/* ==========================================================================
   Wahyu Pebrianto - personal site
   Plain CSS (no build step).  One file, organised in sections:
     1. Design tokens (colours, type, spacing)   2. Base / reset
     3. Layout (header, footer, container)       4. Components
     5. Prose (article typography, code, tables) 6. Syntax highlighting
     7. Utilities, motion, print
   Light/dark: tokens use light-dark(); <html data-theme="light|dark"> (set by
   a tiny inline script in <head>) forces a scheme, otherwise the OS decides.
   ========================================================================== */

/* 1. Design tokens -------------------------------------------------------- */
:root {
  color-scheme: light dark;

  --bg:          light-dark(#ffffff, #0f1419);
  --bg-soft:     light-dark(#f5f7fa, #171d24);
  --fg:          light-dark(#1f2933, #e3e8ee);
  --fg-muted:    light-dark(#586574, #a0abb8);
  --heading:     light-dark(#002244, #dbe8f7);
  --border:      light-dark(#dfe4ea, #2a323c);
  --accent:      light-dark(#0b57b0, #7db9ff);
  --accent-soft: light-dark(#e8f1fc, #1b2a3d);
  --on-accent:   light-dark(#ffffff, #0f1419);
  --focus:       light-dark(#0b57b0, #7db9ff);
  --code-bg:     light-dark(#f4f6f8, #161c23);

  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;

  --step--1: 0.875rem;
  --step-0:  1rem;
  --step-1:  1.25rem;
  --step-2:  1.563rem;
  --step-3:  clamp(1.75rem, 1.4rem + 1.4vw, 2.25rem);

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2.5rem;
  --space-7: 4rem;

  --radius: 8px;
  --container: 68rem;
  --measure: 46rem;
  --header-h: 3.75rem;
}

:root[data-theme="light"] { color-scheme: light; }
:root[data-theme="dark"]  { color-scheme: dark; }

/* 2. Base / reset --------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-padding-top: calc(var(--header-h) + var(--space-4));
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-sans);
  font-size: var(--step-0);
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, h5, h6 {
  margin: var(--space-6) 0 var(--space-3);
  color: var(--heading);
  font-weight: 600;
  line-height: 1.25;
  text-wrap: balance;
}
h1 { font-size: var(--step-3); }
h2 { font-size: var(--step-2); }
h3 { font-size: var(--step-1); }
h4 { font-size: var(--step-0); }

p, ul, ol, dl, table, pre, blockquote, figure { margin: 0 0 var(--space-4); }
ul, ol { padding-left: 1.5em; }

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}
a:hover { text-decoration-thickness: 2px; }

img, svg, video { max-width: 100%; }
img { height: auto; border-radius: var(--radius); }

hr { border: 0; border-top: 1px solid var(--border); margin: var(--space-6) 0; }

:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
  border-radius: 4px;
}

::selection { background: var(--accent-soft); color: var(--fg); }

/* 3. Layout --------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

.site-main { flex: 1 0 auto; padding-block: var(--space-5) var(--space-7); }
.site-main .container > :first-child { margin-top: 0; }

.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -4rem;
  z-index: 200;
  padding: var(--space-2) var(--space-4);
  background: var(--accent);
  color: var(--on-accent);
  border-radius: var(--radius);
  text-decoration: none;
}
.skip-link:focus { top: var(--space-3); }

/* Header + navigation */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  -webkit-backdrop-filter: saturate(1.4) blur(8px);
  backdrop-filter: saturate(1.4) blur(8px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  min-height: var(--header-h);
}
.brand {
  margin-right: auto;
  color: var(--heading);
  font-weight: 700;
  font-size: var(--step-1);
  letter-spacing: -0.01em;
  text-decoration: none;
  white-space: nowrap;
}
.brand:hover { text-decoration: none; color: var(--accent); }

.nav-list { display: flex; align-items: center; gap: var(--space-1); margin: 0; padding: 0; list-style: none; }
.nav-item { position: relative; display: flex; align-items: center; }
.nav-link {
  display: block;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius);
  color: var(--fg);
  font-weight: 500;
  text-decoration: none;
}
.nav-link:hover { background: var(--bg-soft); color: var(--accent); }
.nav-link[aria-current="page"] { color: var(--accent); background: var(--accent-soft); }

/* Sub-menu (only rendered when a research theme is `ready`) */
.sub-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.75rem;
  height: 1.75rem;
  margin-left: -0.35rem;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: transparent;
  color: var(--fg-muted);
  cursor: pointer;
}
.sub-toggle .icon { width: 1rem; height: 1rem; }
.sub-toggle:hover { background: var(--bg-soft); color: var(--accent); }
.sub-list {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  z-index: 110;
  min-width: 16rem;
  margin: 0;
  padding: var(--space-2);
  list-style: none;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: 0 8px 24px rgb(0 0 0 / 0.12);
}
.sub-list a {
  display: block;
  padding: var(--space-2) var(--space-3);
  border-radius: 6px;
  color: var(--fg);
  text-decoration: none;
}
.sub-list a:hover, .sub-list a[aria-current="page"] { background: var(--bg-soft); color: var(--accent); }
.has-sub:hover > .sub-list,
.has-sub:focus-within > .sub-list,
.has-sub.open > .sub-list { display: block; }

