/*
 * Zili — "ink and grid"
 *
 * The palette is lifted from the app's own icon: cinnabar seal ink pressed into
 * warm paper. The recurring structural device is the 田字格 (tián zì gé), the
 * cross-ruled square Chinese learners write characters into — used to frame the
 * seal and to mark each feature, never as loose decoration.
 */

/* Instrument Sans and Instrument Serif are self-hosted (SIL OFL 1.1; see the
   OFL-*.txt files beside the woff2s). latin-ext carries the pinyin tone marks. */

@font-face {
  font-family: "Instrument Sans";
  src: url("fonts/instrument-sans-latin.woff2") format("woff2");
  font-weight: 400 700;
  font-style: normal;
  font-display: swap;
  unicode-range:
    U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC,
    U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212,
    U+2215, U+FEFF, U+FFFD;
}

@font-face {
  font-family: "Instrument Sans";
  src: url("fonts/instrument-sans-latin-ext.woff2") format("woff2");
  font-weight: 400 700;
  font-style: normal;
  font-display: swap;
  unicode-range:
    U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304,
    U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB,
    U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
}

@font-face {
  font-family: "Instrument Serif";
  src: url("fonts/instrument-serif-latin.woff2") format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
  unicode-range:
    U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC,
    U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212,
    U+2215, U+FEFF, U+FFFD;
}

@font-face {
  font-family: "Instrument Serif";
  src: url("fonts/instrument-serif-latin-ext.woff2") format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
  unicode-range:
    U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304,
    U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB,
    U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
}

:root {
  color-scheme: light dark;

  /* Paper and ink. --paper is the AppIcon.icon fill, converted from display-p3. */
  --paper: light-dark(#eee3d0, #14100d);
  --paper-lift: light-dark(#f7f1e6, #1e1915);
  --paper-sink: light-dark(#e6d9c2, #0e0b09);
  --ink: light-dark(#1a1613, #f2e9dc);
  --ink-soft: light-dark(#6b6259, #a89c8c);
  --rule: light-dark(#d3c4a9, #322a22);

  /* The seal's own ink, and the app's brighter QuizSeal for lifts. */
  --cinnabar: light-dark(#c0201a, #e8564a);
  --cinnabar-lift: light-dark(#d8382e, #f0736a);

  --font-display: "Instrument Serif", "Iowan Old Style", Georgia, serif;
  --font-ui:
    "Instrument Sans", -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
  --font-han: "PingFang SC", "Hiragino Sans GB", "Noto Serif SC", serif;

  --measure: 34rem;
  --page-width: 70rem;
  --gutter: clamp(1.25rem, 5vw, 3.5rem);
  --section-gap: clamp(4.5rem, 11vw, 9rem);

  --stamp-ease: cubic-bezier(0.2, 1.2, 0.35, 1);
}

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

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-ui);
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

h1,
h2 {
  font-family: var(--font-display);
  font-weight: 400;
  line-height: 1.02;
  letter-spacing: -0.015em;
  text-wrap: balance;
  margin-block: 0 0.4em;
}

h1 {
  font-size: clamp(3rem, 8vw, 5.25rem);
}

h2 {
  font-size: clamp(2rem, 4.4vw, 3.1rem);
}

h3 {
  margin-block: 0 0.35em;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -0.005em;
}

p {
  margin-block: 0 1rem;
  max-width: var(--measure);
  text-wrap: pretty;
}

a {
  color: var(--cinnabar);
  text-underline-offset: 0.2em;
}

img {
  max-width: 100%;
  height: auto;
}

:where(a, button):focus-visible {
  outline: 2px solid var(--cinnabar);
  outline-offset: 3px;
  border-radius: 2px;
}

.skip-link {
  position: absolute;
  inset-inline-start: -100vw;
  top: 0;
  z-index: 10;
  padding: 0.75rem 1rem;
  background: var(--paper-lift);
}

.skip-link:focus {
  inset-inline-start: 0;
}

/* An eyebrow: small, wide-tracked, the page's utility voice. */
.eyebrow {
  margin: 0 0 0.75rem;
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

/* ---------- 田字格 ---------- */

/* The practice square: a hairline box quartered by dashed centre lines. It
   frames the seal in the hero and carries each feature's character. */
.tianzige {
  position: relative;
  display: grid;
  place-items: center;
  aspect-ratio: 1;
  border: 1px solid var(--rule);
}

.tianzige::before,
.tianzige::after {
  content: "";
  position: absolute;
  border-style: dashed;
  border-color: var(--rule);
  opacity: 0.85;
}

.tianzige::before {
  inset-inline: 0;
  top: 50%;
  border-width: 1px 0 0;
}

.tianzige::after {
  inset-block: 0;
  left: 50%;
  border-width: 0 0 0 1px;
}

/* ---------- Header ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 5;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: blur(14px) saturate(1.3);
  border-bottom: 1px solid var(--rule);
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.25rem;
  max-width: var(--page-width);
  margin-inline: auto;
  padding: 0.85rem var(--gutter);
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  margin-inline-end: auto;
  color: inherit;
  text-decoration: none;
}

