/* Hallmark · macrostructure: Narrative Workflow · hero: dual learning route map · tone: warm, trustworthy, progressive · anchor hue: forest-green
 * theme: custom · vibe: "cream, forest, steady growth" · paper: oklch(96.8% 0.018 94) · accent: oklch(43% 0.12 150)
 * display: Noto Serif SC · body: Noto Sans SC · axes: light / roman-serif / chromatic-green ~150deg
 * studied: no · context: explicit · v0.8.0
 */
/* Hallmark · pre-emit critique: P5 H5 E5 S5 R5 V5 */
/* Hallmark · layout, typography, content, motion, N7 nav and Ft8 footer intentionally unchanged · palette-only revision */

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

html {
  scroll-behavior: smooth;
  overflow-x: clip;
  background: var(--color-paper);
}

body {
  margin: 0;
  min-width: 0;
  overflow-x: clip;
  background: var(--color-paper);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-m);
  line-height: var(--leading-body);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

body,
button,
a,
summary {
  -webkit-tap-highlight-color: var(--color-transparent);
}

img,
svg {
  display: block;
  max-width: 100%;
}

img {
  height: auto;
}

a {
  color: inherit;
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.2em;
}

button {
  color: inherit;
  font: inherit;
}

h1,
h2,
h3,
p,
ul,
ol,
figure,
pre {
  margin-block-start: 0;
}

h1,
h2,
h3 {
  min-width: 0;
  color: inherit;
  font-family: var(--font-display);
  font-style: normal;
  font-weight: 700;
  letter-spacing: -0.035em;
  line-height: var(--leading-heading);
  overflow-wrap: anywhere;
  text-wrap: balance;
}

em {
  color: inherit;
  font-style: normal;
}

p,
li {
  text-wrap: pretty;
}

ul,
ol {
  padding-inline-start: 0;
}

::selection {
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 3px;
}

a:active,
summary:active {
  color: var(--color-accent-deep);
}

a[aria-disabled="true"],
button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

.button.primary:focus-visible,
.menu-button:focus-visible {
  outline-color: var(--color-focus-on-dark);
  box-shadow: 0 0 0 6px var(--color-focus);
}

.button.paper:focus-visible {
  outline-color: var(--color-focus);
  box-shadow: 0 0 0 6px var(--color-focus-on-dark);
}

.skip-link {
  position: fixed;
  z-index: calc(var(--z-header) + 2);
  inset-block-start: var(--space-s);
  inset-inline-start: var(--space-s);
  padding: var(--space-xs) var(--space-s);
  background: var(--color-ink);
  color: var(--color-dark-ink);
  font-weight: 800;
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.section,
.hero {
  width: min(100%, var(--content-wide));
  margin-inline: auto;
  padding-inline: clamp(1rem, 4vw, 4.25rem);
}

.section {
  padding-block: clamp(4.5rem, 9vw, 8rem);
}

.eyebrow {
  display: none;
}

.hero .eyebrow,
.story-layout .eyebrow {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  margin-block-end: var(--space-m);
  color: var(--color-accent-deep);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 900;
  letter-spacing: 0.13em;
  line-height: 1.4;
}

.eyebrow span {
  width: 1.75rem;
  height: var(--stroke-bold);
  background: var(--color-accent);
}

.site-header {
  position: sticky;
  z-index: var(--z-header);
  inset-block-start: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  min-height: var(--header-height);
  padding-inline: clamp(1rem, 3vw, 3.5rem);
  background: var(--color-paper);
  color: var(--color-ink);
  border-block: var(--stroke-bold) solid var(--color-ink);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  width: fit-content;
  min-width: 0;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  flex: 0 0 auto;
  place-items: center;
  width: 2.65rem;
  aspect-ratio: 1;
  background: var(--color-accent);
  color: var(--color-accent-ink);
  border: var(--stroke-bold) solid var(--color-ink);
  font-family: var(--font-display);
  font-size: var(--text-l);
  font-weight: 900;
  line-height: 1;
}

.brand > span:last-child {
  display: grid;
  min-width: 0;
  line-height: 1.2;
}

.brand strong {
  font-family: var(--font-display);
  font-size: 1.02rem;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.brand small {
  display: none;
  color: var(--color-neutral);
  font-size: 0.67rem;
  letter-spacing: 0.04em;
  white-space: nowrap;
}

.menu-button {
  min-width: 3.5rem;
  min-height: 2.75rem;
  padding-inline: var(--space-s);
  background: var(--color-ink);
  color: var(--color-dark-ink);
  border: var(--stroke-bold) solid var(--color-ink);
  border-radius: 0;
  font-size: var(--text-s);
  font-weight: 900;
  letter-spacing: 0.08em;
  cursor: pointer;
  white-space: nowrap;
  transition:
    background-color var(--duration-fast) var(--ease-out),
    color var(--duration-fast) var(--ease-out),
    transform 100ms var(--ease-out);
}

.menu-button:active {
  transform: translateY(1px);
}

#site-nav {
  position: absolute;
  inset-block-start: calc(100% + var(--stroke-bold));
  inset-inline: 0;
  display: none;
  padding: var(--space-s);
  background: var(--color-paper);
  color: var(--color-ink);
  border-block-end: var(--stroke-bold) solid var(--color-ink);
}

