/* Hannes Gao – personal page. Material 3 inspired, no external resources. */

:root {
  --primary: #006a60;
  --on-primary: #ffffff;
  --primary-container: #9ef2e4;
  --on-primary-container: #00201c;
  --secondary-container: #cce8e2;
  --on-secondary-container: #05201c;
  --surface: #f4fbf8;
  --surface-lowest: #ffffff;
  --surface-low: #eff5f2;
  --surface-container: #e9efec;
  --on-surface: #171d1b;
  --on-surface-variant: #3f4946;
  --outline: #6f7976;
  --outline-variant: #bec9c5;
  --sponsor: #bf3989;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --primary: #82d5c8;
    --on-primary: #003731;
    --primary-container: #005048;
    --on-primary-container: #9ef2e4;
    --secondary-container: #334b47;
    --on-secondary-container: #cce8e2;
    --surface: #0e1513;
    --surface-lowest: #090f0e;
    --surface-low: #171d1b;
    --surface-container: #1b2120;
    --on-surface: #dde4e1;
    --on-surface-variant: #bec9c5;
    --outline: #899390;
    --outline-variant: #3f4946;
    --sponsor: #db61a2;
  }
}

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

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

body {
  margin: 0;
  background: var(--surface);
  color: var(--on-surface);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
}

a {
  color: var(--primary);
  text-underline-offset: 0.15em;
}

a:focus-visible {
  outline: 3px solid var(--primary);
  outline-offset: 2px;
}

.page {
  max-width: 52rem;
  margin: 0 auto;
  padding: 40px 16px 24px;
}

/* ---------- Language switch (no JavaScript) ---------- */
.lang-radio {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

body:has(#lang-de:checked) .page [lang="en"]:not(.lang-switch *),
body:has(#lang-en:checked) .page [lang="de"]:not(.lang-switch *, .card--legal, .card--legal *) {
  display: none;
}

.lang-switch {
  display: inline-flex;
  padding: 4px;
  border: 1px solid var(--outline-variant);
  border-radius: 999px;
  background: var(--surface-lowest);
}

.lang-switch label {
  padding: 6px 14px;
  border-radius: 999px;
  color: var(--on-surface-variant);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
}

body:has(#lang-de:checked) label[for="lang-de"],
body:has(#lang-en:checked) label[for="lang-en"] {
  background: var(--secondary-container);
  color: var(--on-secondary-container);
}

body:has(.lang-radio:focus-visible) .lang-switch {
  outline: 3px solid var(--primary);
  outline-offset: 2px;
}

/* ---------- Hero ---------- */
.hero {
  margin-bottom: 24px;
  padding: 28px;
  border-radius: 28px;
  background: var(--surface-container);
}

.hero__top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.avatar {
  display: grid;
  place-items: center;
  width: 64px;
  height: 64px;
  border-radius: 20px;
  background: var(--primary-container);
  color: var(--on-primary-container);
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.hero__name {
  margin: 20px 0 0;
  font-size: clamp(2rem, 6vw, 2.75rem);
  font-weight: 500;
  line-height: 1.15;
  letter-spacing: -0.01em;
}

.hero__role {
  margin: 6px 0 0;
  color: var(--on-surface-variant);
  font-size: 1.0625rem;
}

.hero__links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 20px;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 40px;
  padding: 0 18px 0 14px;
  border: 0;
  border-radius: 999px;
  font-size: 0.875rem;
  font-weight: 500;
  white-space: nowrap;
  text-decoration: none;
}

.btn:hover {
  filter: brightness(1.06);
}

.btn--sm {
  height: 36px;
  padding: 0 14px 0 12px;
  font-size: 0.8125rem;
}

/* Icon-only buttons (GitHub, LinkedIn, X) */
.btn--icon {
  width: 40px;
  padding: 0;
  gap: 0;
}

.btn--icon .icon {
  width: 20px;
  height: 20px;
}

/* The three icon buttons always wrap together. */
.hero__social {
  display: inline-flex;
  gap: 8px;
}

.hero__sponsor {
  margin-left: auto;
}

.btn--filled {
  background: var(--primary);
  color: var(--on-primary);
}

.btn--tonal {
  background: var(--secondary-container);
  color: var(--on-secondary-container);
}

.btn--outlined {
  border: 1px solid var(--outline);
  background: transparent;
  color: var(--primary);
}

.btn--sponsor {
  border: 1px solid var(--outline-variant);
  background: var(--surface-lowest);
  color: var(--on-surface);
}

