/* Self-hosted Latin fonts; Chinese uses the system CJK font. */
@font-face {
  font-family: 'Space Grotesk';
  font-weight: 500;
  font-display: swap;
  src: url(/fonts/space-grotesk-latin-500-normal.woff2) format('woff2');
}
@font-face {
  font-family: 'Space Grotesk';
  font-weight: 700;
  font-display: swap;
  src: url(/fonts/space-grotesk-latin-700-normal.woff2) format('woff2');
}
@font-face {
  font-family: 'IBM Plex Sans';
  font-weight: 400;
  font-display: swap;
  src: url(/fonts/ibm-plex-sans-latin-400-normal.woff2) format('woff2');
}
@font-face {
  font-family: 'IBM Plex Sans';
  font-weight: 500;
  font-display: swap;
  src: url(/fonts/ibm-plex-sans-latin-500-normal.woff2) format('woff2');
}
@font-face {
  font-family: 'IBM Plex Sans';
  font-weight: 600;
  font-display: swap;
  src: url(/fonts/ibm-plex-sans-latin-600-normal.woff2) format('woff2');
}
@font-face {
  font-family: 'IBM Plex Mono';
  font-weight: 500;
  font-display: swap;
  src: url(/fonts/ibm-plex-mono-latin-500-normal.woff2) format('woff2');
}

:root {
  --paper: #f5f2ea;
  --surface: #ffffff;
  --surface-2: #fbf9f4;
  --line: #e4ded0;
  --chip: #e9e4d8;
  --ink: #152238;
  --ink-2: #5c5a52;
  --ink-3: #6b675d;
  --navy: #1b2a4a;
  --on-navy: #f5f2ea;
  --on-navy-2: #c9cfdb;
  --accent: #c4501a;
  --accent-ink: #c4501a;
  --accent-soft: #fbe9df;
  --accent-on-navy: #f08a55;
  --icon-soft: #e7ebf3;
  --ok: #2f7a4b;
  --ok-soft: #eef7f1;
  --font-display: 'Space Grotesk', 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
  --font-body:
    'IBM Plex Sans', system-ui, -apple-system, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei',
    'Noto Sans SC', sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, Menlo, Consolas, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #111827;
    --surface: #182236;
    --surface-2: #1c273d;
    --line: #2a3650;
    --chip: #222d44;
    --ink: #eef0f4;
    --ink-2: #b7bdcc;
    --ink-3: #9ba2b5;
    --navy: #22335c;
    --accent-ink: #f08a55;
    --accent-soft: #3a2519;
    --icon-soft: #24304a;
    --ok: #6cc78e;
    --ok-soft: #1c3528;
    color-scheme: dark;
  }
}

* {
  box-sizing: border-box;
}
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 16px/1.7 var(--font-body);
}
a {
  color: var(--accent-ink);
}
:focus-visible {
  outline: 2px solid var(--accent-ink);
  outline-offset: 2px;
}
.wrap {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}
.doc .wrap,
.center .wrap {
  max-width: 820px;
}

/* ---------------------------------------------------------------- header, footer */

header.site {
  border-bottom: 1px solid var(--line);
}
header.site .wrap {
  display: flex;
  align-items: center;
  gap: 16px;
  min-height: 72px;
  flex-wrap: wrap;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--ink);
  text-decoration: none;
}
.brand b {
  color: var(--accent-ink);
}
.brand img {
  width: 32px;
  height: 32px;
}
nav {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 24px;
  font-size: 15px;
}
nav a {
  color: var(--ink);
  text-decoration: none;
}
nav a:hover {
  color: var(--accent-ink);
}
footer.site {
  border-top: 1px solid var(--line);
  padding: 28px 0 36px;
  font-size: 14px;
  color: var(--ink-2);
}
footer.site .wrap {
  display: flex;
  align-items: center;
  gap: 24px;
  flex-wrap: wrap;
}
footer.site a {
  color: var(--ink-2);
}
footer.site .wrap > :first-child {
  margin-right: auto;
}