#site-nav.open {
  display: grid;
}

#site-nav a {
  display: flex;
  align-items: center;
  min-height: 2.8rem;
  padding-inline: var(--space-xs);
  border-block-end: var(--stroke) solid var(--color-rule);
  font-size: var(--text-s);
  font-weight: 800;
  text-decoration: none;
  white-space: nowrap;
}

.header-action {
  display: none;
  align-items: center;
  min-height: 2.75rem;
  padding-inline: var(--space-s);
  background: var(--color-accent);
  color: var(--color-accent-ink);
  border: var(--stroke-bold) solid var(--color-ink);
  font-size: var(--text-s);
  font-weight: 900;
  text-decoration: none;
  white-space: nowrap;
  transition:
    background-color var(--duration-fast) var(--ease-out),
    transform 100ms var(--ease-out);
}

.header-action:active {
  transform: translateY(1px);
}

.hero {
  display: grid;
  gap: clamp(2.5rem, 7vw, 6rem);
  align-items: center;
  min-height: calc(88svh - var(--header-height));
  padding-block-start: clamp(4.5rem, 9vw, 8rem);
  padding-block-end: clamp(6rem, 12vw, 10rem);
}

.hero-copy {
  min-width: 0;
}

.hero h1 {
  max-width: 11ch;
  margin-block-end: var(--space-l);
  font-size: var(--text-hero);
  line-height: var(--leading-tight);
}

.hero h1 span,
.hero h1 em {
  display: block;
}

.hero h1 em {
  position: relative;
  width: fit-content;
  color: var(--color-accent-deep);
}

.hero h1 em::after {
  content: "";
  position: absolute;
  inset-inline: 0;
  inset-block-end: -0.08em;
  height: 0.08em;
  background: var(--color-accent);
  transform: rotate(-0.8deg);
}

.hero-text {
  max-width: 44rem;
  margin-block-end: var(--space-l);
  color: var(--color-neutral);
  font-size: clamp(1rem, 1.6vw, 1.16rem);
}

.hero-actions,
.cpp-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-block-end: var(--space-xl);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 3rem;
  padding-inline: 1.25rem;
  border: var(--stroke-bold) solid var(--color-ink);
  border-radius: 0;
  font-size: var(--text-s);
  font-weight: 900;
  letter-spacing: 0.025em;
  text-decoration: none;
  white-space: nowrap;
  transition:
    background-color var(--duration-fast) var(--ease-out),
    color var(--duration-fast) var(--ease-out),
    transform 100ms var(--ease-out);
}

.button.primary {
  background: var(--color-ink);
  color: var(--color-dark-ink);
}

.button.secondary {
  background: var(--color-transparent);
  color: var(--color-ink);
}

.button:active {
  transform: translateY(1px);
}

.button[aria-disabled="true"],
.button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.trust-list {
  display: grid;
  gap: var(--space-2xs);
  margin: 0;
  list-style: none;
  color: var(--color-neutral);
  font-size: var(--text-s);
}

.trust-list li {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.trust-list i {
  color: var(--color-accent-deep);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-style: normal;
  font-variant-numeric: tabular-nums;
  font-weight: 800;
}

.hero-visual {
  position: relative;
  min-width: 0;
}

.path-board {
  position: relative;
  z-index: 1;
  padding: clamp(1rem, 3vw, 2rem);
  background: var(--color-surface);
  color: var(--color-ink);
  border: var(--stroke-bold) solid var(--color-ink);
  box-shadow: 0.7rem 0.7rem 0 var(--color-paper-3);
  animation: route-enter 620ms var(--ease-out) both;
}

.board-kicker {
  margin-block-end: var(--space-l);
  padding-block-end: var(--space-xs);
  border-block-end: var(--stroke-bold) solid var(--color-ink);
  color: var(--color-accent-deep);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 800;
  letter-spacing: 0.12em;
}

.path-track {
  position: relative;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  gap: var(--space-s);
  align-items: center;
  min-height: 7.2rem;
  padding: var(--space-s);
  background: var(--color-paper-2);
  color: var(--color-ink);
  border: var(--stroke) solid var(--color-rule-2);
}

.path-track > div {
  min-width: 0;
}

.path-track small,
.path-track strong {
  display: block;
}

.path-track small {
  margin-block-end: var(--space-3xs);
  color: var(--color-neutral);
  font-size: var(--text-xs);
}

.path-track strong {
  font-family: var(--font-display);
  font-size: clamp(1rem, 2vw, 1.35rem);
}

.path-track > b {
  color: var(--color-accent-deep);
  font-family: var(--font-body);
  font-size: var(--text-s);
}

.track-icon {
  display: grid;
  place-items: center;
  width: 2.75rem;
  aspect-ratio: 1;
  background: var(--color-accent);
  color: var(--color-accent-ink);
  border: var(--stroke-bold) solid var(--color-ink);
  border-radius: 50%;
  font-family: var(--font-body);
  font-size: var(--text-s);
  font-weight: 900;
}

.code-track {
  background: var(--color-dark-surface);
  color: var(--color-dark-ink);
  border-color: var(--color-dark-surface);
}

