/* Xin Liu — site styles, al-folio layout.
   Layout: sticky navbar; 800px reading container; home = profile card + news + selected publications + education;
   blog = list of essays and a 680px serif reading column for each post. Every color comes from the tokens below. */

:root {
  --bg: #ffffff;
  --fg: #000000;
  --muted: #828282;
  --theme: #0076df;
  --divider: #e8e8e8;
  --card: #f5f5f5;
  --hover: #f8f8f8;
  --code-bg: #f3f4f6;
  --logo-bg: #ffffff;
  --font: 'Roboto', 'Helvetica Neue', Arial, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-serif: Georgia, 'Noto Serif SC', 'Source Han Serif SC', 'Songti SC', 'SimSun', serif;
  --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #1c1c1d; --fg: #e2e2e2; --muted: #9a9a9a; --theme: #4da3ff;
    --divider: #424246; --card: #212529; --hover: #2a2a2b; --code-bg: #26292d; --logo-bg: #ffffff;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #1c1c1d; --fg: #e2e2e2; --muted: #9a9a9a; --theme: #4da3ff;
  --divider: #424246; --card: #212529; --hover: #2a2a2b; --code-bg: #26292d; --logo-bg: #ffffff;
  color-scheme: dark;
}

html, body { margin: 0; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
img { max-width: 100%; }
[hidden] { display: none !important; }
body { background: var(--bg); color: var(--fg); font-family: var(--font); font-size: 16px; line-height: 1.55; font-weight: 400; -webkit-font-smoothing: antialiased; }
body::before { content: ""; position: fixed; inset: 0 0 auto; height: env(safe-area-inset-top, 0px); z-index: 10; background: var(--bg); }
a { color: var(--theme); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible, button:focus-visible { outline: 2px solid var(--theme); outline-offset: 2px; }
p { margin: 0 0 1rem; }
code { font-family: var(--font-mono); font-size: .9em; }

/* navbar */
.navbar {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 9;
  background: var(--bg); border-bottom: 1px solid var(--divider);
  padding-block: 0;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}
.navbar .inner { max-width: 800px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; min-height: 58px; gap: 16px; flex-wrap: wrap; }
.brand { font-size: 1.25rem; color: var(--fg); letter-spacing: .01em; }
.brand b { font-weight: 700; }
.brand:hover { text-decoration: none; color: var(--theme); }
.navlinks { display: flex; align-items: center; gap: 22px; margin: 0; padding: 0; list-style: none; flex-wrap: wrap; }
.navlinks a { color: var(--fg); font-size: 1rem; }
.navlinks a:hover { color: var(--theme); text-decoration: none; }
.navlinks .current { font-weight: 700; }
.vis { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
#theme-toggle { background: none; border: 0; padding: 4px; cursor: pointer; color: var(--fg); display: grid; place-items: center; }
#theme-toggle:hover { color: var(--theme); }
#theme-toggle svg { width: 18px; height: 18px; }

.container {
  max-width: 800px; margin: 0 auto;
  padding-block: 2.5rem 3rem;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}

/* home header */
.post-title-home { font-size: 2.5rem; font-weight: 300; line-height: 1.15; margin: 0 0 .25rem; text-wrap: balance; }
.post-title-home b { font-weight: 700; }
.post-title-home .zh { font-weight: 300; color: var(--muted); font-size: 1.6rem; margin-left: .5rem; }
.desc { color: var(--muted); margin-bottom: 1.5rem; }
.profile { float: right; width: 24%; margin: 0 0 1rem 1.5rem; }
.profile .img { width: 100%; aspect-ratio: 1 / 1; border-radius: 50%; overflow: hidden; background: var(--card); color: var(--muted); display: grid; place-items: center; font-size: 2.2rem; font-weight: 300; }
.profile .img img { width: 100%; height: 100%; object-fit: cover; display: block; }
.profile .more-info { font-size: .85rem; color: var(--muted); text-align: center; margin-top: .5rem; line-height: 1.4; }
.clearfix::after { content: ""; display: table; clear: both; }

.profile-links { display: flex; justify-content: center; align-items: center; gap: 18px; margin-top: .8rem; }
.profile-links a { display: inline-flex; align-items: center; color: var(--fg); }
.profile-links a:hover { color: var(--theme); text-decoration: none; }
.profile-links svg, .profile-links i { width: 22px; height: 22px; flex: none; font-size: 22px; line-height: 1; }
.btn .hf { font-size: 1.05em; line-height: 1; }
.addr { user-select: all; }

h2 { font-size: 1.5rem; font-weight: 400; margin: 2.5rem 0 1rem; }
section, header { scroll-margin-top: 72px; }
h2 a { color: inherit; }
h2 a:hover { color: var(--theme); text-decoration: none; }