.wordmark__seal {
  width: 1.6rem;
  height: 1.6rem;
}

.wordmark__latin {
  font-family: var(--font-display);
  font-size: 1.35rem;
  letter-spacing: 0.01em;
}

.nav-toggle {
  display: none;
  padding: 0.4rem 0.8rem;
  font: inherit;
  font-size: 0.875rem;
  color: inherit;
  background: none;
  border: 1px solid var(--rule);
  border-radius: 0.4rem;
}

.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1.4rem;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 0.9375rem;
}

.nav-links a {
  position: relative;
  color: var(--ink-soft);
  text-decoration: none;
  transition: color 0.18s ease;
}

/* A cinnabar tick under the section you're reading — the page's only nav state. */
.nav-links a::after {
  content: "";
  position: absolute;
  inset-inline: 0;
  bottom: -0.4rem;
  height: 2px;
  background: var(--cinnabar);
  transform: scaleX(0);
  transition: transform 0.22s var(--stamp-ease);
}

.nav-links a:hover,
.nav-links a[aria-current],
.nav-links a[data-in-view] {
  color: var(--ink);
}

.nav-links a[aria-current]::after,
.nav-links a[data-in-view]::after {
  transform: scaleX(1);
}

/* ---------- Buttons ---------- */

.app-store-badge {
  display: inline-block;
  padding: 0.8rem 1.4rem;
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--paper-lift);
  text-decoration: none;
  background: var(--cinnabar);
  border-radius: 0.45rem;
  transition:
    background 0.18s ease,
    transform 0.18s var(--stamp-ease);
}

.app-store-badge:hover {
  background: var(--cinnabar-lift);
  transform: translateY(-1px);
}

.app-store-badge--small {
  padding: 0.45rem 0.9rem;
  font-size: 0.875rem;
}

.link-button {
  display: inline-block;
  padding: 0.7rem 1.3rem;
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--ink);
  text-decoration: none;
  border: 1px solid var(--ink);
  border-radius: 0.45rem;
  transition:
    background 0.18s ease,
    color 0.18s ease;
}

.link-button:hover {
  color: var(--paper);
  background: var(--ink);
}

/* ---------- Hero ---------- */

.hero {
  display: grid;
  grid-template-columns: minmax(0, auto) minmax(0, 1fr);
  align-items: center;
  gap: clamp(2rem, 7vw, 5.5rem);
  max-width: var(--page-width);
  margin-inline: auto;
  padding: clamp(3.5rem, 9vw, 6.5rem) var(--gutter) var(--section-gap);
}

/* The thesis: the app's own chop, sitting in a practice square. */
.hero__seal-cell {
  width: clamp(11rem, 26vw, 17rem);
}

.hero__seal {
  width: 74%;
  height: auto;
}

.hero__title {
  margin-block-end: 0.5rem;
}

.hero__title .hero__hanzi {
  font-family: var(--font-han);
  font-size: 0.42em;
  letter-spacing: 0.08em;
  color: var(--ink-soft);
  vertical-align: 0.5em;
  margin-inline-start: 0.5rem;
}

.hero__tagline {
  max-width: 22ch;
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 3.4vw, 2.4rem);
  line-height: 1.15;
  letter-spacing: -0.01em;
  margin-block-end: 1.25rem;
}

.hero__subhead {
  color: var(--ink-soft);
  max-width: 40ch;
}

.hero__cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.25rem;
  margin-block: 2.25rem 0;
  max-width: none;
}

.hero__platforms {
  margin: 0;
  font-size: 0.875rem;
  color: var(--ink-soft);
}

/* The stamp: the chop presses into the paper once, on load. */
@media (prefers-reduced-motion: no-preference) {
  .hero__seal {
    animation: stamp 0.62s var(--stamp-ease) both;
  }

  .hero__seal-cell {
    animation: fade-in 0.5s ease both;
  }
}

@keyframes stamp {
  from {
    opacity: 0;
    transform: scale(1.32) rotate(-4deg);
  }

  60% {
    opacity: 1;
  }

  to {
    opacity: 1;
    transform: scale(1) rotate(0);
  }
}

@keyframes fade-in {
  from {
    opacity: 0;
  }

  to {
    opacity: 1;
  }
}

/* ---------- Intro ---------- */

.intro {
  max-width: var(--page-width);
  margin-inline: auto;
  padding: var(--section-gap) var(--gutter);
  border-block-start: 1px solid var(--rule);
}

.intro__body {
  max-width: 46rem;
}

.intro__body p {
  max-width: none;
  font-size: 1.1875rem;
}

.intro__body p + p {
  margin-block-start: 1.25rem;
}

/* ---------- Features ---------- */

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

/* Equal columns so a reversed row can swap sides without resizing either one. */
.feature {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  align-items: center;
  gap: clamp(2rem, 6vw, 4.5rem);
  padding-block: clamp(3.5rem, 7vw, 5.5rem);
  border-block-start: 1px solid var(--rule);
}

