/* Houyu Zhou — personal homepage */

:root {
  --bg: #ffffff;
  --text: #16181d;
  --muted: #5f6570;
  --rule: #e4e6ea;
  --accent: #a3271d;
  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
}

/* Dark colors: follow the system unless the toggle chose light, or when it chose dark */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #111317;
    --text: #e9eaec;
    --muted: #9aa0aa;
    --rule: #2a2d33;
    --accent: #f08a7e;
  }
}
:root[data-theme="dark"] {
  --bg: #111317;
  --text: #e9eaec;
  --muted: #9aa0aa;
  --rule: #2a2d33;
  --accent: #f08a7e;
}

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

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--serif);
  font-size: 1.06rem;
  line-height: 1.6;
  font-optical-sizing: auto;
}

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.15s;
}
a:hover { border-bottom-color: currentColor; }

.page {
  position: relative;
  max-width: 52rem;
  margin: 0 auto;
  padding: 4.5rem 1.5rem 3rem;
}

/* Light/dark toggle: the moon shows in light mode, the sun in dark mode */

.theme-toggle {
  position: absolute;
  top: 1.4rem;
  right: 1.5rem;
  display: grid;
  place-items: center;
  width: 2rem;
  height: 2rem;
  padding: 0;
  border: 1px solid var(--rule);
  border-radius: 50%;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}
.theme-toggle:hover { color: var(--accent); border-color: var(--accent); }

.theme-toggle svg {
  width: 1rem;
  height: 1rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.icon-sun { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .icon-sun { display: block; }
  :root:not([data-theme="light"]) .icon-moon { display: none; }
}
:root[data-theme="dark"] .icon-sun { display: block; }
:root[data-theme="dark"] .icon-moon { display: none; }

/* Header */

.masthead {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 2rem;
  align-items: end;
  padding-bottom: 2.2rem;
  border-bottom: 1px solid var(--rule);
}

.masthead h1 {
  margin: 0;
  font-size: 2.6rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.1;
}

.role {
  margin: 0.6rem 0 0;
  color: var(--muted);
  font-size: 1.1rem;
}

.links {
  margin: 1.1rem 0 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem 1.2rem;
  font-family: var(--sans);
  font-size: 0.86rem;
  letter-spacing: 0.01em;
}

.portrait {
  width: 9.5rem;
  height: 9.5rem;
  border-radius: 0.6rem;
  object-fit: cover;
  display: block;
}

/* Sections */

section { margin-top: 2.4rem; }

section + section {
  border-top: 1px solid var(--rule);
  padding-top: 2.4rem;
}

h2 {
  margin: 0 0 1.2rem;
  font-family: var(--sans);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
}

h3 {
  margin: 1.8rem 0 0.6rem;
  font-family: var(--sans);
  font-size: 0.86rem;
  font-weight: 600;
  color: var(--muted);
}

p { margin: 0 0 1rem; }

/* Entries: text on the left, date on the right, optional second line */

.entries,
.list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.entry { margin-bottom: 0.9rem; }
.compact .entry { margin-bottom: 0.45rem; }

.entry-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1.5rem;
}

.date {
  flex-shrink: 0;
  white-space: nowrap;
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.entry-sub {
  color: var(--muted);
  font-size: 0.97rem;
}

.list li { margin-bottom: 0.2rem; }

footer {
  margin-top: 4rem;
  padding-top: 1rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.8rem;
  color: var(--muted);
}

/* Narrow screens */

@media (max-width: 640px) {
  .page { padding: 2.5rem 1rem 2rem; }
  .theme-toggle { top: 1rem; right: 1rem; }
  .masthead { grid-template-columns: 1fr; gap: 1.2rem; }
  .portrait { order: -1; width: 7rem; height: 7rem; }
  .masthead h1 { font-size: 2.1rem; }
  .entry-head { flex-direction: column; gap: 0; }
}