color:#3776ab!important}
.tag-go{background:rgba(0,173,216,.1)!important;color:#00add8!important}
.tag-php{background:rgba(119,123,180,.1)!important;color:#777bb4!important}
.tag-db{background:rgba(0,117,143,.1)!important;color:#00758f!important}