/* ===========================================================================
   Yue Ma — personal academic site
   One stylesheet. No build step, no framework, no external requests.

     1. Fonts       self-hosted Satoshi
     2. Tokens      design variables; the only place raw values live
     3. Base        reset, document defaults, typography
     4. Layout      container, header, footer, sections
     5. Components  hero, cards, rows, prose, links, buttons
     6. Utilities   small single-purpose helpers

   Editing rule: change values in Tokens, not in the rules below. If a colour
   is chosen for contrast, record the measured ratio in a comment next to it.
   =========================================================================== */


/* ---------------------------------------------------------------------------
   1. FONTS — served from /assets/fonts, so the page makes no third-party
   requests. Satoshi (Fontshare). Only 400/500/700 are shipped.
   --------------------------------------------------------------------------- */
@font-face{font-family:Satoshi;src:url(/assets/fonts/satoshi-400.woff2) format('woff2');font-weight:400;font-style:normal;font-display:swap}
@font-face{font-family:Satoshi;src:url(/assets/fonts/satoshi-500.woff2) format('woff2');font-weight:500;font-style:normal;font-display:swap}
@font-face{font-family:Satoshi;src:url(/assets/fonts/satoshi-700.woff2) format('woff2');font-weight:700;font-style:normal;font-display:swap}


/* ---------------------------------------------------------------------------
   2. TOKENS
   Soft, low-saturation blue. Surfaces are translucent so the background wash
   reads through them rather than sitting behind an opaque slab.
   --------------------------------------------------------------------------- */
:root{
  --bg:#f1f6fb;
  --card:rgba(255,255,255,.72);
  --card-solid:#fbfcfe;
  --fg:#101f2e;                    /* 15.4:1 on --bg */
  --muted:#526c87;                 /*  5.0:1 on --bg */
  --border:rgba(22,62,105,.13);
  --border-hi:rgba(22,62,105,.27);
  --soft:rgba(22,62,105,.045);
  --blue:#3a7ebb;                  /*  4.0:1 on --bg — non-text accent */
  --blue-ink:#1a4e7a;              /*  8.7:1 with white — button fill */
  --blue-soft:rgba(58,126,187,.12);

  --sans:Satoshi,ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,
         "PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans SC",sans-serif;
  --mono:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,monospace;

  --text:16.5px;
  --meta:13px;
  --wrap:1000px;
  --gutter:28px;
  --gap-section:52px;
  --r:8px;
}

@media (prefers-color-scheme:dark){
  :root{
    --bg:#08131d;
    --card:rgba(255,255,255,.045);
    --card-solid:#0e1e2d;
    --fg:#e3edf8;                  /* 15.8:1 */
    --muted:#8ba6c2;               /*  7.4:1 */
    --border:rgba(150,200,245,.14);
    --border-hi:rgba(150,200,245,.28);
    --soft:rgba(150,200,245,.05);
    --blue:#5aa9e0;                /*  7.3:1 */
    --blue-ink:#8ec8f0;
    --blue-soft:rgba(90,169,224,.13);
  }
}

@media (max-width:860px){ :root{ --gutter:20px; --gap-section:40px; } }


/* ---------------------------------------------------------------------------
   3. BASE
   --------------------------------------------------------------------------- */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}

body{
  margin:0;min-height:100vh;display:flex;flex-direction:column;
  background:var(--bg);color:var(--fg);
  font-family:var(--sans);font-size:var(--text);line-height:1.62;
  -webkit-font-smoothing:antialiased;position:relative;
}

/* Backdrop: three low-opacity blue washes plus a faint grid. Fixed, so the
   page scrolls over them. Pure CSS — no image, no request. */
body::before{
  content:"";position:fixed;inset:0;z-index:-2;pointer-events:none;
  background:
    radial-gradient(58% 44% at 78% -6%, rgba(96,164,228,.26), transparent 68%),
    radial-gradient(46% 38% at 8% 4%,  rgba(126,186,235,.20), transparent 70%),
    radial-gradient(70% 50% at 50% 108%, rgba(108,158,220,.15), transparent 72%);
}
body::after{
  content:"";position:fixed;inset:0;z-index:-1;pointer-events:none;opacity:.55;
  background:linear-gradient(var(--border) 1px,transparent 1px) 0 0/100% 88px,
             linear-gradient(90deg,var(--border) 1px,transparent 1px) 0 0/88px 100%;
  -webkit-mask-image:radial-gradient(120% 90% at 50% 0%,#000 20%,transparent 78%);
          mask-image:radial-gradient(120% 90% at 50% 0%,#000 20%,transparent 78%);
}

