/* 进阶汉语 — shared site shell: tokens, header, footer, buttons. */
:root{
  --ls-navy:#385430;
  --ls-blue:#538047;
  --ls-blue-strong:#456b3a;
  --ls-ink:#344030;
  --ls-muted:#6a7467;
  --ls-line:#e6ece4;
  --ls-bg:#f9fbf8;
  --ls-tint:#f0f5ef;
  --ls-card:#fff;
  --ls-shadow:0 6px 22px rgba(56,84,48,.08);
  --ls-shadow-sm:0 2px 10px rgba(56,84,48,.06);
  --ls-radius:10px;
  --ls-sans:"Noto Sans","Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --ls-serif:"Noto Serif SC","Songti SC","STSong","SimSun",serif;
  --ls-wrap:1160px;
}

html{scroll-behavior:smooth;scroll-padding-top:88px}
body{margin:0;font-family:var(--ls-sans);color:var(--ls-ink);background:var(--ls-bg)!important;background-image:none!important}
body::before,body::after{content:none!important;display:none!important}

.ls-wrap{max-width:var(--ls-wrap);margin:0 auto;padding:0 28px}

/* ---------- Buttons ---------- */
.ls-btn{display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:44px;padding:0 24px;border-radius:6px;border:1.5px solid var(--ls-blue);font:600 15px/1 var(--ls-sans);letter-spacing:.02em;text-decoration:none;cursor:pointer;transition:background .18s,color .18s,border-color .18s,transform .18s,box-shadow .18s;white-space:nowrap}
.ls-btn svg{width:17px;height:17px;flex:none;transition:transform .18s}
.ls-btn:hover svg{transform:translateX(3px)}
.ls-btn-primary{background:var(--ls-blue);color:#fff}
.ls-btn-primary:hover{background:var(--ls-blue-strong);border-color:var(--ls-blue-strong);box-shadow:0 6px 16px rgba(83,128,71,.24)}
.ls-btn-ghost{background:rgba(255,255,255,.85);color:var(--ls-blue)}
.ls-btn-ghost:hover{background:#fff;box-shadow:var(--ls-shadow-sm)}
.ls-btn:focus-visible,.ls-nav a:focus-visible,.ls-lang button:focus-visible,.ls-link:focus-visible{outline:3px solid #bcd8b4;outline-offset:3px}
.ls-link{display:inline-flex;align-items:center;gap:8px;color:var(--ls-blue);font-weight:600;font-size:14px;text-decoration:none}
.ls-link svg{width:16px;height:16px;transition:transform .18s}
.ls-link:hover svg{transform:translateX(3px)}

/* ---------- Header ---------- */
body>header.ls-header{position:sticky;top:0;z-index:50}
/* Keep the public-site frame constant; only the learning content varies by route. */
.ls-header{--ls-navy:#253720;--ls-blue:#2e4229;--ls-blue-strong:#253720;--ls-ink:#253720;--ls-muted:#657062;--ls-line:#e3e4e5;--ls-tint:#f8f4ed;--ls-header-gold:#c3757a;background:rgba(255,255,255,.96);backdrop-filter:saturate(1.4) blur(10px);-webkit-backdrop-filter:saturate(1.4) blur(10px);border-bottom:1px solid var(--ls-line);margin:0!important;padding:0!important}
.ls-header-inner{max-width:1500px;margin:0 auto;height:82px;padding:0 42px;display:flex;align-items:center;gap:24px}
.ls-brand{display:flex;align-items:center;gap:11px;text-decoration:none;color:var(--ls-navy);flex:none}
.ls-brand img{width:50px;height:50px;border-radius:50%;object-fit:contain;display:block}
.ls-brand span{display:flex;flex-direction:column;line-height:1.15}
.ls-brand strong{font:700 22px/1.2 var(--ls-serif);letter-spacing:.03em;color:var(--ls-navy)}
.ls-brand small{font:500 14px/1.3 Georgia,var(--ls-serif);color:var(--ls-navy);letter-spacing:.01em;margin-top:3px}
.ls-nav{display:flex;align-items:stretch;gap:4px;margin:0 auto;height:100%}
.ls-nav>a,.ls-nav-group>a{position:relative;display:flex;align-items:center;height:100%;padding:0 12px;color:var(--ls-ink);font-size:14px;font-weight:500;text-decoration:none;white-space:nowrap;transition:color .15s}
.ls-nav>a::after,.ls-nav-group>a::after{content:"";position:absolute;left:12px;right:12px;bottom:9px;height:3px;border-radius:0;background:var(--ls-header-gold);transform:scaleX(0);transition:transform .2s}
.ls-nav>a:hover,.ls-nav-group>a:hover,.ls-nav a[aria-current="page"]{color:var(--ls-blue)}
.ls-nav>a[aria-current="page"]::after,.ls-nav-group>a[aria-current="page"]::after{transform:scaleX(1)}
.ls-nav-group{position:relative;display:flex}
.ls-nav-group>a .ls-caret{width:12px;height:12px;margin-left:4px;opacity:.6}
.ls-subnav{position:absolute;top:calc(100% - 6px);left:50%;min-width:236px;padding:8px;background:#fff;border:1px solid var(--ls-line);border-radius:10px;box-shadow:0 14px 34px rgba(56,84,48,.14);opacity:0;visibility:hidden;transform:translate(-50%,6px);transition:opacity .16s,transform .16s,visibility .16s}
.ls-nav-group:hover .ls-subnav,.ls-nav-group:focus-within .ls-subnav{opacity:1;visibility:visible;transform:translate(-50%,0)}
.ls-subnav a{display:block;padding:10px 12px;border-radius:7px;color:var(--ls-navy);font-weight:600;font-size:15px;text-decoration:none}
.ls-subnav a small{display:block;margin-top:2px;font-weight:400;font-size:12.5px;color:var(--ls-muted)}
.ls-subnav a:hover,.ls-subnav a[aria-current="page"]{background:var(--ls-tint);color:var(--ls-blue)}
.ls-header-tools{display:flex;align-items:center;gap:18px;flex:none}
.ls-lang{display:flex;gap:2px}
.ls-lang button{border:0;background:none;padding:6px 7px;font:500 13px/1 var(--ls-sans);color:var(--ls-muted);cursor:pointer;border-radius:4px}
.ls-lang button[aria-pressed="true"]{color:var(--ls-blue);font-weight:700}
.ls-lang button:hover{color:var(--ls-blue)}
html.ls-no-i18n .ls-lang{display:flex}
.ls-header .ls-btn{min-height:42px;padding:10px 20px;border-radius:2px;font-size:14px;font-weight:500;line-height:1.4;box-shadow:none}
.ls-menu-toggle{display:none;margin-left:auto;width:44px;height:44px;border:1px solid var(--ls-line);border-radius:8px;background:#fff;color:var(--ls-navy);cursor:pointer;align-items:center;justify-content:center}
.ls-menu-toggle svg{width:22px;height:22px}