.btn--sponsor .icon {
  color: var(--sponsor);
}

.icon {
  flex: none;
  width: 18px;
  height: 18px;
  fill: currentColor;
}

/* ---------- Cards ---------- */
main {
  display: grid;
  gap: 16px;
}

.card {
  min-width: 0;
  padding: 22px 24px 24px;
  border: 1px solid var(--outline-variant);
  border-radius: 20px;
  background: var(--surface-lowest);
  overflow-wrap: anywhere;
}

.card__title {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0 0 14px;
  font-size: 1.125rem;
  font-weight: 500;
  line-height: 1.5rem;
}

.card__title .icon {
  width: 36px;
  height: 36px;
  padding: 8px;
  border-radius: 12px;
  background: var(--primary-container);
  color: var(--on-primary-container);
}

.card p {
  margin: 0 0 12px;
}

.card p:last-child {
  margin-bottom: 0;
}

.card h3 {
  margin: 18px 0 6px;
  font-size: 0.9375rem;
  font-weight: 600;
}

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 16px 0 0;
  padding: 0;
  list-style: none;
}

.chips li {
  padding: 4px 12px;
  border: 1px solid var(--outline-variant);
  border-radius: 8px;
  color: var(--on-surface-variant);
  font-size: 0.8125rem;
  font-weight: 500;
}

/* ---------- Projects ---------- */
.projects {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 18rem), 1fr));
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.project {
  display: flex;
  flex-direction: column;
  min-width: 0;
  padding: 16px 18px 18px;
  border-radius: 16px;
  background: var(--surface-low);
}

.project--featured {
  grid-column: 1 / -1;
  background: var(--secondary-container);
  color: var(--on-secondary-container);
}

.project__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 4px 12px;
}

.project h3 {
  margin: 0 0 6px;
  font-size: 1rem;
  font-weight: 600;
}

.project p {
  margin: 0 0 14px;
  font-size: 0.9375rem;
}

.project__links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: auto;
}

.tag {
  color: var(--on-surface-variant);
  font-size: 0.75rem;
  font-weight: 500;
}

.project--featured .tag {
  color: inherit;
  opacity: 0.8;
}

/* ---------- Legal ---------- */
.legal-note {
  margin: 8px 4px 0;
  color: var(--on-surface-variant);
  font-size: 0.875rem;
}

.card--legal {
  font-size: 0.9375rem;
}

.card--legal .meta + h3,
.legal-grid h3 {
  margin-top: 0;
}

.legal-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 14rem), 1fr));
  gap: 14px 24px;
}

.meta {
  color: var(--on-surface-variant);
  font-size: 0.875rem;
}

/* Collapsible legal sections: closed until the heading is clicked. The flex row sits inside
   <summary> (a block), so the expand button stays at the right edge in every browser. */
details.card--legal > summary {
  display: block;
  list-style: none;
  cursor: pointer;
  border-radius: 12px;
}

details.card--legal > summary::-webkit-details-marker {
  display: none;
}

details.card--legal > summary .card__title {
  margin: 0;
}

details.card--legal > summary:focus-visible {
  outline: 3px solid var(--primary);
  outline-offset: 4px;
}

.card__summary-text {
  flex: 1;
  min-width: 0;
  overflow-wrap: normal;
}

/* Round expand button, flush with the card's right content edge. */
.chevron {
  display: grid;
  flex: none;
  place-items: center;
  width: 36px;
  height: 36px;
  margin-left: auto;
  border-radius: 999px;
  background: var(--surface-container);
  color: var(--on-surface-variant);
}

.card__title .chevron .icon {
  width: 24px;
  height: 24px;
  padding: 0;
  border-radius: 0;
  background: none;
  color: inherit;
  transition: transform 150ms ease;
}

details.card--legal > summary:hover .chevron {
  background: var(--secondary-container);
  color: var(--on-secondary-container);
}

details[open] > summary .chevron .icon {
  transform: rotate(180deg);
}

details.card--legal > .card__body {
  margin-top: 16px;
}

/* ---------- Footer ---------- */
.footer {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 16px;
  margin-top: 24px;
  padding: 16px 4px 0;
  border-top: 1px solid var(--outline-variant);
  color: var(--on-surface-variant);
  font-size: 0.8125rem;
}

.footer nav {
  display: flex;
  gap: 16px;
}

@media (max-width: 479px) {
  .page {
    padding-top: 16px;
  }

  .hero {
    padding: 20px;
  }

  .card {
    padding: 18px 16px 20px;
  }
}

/* Icon sprite: symbols only, never rendered itself. */
.sprite {
  position: absolute;
  width: 0;
  height: 0;
  overflow: hidden;
}