.code-track small {
  color: var(--color-dark-muted);
}

.code-track > b {
  color: var(--color-focus-on-dark);
}

.code-track .track-icon {
  background: var(--color-dark-ink);
  color: var(--color-dark-surface);
  border-color: var(--color-dark-ink);
}

.path-bridge {
  position: relative;
  display: flex;
  justify-content: space-around;
  width: 42%;
  min-width: 8rem;
  height: 2.8rem;
  margin-inline: auto;
}

.path-bridge::before {
  content: "";
  position: absolute;
  inset-block: 0;
  inset-inline-start: 50%;
  width: var(--stroke-bold);
  background: var(--color-accent);
}

.path-bridge i {
  align-self: center;
  width: 0.35rem;
  aspect-ratio: 1;
  background: var(--color-accent);
  border-radius: 50%;
}

.board-note {
  display: grid;
  gap: var(--space-3xs);
  margin-block-start: var(--space-l);
  padding-block-start: var(--space-s);
  border-block-start: var(--stroke) solid var(--color-rule);
}

.board-note span {
  color: var(--color-muted);
  font-size: var(--text-xs);
}

.board-note strong {
  font-family: var(--font-display);
  font-size: var(--text-l);
}

.hero-ring {
  display: none;
}

.section-heading {
  display: grid;
  gap: var(--space-l);
  margin-block-end: clamp(2.5rem, 6vw, 5rem);
  padding-block-end: var(--space-l);
  border-block-end: var(--stroke-bold) solid var(--color-ink);
}

.section-heading h2,
.story-copy h2,
.cpp-copy h2,
.quality-guard h2,
.closing h2 {
  margin-block-end: 0;
  font-size: var(--text-2xl);
}

.section-heading > p,
.section-heading > div > p:not(.eyebrow) {
  max-width: var(--content-reading);
  margin-block-end: 0;
  color: var(--color-neutral);
}

.product-hub {
  position: relative;
  padding-block-start: clamp(5rem, 11vw, 9rem);
  border-block-start: var(--stroke) solid var(--color-rule);
}

.product-hub::before {
  content: "路线选择";
  display: block;
  width: fit-content;
  margin-block-end: var(--space-s);
  padding: var(--space-3xs) var(--space-xs);
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-size: var(--text-xs);
  font-weight: 900;
  letter-spacing: 0.08em;
}

.product-grid {
  display: grid;
  gap: var(--space-l);
}

.product-card {
  position: relative;
  display: flex;
  flex-direction: column;
  min-width: 0;
  padding-block: var(--space-l);
  border-block: var(--stroke-bold) solid var(--color-ink);
}

.product-card::before {
  content: "";
  position: absolute;
  inset-block-start: -0.55rem;
  inset-inline-start: clamp(2rem, 20%, 6rem);
  width: 0.7rem;
  aspect-ratio: 1;
  background: var(--color-accent);
  border: var(--stroke-bold) solid var(--color-ink);
  border-radius: 50%;
}

.product-card-top {
  display: flex;
  justify-content: space-between;
  gap: var(--space-s);
  align-items: center;
  margin-block-end: var(--space-m);
}

.product-card-top span {
  color: var(--color-accent-deep);
  font-family: var(--font-body);
  font-size: var(--text-l);
  font-variant-numeric: tabular-nums;
  font-weight: 900;
}

.product-card-top b {
  padding: var(--space-3xs) var(--space-xs);
  background: var(--color-paper-3);
  color: var(--color-ink-2);
  border: var(--stroke) solid var(--color-rule-2);
  font-size: var(--text-xs);
}

.product-card > small {
  color: var(--color-muted);
  font-size: var(--text-xs);
}

.product-card h3 {
  margin-block: var(--space-xs) var(--space-s);
  font-size: clamp(2rem, 5vw, 4.4rem);
  line-height: 1.05;
}

.product-card > p {
  max-width: 58ch;
  color: var(--color-neutral);
}

.product-facts {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2xs);
  margin-block: auto var(--space-l);
  list-style: none;
}

.product-facts li {
  padding: var(--space-3xs) var(--space-xs);
  background: var(--color-paper-2);
  color: var(--color-ink-2);
  border: var(--stroke) solid var(--color-rule);
  font-size: var(--text-xs);
}

.product-card > a {
  width: fit-content;
  min-height: 2.75rem;
  display: inline-flex;
  align-items: center;
  color: var(--color-accent-deep);
  font-weight: 900;
  white-space: nowrap;
}

.product-story {
  position: relative;
  border-block-start: var(--stroke-bold) solid var(--color-ink);
}

.wrongbook-story {
  background: var(--color-surface);
  color: var(--color-ink);
}

.wrongbook-story::before {
  content: "";
  position: absolute;
  z-index: 0;
  inset-block: 0;
  inset-inline-start: clamp(1rem, 3vw, 3rem);
  width: var(--stroke-bold);
  background: var(--color-accent-soft);
}

.wrongbook-story > .section {
  position: relative;
  z-index: 1;
}

.story-layout {
  display: grid;
  gap: clamp(2.5rem, 7vw, 6rem);
  align-items: start;
}

.story-copy {
  min-width: 0;
}

.story-copy > p:not(.eyebrow) {
  max-width: var(--content-reading);
  color: var(--color-neutral);
}

