/* SeekFlaw 教程中心样式。手写、不依赖 CDN；避开老安卓内置浏览器（Chrome 75 / X5）不支持的写法：flex gap、clamp、inset、aspect-ratio。 */
*{box-sizing:border-box}
html{scroll-behavior:smooth}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body{margin:0;font:16px/1.8 -apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei","Noto Sans CJK SC",sans-serif;color:#1f2937;background:#fff;-webkit-text-size-adjust:100%}
a{color:#1a6dff;text-decoration:none}
a:hover{text-decoration:underline}
a:focus,button:focus,input:focus,summary:focus{outline:2px solid #1a6dff;outline-offset:2px}
/* 鼠标/触摸点按钮后不留焦点框；键盘仍显示（老内核不认 :focus-visible 时整条规则被忽略，保持上面的默认焦点框） */
.menu-btn:focus:not(:focus-visible){outline:none}
.skip{position:absolute;left:-999px;top:0;background:#1a6dff;color:#fff;padding:8px 14px;z-index:100}
.skip:focus{left:8px;top:8px}

/* 顶栏 */
.topbar{position:fixed;top:0;left:0;right:0;height:52px;background:#fff;border-bottom:1px solid #e5e7eb;display:flex;align-items:center;padding:0 16px;z-index:50}
.topbar .brand{font-weight:700;color:#111827;font-size:17px;margin-left:4px}
.topbar .brand:hover{text-decoration:none}
.topbar .brand b{color:#1a6dff}
.topbar .spacer{flex:1}
.topbar .homelink{margin-left:14px;color:#374151;font-size:14px;white-space:nowrap}.topbar .homelink:hover{color:#1a6dff;text-decoration:none}
.cta{background:#1a6dff;color:#fff!important;padding:7px 16px;border-radius:18px;font-size:14px;line-height:1.4}
.cta:hover{text-decoration:none;background:#1558d6}
.menu-btn{display:none;border:0;background:none;font-size:22px;line-height:1;padding:8px;margin-left:-8px;cursor:pointer;color:#374151}

/* 布局 */
.layout{padding-top:52px}
.sidebar{position:fixed;top:52px;bottom:0;left:0;width:300px;overflow-y:auto;background:#f8fafc;border-right:1px solid #e5e7eb;padding:16px;z-index:40;-webkit-overflow-scrolling:touch}
.main{margin-left:300px;padding:28px 32px 64px;max-width:1100px}
.tutorial-content{max-width:820px}
.toc{display:none}

/* 侧栏 */
.search input{width:100%;padding:9px 12px;border:1px solid #d1d5db;border-radius:8px;font-size:15px;background:#fff}
.results{margin-top:10px}
.results .res{display:block;padding:9px 10px;border:1px solid #e5e7eb;border-radius:8px;background:#fff;margin-bottom:8px;color:#111827}
.results .res:hover{border-color:#1a6dff;text-decoration:none}
.results .res b{display:block;font-size:14px;line-height:1.5}
.results .res span{display:block;font-size:12.5px;color:#6b7280;line-height:1.55;margin-top:2px}
.results mark{background:#fde68a;color:inherit;padding:0 1px}
.results .none{color:#6b7280;font-size:14px;padding:6px 2px}
.nav-top{margin:14px 0 8px}
.nav-a{display:block;padding:7px 10px;border-radius:6px;color:#374151;font-size:14.5px;line-height:1.5}
a.nav-a:hover{background:#e8eefb;text-decoration:none}
a.nav-a.cur{background:#1a6dff;color:#fff}
a.nav-a.cur .nav-no{color:#cfe0ff}
.nav-no{display:inline-block;min-width:44px;margin-right:6px;color:#1a6dff;font-weight:600;font-size:12.5px}
.grp{margin:4px 0}
.grp summary{cursor:pointer;font-weight:700;color:#111827;padding:7px 10px;border-radius:6px;font-size:14.5px;list-style:none}
.grp summary::-webkit-details-marker{display:none}
.grp summary:before{content:"▸";display:inline-block;width:16px;color:#9ca3af}
.grp[open] summary:before{content:"▾"}
.grp ul{list-style:none;margin:0 0 6px;padding:0}
.soon-item{color:#9ca3af}
.soon{display:inline-block;margin-left:6px;padding:0 6px;border-radius:9px;background:#f3f4f6;color:#9ca3af;font-size:11.5px;line-height:1.7;font-style:normal;white-space:nowrap}

/* 正文 */
.crumbs{font-size:13.5px;color:#6b7280;margin-bottom:6px}
.tutorial-content h1{font-size:28px;line-height:1.4;margin:6px 0 18px;color:#111827}
.h1-tag{display:inline-block;margin-right:10px;padding:1px 10px;border-radius:6px;background:#e8f0ff;color:#1a6dff;font-size:16px;font-weight:600;vertical-align:4px}
.tutorial-content h2{font-size:21px;line-height:1.45;margin:36px 0 12px;padding-bottom:8px;border-bottom:1px solid #e5e7eb;color:#111827;scroll-margin-top:68px}
.tutorial-content h3{font-size:17px;margin:24px 0 8px;color:#111827;scroll-margin-top:68px}
.tutorial-content p{margin:12px 0}
.tutorial-content ul,.tutorial-content ol{padding-left:24px;margin:10px 0}
.tutorial-content li{margin:6px 0}
.tutorial-content blockquote{margin:16px 0;padding:10px 16px;background:#eff6ff;border-left:4px solid #1a6dff;border-radius:0 8px 8px 0;color:#1e3a8a}
.tutorial-content blockquote p{margin:6px 0}
.tutorial-content hr{border:0;border-top:1px solid #e5e7eb;margin:28px 0}
.tutorial-content code{background:#f3f4f6;padding:1px 6px;border-radius:4px;font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:.9em;color:#b42318}
.tutorial-content img{max-width:100%;height:auto;display:block;margin:14px 0;border:1px solid #e5e7eb;border-radius:8px;cursor:zoom-in;background:#f3f4f6;min-height:40px}
.table-wrap{overflow-x:auto;margin:14px 0;-webkit-overflow-scrolling:touch}
.tutorial-content table{border-collapse:collapse;min-width:100%;font-size:15px}
.tutorial-content th,.tutorial-content td{border:1px solid #e5e7eb;padding:8px 12px;text-align:left;vertical-align:top;line-height:1.6}
.tutorial-content th{background:#f8fafc;font-weight:600;white-space:nowrap}