/* CJK needs a little more air than Latin at the same size. */
[lang^="zh"]{line-height:1.8}

h1,h2,h3,h4{margin:0;font-weight:700;letter-spacing:-.022em;line-height:1.25;text-wrap:balance}
h1{font-size:46px;line-height:1.06;letter-spacing:-.033em}
h2{font-size:26px}
h3{font-size:17.5px;letter-spacing:-.015em}
@media (max-width:860px){ h1{font-size:33px} h2{font-size:22px} }

p,ul,ol,dl,figure,table{margin:0}
img{max-width:100%;height:auto;display:block}
code,kbd,samp,pre{font-family:var(--mono);font-size:.92em}
a{color:inherit}

:focus-visible{outline:2px solid var(--blue);outline-offset:2px;border-radius:3px}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important}
}


/* ---------------------------------------------------------------------------
   4. LAYOUT
   --------------------------------------------------------------------------- */
.c{width:100%;max-width:var(--wrap);margin-inline:auto;padding-inline:var(--gutter)}
main{flex:1}

.site-header{
  position:sticky;top:0;z-index:9;
  background:color-mix(in srgb,var(--bg) 72%,transparent);
  backdrop-filter:blur(14px) saturate(1.3);
  border-bottom:1px solid var(--border);
}
.site-header .c{display:flex;align-items:center;justify-content:space-between;min-height:60px;gap:14px 20px;flex-wrap:wrap;padding-block:8px}
.brand{font-weight:700;font-size:15.5px;letter-spacing:-.02em;text-decoration:none;color:inherit}
.site-nav ul{display:flex;gap:22px;flex-wrap:wrap;list-style:none;margin:0;padding:0}
.site-nav a{color:var(--muted);text-decoration:none;font-size:15px}
.site-nav a:hover{color:var(--fg)}
.site-nav a[aria-current="page"]{color:var(--fg);font-weight:500}
.hlinks{display:flex;gap:14px;font-size:14px;list-style:none;margin:0;padding:0}
.hlinks a{color:var(--muted);text-decoration:none}
.hlinks a:hover{color:var(--fg)}

.section{padding:0 0 var(--gap-section)}
.sh{display:flex;justify-content:space-between;align-items:baseline;gap:16px;margin-bottom:16px;flex-wrap:wrap}
.sh h2{font-size:15px;font-weight:500;color:var(--muted);letter-spacing:0}
.sh a{font-size:14.5px;color:var(--muted);text-decoration:none;white-space:nowrap}
.sh a:hover{color:var(--fg)}

.site-footer{border-top:1px solid var(--border);margin-top:auto}
.site-footer .c{display:flex;justify-content:space-between;gap:10px 24px;flex-wrap:wrap;
  font-family:var(--mono);font-size:12.5px;color:var(--muted);padding-block:22px 40px}
.site-footer a{color:var(--muted);text-decoration:none}
.site-footer a:hover{color:var(--fg)}
.site-footer ul{display:flex;gap:16px;flex-wrap:wrap;list-style:none;margin:0;padding:0}


/* ---------------------------------------------------------------------------
   5. COMPONENTS
   --------------------------------------------------------------------------- */

/* Hero ------------------------------------------------------------------- */
.hero{padding:52px 0 46px;display:flex;gap:44px;align-items:flex-start}
.hero__text{flex:1;min-width:0}
/* Circular, with the diameter equal to the square it replaced (164px). */
.pf{width:164px;height:164px;flex-shrink:0;border-radius:50%;
    border:1px solid var(--border);background:var(--card-solid);
    object-fit:cover;object-position:50% 42%;margin-top:4px}
.badge{display:inline-block;font-size:13.5px;border:1px solid var(--border);background:var(--card);
       backdrop-filter:blur(8px);border-radius:999px;padding:6px 15px;color:var(--muted);margin-bottom:22px}
.sub{font-size:17.5px;color:var(--muted);margin:18px 0 0;max-width:62ch;line-height:1.55}
.hero--page{display:block;padding:46px 0 34px}
@media (max-width:860px){
  .hero{padding:36px 0 32px;flex-direction:column-reverse;gap:24px;align-items:flex-start}
  .pf{width:104px;height:104px}
  .hero--page{padding:32px 0 24px}
}

/* Buttons — one filled, one outline. Keep it to these two. */
.btns{display:flex;gap:9px;margin-top:24px;flex-wrap:wrap}
.btn{font-size:15px;padding:10px 20px;border-radius:999px;text-decoration:none;font-weight:500;display:inline-block}
.btn--p{background:var(--blue-ink);color:#fff;border:1px solid var(--blue-ink)}
.btn--p:hover{background:var(--blue);border-color:var(--blue)}
.btn--s{border:1px solid var(--border);color:var(--fg);background:var(--card);backdrop-filter:blur(8px)}
.btn--s:hover{border-color:var(--border-hi)}
@media (prefers-color-scheme:dark){ .btn--p{color:#08131d} }