/* ---------------------------------------------------------------- type */

main {
  padding: 48px 0 72px;
}
h1 {
  font-family: var(--font-display);
  font-size: 34px;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin: 0 0 12px;
}
h2 {
  font-family: var(--font-display);
  font-size: 24px;
  letter-spacing: -0.01em;
  margin: 40px 0 12px;
}
h3 {
  font-size: 18px;
  font-weight: 600;
  margin: 24px 0 6px;
}
.lead {
  font-size: 19px;
  color: var(--ink-2);
  max-width: 640px;
}
.muted {
  color: var(--ink-2);
  font-size: 15px;
}
.eyebrow {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--accent-ink);
  background: var(--accent-soft);
  padding: 5px 12px;
  border-radius: 999px;
}
.mono {
  font-family: var(--font-mono);
}

/* ---------------------------------------------------------------- buttons */

.cta {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-height: 52px;
  padding: 0 24px;
  border-radius: 14px;
  background: var(--navy);
  color: var(--on-navy);
  text-decoration: none;
  font-weight: 600;
}
.cta.disabled {
  cursor: default;
  opacity: 0.92;
}
.cta.ghost {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--ink-3);
}
.cta-small {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 14px;
  border-radius: 10px;
  background: var(--chip);
  color: var(--ink-2);
  font-size: 14px;
  font-weight: 600;
}

/* ---------------------------------------------------------------- landing */

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
  gap: 56px;
  align-items: center;
  padding: 24px 0 72px;
}
.hero h1 {
  font-size: clamp(40px, 5vw, 62px);
  line-height: 1.08;
  letter-spacing: -0.03em;
  margin: 22px 0 20px;
}
.hero h1 em {
  font-style: normal;
  color: var(--accent-ink);
}
.hero .lead {
  margin: 0 0 28px;
}
.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}
.perks {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
  margin: 20px 0 0;
  padding: 0;
  list-style: none;
  font-size: 14px;
  color: var(--ink-2);
}

/* The browser mock: a practice question with QuizPilot's suggestion and panel. */
.mock {
  position: relative;
  padding-bottom: 80px;
}
.mock-window {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 18px;
  box-shadow: 0 30px 60px -30px rgba(27, 42, 74, 0.35);
  overflow: hidden;
}
.mock-bar {
  height: 38px;
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 0 14px;
  background: var(--chip);
}
.mock-bar i {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--line);
}
.mock-bar span {
  margin-left: 12px;
  flex: 1;
  height: 22px;
  border-radius: 6px;
  background: var(--surface);
  font: 11px/22px var(--font-mono);
  color: var(--ink-3);
  padding: 0 10px;
  overflow: hidden;
  white-space: nowrap;
}
.mock-body {
  padding: 24px 28px 28px;
  display: grid;
  gap: 10px;
}
.mock-q {
  font-weight: 600;
  font-size: 17px;
  margin-bottom: 4px;
}
.opt {
  display: flex;
  align-items: center;
  gap: 12px;
  min-height: 44px;
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: 10px;
  font-size: 15px;
}
.opt::before {
  content: '';
  width: 16px;
  height: 16px;
  border-radius: 50%;
  border: 2px solid var(--line);
}
.opt.pick {
  border: 2px solid var(--ok);
  background: var(--ok-soft);
  font-weight: 600;
  padding: 0 13px;
}
.opt.pick::before {
  border: 5px solid var(--ok);
}
.opt small {
  margin-left: auto;
  color: var(--ok);
  font: 500 12px var(--font-mono);
}
.float {
  position: absolute;
  right: -12px;
  bottom: 0;
  width: 290px;
  background: #1b2a4a;
  color: var(--on-navy);
  border-radius: 16px;
  box-shadow: 0 24px 48px -16px rgba(21, 34, 56, 0.5);
  padding: 16px;
  display: grid;
  gap: 12px;
  font-size: 13px;
}
.float-head {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
}
.float-head span {
  margin-left: auto;
  font-weight: 400;
  color: var(--on-navy-2);
  font-size: 12px;
}
.bar {
  height: 4px;
  border-radius: 999px;
  background: rgba(245, 242, 234, 0.15);
}
.bar::after {
  content: '';
  display: block;
  width: 15%;
  height: 4px;
  border-radius: 999px;
  background: var(--accent-on-navy);
}
.float-answer {
  background: rgba(245, 242, 234, 0.08);
  border-radius: 10px;
  padding: 10px 12px;
}
.float-answer div {
  display: flex;
  justify-content: space-between;
}
.float-answer b {
  color: #9ed4b0;
  font: 500 13px var(--font-mono);
}
.float-answer p {
  margin: 2px 0 0;
  font-size: 11.5px;
  color: var(--on-navy-2);
}
.float-stop {
  display: block;
  text-align: center;
  padding: 9px;
  border-radius: 10px;
  background: var(--on-navy);
  color: #152238;
  font-weight: 600;
}