@media (max-width:1180px){
  .ls-header-inner{padding:0 28px;gap:16px}
  .ls-nav>a,.ls-nav-group>a{padding:0 8px;font-size:14.5px}
  .ls-nav>a::after,.ls-nav-group>a::after{left:8px;right:8px}
  .ls-header-tools{gap:12px}
}
@media (max-width:1040px){
  .ls-menu-toggle{display:inline-flex}
  .ls-header-inner{height:64px;padding:0 18px}
  .ls-brand img{width:40px;height:40px}
  .ls-brand small{font-size:12px}
  .ls-header-tools{display:none}
  .ls-nav{position:fixed;inset:64px 0 auto 0;height:auto;max-height:calc(100dvh - 64px);overflow:auto;flex-direction:column;gap:0;margin:0;padding:8px 18px 22px;background:#fff;border-bottom:1px solid var(--ls-line);box-shadow:0 16px 30px rgba(56,84,48,.12);display:none}
  .ls-header.is-open .ls-nav{display:flex}
  .ls-nav>a,.ls-nav-group>a{height:auto;padding:14px 4px;border-bottom:1px solid #f1f4f1;font-size:16px}
  .ls-nav>a::after,.ls-nav-group>a::after{display:none}
  .ls-nav-group{flex-direction:column}
  .ls-nav-group>a .ls-caret{display:none}
  .ls-subnav{position:static;opacity:1;visibility:visible;transform:none;box-shadow:none;border:0;padding:4px 0 8px 12px;min-width:0}
  .ls-nav .ls-mobile-tools{display:flex}
}
.ls-mobile-tools{display:none;align-items:center;justify-content:space-between;gap:12px;padding-top:16px}
@media (max-width:520px){
  .ls-brand strong{font-size:17px}
  .ls-brand img{width:38px;height:38px}
}

/* Retire the previous shell wherever old markup still appears. */
.site-masthead,.section-navigation{display:none!important}

