/* ============================================================
   Akhil S. Pillai — personal site
   Design: "typeset like the paper" — journal-page white,
   STIX Two Text (the typeface of scientific publishing),
   IBM Plex Mono for apparatus, cobalt/red vorticity accents.
   ============================================================ */

:root {
  --paper:        #FCFCFA;
  --ink:          #161A20;
  --ink-soft:     #4B5263;
  --ink-faint:    #8A8F9B;
  --cobalt:       #1B4FA0;
  --cobalt-deep:  #143C7C;
  --cobalt-tint:  #9DB6DC;
  --red:          #AC4238;
  --hairline:     #E5E5DF;
  --wash:         #F3F3EF;
  --serif: "STIX Two Text", "STIX Two Math", Georgia, "Times New Roman", serif;
  --mono:  "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --w: 46rem;
}

/* ---------- base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.0625rem;
  line-height: 1.68;
  font-feature-settings: "kern", "liga";
  text-rendering: optimizeLegibility;
}
::selection { background: rgba(27, 79, 160, 0.16); }

.site-nav, .content, .footer-inner {
  max-width: var(--w);
  margin-inline: auto;
  padding-inline: 1.25rem;
}

a { color: var(--cobalt); }
.content a {
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  text-decoration-color: var(--cobalt-tint);
}
.content a:hover { text-decoration-color: var(--cobalt); }

:focus-visible {
  outline: 2px solid var(--cobalt);
  outline-offset: 2px;
  border-radius: 1px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--mono);
  font-size: 0.8rem;
  padding: 0.5rem 0.9rem;
  z-index: 10;
}
.skip-link:focus { left: 0.5rem; top: 0.5rem; }

/* ---------- header / nav ---------- */
.site-header { border-bottom: 1px solid var(--hairline); }
.site-nav {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.6rem 1.5rem;
  padding-block: 1.15rem;
}
.brand {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.06rem;
  letter-spacing: 0.005em;
  color: var(--ink);
  text-decoration: none;
}
.brand:hover { color: var(--cobalt); }
.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1.35rem;
  list-style: none;
  margin: 0;
  padding: 0;
}
.nav-links a {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-soft);
  text-decoration: none;
  padding-bottom: 0.2rem;
  border-bottom: 2px solid transparent;
}
.nav-links a:hover { color: var(--cobalt); }
.nav-links a[aria-current="page"] {
  color: var(--cobalt);
  border-bottom-color: var(--cobalt);
}

/* ---------- shared headings & apparatus ---------- */
.eyebrow {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--ink-soft);
  margin: 0 0 0.55rem;
}
.eyebrow::before {
  content: "";
  width: 1.3rem;
  height: 1px;
  background: var(--cobalt);
  flex: none;
}

h1, h2, h3 { font-family: var(--serif); color: var(--ink); }
h1 {
  font-size: clamp(2.1rem, 5.5vw, 2.9rem);
  font-weight: 600;
  line-height: 1.12;
  letter-spacing: -0.012em;
  margin: 0;
}
h2 { font-size: 1.42rem; font-weight: 600; line-height: 1.25; margin: 0.4rem 0 1rem; }
h3 { font-size: 1.18rem; font-weight: 600; line-height: 1.3;  margin: 0 0 0.3rem; }

.page-head { padding: 3.2rem 0 0.4rem; }
.page-subtitle {
  font-size: 1.08rem;
  font-style: italic;
  color: var(--ink-soft);
  margin: 0.7rem 0 0;
  max-width: 56ch;
}

section { margin-top: 3.4rem; }

/* ---------- hero (home) ---------- */
.hero { padding-top: 3.6rem; }
.hero-intro {
  display: flex;
  align-items: flex-start;
  gap: 1.7rem;
  margin-top: 1.5rem;
}
.portrait {
  flex: none;
  width: 148px;
  height: auto;
  border: 1px solid var(--hairline);
  border-radius: 3px;
}
.hero-intro .lede { flex: 1; min-width: 0; margin-top: 0.15rem; }
.hero .affiliation {
  font-style: italic;
  font-size: 1.05rem;
  color: var(--ink-soft);
  margin: 0.85rem 0 0;
}
.hero .lede {
  font-size: 1.1rem;
  line-height: 1.72;
  max-width: 60ch;
  margin: 1.35rem 0 0;
}
.hero-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1.5rem;
  margin: 1.6rem 0 0;
  padding: 0;
  list-style: none;
}
.hero-links a {
  font-family: var(--mono);
  font-size: 0.74rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--cobalt);
}
.hero-links a::after { content: "\2197"; margin-left: 0.3rem; font-size: 0.85em; }
.hero-links a:hover { color: var(--cobalt-deep); text-decoration: underline; text-underline-offset: 3px; }