.header-actions { display: flex; align-items: center; gap: var(--space-2); }
.lang-switch {
  padding: var(--space-1) var(--space-3);
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--fg);
  font-size: var(--step--1);
  font-weight: 600;
  text-decoration: none;
}
.lang-switch:hover { border-color: var(--accent); color: var(--accent); }

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  padding: 0;
  border: 1px solid transparent;
  border-radius: var(--radius);
  background: transparent;
  color: var(--fg);
  cursor: pointer;
}
.icon-btn:hover { background: var(--bg-soft); color: var(--accent); }

.icon { width: 1.25rem; height: 1.25rem; flex: none; vertical-align: middle; }

/* Theme toggle only works with JS; show the icon that matches the target theme. */
.theme-toggle { display: none; }
.js .theme-toggle { display: inline-flex; }
:root[data-theme="dark"] .when-light, :root:not([data-theme="dark"]) .when-dark { display: none; }

/* Mobile nav button is JS-only; without JS the nav simply stays visible. */
.nav-toggle { display: none; }
.nav-toggle .when-open { display: none; }
.nav-toggle[aria-expanded="true"] .when-open { display: inline-flex; }
.nav-toggle[aria-expanded="true"] .when-closed { display: none; }

@media (max-width: 52rem) {
  .header-inner { flex-wrap: wrap; row-gap: 0; padding-block: var(--space-2); }
  .js .nav-toggle { display: inline-flex; order: 3; }
  .header-actions { order: 2; }
  .site-nav { order: 4; flex-basis: 100%; }
  .js .site-nav { display: none; }
  .js .site-nav.open { display: block; }
  .nav-list { flex-direction: column; align-items: stretch; padding-bottom: var(--space-3); }
  .nav-item { flex-wrap: wrap; }
  .nav-link { flex: 1; }
  .sub-list {
    display: block;
    position: static;
    flex-basis: 100%;
    min-width: 0;
    margin-left: var(--space-4);
    padding: 0;
    border: 0;
    box-shadow: none;
    background: transparent;
  }
  .sub-toggle { display: none; }
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-soft);
  padding-block: var(--space-5);
  color: var(--fg-muted);
  font-size: var(--step--1);
  text-align: center;
}
.site-footer p { margin: 0; }
.site-footer a { color: inherit; }
.site-footer a:hover { color: var(--accent); }
.footer-inner { display: flex; flex-direction: column; align-items: center; gap: var(--space-3); }

.social-list { display: flex; flex-wrap: wrap; gap: var(--space-2); margin: 0; padding: 0; list-style: none; }
.footer-inner .social-list { justify-content: center; }
.social-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border: 1px solid var(--border);
  border-radius: 50%;
  color: var(--fg);
}
.social-link:hover { border-color: var(--accent); color: var(--accent); }
.social-link .icon { width: 1.2rem; height: 1.2rem; }

/* 4. Components ----------------------------------------------------------- */
.page-title { margin-top: 0; }
.section-title { margin-top: var(--space-5); font-size: var(--step-1); }
.eyebrow { margin-bottom: var(--space-2); font-size: var(--step--1); }
.eyebrow a { text-decoration: none; }
.muted { color: var(--fg-muted); }

.button {
  display: inline-block;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius);
  background: var(--accent);
  color: var(--on-accent);
  font-weight: 600;
  text-decoration: none;
}
.button:hover { filter: brightness(1.1); text-decoration: none; }

.badge {
  display: inline-block;
  padding: 0 var(--space-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--fg-muted);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  vertical-align: 0.05em;
}

.notice {
  padding: var(--space-3) var(--space-4);
  border-left: 4px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  background: var(--accent-soft);
}

/* Home */
.hero {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  padding-block: var(--space-5) var(--space-6);
}
.hero-photo {
  width: 10rem;
  height: 10rem;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--border);
  flex: none;
}
.hero-text h1 { margin: 0 0 var(--space-1); }
.hero-text p { margin: 0 0 var(--space-2); }
.hero-role { color: var(--accent); font-size: var(--step-1); font-weight: 600; }
.hero-affiliation { color: var(--fg-muted); }
.hero-text .social-list { margin-top: var(--space-3); }

.home-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 20rem); gap: var(--space-6); align-items: start; }
.home-side .section-title:first-child { margin-top: 0; }
.bio p { max-width: var(--measure); }

