/* ============================================================================
   Guide to Uni — shared stylesheet  (served at /app.css)
   Single source of truth for design tokens, base, fluid type/space scale,
   and the components shared across pages (nav, footer, buttons, layout).

   Loaded on every page after /fonts.css. Page-unique CSS stays inline in
   each page's <style>. Edit shared look-and-feel HERE, once.

   Responsive model:
     - Type & spacing are FLUID via clamp() — they scale smoothly with the
       viewport, so most pages need no breakpoints at all.
     - Two documented breakpoints handle genuine LAYOUT changes only:
         900px → multi-column grids stack; nav collapses to a hamburger.
         640px → footer goes single-column; side padding tightens.
   ========================================================================= */

/* ---- i18n flash guard --------------------------------------------------- */
/* Pages ship English markup and site.js swaps it to 简/繁 after parse. For a
   non-English visitor the head sets html.i18n-wait BEFORE first paint, so the
   English text is hidden until the swap lands — no English flash. English
   visitors never get the class, so they pay nothing. visibility (not display)
   keeps layout, so there's no shift on reveal. site.js clears it after apply();
   a head-side timer clears it too, in case site.js never runs. */
html.i18n-wait body{visibility:hidden}

/* ---- tokens ------------------------------------------------------------- */
:root{
  --bg:#FBFAF6;--panel:#fff;--panel2:#F3F1EA;--line:#E6E1D4;
  --ink:#18223B;--muted:#5B6275;--faint:#9A98A0;
  --navy:#1B2A4A;--navy2:#27406B;--gold:#A8781E;--goldw:#C9A227;
  --good:#2F7D5B;--warn:#B5852A;--danger:#B23A3A;
  --radius:8px;                                 /* app-style pages (consult, start) */
  --serif:'Newsreader',ui-serif,Georgia,serif;
  --sans:'Hanken Grotesk',-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;

  /* fluid type scale — min for ~360px phones, max for desktop */
  --step-hero:clamp(33px,5.4vw + 12px,51px);   /* hero h1            */
  --step-1:clamp(28px,3.2vw + 14px,38px);       /* big headings       */
  --step-2:clamp(26px,2.4vw + 14px,34px);       /* section h2         */
  --step-3:clamp(20px,1vw + 16px,25px);         /* sub-heads / quotes */
  --lede:clamp(16px,0.7vw + 14px,18.5px);

  /* fluid spacing */
  --wrap-pad:clamp(20px,5vw,40px);              /* horizontal gutter  */
  --space-section:clamp(46px,9vw,78px);         /* vertical section   */
}

/* ---- reset + base ------------------------------------------------------- */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{background:var(--bg);color:var(--ink);font-family:var(--sans);font-size:16px;line-height:1.62;-webkit-font-smoothing:antialiased}
img,svg{max-width:100%}
h2{font-family:var(--serif);font-weight:500;letter-spacing:-.01em}

/* ---- layout primitives -------------------------------------------------- */
.wrap{max-width:1180px;margin:0 auto;padding:0 var(--wrap-pad)}
.sec{padding-top:var(--space-section);padding-bottom:var(--space-section)}
.sechead{max-width:640px;margin-bottom:clamp(28px,5vw,42px)}
.sechead h2{font-size:var(--step-2);line-height:1.12;margin-top:10px}
.sechead p{font-size:clamp(15px,1vw + 13px,17px);color:var(--muted);margin-top:14px}

/* dark "band" sections */
.band{background:var(--navy);color:#E9ECF4}
.band .sec{padding-top:var(--space-section);padding-bottom:var(--space-section)}
.band h2{color:#fff;font-size:var(--step-2)}
.band .kicker{color:var(--goldw)}
.band .lede{color:#B7BFD4}

/* ---- shared inline text bits ------------------------------------------- */
.eyebrow{font:700 12px var(--sans);letter-spacing:.13em;text-transform:uppercase;color:var(--gold);display:inline-flex;align-items:center;gap:9px}
.eyebrow .ln{width:26px;height:1.5px;background:var(--goldw)}
.kicker{font:700 12px var(--sans);letter-spacing:.13em;text-transform:uppercase;color:var(--gold);margin-bottom:12px}
.lede{font-size:var(--lede);color:var(--muted)}