/* Numbered interest grid --------------------------------------------------- */
.int{display:grid;grid-template-columns:repeat(2,1fr);gap:1px;background:var(--border);
     border:1px solid var(--border);border-radius:var(--r);overflow:hidden;list-style:none;margin:0;padding:0}
.int li{background:var(--card);backdrop-filter:blur(8px);padding:18px 20px}
.int b{display:block;font-size:16px;font-weight:700;letter-spacing:-.01em;margin-bottom:4px}
.int .n{font-family:var(--mono);font-size:12.5px;color:var(--blue);font-style:normal;font-weight:400;margin-right:9px}
.int span{font-size:14.5px;color:var(--muted);line-height:1.5;display:block}
@media (max-width:860px){ .int{grid-template-columns:1fr} }

/* Cards -------------------------------------------------------------------- */
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;list-style:none;margin:0;padding:0}
.grid--2{grid-template-columns:repeat(2,1fr)}
.grid--1{grid-template-columns:1fr}
.card{background:var(--card);backdrop-filter:blur(8px);border:1px solid var(--border);
      border-radius:var(--r);padding:20px;display:flex;flex-direction:column;transition:border-color .15s}
.card:hover{border-color:var(--border-hi)}
.eyebrow{font-family:var(--mono);font-size:11.5px;color:var(--muted);letter-spacing:.02em;margin-bottom:9px}
.card h3{margin:0 0 6px}
.card p{margin:0;font-size:15px;color:var(--muted);line-height:1.5}
.card p+p{margin-top:8px}
.card .foot{margin-top:auto;padding-top:11px;display:flex;gap:14px;font-size:13px;flex-wrap:wrap;list-style:none}
.card .foot{border-top:1px solid var(--border);margin-top:14px;padding-left:0}
.card .foot a{color:var(--muted);text-decoration:none}
.card .foot a:hover{color:var(--fg)}
@media (max-width:860px){ .grid,.grid--2{grid-template-columns:1fr} }

/* Rows — publications, talks, CV, blog index ------------------------------- */
.rows{border:1px solid var(--border);border-radius:var(--r);background:var(--card);
      backdrop-filter:blur(8px);overflow:hidden;list-style:none;margin:0;padding:0}
.row{display:grid;grid-template-columns:78px minmax(0,1fr) auto;gap:16px;padding:15px 20px;align-items:baseline}
.row+.row{border-top:1px solid var(--border)}
.row:hover{background:var(--soft)}
.row .y{font-family:var(--mono);font-size:12.5px;color:var(--muted)}
.row .t{font-size:15.5px;font-weight:500;letter-spacing:-.01em}
.row .a{display:block;font-size:13.5px;color:var(--muted);font-weight:400;margin-top:1px}
.row .contrib{display:block;font-family:var(--mono);font-size:12px;color:var(--blue-ink);margin-top:5px}
.row .up{display:inline-block;font-family:var(--mono);font-size:11px;color:var(--blue-ink);
  border:1px solid var(--border-hi);border-radius:999px;padding:1px 8px;margin-left:9px;
  white-space:nowrap;vertical-align:1px;font-weight:400}
.row .lks{display:flex;gap:6px 12px;flex-wrap:wrap;justify-content:flex-end}
.row .lk{font-family:var(--mono);font-size:12.5px;color:var(--muted);text-decoration:none;white-space:nowrap}
.row .lk:hover{color:var(--blue-ink)}
.row--wide{grid-template-columns:150px minmax(0,1fr)}
@media (max-width:860px){ .row,.row--wide{grid-template-columns:1fr;gap:3px} }

/* Research page — anchored claims and set-off statements ------------------- */
.argument+.argument{margin-top:20px}
.argument b{font-weight:700;letter-spacing:-.012em;display:block}
.argument p{margin:4px 0 0;color:var(--muted)}
.callout{border-left:2px solid var(--blue);padding:2px 0 2px 18px;background:var(--blue-soft);
         border-radius:0 var(--r) var(--r) 0;padding-block:14px;padding-right:18px}