.status-line {
  display: grid;
  gap: var(--space-3xs);
  margin-block-start: var(--space-l);
  padding-block: var(--space-s);
  border-block: var(--stroke-bold) solid var(--color-ink);
}

.status-line span,
.status-line small {
  color: var(--color-neutral);
  font-size: var(--text-xs);
}

.status-line strong {
  font-family: var(--font-display);
  font-size: var(--text-l);
}

.wrongbook-demo {
  position: relative;
  min-width: 0;
  padding: clamp(1rem, 3vw, 2rem);
  background: var(--color-paper-2);
  color: var(--color-ink);
  border: var(--stroke-bold) solid var(--color-ink);
  box-shadow: 0.65rem 0.65rem 0 var(--color-accent-soft);
}

.wrongbook-demo::before {
  content: "诊断路径";
  position: absolute;
  inset-block-start: -1rem;
  inset-inline-end: var(--space-s);
  padding: var(--space-3xs) var(--space-xs);
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-size: var(--text-xs);
  font-weight: 900;
}

.demo-top,
.answer-row,
.demo-score {
  display: flex;
  justify-content: space-between;
  gap: var(--space-s);
  align-items: center;
}

.demo-top {
  padding-block-end: var(--space-xs);
  border-block-end: var(--stroke) solid var(--color-rule-2);
  color: var(--color-neutral);
  font-size: var(--text-xs);
}

.demo-top b {
  color: var(--color-accent-deep);
}

.demo-question {
  margin-block: var(--space-l);
  font-family: var(--font-display);
  font-size: var(--text-l);
  font-weight: 700;
}

.answer-row {
  padding: var(--space-s);
  background: var(--color-surface);
  color: var(--color-ink);
  border: var(--stroke) solid var(--color-rule-2);
}

.answer-row i {
  color: var(--color-accent-deep);
  font-style: normal;
  font-weight: 900;
}

.knowledge-row {
  display: flex;
  align-items: center;
  gap: var(--space-2xs);
  margin-block: var(--space-s);
  color: var(--color-neutral);
  font-size: var(--text-xs);
}

.knowledge-row em {
  color: var(--color-accent-deep);
  font-weight: 900;
}

.cause-card {
  padding-block: var(--space-s);
  border-block: var(--stroke-bold) solid var(--color-ink);
}

.cause-card small,
.cause-card strong {
  display: block;
}

.cause-card small {
  color: var(--color-muted);
  font-size: var(--text-xs);
}

.cause-card strong {
  margin-block: var(--space-3xs) var(--space-2xs);
  font-family: var(--font-display);
  font-size: var(--text-l);
}

.cause-card p {
  margin-block-end: 0;
  color: var(--color-neutral);
}

.demo-score {
  margin-block-start: var(--space-s);
}

.demo-score strong {
  color: var(--color-accent-deep);
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-variant-numeric: tabular-nums;
}

.wrongbook-proof {
  display: grid;
  gap: 0;
  padding-block-start: 0;
}

.wrongbook-proof > div {
  display: grid;
  gap: var(--space-2xs);
  padding-block: var(--space-l);
  border-block-start: var(--stroke) solid var(--color-rule);
}

.wrongbook-proof strong {
  font-family: var(--font-display);
  font-size: var(--text-xl);
}

.wrongbook-proof span {
  color: var(--color-neutral);
  font-size: var(--text-s);
}

.methodology-section {
  padding-block-start: clamp(2rem, 5vw, 4rem);
}

.methodology-grid {
  display: grid;
  gap: 0;
  counter-reset: method;
}

.methodology-grid article {
  position: relative;
  padding-block: var(--space-l);
  border-block-start: var(--stroke-bold) solid var(--color-ink);
  counter-increment: method;
}

.methodology-grid article::before {
  content: counter(method, decimal-leading-zero);
  display: block;
  margin-block-end: var(--space-m);
  color: var(--color-accent-deep);
  font-family: var(--font-body);
  font-weight: 900;
}

.methodology-grid article > span {
  display: none;
}

.methodology-grid h3 {
  margin-block-end: var(--space-s);
  font-size: var(--text-xl);
}

.methodology-grid p {
  color: var(--color-neutral);
}

.methodology-grid small {
  display: block;
  color: var(--color-muted);
}

.methodology-boundary {
  max-width: var(--content-reading);
  margin-block: var(--space-xl) 0;
  padding: var(--space-l);
  background: var(--color-paper-2);
  color: var(--color-neutral);
  border: var(--stroke) solid var(--color-rule-2);
}

.methodology-boundary strong {
  color: var(--color-ink);
}

.quality-guard {
  display: grid;
  gap: var(--space-l);
  background: var(--color-dark-surface);
  color: var(--color-dark-ink);
  border-inline: clamp(1rem, 4vw, 4.25rem) solid var(--color-surface);
}

.quality-guard > p {
  max-width: var(--content-reading);
  margin-block-end: 0;
  color: var(--color-dark-muted);
}

.loop-section {
  padding-block-start: clamp(5rem, 10vw, 9rem);
}

.learning-loop {
  position: relative;
  display: grid;
  gap: 0;
  margin: 0;
  list-style: none;
}