.section-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 24px;
  flex-wrap: wrap;
  margin: 0 0 32px;
}
.section-head h2 {
  font-size: clamp(30px, 3.4vw, 40px);
  margin: 0;
}
.section-head p {
  margin: 0;
  max-width: 440px;
  color: var(--ink-2);
}
section.block {
  padding: 56px 0;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
}
.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 24px;
}
.card h3 {
  margin: 14px 0 8px;
}
.card p {
  margin: 0;
}
.icon {
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border-radius: 12px;
  background: var(--icon-soft);
  color: var(--ink);
}
.icon.accent {
  background: var(--accent-soft);
  color: var(--accent-ink);
}

.steps {
  background: #1b2a4a;
  color: var(--on-navy);
  border-radius: 28px;
  padding: 56px;
  display: grid;
  grid-template-columns: minmax(0, 0.8fr) minmax(0, 2fr);
  gap: 56px;
}
.steps h2 {
  margin: 0 0 12px;
  font-size: clamp(30px, 3.4vw, 40px);
}
.steps p {
  color: var(--on-navy-2);
  margin: 0;
}
.steps ol {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
}
.steps li {
  border-top: 2px solid rgba(245, 242, 234, 0.3);
  padding-top: 18px;
  display: grid;
  gap: 8px;
  align-content: start;
}
.steps li:first-child {
  border-color: var(--accent-on-navy);
}
.steps li span {
  font: 500 14px var(--font-mono);
  color: var(--accent-on-navy);
}
.steps li strong {
  font-size: 18px;
}
.steps li p {
  font-size: 14px;
}
.steps kbd {
  font: 500 12px var(--font-mono);
  padding: 1px 6px;
  border: 1px solid rgba(245, 242, 234, 0.3);
  border-radius: 6px;
}

.plans {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}
.plan {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 30px;
}
.plan.featured {
  border: 2px solid var(--accent);
  padding: 29px;
}
.plan .badge {
  position: absolute;
  top: -13px;
  left: 28px;
  background: var(--accent);
  color: #fff;
  font-size: 12px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 999px;
}
.plan-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
}
.plan-head h3 {
  margin: 0;
  font-size: 22px;
}
.plan-head strong {
  font: 700 28px var(--font-display);
}
.plan ul {
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 10px;
  color: var(--ink-2);
}
.plan li::before {
  content: '✓ ';
  color: var(--ok);
  font-weight: 700;
}
.plan li.minus::before {
  content: '– ';
  color: var(--ink-3);
}

.packs {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}
.pack {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 26px;
  display: grid;
  gap: 4px;
}
.pack span {
  font-size: 14px;
  color: var(--ink-2);
}
.pack strong {
  font: 700 44px/1.1 var(--font-display);
  letter-spacing: -0.02em;
}
.pack em {
  font: 500 15px var(--font-mono);
  font-style: normal;
}
.pack.best {
  background: #1b2a4a;
  border-color: #1b2a4a;
  color: var(--on-navy);
}
.pack.best span {
  color: var(--on-navy-2);
}
.pack .tag {
  position: absolute;
  top: 22px;
  right: 22px;
  font-size: 12px;
  font-weight: 600;
  background: var(--accent-on-navy);
  color: #152238;
  padding: 3px 10px;
  border-radius: 999px;
}

.note {
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 16px 20px;
  font-size: 15px;
  color: var(--ink-2);
}
.responsible {
  display: grid;
  grid-template-columns: minmax(0, 0.5fr) minmax(0, 1.5fr);
  gap: 32px;
  padding: 28px 32px;
}
.responsible h2 {
  font-size: 22px;
  margin: 0;
  color: var(--ink);
}
.responsible p {
  margin: 0;
}