@media (max-width: 52rem) {
  .hero { flex-direction: column; text-align: center; }
  .hero-text .social-list { justify-content: center; }
  .home-grid { grid-template-columns: minmax(0, 1fr); gap: var(--space-4); }
}

.chips { display: flex; flex-wrap: wrap; gap: var(--space-2); margin: 0 0 var(--space-3); padding: 0; list-style: none; }
.chips li > a, .chips li > span {
  display: inline-block;
  padding: 0.15rem var(--space-3);
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--bg-soft);
  color: var(--fg);
  font-size: var(--step--1);
  text-decoration: none;
}
.chips li > a:hover { border-color: var(--accent); color: var(--accent); }

/* Post lists */
.post-list { margin: 0 0 var(--space-4); padding: 0; list-style: none; }
.post-item { padding-block: var(--space-4); border-bottom: 1px solid var(--border); }
.post-item:last-child { border-bottom: 0; }
.post-item-title { margin: 0 0 var(--space-1); font-size: var(--step-1); }
.post-item-title a { color: var(--heading); text-decoration: none; }
.post-item-title a:hover { color: var(--accent); text-decoration: underline; }
.post-meta { margin: 0 0 var(--space-2); color: var(--fg-muted); font-size: var(--step--1); }
.post-item-desc { margin: 0; color: var(--fg); }
.post-list.compact .post-item { padding-block: var(--space-3); }
.post-list.compact .post-item-title { font-size: var(--step-0); }
.post-list.compact .post-item-desc { display: none; }

.year-group { margin-bottom: var(--space-5); }
.year-title { margin: var(--space-5) 0 0; padding-bottom: var(--space-2); border-bottom: 2px solid var(--border); font-size: var(--step-1); }

.filters { display: flex; flex-wrap: wrap; gap: var(--space-2); margin: var(--space-4) 0; }
.filters[hidden] { display: none; }
.chip-btn {
  padding: 0.2rem var(--space-3);
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--bg-soft);
  color: var(--fg);
  font: inherit;
  font-size: var(--step--1);
  cursor: pointer;
}
.chip-btn:hover { border-color: var(--accent); color: var(--accent); }
.chip-btn[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: var(--on-accent); }

/* Post page */
.post, .page.prose, .page > .prose { max-width: var(--measure); }
.page:not(.prose) { max-width: none; }
.post-header { margin-bottom: var(--space-5); }
.post-title { margin: 0 0 var(--space-2); }
.post-footer { margin-top: var(--space-6); padding-top: var(--space-4); border-top: 1px solid var(--border); }

/* Cards (courses, research themes) */
.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(17rem, 1fr)); gap: var(--space-4); margin: var(--space-4) 0; padding: 0; list-style: none; }
.card { padding: var(--space-4) var(--space-5); border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg-soft); }
.card p { margin: 0 0 var(--space-2); }
.card-meta { color: var(--fg-muted); font-size: var(--step--1); }
.card-title { margin: 0 0 var(--space-2); font-size: var(--step-1); }
.card-title a { color: var(--heading); text-decoration: none; }
.card-title a:hover { color: var(--accent); text-decoration: underline; }

.research-logo { display: block; width: min(16rem, 60%); margin: 0 0 var(--space-4); border-radius: 50%; }

/* Publications */
.pub-group h2 { margin-top: var(--space-6); }
.pub-list { margin: 0; padding: 0; list-style: none; }
.pub { display: flex; gap: var(--space-4); padding-block: var(--space-3); border-bottom: 1px solid var(--border); }
.pub:last-child { border-bottom: 0; }
.pub-year { flex: none; width: 3rem; color: var(--fg-muted); font-variant-numeric: tabular-nums; }
.pub-body p { margin: 0 0 var(--space-1); }
.pub-title { font-weight: 600; }
.pub-authors, .pub-venue { color: var(--fg-muted); font-size: var(--step--1); }
.pub-authors strong { color: var(--fg); }

.outline { padding-left: 1.75em; }
.outline li { margin-bottom: var(--space-1); }

/* 5. Prose ---------------------------------------------------------------- */
.prose { overflow-wrap: break-word; }
.prose h2 { margin-top: var(--space-6); }
.prose h3 { margin-top: var(--space-5); }
.prose li { margin-bottom: var(--space-1); }
.prose img { display: block; margin: var(--space-4) 0; }
.prose img.img-center, .img-center { margin-inline: auto; }
.prose figure { margin: var(--space-5) 0; }
.prose figcaption { margin-top: var(--space-2); color: var(--fg-muted); font-size: var(--step--1); text-align: center; }

.prose blockquote {
  margin-inline: 0;
  padding: var(--space-1) var(--space-4);
  border-left: 4px solid var(--border);
  color: var(--fg-muted);
}