.learning-loop::before {
  content: "";
  position: absolute;
  inset-block: 0;
  inset-inline-start: 1.25rem;
  width: var(--stroke-bold);
  background: var(--color-rule-2);
}

.learning-loop li {
  position: relative;
  display: grid;
  grid-template-columns: 2.5rem minmax(0, 1fr);
  gap: var(--space-s);
  padding-block: var(--space-l);
  border-block-start: var(--stroke-bold) solid var(--color-ink);
}

.learning-loop b {
  position: relative;
  z-index: 1;
  display: grid;
  place-items: center;
  width: 2.5rem;
  aspect-ratio: 1;
  background: var(--color-accent);
  color: var(--color-accent-ink);
  border: var(--stroke-bold) solid var(--color-ink);
  border-radius: 50%;
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-variant-numeric: tabular-nums;
}

.learning-loop span {
  align-self: center;
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 700;
}

.learning-loop p {
  grid-column: 2;
  margin-block-end: 0;
  color: var(--color-neutral);
}

.preview-section {
  padding-block-start: clamp(4rem, 8vw, 7rem);
}

.preview-grid {
  display: grid;
  gap: clamp(1.5rem, 4vw, 3rem);
  counter-reset: preview;
}

.preview-grid figure {
  min-width: 0;
  margin-block-end: 0;
  counter-increment: preview;
}

.preview-grid a {
  display: block;
  min-width: 0;
  background: var(--color-paper-2);
  border: var(--stroke) solid var(--color-rule-2);
}

.preview-grid img {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

.preview-grid figcaption {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: var(--space-xs);
  align-items: start;
  padding-block-start: var(--space-xs);
}

.preview-grid figcaption::before {
  content: counter(preview, decimal-leading-zero);
  color: var(--color-accent-deep);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 900;
}

.preview-grid figcaption strong,
.preview-grid figcaption span {
  grid-column: 2;
}

.preview-grid figcaption strong {
  font-family: var(--font-display);
}

.preview-grid figcaption span {
  color: var(--color-muted);
  font-size: var(--text-xs);
}

.cpp-story {
  background: var(--color-paper-2);
  color: var(--color-ink);
}

.cpp-intro {
  display: grid;
  gap: clamp(3rem, 8vw, 7rem);
  align-items: center;
}

.cpp-brandline {
  display: flex;
  gap: var(--space-s);
  align-items: center;
  margin-block-end: var(--space-l);
}

.cpp-brandline img {
  width: 3rem;
  height: 3rem;
}

.cpp-brandline > div {
  display: grid;
}

.cpp-brandline small {
  color: var(--color-muted);
  font-family: var(--font-body);
  font-size: var(--text-xs);
}

.cpp-brandline strong {
  font-family: var(--font-display);
  font-size: var(--text-l);
}

.cpp-copy > p {
  max-width: var(--content-reading);
  color: var(--color-neutral);
}

.star-button {
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

.text-link,
.privacy-link {
  display: inline-flex;
  align-items: center;
  min-height: 2.75rem;
  color: var(--color-accent-deep);
  font-weight: 900;
  white-space: nowrap;
}

.code-note {
  min-width: 0;
  padding: clamp(1.25rem, 4vw, 2.5rem);
  background: var(--color-dark-surface);
  color: var(--color-dark-ink);
  border: var(--stroke-bold) solid var(--color-ink);
  box-shadow: 0.7rem 0.7rem 0 var(--color-accent-soft);
}

.note-label {
  margin-block-end: var(--space-l);
  padding-block-end: var(--space-xs);
  border-block-end: var(--stroke) solid var(--color-dark-rule);
  color: var(--color-dark-muted);
  font-size: var(--text-xs);
}

.code-note pre {
  overflow-x: auto;
  margin-block-end: var(--space-l);
  color: var(--color-dark-ink);
  font-family: var(--font-mono);
  font-size: clamp(0.78rem, 2vw, 0.95rem);
  line-height: 1.8;
}

.code-purple,
.code-mint {
  color: var(--color-focus-on-dark);
}

.code-yellow {
  color: var(--color-dark-ink);
}

.flight-progress {
  display: grid;
  gap: var(--space-xs);
  padding-block: var(--space-s);
  border-block: var(--stroke) solid var(--color-dark-rule);
}

.flight-progress > span {
  display: block;
  height: 0.3rem;
  background: var(--color-dark-rule);
}

.flight-progress > span i {
  display: block;
  width: 42%;
  height: 100%;
  background: var(--color-focus-on-dark);
}

.flight-progress small,
.flight-progress strong {
  display: block;
}

.flight-progress small {
  color: var(--color-dark-muted);
  font-size: var(--text-xs);
}

.achievement-chip {
  width: fit-content;
  margin-block-start: var(--space-s);
  padding: var(--space-3xs) var(--space-xs);
  background: var(--color-dark-raised);
  color: var(--color-dark-ink);
  border: var(--stroke) solid var(--color-dark-rule);
  font-size: var(--text-xs);
}

.cpp-metrics {
  display: grid;
  gap: 0;
  padding-block-start: 0;
  font-variant-numeric: tabular-nums;
}