/* ---- buttons ------------------------------------------------------------ */
/* Hover affordance is a sheen sweep, not a lift: filled CTAs carry a multi-stop
   gradient with a brighter highlight band that glides across on hover, like
   light moving over silk. Gold for the "guide" CTAs, layered blue for "Start". */
.btn{font:600 14.5px var(--sans);padding:11px 18px;border-radius:9px;text-decoration:none;display:inline-block;position:relative;border:1px solid transparent;cursor:pointer;transition:background-color .18s,border-color .18s,color .18s}
.btn-ghost{background:transparent;color:var(--navy);border-color:var(--line)}.btn-ghost:hover{border-color:var(--navy2)}
.btn-light{background:#fff;color:var(--navy)}.btn-light:hover{background:var(--panel2)}
.band .btn-ghost{color:#fff;border-color:rgba(255,255,255,.32)}.band .btn-ghost:hover{border-color:rgba(255,255,255,.6)}

/* gold sheen — "See a real guide →", "Real example →", "Sample guide →" */
.btn-gold{color:#fff;border-color:transparent;background-image:linear-gradient(110deg,var(--gold) 0%,var(--goldw) 26%,#F1D670 50%,var(--goldw) 74%,var(--gold) 100%);background-size:230% 100%;background-position:0 50%;transition:background-position .65s ease,box-shadow .18s}
.btn-gold:hover{background-position:100% 50%;box-shadow:0 2px 16px -7px var(--goldw)}

/* layered-blue sheen — "Start →". Same motion as the gold CTA, navy palette:
   a lighter blue band rides across deep navy. No gold. */
.btn-primary{color:#fff;border-color:transparent;background-image:linear-gradient(110deg,var(--navy) 0%,var(--navy2) 30%,#3F62A6 50%,var(--navy2) 70%,var(--navy) 100%);background-size:230% 100%;background-position:0 50%;transition:background-position .65s ease,box-shadow .18s}
.btn-primary:hover{background-position:100% 50%;box-shadow:0 2px 16px -7px var(--navy2)}

/* "Real example" — gold outline (line, not solid): a masked gold gradient
   hairline with a travelling highlight band that loops gently on hover. */
@keyframes btn-ring{from{background-position:0 50%}to{background-position:100% 50%}}
.btn-demo{background:transparent;color:var(--gold);border-color:transparent;transition:color .18s,background-color .18s,box-shadow .3s}
.btn-demo::before{content:"";position:absolute;inset:0;border-radius:inherit;padding:1px;background-image:linear-gradient(110deg,var(--gold) 0%,var(--goldw) 22%,#F1D670 50%,var(--goldw) 78%,var(--gold) 100%);background-size:300% 100%;background-position:0 50%;-webkit-mask:linear-gradient(#000 0 0) content-box,linear-gradient(#000 0 0);-webkit-mask-composite:xor;mask-composite:exclude;opacity:.9;transition:opacity .3s ease;pointer-events:none}
.btn-demo:hover{color:#946913;background:color-mix(in srgb,var(--gold) 8%,transparent);box-shadow:0 4px 20px -8px var(--goldw)}
.btn-demo:hover::before{opacity:1;animation:btn-ring 2s ease-in-out infinite alternate}

/* larger hero CTAs */
.btn-lg{font-size:16.5px;padding:14px 24px}

@media (prefers-reduced-motion:reduce){.btn-gold,.btn-primary{transition:box-shadow .18s}.btn-demo:hover::before{animation:none}}

/* ---- nav ---------------------------------------------------------------- */
/* <gtu-nav>/<gtu-footer> are custom elements — force block so .nav (sticky bar,
   solid --bg background) and the footer tint actually form a full-width band. */
gtu-nav,gtu-footer{display:block}
.nav{position:sticky;top:0;z-index:40;background:var(--bg);border-bottom:1px solid transparent}
.nav.scrolled{border-bottom-color:var(--line)}
.navin{max-width:1180px;margin:0 auto;padding:16px var(--wrap-pad);display:flex;align-items:center;gap:12px}
/* <gtu-logo> web component (see /logo.js) is layout-transparent; the inner
   <a class="logo"> it renders is the real flex child. */
gtu-logo{display:contents}
.logo{display:flex;align-items:center;gap:10px;font-family:var(--serif);font-weight:600;font-size:19px;color:var(--ink);text-decoration:none;letter-spacing:-.01em}
.star{width:23px;height:23px;flex:none}
/* "Guide to Uni" @19px has no descenders; nudge the wordmark down 2px to
   optically centre its glyph ink against the star. */
.logo .wordmark{line-height:1;position:relative;top:2px}
.links{margin-left:auto;display:flex;gap:22px;align-items:center;font-size:14px;font-weight:500}
.links a:not(.btn){color:var(--muted);text-decoration:none;position:relative}
.links a.btn{text-decoration:none}
.links a:not(.btn):hover{color:var(--ink)}
.links a:not(.btn).active{color:var(--ink)}
.links a:not(.btn).active::after{content:"";position:absolute;left:0;right:0;bottom:-4px;height:2px;background:var(--gold)}