/* ---------- Footer ---------- */
body>footer.ls-footer,footer.ls-footer{position:relative!important;margin:0!important;padding:0!important;border:0;background:#fff;color:var(--ls-muted);font-size:13px;box-shadow:none!important;width:auto!important;transform:none!important;overflow:hidden}
.ls-footer{border-top:1px solid var(--ls-line)!important}
.ls-footer::before{content:"";position:absolute;right:6%;bottom:10px;width:190px;height:190px;background:none center/contain no-repeat;opacity:.035;pointer-events:none}
.ls-footer>*{position:relative;z-index:1}
.ls-footer-main{max-width:var(--ls-wrap);margin:0 auto;padding:22px 28px 18px;display:flex;align-items:center;gap:24px;flex-wrap:wrap}
.ls-footer .ls-brand img{width:36px;height:36px}
.ls-footer .ls-brand strong{font-size:16px}
.ls-footer .ls-brand small{font-size:11px}
.ls-footer-contact{display:flex;align-items:center;gap:20px;flex-wrap:wrap}
.ls-footer-contact a,.ls-footer-contact span{display:inline-flex;align-items:center;gap:7px;color:var(--ls-ink);text-decoration:none;font-size:13px}
.ls-footer-contact a:hover{color:var(--ls-blue)}
.ls-footer-contact svg{width:16px;height:16px;color:var(--ls-navy);flex:none}
.ls-social{display:flex;align-items:center;gap:10px}
.ls-social button{display:inline-flex;align-items:center;gap:7px;border:0;background:none;padding:4px 0;color:var(--ls-ink);font:inherit;font-size:13px;cursor:pointer}
.ls-social button:hover{color:var(--ls-blue)}
.ls-social svg{width:20px;height:20px;color:var(--ls-navy)}
.ls-footer-nav{display:flex;gap:16px;margin-left:auto;flex-wrap:wrap}
.ls-footer-nav a{color:var(--ls-ink);text-decoration:none;font-size:13px}
.ls-footer-nav a:hover{color:var(--ls-blue)}
.ls-footer-sites{max-width:var(--ls-wrap);margin:0 auto;padding:0 28px 16px;display:flex;justify-content:center;flex-wrap:wrap;gap:6px 26px;font-size:12.5px;text-align:center}
.ls-footer-sites a{color:var(--ls-muted);text-decoration:none}
.ls-footer-sites a:hover{color:var(--ls-blue);text-decoration:underline;text-underline-offset:3px}
.ls-footer-sites b{color:var(--ls-navy);font-weight:600;margin-right:6px}
.ls-footer-bottom{max-width:var(--ls-wrap);margin:0 auto;padding:14px 28px 20px;border-top:1px solid #f0f3f0;display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap;font-size:12px;color:var(--ls-muted)}
.ls-footer-bottom a{color:var(--ls-muted);text-decoration:none}
.ls-footer-bottom a[href^="mailto:aliciatalksmandarin"]{display:none}
.ls-footer-bottom a:hover{color:var(--ls-blue)}
.ls-footer .ls-site-feedback{display:flex;align-items:center;justify-content:center;gap:6px 15px;flex-wrap:wrap;padding:12px 24px 16px;margin:0 auto;border-top:1px solid #839bad40;font-size:12px;line-height:1.7;color:inherit}
.ls-footer .ls-site-feedback a{color:inherit;text-decoration:underline;text-underline-offset:3px;overflow-wrap:anywhere}
.ls-footer .ls-site-feedback>span:first-child{opacity:.8}
@media (max-width:860px){
  .ls-footer-main{gap:16px 24px}
  .ls-footer-nav{margin-left:0;width:100%}
}

/* WeChat QR dialog (shared) */
.ls-qr-dialog{border:0;border-radius:14px;padding:26px 28px 22px;max-width:320px;width:calc(100% - 40px);text-align:center;box-shadow:0 24px 60px rgba(29,46,25,.3);color:var(--ls-ink)}
.ls-qr-dialog::backdrop{background:rgba(27,40,24,.5)}
.ls-qr-dialog h2{margin:0 0 12px;font:700 18px/1.3 var(--ls-serif);color:var(--ls-navy)}
.ls-qr-dialog img{width:220px;height:220px;display:block;margin:0 auto}
.ls-qr-dialog p{margin:12px 0 0;font-size:14px;color:var(--ls-muted)}
.ls-qr-close{position:absolute;top:8px;right:10px;width:36px;height:36px;border:0;background:none;font-size:24px;line-height:1;color:var(--ls-muted);cursor:pointer;border-radius:50%}
.ls-qr-close:hover{background:var(--ls-tint);color:var(--ls-navy)}

@media print{.ls-header,.ls-footer{display:none!important}}

/* ---------- Page primitives ---------- */
.ls-page{display:block;padding:40px 0 56px}
.ls-page-head{margin-bottom:26px}
.ls-page-head h1{margin:0;font:700 clamp(28px,3.4vw,36px)/1.25 var(--ls-serif);letter-spacing:.05em;color:var(--ls-navy)}
.ls-page-head p{margin:10px 0 0;color:var(--ls-muted);font-size:15px}
.ls-eyebrow{margin:0 0 10px;font:600 12px/1 var(--ls-sans);letter-spacing:.2em;color:var(--ls-blue)}
.ls-section-head{margin:0 0 16px}
.ls-section-head h2{margin:0;font:700 24px/1.3 var(--ls-serif);letter-spacing:.04em;color:var(--ls-navy)}
.ls-section-head p{margin:6px 0 0;color:var(--ls-muted);font-size:14.5px}
/* Footer: brand left, contact centred, links right */
@media (min-width:861px){
  .ls-footer-main{display:grid;grid-template-columns:auto 1fr auto;gap:24px}
  .ls-footer-nav{flex-wrap:nowrap;white-space:nowrap}
  .ls-footer-contact{justify-content:center}
  .ls-footer-nav{margin-left:0;justify-content:flex-end}
}

/* ---------- Shared background slideshow ---------- */
.ls-slides{position:absolute;inset:0;overflow:hidden}
.ls-slide{position:absolute;inset:0;background:center 40%/cover no-repeat;opacity:0;transition:opacity 1.2s ease}
.ls-slide.is-active{opacity:1}
@media (prefers-reduced-motion:reduce){.ls-slide{transition:none}}

/* Direct navigation: no overlapping snapshots or split-header crossfade. */
@view-transition{navigation:none}
.ls-header{view-transition-name:none}