.feature--reversed .feature__copy {
  order: 2;
}

.feature__copy p {
  color: var(--ink-soft);
}

/* Each feature is marked by the character for what it does, in a practice
   square — the one place the page speaks Chinese without translating itself. */
.feature__mark {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin-block-end: 1.5rem;
}

.feature__glyph {
  width: 3.25rem;
  font-family: var(--font-han);
  font-size: 1.6rem;
  line-height: 1;
  color: var(--cinnabar);
}

.feature__label {
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

.feature__pinyin {
  display: block;
  margin-block-start: 0.2rem;
  font-size: 0.8125rem;
  font-weight: 400;
  letter-spacing: 0.02em;
  text-transform: none;
  color: var(--ink-soft);
  opacity: 0.75;
}

.shot {
  width: 100%;
  max-width: 15.5rem;
  height: auto;
  margin: 0;
  justify-self: center;
  border: 1px solid var(--rule);
  border-radius: 1.6rem;
  box-shadow:
    0 1px 2px color-mix(in srgb, var(--ink) 8%, transparent),
    0 18px 40px -18px color-mix(in srgb, var(--ink) 32%, transparent);
}

/* ---------- Details ---------- */

.details {
  max-width: var(--page-width);
  margin-inline: auto;
  padding: var(--section-gap) var(--gutter);
  border-block-start: 1px solid var(--rule);
}

.details__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15.5rem, 1fr));
  gap: 1px;
  margin: 2.75rem 0 0;
  padding: 0;
  list-style: none;
  background: var(--rule);
  border: 1px solid var(--rule);
}

.details__grid li {
  padding: 1.75rem;
  background: var(--paper);
}

.details__grid p {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--ink-soft);
}

/* ---------- Open source ---------- */

.open-source {
  max-width: var(--page-width);
  margin-inline: auto;
  padding: var(--section-gap) var(--gutter);
  border-block-start: 1px solid var(--rule);
}

/* ---------- Closing ---------- */

.closing-cta {
  margin-block-start: var(--section-gap);
  padding: var(--section-gap) var(--gutter);
  text-align: center;
  background: var(--paper-sink);
  border-block-start: 1px solid var(--rule);
}

.closing-cta__inner {
  max-width: 40rem;
  margin-inline: auto;
}

.closing-cta p {
  max-width: none;
}

.closing-cta__seal {
  width: 2.75rem;
  margin-block-end: 1.75rem;
  opacity: 0.9;
}

.closing-cta__requirements {
  margin-block-start: 1.25rem;
  font-size: 0.875rem;
  color: var(--ink-soft);
}

/* ---------- Prose ---------- */

.prose {
  max-width: 42rem;
  margin-inline: auto;
  padding: clamp(3rem, 8vw, 5rem) var(--gutter) var(--section-gap);
}

.prose h1 {
  font-size: clamp(2.25rem, 5.5vw, 3.25rem);
  margin-block-end: 1.5rem;
}

.prose h2 {
  margin-block-start: 3rem;
  font-size: clamp(1.4rem, 3vw, 1.85rem);
}

.prose h3 {
  margin-block-start: 2rem;
  font-size: 1.0625rem;
}

.prose p {
  max-width: none;
  color: var(--ink-soft);
}

.prose__effective {
  font-size: 0.9375rem;
}

/* ---------- Footer ---------- */

.site-footer {
  padding: 3rem var(--gutter) 4rem;
  background: var(--paper-sink);
  border-block-start: 1px solid var(--rule);
  color: var(--ink-soft);
  font-size: 0.875rem;
}

.site-footer__inner {
  max-width: var(--page-width);
  margin-inline: auto;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  margin: 0 0 1.75rem;
  padding: 0;
  list-style: none;
}

.footer-links a {
  color: var(--ink);
  text-decoration: none;
}

.footer-links a:hover {
  color: var(--cinnabar);
}

.footer-disclaimer,
.footer-copyright {
  max-width: 44rem;
}

.footer-copyright {
  margin-block-start: 1rem;
  margin-block-end: 0;
}

/* ---------- Narrow viewports ---------- */

@media (width < 56rem) {
  .feature {
    grid-template-columns: minmax(0, 1fr);
    justify-items: start;
  }

  .feature--reversed .feature__copy {
    order: 0;
  }

  .shot {
    justify-self: start;
  }
}

@media (width < 48rem) {
  .hero {
    grid-template-columns: minmax(0, 1fr);
    gap: 2.5rem;
  }

  .nav-toggle {
    display: block;
  }

  .nav-links {
    flex-basis: 100%;
    flex-direction: column;
    gap: 0.9rem;
  }

  .nav-links[hidden] {
    display: none;
  }

  .nav-links a::after {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}