.cpp-metrics article {
  position: relative;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: var(--space-3xs) var(--space-s);
  padding-block: var(--space-l);
  border-block-start: var(--stroke-bold) solid var(--color-ink);
}

.cpp-metrics article::after {
  content: "";
  position: absolute;
  inset-block-start: -0.4rem;
  inset-inline-end: 10%;
  width: 0.65rem;
  aspect-ratio: 1;
  background: var(--color-accent);
  border: var(--stroke-bold) solid var(--color-ink);
  border-radius: 50%;
}

.cpp-metrics strong {
  grid-row: span 2;
  color: var(--color-accent-deep);
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 7vw, 5rem);
  line-height: 0.9;
}

.cpp-metrics span {
  align-self: end;
  font-family: var(--font-display);
  font-weight: 700;
}

.cpp-metrics small {
  color: var(--color-muted);
}

.cpp-features {
  padding-block-start: clamp(4rem, 8vw, 7rem);
}

.cpp-feature-grid {
  display: grid;
  gap: 0;
  counter-reset: cpp-feature;
}

.cpp-feature-grid article {
  padding-block: var(--space-l);
  border-block-start: var(--stroke-bold) solid var(--color-ink);
  counter-increment: cpp-feature;
}

.cpp-feature-grid article::before {
  content: counter(cpp-feature, decimal-leading-zero);
  display: block;
  margin-block-end: var(--space-s);
  color: var(--color-accent-deep);
  font-family: var(--font-body);
  font-weight: 900;
}

.cpp-feature-grid article > span {
  display: none;
}

.cpp-feature-grid h3 {
  margin-block-end: var(--space-s);
  font-size: var(--text-xl);
}

.cpp-feature-grid p {
  margin-block-end: 0;
  color: var(--color-neutral);
}

.cpp-disclaimer {
  background: var(--color-dark-surface);
  color: var(--color-dark-ink);
  padding-inline: var(--space-l);
  border-block-start-color: var(--color-dark-surface);
}

.cpp-disclaimer::before {
  color: var(--color-focus-on-dark);
}

.cpp-disclaimer p {
  color: var(--color-dark-muted);
}

.release-section {
  padding-block-start: clamp(6rem, 12vw, 10rem);
}

.release-grid {
  display: grid;
  gap: var(--space-l);
}

.release-card {
  min-width: 0;
  padding-block: var(--space-l);
  border-block: var(--stroke-bold) solid var(--color-ink);
}

.release-meta {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-xs);
  margin-block-end: var(--space-l);
  color: var(--color-muted);
  font-size: var(--text-xs);
}

.release-meta b {
  color: var(--color-accent-deep);
}

.release-card h3 {
  font-size: var(--text-xl);
}

.release-card > p,
.release-card li {
  color: var(--color-neutral);
}

.release-card ul {
  margin-block-end: 0;
  padding-inline-start: var(--space-l);
}

.billing-note {
  display: grid;
  gap: var(--space-xs);
  margin-block-start: var(--space-xl);
  padding: var(--space-l);
  background: var(--color-accent-soft);
  color: var(--color-ink);
  border: var(--stroke) solid var(--color-rule-2);
}

.billing-note strong {
  font-family: var(--font-display);
  font-size: var(--text-l);
}

.billing-note p {
  margin-block-end: 0;
  color: var(--color-neutral);
}

.boundary-section {
  padding-block-start: clamp(4rem, 8vw, 7rem);
}

.boundary-grid {
  display: grid;
  gap: 0;
}

.boundary-grid article {
  padding-block: var(--space-l);
  border-block-start: var(--stroke-bold) solid var(--color-ink);
}

.boundary-number {
  display: block;
  margin-block-end: var(--space-m);
  color: var(--color-accent-deep);
  font-family: var(--font-body);
  font-weight: 900;
}

.boundary-grid h3 {
  font-size: var(--text-xl);
}

.boundary-grid p {
  margin-block-end: 0;
  color: var(--color-neutral);
}

.questions {
  padding-block-start: clamp(4rem, 8vw, 7rem);
}

.faq-list {
  border-block-start: var(--stroke-bold) solid var(--color-ink);
}

.faq-list details {
  border-block-end: var(--stroke-bold) solid var(--color-ink);
}

.faq-list summary {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: var(--space-s);
  align-items: center;
  min-height: 4.5rem;
  padding-block: var(--space-s);
  font-family: var(--font-display);
  font-size: var(--text-l);
  font-weight: 700;
  list-style: none;
  cursor: pointer;
}

.faq-list summary::-webkit-details-marker {
  display: none;
}

.faq-list summary i {
  display: grid;
  place-items: center;
  width: 2.25rem;
  aspect-ratio: 1;
  background: var(--color-paper-2);
  color: var(--color-accent-deep);
  border: var(--stroke) solid var(--color-rule-2);
  border-radius: 50%;
  font-family: var(--font-body);
  font-style: normal;
  transition: transform var(--duration-base) var(--ease-out);
}

.faq-list details[open] summary i {
  transform: rotate(45deg);
}

.faq-list details > p {
  max-width: var(--content-reading);
  margin-block-end: var(--space-l);
  color: var(--color-neutral);
}