.prose code, .prose kbd {
  padding: 0.12em 0.35em;
  border-radius: 4px;
  background: var(--code-bg);
  font-family: var(--font-mono);
  font-size: 0.9em;
}
.prose pre, .prose div.highlight {
  margin: 0 0 var(--space-4);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--code-bg);
  overflow-x: auto;
}
.prose pre { padding: var(--space-3) var(--space-4); line-height: 1.5; }
.prose div.highlight > pre { margin: 0; border: 0; background: transparent; }
.prose pre code { padding: 0; background: transparent; font-size: var(--step--1); }

.table-wrap, .prose table { overflow-x: auto; }
.prose table, .table-wrap table { display: block; width: max-content; max-width: 100%; border-collapse: collapse; }
.table-wrap table { display: table; width: 100%; }
th, td { padding: var(--space-2) var(--space-3); border: 1px solid var(--border); text-align: left; vertical-align: top; }
th { background: var(--bg-soft); font-weight: 600; }

/* 6. Syntax highlighting (Rouge token classes) --------------------------- */
.highlight .c, .highlight .cm, .highlight .c1, .highlight .cs, .highlight .cd { color: light-dark(#6a737d, #8b98a5); font-style: italic; }
.highlight .k, .highlight .kd, .highlight .kn, .highlight .kp, .highlight .kr, .highlight .kt, .highlight .kc { color: light-dark(#cf222e, #ff7b72); }
.highlight .o, .highlight .ow { color: light-dark(#0550ae, #79c0ff); }
.highlight .s, .highlight .s1, .highlight .s2, .highlight .sb, .highlight .sc, .highlight .sd, .highlight .se, .highlight .sh, .highlight .si, .highlight .sx { color: light-dark(#0a3069, #a5d6ff); }
.highlight .m, .highlight .mi, .highlight .mf, .highlight .mh, .highlight .mo, .highlight .il { color: light-dark(#0550ae, #79c0ff); }
.highlight .nf, .highlight .fm, .highlight .nx { color: light-dark(#8250df, #d2a8ff); }
.highlight .nc, .highlight .nn, .highlight .ne { color: light-dark(#953800, #ffa657); }
.highlight .nb, .highlight .bp, .highlight .nt { color: light-dark(#116329, #7ee787); }
.highlight .na, .highlight .nv, .highlight .vi, .highlight .vg { color: light-dark(#0550ae, #79c0ff); }
.highlight .err { color: light-dark(#cf222e, #ff7b72); }
.highlight .gd { color: light-dark(#82071e, #ffdcd7); background: light-dark(#ffebe9, #67060c); }
.highlight .gi { color: light-dark(#116329, #aff5b4); background: light-dark(#dafbe1, #033a16); }

/* 7. Utilities, motion, print -------------------------------------------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}
[hidden] { display: none !important; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
}

@media print {
  :root { color-scheme: light; }
  .site-header, .site-footer, .skip-link, .filters, .post-footer .chips { display: none !important; }
  body { display: block; font-size: 11pt; }
  .container { max-width: none; padding: 0; }
  a { color: inherit; text-decoration: underline; }
  .prose a[href^="http"]::after { content: " (" attr(href) ")"; font-size: 0.85em; }
}

/* Home sidebar: breathing room between stacked sections */
.home-side section + section { margin-top: var(--space-6); }
.home-side .chips + .chips { margin-top: var(--space-2); }
.sub-list { width: max-content; max-width: 22rem; }

/* Figures (inline, theme-aware SVG) */
.figure { margin: var(--space-5) 0; text-align: center; overflow-x: auto; }
.figure-svg { display: block; width: 100%; min-width: 30rem; height: auto; margin: 0 auto; color: var(--fg); }
.figure-svg .fig-bg { fill: var(--bg); }
.figure figcaption { margin-top: var(--space-2); color: var(--fg-muted); font-size: var(--step--1); text-align: left; }

/* "How to cite" box */
.cite { margin: var(--space-5) 0 var(--space-4); padding: var(--space-4) var(--space-5); border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg-soft); }
.cite-title { margin: 0 0 var(--space-2); font-size: var(--step-1); }
.cite-block { margin-top: var(--space-3); }
.cite-label { margin: 0 0 var(--space-1); font-size: var(--step--1); font-weight: 600; }
.cite pre { margin: 0; padding: var(--space-3); border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg); overflow-x: auto; white-space: pre-wrap; word-break: break-word; font-size: var(--step--1); line-height: 1.5; }
.cite code { font-family: var(--font-mono); }
.copy-btn { margin-left: var(--space-2); padding: 0 var(--space-3); border: 1px solid var(--border); border-radius: 999px; background: var(--bg); color: var(--fg); font: inherit; font-size: 0.8rem; cursor: pointer; }
.copy-btn:hover { border-color: var(--accent); color: var(--accent); }