/* 首页 */
.status{color:#4b5563;background:#f8fafc;border:1px solid #e5e7eb;border-radius:8px;padding:10px 14px}
.cta-row{margin:18px 0 8px}
.btn{display:inline-block;background:#1a6dff;color:#fff!important;padding:10px 22px;border-radius:22px;font-weight:600;margin:0 10px 10px 0}
.btn:hover{text-decoration:none;background:#1558d6}
.btn.ghost{background:#fff;color:#1a6dff!important;border:1px solid #1a6dff}
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(310px,1fr));grid-gap:16px;margin:22px 0}
.card{border:1px solid #e5e7eb;border-radius:12px;padding:16px 18px;background:#fff}
.tutorial-content .card h3{margin:0 0 2px;font-size:18px}
.card-d{margin:0 0 8px!important;color:#6b7280;font-size:14px}
.tutorial-content .card ul{list-style:none;padding:0;margin:0}
.tutorial-content .card li{margin:0;padding:5px 0;border-top:1px solid #f3f4f6;font-size:14.5px;line-height:1.55}
.soon-li{color:#9ca3af}

/* 上下篇 / 页脚 */
.pager{display:flex;justify-content:space-between;max-width:820px;margin:40px 0 0}
.pg{display:block;width:48.5%;padding:12px 16px;border:1px solid #e5e7eb;border-radius:10px;color:#111827}
.pg:hover{border-color:#1a6dff;text-decoration:none}
.pg.next{text-align:right}
.pg.none{border:0}
.pg-d{display:block;font-size:12.5px;color:#6b7280}
.pg-t{display:block;font-size:14.5px;font-weight:600;line-height:1.5}
.foot{max-width:820px;margin-top:32px;padding-top:16px;border-top:1px solid #e5e7eb;font-size:13px;color:#6b7280;line-height:1.7}
.foot p{margin:4px 0}

/* 大图 */
.lb{position:fixed;top:0;right:0;bottom:0;left:0;background:rgba(0,0,0,.88);z-index:200;display:none;align-items:center;justify-content:center;padding:16px;cursor:zoom-out}
.lb.on{display:flex}
.lb img{max-width:100%;max-height:100%;background:#fff;border-radius:4px}
.lb button{position:absolute;top:8px;right:14px;border:0;background:none;color:#fff;font-size:34px;line-height:1;cursor:pointer;padding:6px 10px}
.scrim{display:none}

@media (min-width:1280px){
  .main{margin-right:250px}
  .toc{display:block;position:fixed;top:76px;right:20px;width:216px;max-height:calc(100vh - 100px);overflow-y:auto;font-size:13px;line-height:1.55}
  .toc-h{font-weight:700;color:#111827;margin-bottom:6px}
  .toc ul{list-style:none;margin:0;padding:0;border-left:2px solid #e5e7eb}
  .toc li a{display:block;padding:4px 10px;color:#6b7280;margin-left:-2px;border-left:2px solid transparent}
  .toc li.l3 a{padding-left:22px}
  .toc li a:hover{color:#1a6dff;text-decoration:none}
  .toc li a.on{color:#1a6dff;border-left-color:#1a6dff;font-weight:600}
}
@media (max-width:900px){
  .menu-btn{display:inline-block}
  .sidebar{width:84%;max-width:330px;-webkit-transform:translateX(-102%);transform:translateX(-102%);transition:transform .2s;box-shadow:2px 0 14px rgba(0,0,0,.18);padding-bottom:40px}
  body.nav-open .sidebar{-webkit-transform:none;transform:none}
  body.nav-open .scrim{display:block;position:fixed;top:52px;right:0;bottom:0;left:0;background:rgba(0,0,0,.35);z-index:30}
  .main{margin-left:0;padding:20px 16px 56px}
  .tutorial-content h1{font-size:23px}
  .h1-tag{font-size:14px;vertical-align:2px}
  .tutorial-content h2{font-size:19px}
  .pager{display:block}
  .pg{width:100%;margin-bottom:10px}
  .pg.none{display:none}
  .cta{padding:6px 12px;font-size:13px}
  .cards{grid-template-columns:1fr}
}

/* SEO/GEO：品牌定义句 + 同章推荐 */
.brand-def{margin:0 0 14px;padding:10px 14px;border-left:3px solid #c026d3;background:rgba(192,38,211,.06);border-radius:0 8px 8px 0;font-size:.95em}
.related{margin:32px 0 8px;padding-top:16px;border-top:1px solid rgba(128,128,128,.25)}
.related h2{font-size:1.05em;margin:0 0 8px}
.related ul{margin:0;padding-left:1.2em}
.related li{margin:4px 0}