.closing {
  display: grid;
  gap: var(--space-l);
  align-items: end;
  width: min(100%, var(--content-wide));
  margin-inline: auto;
  padding: clamp(3rem, 8vw, 7rem) clamp(1rem, 4vw, 4.25rem);
  background: var(--color-dark-surface);
  color: var(--color-dark-ink);
}

.closing p {
  max-width: var(--content-reading);
  margin-block-end: 0;
  color: var(--color-dark-muted);
}

.button.paper {
  width: fit-content;
  background: var(--color-dark-ink);
  color: var(--color-dark-surface);
  border-color: var(--color-dark-ink);
}

footer {
  overflow: hidden;
  padding-block: clamp(4rem, 8vw, 7rem) var(--space-l);
  background: var(--color-paper-3);
  color: var(--color-ink);
  border-block-start: var(--stroke-bold) solid var(--color-ink);
}

.footer-statement {
  display: flex;
  gap: var(--space-3xl);
  width: max-content;
  margin-block-end: clamp(3rem, 7vw, 6rem);
  padding-block: var(--space-m);
  border-block: var(--stroke-bold) solid var(--color-ink);
  font-family: var(--font-display);
  font-size: clamp(2.4rem, 8vw, 7rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1;
  white-space: nowrap;
  animation: footer-marquee 34s linear infinite;
}

.footer-statement br {
  display: none;
}

.footer-statement::after {
  content: "把每一步学习，变成看得见的成长。";
  padding-inline-end: var(--space-3xl);
}

.footer-brand,
.footer-links,
footer > p:last-child {
  margin-inline: clamp(1rem, 4vw, 4.25rem);
}

.footer-brand {
  margin-block-end: var(--space-l);
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs) var(--space-l);
  padding-block: var(--space-l);
  border-block: var(--stroke) solid var(--color-rule-2);
}

.footer-links a,
.footer-links span {
  display: inline-flex;
  align-items: center;
  min-height: 2.75rem;
  color: var(--color-neutral);
  font-size: var(--text-s);
}

.footer-links a {
  font-weight: 800;
  white-space: nowrap;
}

footer > p:last-child {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-xs);
  margin-block-start: var(--space-l);
  margin-block-end: 0;
  color: var(--color-muted);
  font-size: var(--text-xs);
}

.filing-link {
  display: inline-flex;
  align-items: center;
  min-height: 2.75rem;
  color: var(--color-neutral);
  font-weight: 700;
}

.filing-link:hover {
  color: var(--color-ink);
}

.beian-link img {
  flex: none;
  width: 1.25rem;
  height: 1.25rem;
  margin-inline-end: 0.35rem;
  object-fit: contain;
}

@keyframes route-enter {
  from {
    opacity: 0;
    transform: translateY(0.75rem);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes footer-marquee {
  from {
    transform: translateX(0);
  }
  to {
    transform: translateX(calc(-50% - 3rem));
  }
}

@media (hover: hover) and (pointer: fine) {
  #site-nav a:hover {
    background: var(--color-paper-3);
  }

  .menu-button:hover {
    background: var(--color-accent);
    color: var(--color-accent-ink);
  }

  .header-action:hover,
  .star-button:hover {
    background: var(--color-accent-deep);
  }

  .button.primary:hover {
    background: var(--color-accent);
    color: var(--color-accent-ink);
  }

  .button.secondary:hover {
    background: var(--color-ink);
    color: var(--color-dark-ink);
  }

  .product-card > a:hover,
  .text-link:hover,
  .privacy-link:hover {
    color: var(--color-ink);
  }

  .preview-grid a:hover {
    border-color: var(--color-ink);
  }

  .footer-statement:hover {
    animation-play-state: paused;
  }
}

footer:focus-within .footer-statement {
  animation-play-state: paused;
}

@media (pointer: coarse) {
  .button,
  .menu-button,
  .header-action,
  #site-nav a,
  .product-card > a,
  .text-link,
  .privacy-link,
  .footer-links a {
    min-height: 3rem;
  }
}

@media (min-width: 40rem) {
  .brand small {
    display: block;
  }

  .section-heading.split-heading {
    grid-template-columns: minmax(0, 1.2fr) minmax(16rem, 0.8fr);
    align-items: end;
  }

  .product-grid {
    grid-template-columns: minmax(0, 1.18fr) minmax(0, 0.82fr);
    gap: clamp(2rem, 5vw, 5rem);
  }

  .story-layout,
  .cpp-intro {
    grid-template-columns: minmax(0, 1.08fr) minmax(18rem, 0.92fr);
  }

  .wrongbook-proof {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .wrongbook-proof > div:nth-child(odd) {
    padding-inline-end: var(--space-l);
  }

  .wrongbook-proof > div:nth-child(even) {
    padding-inline-start: var(--space-l);
    border-inline-start: var(--stroke) solid var(--color-rule);
  }

  .methodology-grid,
  .cpp-feature-grid,
  .boundary-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .methodology-grid article:nth-child(odd),
  .cpp-feature-grid article:nth-child(odd),
  .boundary-grid article:nth-child(odd) {
    padding-inline-end: var(--space-l);
  }

  .methodology-grid article:nth-child(even),
  .cpp-feature-grid article:nth-child(even),
  .boundary-grid article:nth-child(even) {
    padding-inline-start: var(--space-l);
    border-inline-start: var(--stroke) solid var(--color-rule);
  }