/* language globe dropdown */
.langdd{position:relative;display:flex}
.langbtn{display:flex;align-items:center;justify-content:center;width:34px;height:34px;border:1px solid transparent;border-radius:9px;background:transparent;color:var(--muted);cursor:pointer;padding:0}
.langbtn:hover{color:var(--ink)}
.langbtn svg{width:18px;height:18px}
.langmenu{display:none;position:absolute;top:calc(100% + 8px);right:0;min-width:158px;background:var(--panel);border:1px solid var(--line);border-radius:11px;box-shadow:0 18px 44px -18px rgba(24,34,59,.32);padding:6px;z-index:60}
.langdd.open .langmenu{display:block}
.langmenu button{display:flex;align-items:center;justify-content:space-between;gap:14px;width:100%;font:500 13.5px var(--sans);padding:8px 11px;border:0;border-radius:7px;background:transparent;color:var(--ink);cursor:pointer;text-align:left}
.langmenu button:hover{background:var(--panel2)}
.langmenu button .chk{visibility:hidden;color:var(--gold);font-weight:700}
.langmenu button.on .chk{visibility:visible}

/* mobile hamburger menu */
.menubtn{display:none;width:38px;height:36px;flex:none;border:1px solid var(--line);border-radius:9px;background:var(--panel);cursor:pointer;flex-direction:column;align-items:center;justify-content:center;gap:4px;padding:0}
.menubtn span{display:block;width:16px;height:2px;background:var(--ink);border-radius:2px;transition:.15s}
.menubtn[aria-expanded="true"] span:nth-child(1){transform:translateY(6px) rotate(45deg)}
.menubtn[aria-expanded="true"] span:nth-child(2){opacity:0}
.menubtn[aria-expanded="true"] span:nth-child(3){transform:translateY(-6px) rotate(-45deg)}
.mmenu{display:none;position:absolute;top:100%;left:0;right:0;background:var(--panel);border-bottom:1px solid var(--line);box-shadow:0 18px 40px -24px rgba(24,34,59,.35);padding:6px var(--wrap-pad) 12px}
.mmenu.open{display:block}
.mmenu a{display:block;padding:13px 2px;font-size:15px;font-weight:500;color:var(--ink);text-decoration:none;border-top:1px solid var(--line)}
.mmenu a:first-child{border-top:0}
.mmenu a.active{color:var(--gold);font-weight:600}
.mlang{display:flex;gap:8px;padding:13px 2px 4px;border-top:1px solid var(--line)}
.mlang button{flex:1;font:600 13px var(--sans);padding:9px 6px;border:1px solid var(--line);border-radius:9px;background:transparent;color:var(--muted);cursor:pointer}
.mlang button.on{background:var(--navy);border-color:var(--navy);color:#fff}

/* ---- footer ------------------------------------------------------------- */
footer,gtu-footer{border-top:1px solid var(--line);background:var(--panel2)}
.footin{max-width:1180px;margin:0 auto;padding:46px var(--wrap-pad) 38px;display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr;gap:40px;align-items:start}
.fbrand .logo{font-size:17px}
.fbrand .star{width:20px;height:20px}
.fconv{font-size:12.5px;color:var(--muted);margin-top:12px;max-width:36ch;line-height:1.6}
.flang{display:flex;align-items:center;gap:4px}
.flang button{font:600 12px var(--sans);padding:4px 8px;border:0;border-radius:6px;background:transparent;color:var(--faint);cursor:pointer}
.flang button:hover{color:var(--ink)}
.flang button.on{color:var(--gold)}
.flang .sep{color:var(--line);font-size:11px}
.flabel{font:700 11px var(--sans);letter-spacing:.13em;text-transform:uppercase;color:var(--gold);margin-bottom:13px}
.fcol a{display:block;font-size:12.5px;color:var(--muted);text-decoration:none;padding:3.5px 0}
.fcol a:hover{color:var(--ink)}
.footbase{border-top:1px solid var(--line)}
.footbase-in{max-width:1180px;margin:0 auto;padding:15px var(--wrap-pad);display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:10px;font-size:11.5px;color:var(--faint)}
/* language switcher sits on the copyright line (right); kill its old in-column top margin */
.footbase-in .flang,.footbase-in .flangs{margin:0}

/* ============================================================================
   Chinese typography — single source of truth for every static page.

   Strategy: under html[lang^="zh"] we REASSIGN the font tokens to the CJK sans
   stack, so every var(--serif)/var(--sans)/var(--*-cjk) usage on every page
   flips to PingFang at once. No per-page selector list to maintain, and no
   element can silently fall through Newsreader → Georgia → the browser's
   default Songti/SimSun serif (the dated look we must never ship).

   Owner decision 2026-06-12: Chinese never uses serif. The ONLY Latin serif we
   keep is the "Guide to Uni" wordmark — Latin brand text, pinned back below.

   Hanzi also wants its own metrics: looser leading, no Latin negative tracking,
   no synthesised italics, eased uppercase tracking, and proper CJK line-breaks.
   Set them ONCE here; pages should not redeclare them.
   ========================================================================= */
:root{
  --cjk:"PingFang SC","PingFang TC","Microsoft YaHei","Hiragino Sans GB","Noto Sans CJK SC",sans-serif;
  /* legacy aliases — kept so existing per-page var(--serif-cjk) refs resolve */
  --serif-cjk:var(--cjk);
  --sans-cjk:var(--cjk);
}
html[lang^="zh"]{--serif:var(--cjk);--sans:var(--cjk);line-break:strict;overflow-wrap:break-word}
/* the Latin wordmark is brand text, not Chinese — keep it in the brand serif */
html[lang^="zh"] .logo,
html[lang^="zh"] .wordmark{font-family:'Newsreader',ui-serif,Georgia,serif}

html[lang^="zh"] body{line-height:1.8}
/* headings: drop Latin tracking, loosen leading, render a real heavy weight.
   Class-qualified so these beat each page's plain `.hero h1`/`.sechead h2`. */
html[lang^="zh"] h2,
html[lang^="zh"] h3,
html[lang^="zh"] .ph,
html[lang^="zh"] .hero h1,
html[lang^="zh"] .phero h1,
html[lang^="zh"] .chead h1{letter-spacing:0;line-height:1.32;font-weight:700;font-synthesis:weight style}
html[lang^="zh"] .sechead h2{line-height:1.32}
/* one shared Chinese hero scale — Hanzi is denser/wider than Latin, so heroes
   want a smaller ceiling than --step-hero. Pages no longer size heroes themselves. */
html[lang^="zh"] .hero h1,
html[lang^="zh"] .phero h1,
html[lang^="zh"] .chead h1{font-size:clamp(28px,4vw + 11px,42px)}
html[lang^="zh"] .final h2{line-height:1.36}
/* wide Latin uppercase tracking reads as gaps on Hanzi — ease it everywhere */
html[lang^="zh"] .eyebrow,
html[lang^="zh"] .kicker,
html[lang^="zh"] .ptag,
html[lang^="zh"] .rlabel,
html[lang^="zh"] .flabel{letter-spacing:.04em}
/* synthesised obliques look broken on Hanzi — render emphasis upright + heavier */
html[lang^="zh"] em,
html[lang^="zh"] i{font-style:normal;font-weight:600}
/* body copy leading */
html[lang^="zh"] .lede,
html[lang^="zh"] .vs li,
html[lang^="zh"] .step p,
html[lang^="zh"] .ptext{line-height:1.8}
/* don't clip wrapped Chinese */
html[lang^="zh"] .metric .v{font-size:16px;white-space:normal}

/* ============================================================================
   Breakpoint 900px — layout collapse + nav → hamburger
   ========================================================================= */
@media(max-width:900px){
  .links a:not(.btn-primary){display:none}
  .links .langdd{display:none}
  .menubtn{display:flex}
  .footin{grid-template-columns:1fr 1fr}
}
@media(min-width:901px){.mmenu{display:none}}

/* ============================================================================
   Breakpoint 640px — single-column footer + tighter mobile gutters
   ========================================================================= */
@media(max-width:640px){
  .footin{grid-template-columns:1fr;gap:32px}
  .footbase-in{flex-direction:column;align-items:flex-start;gap:10px}
}