/* Long-form prose (blog posts) -------------------------------------------- */
.prose{max-width:68ch}
.prose>*+*{margin-top:1.2em}
.prose h2{font-size:22px;margin-top:1.8em}
.prose h3{font-size:18px;margin-top:1.5em}
.prose ul,.prose ol{padding-left:1.3em}
.prose li+li{margin-top:.35em}
.prose a{text-decoration:underline;text-decoration-thickness:1px;text-underline-offset:3px;color:var(--blue-ink)}
.prose a:hover{text-decoration-thickness:2px}
.prose pre{background:var(--card-solid);border:1px solid var(--border);border-radius:var(--r);
           padding:14px 16px;overflow-x:auto}
.prose>ul>li>ul{margin-top:.35em}
.prose ul ul{list-style:none;padding-left:1.1em}
.prose ul ul>li::before{content:"–";color:var(--muted);margin-right:.5em;margin-left:-1.1em}
.prose h2{scroll-margin-top:80px}
.prose blockquote{margin:0;border-left:2px solid var(--blue);background:var(--blue-soft);
  border-radius:0 var(--r) var(--r) 0;padding:14px 18px}
.prose blockquote p{margin:0}
.prose table{width:100%;border-collapse:collapse;font-size:15px;display:block;overflow-x:auto}
.prose th,.prose td{text-align:left;padding:9px 12px;border-bottom:1px solid var(--border);vertical-align:top}
.prose th{font-family:var(--mono);font-size:11.5px;font-weight:400;color:var(--muted);
  text-transform:uppercase;letter-spacing:.06em;white-space:nowrap}

/* Tags and the tag filter on /blog/. ------------------------------------- */
.tagbar{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-bottom:16px}
.tagbar .lbl{font-family:var(--mono);font-size:11.5px;color:var(--muted);
  text-transform:uppercase;letter-spacing:.08em;margin-right:2px}
.tagbtn{font-family:var(--mono);font-size:12px;padding:4px 11px;border-radius:999px;
  border:1px solid var(--border);background:var(--card);backdrop-filter:blur(8px);
  color:var(--muted);cursor:pointer;font-weight:400}
.tagbtn:hover{border-color:var(--border-hi);color:var(--fg)}
.tagbtn[aria-pressed="true"]{background:var(--blue-ink);border-color:var(--blue-ink);color:#fff}
@media (prefers-color-scheme:dark){ .tagbtn[aria-pressed="true"]{color:#08131d} }

/* Tags shown on each row. Anchors, so they work with JavaScript disabled. */
.tags{display:flex;flex-wrap:wrap;gap:6px;margin-top:7px;list-style:none;padding:0}
.tags a{font-family:var(--mono);font-size:11px;color:var(--muted);text-decoration:none;
  border:1px solid var(--border);border-radius:999px;padding:1px 8px}
.tags a:hover{border-color:var(--border-hi);color:var(--fg)}
.row[hidden]{display:none}
.empty-note{color:var(--muted);font-size:15px;padding:16px 20px}

/* Table of contents for long posts. */
.toc{border:1px solid var(--border);border-radius:var(--r);background:var(--card);
  backdrop-filter:blur(8px);padding:18px 20px}
.toc p{margin:0 0 10px;font-family:var(--mono);font-size:11.5px;text-transform:uppercase;
  letter-spacing:.08em;color:var(--muted)}
.toc ol{margin:0;padding-left:1.3em;font-size:15px}
.toc li+li{margin-top:5px}
.toc a{color:inherit;text-decoration:none}
.toc a:hover{color:var(--blue-ink);text-decoration:underline;text-underline-offset:3px}

/* Links -------------------------------------------------------------------- */
.link{color:var(--blue-ink);text-decoration:underline;text-decoration-thickness:1px;text-underline-offset:3px}
.link:hover{text-decoration-thickness:2px}
.link-row{display:flex;flex-wrap:wrap;gap:6px 16px;margin-top:10px;font-size:14px;list-style:none;padding:0}

/* Language switch on bilingual posts. Plain links, never a JS toggle. */
.lang-switch{display:flex;gap:14px;font-family:var(--mono);font-size:12.5px;color:var(--muted);list-style:none;padding:0;margin:0}
.lang-switch a{text-decoration:none;color:var(--muted)}
.lang-switch a:hover{color:var(--fg)}
.lang-switch [aria-current="true"]{color:var(--fg)}


/* ---------------------------------------------------------------------------
   6. UTILITIES
   --------------------------------------------------------------------------- */
.muted{color:var(--muted)}
.meta{font-size:var(--meta);line-height:1.6}
.mono{font-family:var(--mono)}
.measure{max-width:68ch}
.stack>*+*{margin-top:20px}
.mt-1{margin-top:8px}.mt-2{margin-top:16px}.mt-3{margin-top:24px}.mt-4{margin-top:32px}

.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;
         clip-path:inset(50%);white-space:nowrap;border:0}
.skip-link{position:absolute;left:-9999px;top:0;z-index:20;padding:8px 16px;
           background:var(--card-solid);border:1px solid var(--border);border-radius:var(--r)}
.skip-link:focus{left:8px;top:8px}

[id]{scroll-margin-top:76px}