/* ---------- figures (incl. Fig. 1 vortex street) ---------- */
.fig { margin: 2.7rem 0 0; }
.fig img, .fig svg { display: block; width: 100%; height: auto; }
.fig figcaption {
  font-family: var(--mono);
  font-size: 0.72rem;
  line-height: 1.6;
  color: var(--ink-soft);
  border-top: 1px solid var(--hairline);
  margin-top: 0.55rem;
  padding-top: 0.6rem;
}
.fig .figno { color: var(--cobalt); font-weight: 600; }

.vortex path, .vortex circle { fill: none; stroke-linecap: round; stroke-linejoin: round; }
.vortex .cyl      { fill: var(--paper); stroke: var(--ink);    stroke-width: 1.7; }
.vortex .stream   { stroke: var(--ink-faint);  stroke-width: 1.2; opacity: 0.75; }
.vortex .wakeline { stroke: var(--ink-faint);  stroke-width: 1;   opacity: 0.4; stroke-dasharray: 2 5; }
.vortex .vortex-a { stroke: var(--red);    stroke-width: 1.4; opacity: 0.85; }
.vortex .vortex-b { stroke: var(--cobalt); stroke-width: 1.4; opacity: 0.85; }
.vortex .vortex-a, .vortex .vortex-b {
  stroke-dasharray: 460 14;
  animation: shed 11s linear infinite;
}
@keyframes shed { to { stroke-dashoffset: -474; } }

/* ---------- news ---------- */
.news { margin: 0; padding: 0; list-style: none; }
.news li {
  display: grid;
  grid-template-columns: 6.8rem 1fr;
  gap: 1.3rem;
  padding: 0.85rem 0;
  border-top: 1px solid var(--hairline);
}
.news time, .news .when {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-faint);
  padding-top: 0.3rem;
  white-space: nowrap;
}
.news p { margin: 0; font-size: 1rem; line-height: 1.62; }

.more-link {
  font-family: var(--mono);
  font-size: 0.74rem;
  letter-spacing: 0.08em;
  margin-top: 1.1rem;
}

/* ---------- research projects ---------- */
.project { padding: 2.1rem 0 0.4rem; margin-top: 2.1rem; border-top: 1px solid var(--hairline); }
.project:first-of-type { border-top: none; margin-top: 0.6rem; padding-top: 0.6rem; }
.project .meta {
  font-family: var(--mono);
  font-size: 0.73rem;
  color: var(--ink-soft);
  margin: 0.4rem 0 1rem;
  line-height: 1.8;
}
.project .meta b { color: var(--ink); font-weight: 600; }
.tag {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.66rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--cobalt);
  border: 1px solid var(--cobalt-tint);
  border-radius: 2px;
  padding: 0.1rem 0.45rem;
  vertical-align: 0.18em;
  margin-left: 0.55rem;
}

/* ---------- experience timeline ---------- */
.role {
  display: grid;
  grid-template-columns: 8.6rem 1fr;
  gap: 1.4rem;
  padding: 1.15rem 0;
  border-top: 1px solid var(--hairline);
}
.role .when {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-faint);
  padding-top: 0.35rem;
  line-height: 1.7;
}
.role h3 { font-size: 1.08rem; }
.role .where { font-style: italic; color: var(--ink-soft); font-size: 0.97rem; margin: 0.1rem 0 0.45rem; }
.role ul { margin: 0.45rem 0 0; padding-left: 1.15rem; }
.role li { font-size: 0.99rem; line-height: 1.6; margin: 0.3rem 0; }
.role p  { font-size: 0.99rem; line-height: 1.62; margin: 0.45rem 0 0; }

.tags { display: flex; flex-wrap: wrap; gap: 0.45rem; padding: 0; margin: 0.9rem 0 0; list-style: none; }
.tags .tag { margin-left: 0; color: var(--ink-soft); border-color: var(--hairline); }

/* ---------- publications ---------- */
.pub { padding: 1.1rem 0; border-top: 1px solid var(--hairline); }
.pub .pub-title { font-weight: 600; margin: 0; }
.pub .pub-detail { font-size: 0.98rem; color: var(--ink-soft); margin: 0.3rem 0 0; }

/* ---------- blog list ---------- */
.post-item { padding: 1.25rem 0; border-top: 1px solid var(--hairline); }
.post-item time {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-faint);
}
.post-item h2 { font-size: 1.28rem; margin: 0.35rem 0 0.3rem; }
.post-item h2 a { color: var(--ink); text-decoration: none; }
.post-item h2 a:hover { color: var(--cobalt); }
.post-item .excerpt { color: var(--ink-soft); font-size: 0.99rem; margin: 0; }
.empty-state { color: var(--ink-soft); font-style: italic; }

/* ---------- post body / long-form prose ---------- */
.post-body { margin-top: 1.6rem; }
.post-body p { margin: 1.05em 0; }
.post-body h2 { margin: 2.1em 0 0.6em; font-size: 1.34rem; }
.post-body h3 { margin: 1.8em 0 0.5em; }
.post-body blockquote {
  margin: 1.4em 0;
  padding: 0.1em 0 0.1em 1.1em;
  border-left: 2px solid var(--cobalt);
  color: var(--ink-soft);
  font-style: italic;
}
.post-body hr { border: 0; border-top: 1px solid var(--hairline); margin: 2.4em 0; }
.post-body img { max-width: 100%; height: auto; }
.post-body table { border-collapse: collapse; width: 100%; font-size: 0.95rem; margin: 1.4em 0; }
.post-body th, .post-body td { border: 1px solid var(--hairline); padding: 0.45rem 0.65rem; text-align: left; }
.post-body th { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-soft); }
mjx-container[display="true"] { overflow-x: auto; overflow-y: hidden; padding: 2px 0; }
.post-back { margin-top: 2.6rem; font-family: var(--mono); font-size: 0.78rem; }
.post-body sup { font-size: 0.68em; line-height: 0; color: var(--cobalt); }
.refs { font-size: 0.88rem; color: var(--ink-soft); padding-left: 1.25rem; }
.refs li { margin: 0.4rem 0; line-height: 1.55; }

/* ---------- code ---------- */
code, pre { font-family: var(--mono); }
code {
  font-size: 0.85em;
  background: var(--wash);
  border: 1px solid var(--hairline);
  border-radius: 3px;
  padding: 0.08em 0.35em;
}
pre {
  background: var(--wash);
  border: 1px solid var(--hairline);
  border-radius: 3px;
  padding: 1rem 1.15rem;
  overflow-x: auto;
  line-height: 1.55;
  font-size: 0.82rem;
  margin: 1.45em 0;
}
pre code { background: none; border: none; padding: 0; font-size: inherit; }

/* Rouge — restrained scholarly palette */
.highlight .c, .highlight .c1, .highlight .cm, .highlight .cp { color: #8a8f9b; font-style: italic; }
.highlight .k, .highlight .kd, .highlight .kn, .highlight .kr,
.highlight .kt, .highlight .kp, .highlight .ow { color: var(--cobalt-deep); font-weight: 600; }
.highlight .s, .highlight .s1, .highlight .s2, .highlight .sb, .highlight .sh { color: #3e6b45; }
.highlight .m, .highlight .mi, .highlight .mf, .highlight .mh { color: #8a5a1b; }
.highlight .nf, .highlight .nc, .highlight .nn { color: #44309a; }
.highlight .o { color: #374151; }
.highlight .nb { color: #0f5e66; }

/* ---------- buttons ---------- */
.btn {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.74rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink);
  background: transparent;
  border: 1.5px solid var(--ink);
  border-radius: 2px;
  padding: 0.6rem 1.1rem;
  text-decoration: none !important;
  transition: background 120ms ease, color 120ms ease;
}
.btn:hover { background: var(--ink); color: var(--paper); }

/* ---------- footer ---------- */
.site-footer { margin-top: 5rem; border-top: 1px solid var(--hairline); }
.footer-inner { padding-block: 1.7rem 2.6rem; }
.footer-links { display: flex; flex-wrap: wrap; gap: 0.4rem 1.2rem; margin: 0; }
.footer-links a {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-soft);
  text-decoration: none;
}
.footer-links a:hover { color: var(--cobalt); }
.colophon { font-family: var(--mono); font-size: 0.68rem; color: var(--ink-faint); margin: 0.8rem 0 0; }

/* ---------- responsive ---------- */
@media (max-width: 640px) {
  body { font-size: 1.02rem; }
  .page-head, .hero { padding-top: 2.4rem; }
  .hero-intro { flex-direction: column; gap: 1rem; margin-top: 1.2rem; }
  .portrait { width: 124px; }
  .news li, .role { grid-template-columns: 1fr; gap: 0.15rem; }
  .news time, .role .when { padding-top: 0; }
  .hero-links { gap: 0.5rem 1.1rem; }
}

/* ---------- motion & print ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}
@media print {
  .site-header, .site-footer, .skip-link { display: none; }
  body { font-size: 11pt; }
}

/* ---------- support / donation block ---------- */
.support {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--hairline);
}
.support-note {
  font-size: 0.95rem;
  color: var(--ink-soft);
  margin: 0 0 1rem;
  max-width: 58ch;
}
.support-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.7rem 0.9rem;
  margin: 0;
}
.support-btn {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--paper);
  background: var(--cobalt);
  border: 1.5px solid var(--cobalt);
  border-radius: 2px;
  padding: 0.5rem 1rem;
  text-decoration: none !important;
  transition: background 120ms ease, color 120ms ease;
}
.support-btn:hover { background: var(--cobalt-deep); border-color: var(--cobalt-deep); }
.support-btn.alt { color: var(--cobalt); background: transparent; }
.support-btn.alt:hover { color: var(--paper); background: var(--cobalt); }
.support-upi { font-size: 0.78rem; color: var(--ink-faint); }