/* news; the "three philosophers" table reuses the same two-column form */
.news table, .thinkers { width: 100%; border-collapse: collapse; }
.news td, .thinkers td { padding: .45rem .3rem; vertical-align: top; border-top: 1px solid var(--divider); }
.news tr:first-child td, .thinkers tr:first-child td { border-top: 0; }
.news td.date, .thinkers td.date { width: 7.5rem; white-space: nowrap; color: var(--muted); font-size: .9rem; font-variant-numeric: tabular-nums; text-align: right; padding-right: 1rem; }
.thinkers td.date { width: 8.5rem; }

/* publications */
.bibliography { list-style: none; margin: 0; padding: 0; }
.bibliography li { margin-bottom: 1.5rem; padding-bottom: 1.5rem; border-bottom: 1px solid var(--divider); }
.bibliography li:last-child { border-bottom: 0; }
.pub { display: grid; grid-template-columns: 30% 1fr; gap: 20px; align-items: center; }
.preview { min-width: 0; }
.preview img { display: block; width: 100%; height: auto; padding: 4px; box-sizing: border-box; border-radius: 6px; border: 1px solid var(--divider); background: #ffffff; }
.preview .ph { width: 100%; aspect-ratio: 8 / 5; border-radius: 6px; background: var(--card); color: var(--theme); display: grid; place-items: center; }
.preview svg { width: 82%; height: 82%; display: block; }
.interests { margin: 0 0 1rem; padding-left: 1.3em; }
.interests li { margin-bottom: .25rem; }
.path-note { margin-top: 1rem; color: var(--muted); font-size: .95rem; }
.hobbies { margin-top: 1.25rem; }
.pub .body { min-width: 0; }
.pub .title { font-weight: 500; font-size: 1.05rem; line-height: 1.35; }
.pub .title a { color: var(--fg); }
.pub .title a:hover { color: var(--theme); text-decoration: none; }
.pub .author { margin-top: .25rem; }
.pub .author em { font-style: normal; border-bottom: 1px solid var(--fg); }
.pub .periodical { color: var(--muted); font-size: .95rem; }
.pub .periodical em { font-style: italic; }
.pub .note { margin: .5rem 0 .6rem; font-size: .95rem; }
.links { display: flex; flex-wrap: wrap; gap: 6px; }
.btn {
  display: inline-block; border: 1px solid var(--theme); color: var(--theme); border-radius: 4px;
  padding: 3px 9px; font-size: .72rem; font-weight: 500; letter-spacing: .04em; text-transform: uppercase; line-height: 1.5;
}
.btn:hover { text-decoration: none; }
@media (hover: hover) { .btn:hover { background: var(--theme); color: var(--bg); } }
.btn:active { background: var(--theme); color: var(--bg); }
.btn.soon { border-style: dashed; color: var(--muted); border-color: var(--divider); pointer-events: none; }

/* education */
.edu { list-style: none; margin: 0; padding: 0; }
.edu li { display: grid; grid-template-columns: 52px 1fr auto; gap: 16px; align-items: center; padding: .7rem 0; border-top: 1px solid var(--divider); }
.edu li:first-child { border-top: 0; }
.logo { position: relative; width: 52px; height: 52px; border-radius: 8px; overflow: hidden; background: var(--card); color: var(--muted); display: grid; place-items: center; font-size: .8rem; font-weight: 500; }
.logo img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: contain; padding: 5px; box-sizing: border-box; background: var(--logo-bg); }
.edu .school { font-weight: 500; }
.edu .deg { display: block; color: var(--muted); font-size: .9rem; }
.edu .when { color: var(--muted); font-size: .9rem; white-space: nowrap; font-variant-numeric: tabular-nums; }

footer { border-top: 1px solid var(--divider); margin-top: 3rem; padding: 1rem 0; color: var(--muted); font-size: .85rem; text-align: center; }
.notice { color: var(--muted); }

/* blog index */
.blog-head h1 { font-size: 2.5rem; font-weight: 300; line-height: 1.15; margin: 0 0 .25rem; }
.blog-head p { color: var(--muted); margin-bottom: 2rem; max-width: 60ch; }
.year { font-size: .85rem; color: var(--muted); font-weight: 500; letter-spacing: .06em; margin: 2rem 0 .25rem; padding-bottom: .3rem; border-bottom: 1px solid var(--divider); font-variant-numeric: tabular-nums; }
.year:first-child { margin-top: 0; }
.post-item { padding: 1rem 0; border-bottom: 1px solid var(--divider); }
.post-item:last-child { border-bottom: 0; }
.post-item-title { font-size: 1.25rem; font-weight: 500; margin: 0 0 .3rem; line-height: 1.35; text-wrap: balance; }
.post-item-title a { color: var(--fg); }
.post-item-title a:hover { color: var(--theme); text-decoration: none; }
.post-item-summary { margin: 0 0 .4rem; max-width: 66ch; }
.post-item-meta { margin: 0; color: var(--muted); font-size: .85rem; }
.tag { color: var(--muted); }
.tag::before { content: "#"; opacity: .6; }