  .quality-guard {
    grid-template-columns: minmax(0, 0.9fr) minmax(16rem, 1.1fr);
    align-items: end;
  }

  .learning-loop li {
    grid-template-columns: 3rem minmax(10rem, 0.55fr) minmax(0, 1.45fr);
    align-items: start;
  }

  .learning-loop::before {
    inset-inline-start: 1.5rem;
  }

  .learning-loop b {
    width: 3rem;
  }

  .learning-loop p {
    grid-column: 3;
    margin-block-end: 0;
  }

  .preview-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .preview-grid .preview-wide {
    grid-column: span 2;
  }

  .cpp-metrics {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .cpp-metrics article:nth-child(odd) {
    padding-inline-end: var(--space-l);
  }

  .cpp-metrics article:nth-child(even) {
    padding-inline-start: var(--space-l);
    border-inline-start: var(--stroke) solid var(--color-rule);
  }

  .release-grid {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
  }

  .closing {
    grid-template-columns: minmax(0, 1fr) auto;
  }
}

@media (min-width: 60rem) {
  .site-header {
    grid-template-columns: auto minmax(0, 1fr) auto;
    gap: var(--space-l);
  }

  .menu-button {
    display: none;
  }

  #site-nav,
  #site-nav.open {
    position: static;
    display: flex;
    justify-content: center;
    gap: 0;
    min-width: 0;
    padding: 0;
    background: var(--color-transparent);
    border: 0;
  }

  #site-nav a {
    min-height: 2.75rem;
    padding-inline: clamp(0.5rem, 1vw, 1rem);
    border-block: 0;
    border-inline-end: var(--stroke) solid var(--color-rule);
    font-size: clamp(0.7rem, 0.75vw, 0.82rem);
  }

  #site-nav a:first-child {
    border-inline-start: var(--stroke) solid var(--color-rule);
  }

  .header-action {
    display: inline-flex;
  }

  .hero {
    grid-template-columns: minmax(0, 1.06fr) minmax(24rem, 0.94fr);
  }

  .path-board {
    transform: rotate(0.7deg);
  }

  .wrongbook-proof {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .wrongbook-proof > div {
    padding-inline: var(--space-l);
    border-inline-start: var(--stroke) solid var(--color-rule);
  }

  .wrongbook-proof > div:first-child {
    padding-inline-start: 0;
    border-inline-start: 0;
  }

  .methodology-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .methodology-grid article {
    padding-inline: var(--space-l);
    border-inline-start: var(--stroke) solid var(--color-rule);
  }

  .methodology-grid article:nth-child(3n + 1) {
    padding-inline-start: 0;
    border-inline-start: 0;
  }

  .methodology-grid article:nth-child(3n) {
    padding-inline-end: 0;
  }

  .preview-grid {
    grid-template-columns: repeat(12, minmax(0, 1fr));
    align-items: start;
  }

  .preview-grid figure {
    grid-column: span 5;
  }

  .preview-grid .preview-wide {
    grid-column: span 7;
  }

  .preview-grid figure:nth-child(2),
  .preview-grid figure:nth-child(4) {
    margin-block-start: var(--space-3xl);
  }

  .cpp-metrics {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }

  .cpp-metrics article,
  .cpp-metrics article:nth-child(odd),
  .cpp-metrics article:nth-child(even) {
    display: block;
    padding-inline: var(--space-l);
    border-inline-start: var(--stroke) solid var(--color-rule);
  }

  .cpp-metrics article:first-child {
    padding-inline-start: 0;
    border-inline-start: 0;
  }

  .cpp-metrics article:last-child {
    padding-inline-end: 0;
  }

  .cpp-metrics span,
  .cpp-metrics small {
    display: block;
  }

  .cpp-metrics span {
    margin-block-start: var(--space-s);
  }

  .cpp-feature-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .cpp-feature-grid article {
    padding-inline: var(--space-l);
    border-inline-start: var(--stroke) solid var(--color-rule);
  }

  .cpp-feature-grid article:nth-child(3n + 1) {
    padding-inline-start: 0;
    border-inline-start: 0;
  }

  .cpp-feature-grid article:nth-child(3n) {
    padding-inline-end: 0;
  }

  .boundary-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .boundary-grid article,
  .boundary-grid article:nth-child(odd),
  .boundary-grid article:nth-child(even) {
    padding-inline: var(--space-l);
    border-inline-start: var(--stroke) solid var(--color-rule);
  }

  .boundary-grid article:first-child {
    padding-inline-start: 0;
    border-inline-start: 0;
  }

  .boundary-grid article:last-child {
    padding-inline-end: 0;
  }
}

@media (min-width: 90rem) {
  .section,
  .hero {
    padding-inline: 2rem;
  }

  .site-header {
    padding-inline: 3rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto;
  }

  .path-board {
    animation: none;
  }

  .footer-statement {
    animation: none;
  }

  .button,
  .menu-button,
  .header-action,
  .faq-list summary i {
    transition-duration: 0.01ms;
  }

  .button:active,
  .menu-button:active,
  .header-action:active,
  .faq-list details[open] summary i {
    transform: none;
  }
}