@media (max-width: 900px) {
  .hero,
  .steps,
  .responsible {
    grid-template-columns: 1fr;
  }
  .hero {
    gap: 36px;
    padding-bottom: 40px;
  }
  .steps {
    padding: 32px 24px;
    gap: 28px;
  }
  .steps ol {
    grid-template-columns: 1fr;
  }
  .plans {
    grid-template-columns: 1fr;
  }
  .packs {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .float {
    right: 8px;
  }
}
@media (max-width: 640px) {
  .wrap {
    padding: 0 16px;
  }
  header.site nav a.hide-sm {
    display: none;
  }
  nav {
    gap: 16px;
  }
  .mock {
    padding-bottom: 0;
  }
  .float {
    position: static;
    width: auto;
    margin-top: 12px;
  }
  .pack {
    padding: 18px;
  }
  .pack strong {
    font-size: 32px;
  }
  .hero-actions .cta {
    width: 100%;
    justify-content: center;
  }
  .responsible {
    padding: 20px;
    gap: 8px;
  }
}

/* ---------------------------------------------------------------- documents */

.table-wrap {
  overflow-x: auto;
}
table {
  border-collapse: collapse;
  width: 100%;
  font-size: 15px;
}
th,
td {
  text-align: left;
  padding: 8px 12px;
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
}
th {
  color: var(--ink-2);
  font-weight: 500;
}
td.num,
th.num {
  text-align: right;
  font-variant-numeric: tabular-nums;
}
.doc h2 {
  border-top: 1px solid var(--line);
  padding-top: 24px;
}
.doc ul {
  padding-left: 22px;
}
.center {
  min-height: 70vh;
  display: grid;
  place-items: center;
  text-align: center;
}

/* ---------------------------------------------------------------- Jev */

.jev-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}
.jev-stat {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 26px;
}
.jev-stat strong {
  display: block;
  font: 700 52px/1.05 var(--font-display);
  letter-spacing: -0.03em;
  color: var(--accent-ink);
}
.jev-stat span {
  display: block;
  margin-top: 4px;
  font-size: 18px;
  font-weight: 600;
}
.jev-stat p {
  margin: 12px 0 0;
  font-size: 14px;
  color: var(--ink-2);
}
.jev-quote {
  margin: 22px 0 0;
  padding: 20px 24px;
  border-radius: 16px;
  background: #1b2a4a;
  color: var(--on-navy);
  font-size: 16px;
  line-height: 1.65;
}
.jev-quote footer {
  margin-top: 8px;
  font-size: 14px;
  color: var(--on-navy-2);
}
.jev-quote a {
  color: var(--accent-on-navy);
}
.jev .fine {
  margin: 14px 0 0;
  font-size: 13px;
  color: var(--ink-3);
}
@media (max-width: 900px) {
  .jev-stats {
    grid-template-columns: 1fr;
  }
  .jev-stat strong {
    font-size: 42px;
  }
}
.jev-zh {
  margin: 8px 0 0;
  font-size: 14px;
  color: var(--on-navy-2);
}

/* ---------------------------------------------------------------- open source */

nav a.gh {
  display: inline-flex;
  align-items: center;
  color: var(--ink);
}
nav a.gh:hover {
  color: var(--accent-ink);
}
footer.site a.gh-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.oss {
  margin-top: 56px;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 24px;
  padding: 28px 32px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 20px;
}
.oss-mark {
  color: var(--ink);
  display: grid;
  place-items: center;
}
.oss h2 {
  margin: 0 0 6px;
  font-size: 22px;
}
.oss p {
  margin: 0;
  color: var(--ink-2);
  font-size: 15px;
}
@media (max-width: 760px) {
  .oss {
    grid-template-columns: 1fr;
    padding: 22px;
  }
  .oss .cta {
    justify-content: center;
  }
}

/* ---------------------------------------------------------------- FAQ */

.qa-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}
.qa {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 20px 22px;
}
.qa h3 {
  margin: 0 0 8px;
  font-size: 17px;
}
.qa p {
  margin: 0;
  font-size: 15px;
  color: var(--ink-2);
}
@media (max-width: 760px) {
  .qa-grid {
    grid-template-columns: 1fr;
  }
}