/* post */
.post { max-width: 680px; margin: 0 auto; }
.post-back { font-size: .9rem; margin-bottom: 2rem; }
.post-title { font-family: var(--font-serif); font-size: 2rem; font-weight: 600; line-height: 1.3; margin: 0 0 .6rem; text-wrap: balance; }
.post-meta { color: var(--muted); font-size: .9rem; margin: 0 0 2.5rem; font-family: var(--font); }
.post-body { font-family: var(--font-serif); font-size: 1.0625rem; line-height: 1.8; }
.post:lang(zh) .post-body { line-height: 1.95; text-align: justify; letter-spacing: .01em; }
.post-body p { margin: 0 0 1.25em; }
.post-body h2 { font-family: var(--font-serif); font-size: 1.4rem; font-weight: 600; margin: 2.2em 0 .8em; line-height: 1.35; }
.post-body h3 { font-family: var(--font-serif); font-size: 1.15rem; font-weight: 600; margin: 1.8em 0 .6em; }
.post-body blockquote { margin: 1.5em 0; padding: .2em 0 .2em 1.2em; border-left: 3px solid var(--divider); color: var(--muted); }
.post-body blockquote p:last-child { margin-bottom: 0; }
.post-body ul, .post-body ol { padding-left: 1.6em; margin: 0 0 1.25em; }
.post-body li { margin-bottom: .35em; }
.post-body li > p { margin-bottom: .5em; }
.post-body img { display: block; max-width: 100%; height: auto; margin: 1.75em auto; border-radius: 4px; }
.post-body code { background: var(--code-bg); padding: .1em .35em; border-radius: 3px; font-size: .85em; }
.post-body pre { background: var(--code-bg); padding: .9em 1.1em; border-radius: 6px; overflow-x: auto; margin: 0 0 1.25em; line-height: 1.5; }
.post-body pre code { background: none; padding: 0; font-size: .85rem; }
.post-body hr { border: 0; border-top: 1px solid var(--divider); margin: 2.5em auto; width: 30%; }
.post-body .tbl { overflow-x: auto; margin: 0 0 1.25em; }
.post-body table { border-collapse: collapse; font-family: var(--font); font-size: .92rem; min-width: 100%; }
.post-body th, .post-body td { border: 1px solid var(--divider); padding: .4em .7em; text-align: left; }
.post-body .math-display { display: block; overflow-x: auto; text-align: center; margin: 1.25em 0; }
.fnref { font-size: .75em; line-height: 0; vertical-align: super; }
.fnref a { padding: 0 .15em; }
.footnotes { margin-top: 3rem; padding-top: 1rem; border-top: 1px solid var(--divider); font-family: var(--font-serif); font-size: .92rem; color: var(--muted); }
.footnotes ol { padding-left: 1.4em; margin: 0; }
.footnotes li { margin-bottom: .5em; }
.fn-back { margin-left: .3em; }

@media (max-width: 640px) {
  .container { padding-block: 1.75rem 2rem; }
  h2 { margin-top: 2.25rem; }
  .post-title-home { font-size: 2rem; }
  .post-title-home .zh { display: block; margin: .2rem 0 0; }
  .profile { float: none; width: 52%; max-width: 200px; margin: 0 auto 1.5rem; }
  /* icons stay 22px; the padding makes each one a ~42px tap target */
  .profile-links { gap: 6px; margin-top: .4rem; }
  .profile-links a { padding: 10px; }
  .pub { grid-template-columns: 1fr; gap: 12px; }
  .links { gap: 8px; }
  .btn { padding: 6px 12px; font-size: .75rem; }
  .edu li { grid-template-columns: 44px 1fr; column-gap: 14px; row-gap: 0; }
  .edu .logo { grid-row: span 2; width: 44px; height: 44px; }
  .edu .when { grid-column: 2; font-size: .85rem; }
  /* date-and-text tables stack: the date becomes a small label above its entry */
  .news table, .news tbody, .news tr, .news td,
  .thinkers, .thinkers tbody, .thinkers tr, .thinkers td { display: block; width: auto; }
  .news tr, .thinkers tr { padding: .7rem 0; border-top: 1px solid var(--divider); }
  .news tr:first-child, .thinkers tr:first-child { border-top: 0; padding-top: 0; }
  .news td, .thinkers td { padding: 0; border: 0; }
  .news td.date, .thinkers td.date { width: auto; text-align: left; white-space: normal; padding: 0 0 .15rem; font-size: .85rem; }
  .news td.date:empty { display: none; }
  .navlinks a { display: inline-block; padding-block: 8px; }
  #theme-toggle { padding: 10px; margin: -6px; }
  .blog-head h1 { font-size: 2rem; }
  .post-title { font-size: 1.6rem; }
  .post-body { font-size: 1rem; }
}
/* small phones (iPhone SE and similar): keep the navbar on one row */
@media (max-width: 380px) {
  .navbar .inner { gap: 10px; }
  .brand { font-size: 1.1rem; }
  .navlinks { gap: 14px; }
  .navlinks a { font-size: .92rem; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }