/*
  Yi Fan (Eric) Wang, personal site.
  Color encodes category only (study, research, work, projects, activities);
  everything else is ink on paper.
*/

/* Local fallbacks scaled to the web fonts' widths, so text does not reflow when they load. */
@font-face {
  font-family: "Source Sans 3 Fallback";
  src: local("Arial"), local("ArialMT");
  font-weight: 400;
  size-adjust: 92.9%;
}

@font-face {
  font-family: "Source Sans 3 Fallback";
  src: local("Arial Bold"), local("Arial-BoldMT");
  font-weight: 600 700;
  size-adjust: 89.1%;
}

@font-face {
  font-family: "Source Serif 4 Fallback";
  src: local("Georgia Bold"), local("Georgia-Bold");
  font-weight: 600 700;
  size-adjust: 79.2%;
}

:root {
  color-scheme: light dark;

  --paper: #ffffff;
  --ink: #1e2430;
  --muted: #59616f;
  --rule: #d5dae1;
  --grid: #e8ebef;

  --c-study: #0072b2;
  --c-research: #009e73;
  --c-work: #d55e00;
  --c-projects: #cc79a7;
  --c-activities: #737b89;

  --serif: "Source Serif 4", "Source Serif 4 Fallback", Georgia, "Times New Roman", serif;
  --sans: "Source Sans 3", "Source Sans 3 Fallback", system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;

  --s-1: 0.25rem;
  --s-2: 0.5rem;
  --s-3: 0.75rem;
  --s-4: 1rem;
  --s-5: 1.5rem;
  --s-6: 2rem;
  --s-7: 3rem;
  --s-8: 4rem;
  --s-9: 6rem;

  --page: 72rem;
  --gutter: 1rem;
  --rail: 13rem; /* metadata rail, also the chart's label column */
  --gap: 2rem;
  --measure: 36rem; /* about 70 characters of body text */
  --header-h: 3.5rem;

  /* Chart axis: months since Sep 2022. --span ends with Jun 2027; --asof is Oct 29, 2026
     and must change together with the "Oct 2026" labels in index.html. */
  --span: 58;
  --asof: 49.9;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #161a21;
    --ink: #e6e9ef;
    --muted: #a3abb8;
    --rule: #2e3541;
    --grid: #232933;
    --c-study: #56b4e9;
    --c-activities: #6e7686;
  }
}

@media (min-width: 48rem) {
  :root {
    --gutter: 2rem;
  }
}

@media (max-width: 39.99rem) {
  :root {
    --rail: 7rem;
    --gap: 1rem;
  }
}

.cat-study { --cat: var(--c-study); }
.cat-research { --cat: var(--c-research); }
.cat-work { --cat: var(--c-work); }
.cat-projects { --cat: var(--c-projects); }
.cat-activities { --cat: var(--c-activities); }

/* Base */

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1.125rem;
  line-height: 1.6;
  font-kerning: normal;
}

h1,
h2,
h3,
p,
ul,
dl,
dd,
figure {
  margin: 0;
}

h1,
h2,
h3 {
  text-wrap: balance;
}

p,
li,
dd {
  text-wrap: pretty;
}

ul {
  padding: 0;
}

[role="list"] {
  list-style: none;
}

a {
  color: inherit;
  text-decoration-line: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
  text-decoration-color: color-mix(in srgb, currentColor 45%, transparent);
}

a:hover {
  text-decoration-color: currentColor;
  text-decoration-thickness: 2px;
}

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

main:focus {
  outline: none;
}

abbr[title] {
  text-decoration: underline dotted;
  text-underline-offset: 0.2em;
  cursor: help;
}

time {
  white-space: nowrap;
}

sub {
  position: relative;
  bottom: -0.25em;
  font-size: 0.7em;
  line-height: 0;
  vertical-align: baseline;
}

.nowrap {
  white-space: nowrap;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: var(--s-2);
  left: var(--gutter);
  z-index: 100;
  padding: var(--s-2) var(--s-4);
  background: var(--ink);
  color: var(--paper);
  font-weight: 600;
  text-decoration: none;
  translate: 0 -200%;
}

.skip-link:focus {
  translate: none;
}

.wrap {
  max-width: var(--page);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

/* Header */

.site-header {
  background: var(--paper);
  border-bottom: 1px solid var(--rule);
}

.header-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  column-gap: var(--s-6);
  min-height: var(--header-h);
  padding-block: var(--s-2);
}

.site-name {
  font-family: var(--serif);
  font-size: 1.125rem;
  font-weight: 600;
  text-decoration: none;
}

.nav-list {
  display: flex;
  flex-wrap: wrap;
  column-gap: var(--s-5);
}

.nav-list a {
  display: inline-block;
  padding-block: var(--s-1);
  color: var(--muted);
  font-size: 1rem;
  text-decoration: none;
}

.nav-list a:hover {
  color: var(--ink);
  text-decoration: underline;
}

.nav-list li:last-child a {
  color: var(--ink);
  font-weight: 600;
}

/* 56rem: the header measures about 54rem on one line, so it only sticks when it cannot wrap. */
@media (min-width: 56rem) and (min-height: 36rem) {
  html {
    scroll-padding-top: calc(var(--header-h) + var(--s-4));
  }

  .site-header {
    position: sticky;
    top: 0;
    z-index: 10;
  }
}

/* Hero */

.hero {
  display: grid;
  grid-template-columns: var(--rail) minmax(0, 1fr);
  column-gap: var(--gap);
  align-items: center;
  padding-top: var(--s-7);
}

/* The portrait sits in the rail column, directly above the chart's labels, cropped as a circle. */
.portrait {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 1;
  object-fit: cover;
  border-radius: 50%;
  background: var(--grid);
}

.hero h1 {
  font-family: var(--serif);
  font-size: clamp(2.5rem, 1.5rem + 4.5vw, 4.5rem);
  font-weight: 600;
  line-height: 1.05;
  letter-spacing: -0.02em;
}

.lede {
  max-width: 36rem;
  margin-top: var(--s-4);
  font-size: clamp(1.125rem, 1rem + 0.5vw, 1.3125rem);
  line-height: 1.5;
}

.hero-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0 var(--s-5);
  margin-top: var(--s-4);
}

.hero-links a {
  display: inline-block;
  padding-block: var(--s-1);
  font-weight: 600;
}

/* Timeline chart */

.timeline {
  margin-top: var(--s-6);
}

.tl-plot {
  position: relative;
  padding-block: 1.5rem 1.75rem;
}

.tl-rows {
  position: relative;
  z-index: 1;
}

.tl-rows a {
  display: grid;
  grid-template-columns: var(--rail) minmax(0, 1fr);
  column-gap: var(--gap);
  align-items: center;
  min-height: 1.75rem;
  padding-block: 0.125rem;
  text-decoration: none;
}

.tl-label {
  font-size: 0.9375rem;
  line-height: 1.3;
  text-wrap: balance;
  text-decoration-line: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
  text-decoration-color: color-mix(in srgb, currentColor 30%, transparent);
}

.tl-rows a:hover .tl-label,
.tl-rows a:focus-visible .tl-label {
  text-decoration-color: currentColor;
}

.tl-track {
  position: relative;
  align-self: stretch;
}

/* A faint guide per row, as in a dot plot, so the eye can travel from label to mark. */
.tl-track::before {
  content: "";
  position: absolute;
  top: 50%;
  right: 0;
  left: 0;
  border-top: 1px solid var(--grid);
}

.tl-bar,
.tl-dot {
  position: absolute;
  top: 50%;
  background: var(--cat);
  print-color-adjust: exact;
}

.tl-bar {
  left: calc(var(--start) / var(--span) * 100%);
  width: calc((var(--end) - var(--start)) / var(--span) * 100%);
  height: 0.625rem;
  border-radius: 2px;
  translate: 0 -50%;
}

.tl-bar.is-expected {
  background: none;
  border: 1.5px dashed var(--cat);
}

/* Ongoing bars end exactly at the "as of" line; a minimum width grows leftward. */
.tl-bar.is-ongoing {
  right: calc((var(--span) - var(--asof)) / var(--span) * 100%);
  left: auto;
  width: max(0.375rem, calc((var(--asof) - var(--start)) / var(--span) * 100%));
}

.tl-dot {
  left: calc(var(--at) / var(--span) * 100%);
  width: 0.75rem;
  height: 0.75rem;
  border-radius: 50%;
  translate: -50% -50%;
}

.tl-axis {
  position: absolute;
  inset: 0 0 0 calc(var(--rail) + var(--gap));
  z-index: 0;
  pointer-events: none;
}

.tl-year,
.tl-asof {
  position: absolute;
  bottom: 1.75rem;
  border-left: 1px solid var(--grid);
}

.tl-year {
  top: 1.5rem;
  left: calc(var(--at) / var(--span) * 100%);
}

.tl-asof {
  top: 1.25rem;
  left: calc(var(--asof) / var(--span) * 100%);
  border-left-color: var(--muted);
}

.tl-year > span,
.tl-asof > span {
  position: absolute;
  color: var(--muted);
  font-size: 0.875rem;
  font-variant-numeric: tabular-nums;
  line-height: 1.25rem;
  white-space: nowrap;
  translate: -50% 0;
}

.tl-year > span {
  bottom: -1.5rem;
}

.tl-asof > span {
  top: -1.25rem;
}

figcaption {
  max-width: var(--measure);
  margin-top: var(--s-3);
  color: var(--muted);
  font-size: 0.9375rem;
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0 var(--s-5);
  margin-bottom: var(--s-1);
  color: var(--ink);
}

.legend li::before,
.section:is(.cat-study, .cat-research, .cat-work, .cat-projects, .cat-activities) .section-title::before {
  content: "";
  display: inline-block;
  width: 1rem;
  height: 0.5rem;
  margin-right: 0.5rem;
  border-radius: 2px;
  background: var(--cat);
  vertical-align: 0.1em;
  print-color-adjust: exact;
}

@media (min-width: 48rem) {
  .section-title::before {
    margin-left: -1.5rem;
  }
}

@media (hover: hover) and (pointer: fine) {
  .tl-rows:has(a:hover) a:not(:hover) .tl-track {
    opacity: 0.35;
  }
}

.tl-rows:has(a:focus-visible) a:not(:focus-visible) .tl-track {
  opacity: 0.35;
}

/* Sections and entries */

.section {
  margin-top: var(--s-9);
}

.section-title {
  font-family: var(--serif);
  font-size: clamp(1.625rem, 1.3rem + 1vw, 2rem);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

/* About prose sits in the content column, beside the rail, like entry bodies. */
.about {
  max-width: var(--measure);
  margin-top: var(--s-5);
  margin-left: calc(var(--rail) + var(--gap));
}

.entry {
  position: relative;
  display: grid;
  grid-template-columns: var(--rail) minmax(0, 1fr);
  grid-template-areas:
    "meta head"
    "meta body";
  column-gap: var(--gap);
  margin-top: var(--s-6);
}

/* Marks the entry reached from the chart; it sits in the gutter, so nothing shifts. */
.entry::before {
  content: "";
  position: absolute;
  top: 0.25rem;
  bottom: 0.25rem;
  left: calc(-1 * var(--s-3));
  width: 3px;
  border-radius: 2px;
}

.entry:target::before {
  background: var(--cat, var(--ink));
}

.entry-head {
  grid-area: head;
  max-width: var(--measure);
}

.entry-head h3 {
  font-size: 1.1875rem;
  font-weight: 600;
  line-height: 1.35;
}

.entry-org {
  color: var(--muted);
}

.entry-meta {
  grid-area: meta;
  padding-top: 0.125rem;
  color: var(--muted);
  font-size: 1rem;
  font-variant-numeric: tabular-nums;
  line-height: 1.5;
}

.rail-link {
  display: inline-block;
  padding-block: 0.125rem;
  color: var(--ink);
}

.entry-body {
  grid-area: body;
  max-width: var(--measure);
}

.points {
  margin-top: var(--s-3);
  padding-left: 1.15em;
}

.points li + li {
  margin-top: var(--s-2);
}

.points li::marker {
  color: var(--muted);
}

.entry-body > p:first-child {
  margin-top: var(--s-3);
}

.courses {
  margin-top: var(--s-3);
}

.courses strong {
  font-weight: 600;
}

.pairs {
  margin-top: var(--s-5);
}

.pairs > div {
  display: grid;
  grid-template-columns: var(--rail) minmax(0, 1fr);
  column-gap: var(--gap);
  padding-block: var(--s-2);
}

.pairs dt {
  padding-top: 0.0625rem;
  color: var(--muted);
  font-size: 1rem;
}

.pairs dd {
  grid-column: 2;
  max-width: var(--measure);
}

.pairs dd + dd {
  margin-top: var(--s-1);
}

.contact-lede {
  margin-top: var(--s-4);
}

/* Footer */

.site-footer {
  margin-top: var(--s-9);
  border-top: 1px solid var(--rule);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--s-2) var(--s-5);
  padding-block: var(--s-6);
  color: var(--muted);
  font-size: 0.9375rem;
}

/* Small screens */

@media (max-width: 39.99rem) {
  .hero {
    grid-template-columns: minmax(0, 1fr);
    row-gap: var(--s-5);
    padding-top: var(--s-6);
  }

  .portrait {
    width: 7rem;
  }

  .tl-label {
    font-size: 0.875rem;
  }

  .section {
    margin-top: var(--s-8);
  }

  .about {
    margin-left: 0;
  }

  .entry {
    grid-template-columns: minmax(0, 1fr);
    grid-template-areas:
      "head"
      "meta"
      "body";
  }

  .entry-meta {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    column-gap: var(--s-4);
    margin-top: var(--s-1);
  }

  .pairs > div {
    grid-template-columns: minmax(0, 1fr);
  }

  .pairs dd {
    grid-column: 1;
  }
}

/* Touch screens get 44px targets. */

@media (pointer: coarse) {
  .tl-rows a {
    min-height: 2.75rem;
  }

  .nav-list a,
  .hero-links a,
  .rail-link,
  .footer-inner a {
    display: inline-flex;
    align-items: center;
    min-block-size: 2.75rem;
  }
}

@media (prefers-reduced-motion: no-preference) {
  html {
    scroll-behavior: smooth;
  }

  .tl-track {
    transition: opacity 0.15s ease;
  }
}

@media (forced-colors: active) {
  .tl-bar,
  .tl-dot,
  .legend li::before,
  .section-title::before,
  .entry:target::before {
    forced-color-adjust: none;
    background: CanvasText;
  }

  .tl-bar.is-expected {
    background: none;
    border-color: CanvasText;
  }
}