:root {
  --color-page: #FFFFFF;
  --color-panel: #F7F7F8;
  --color-panel-strong: #F1F2F4;
  --color-line: #E7E8EA;
  --color-brand: #DF5347;
  --color-brand-deep: #C23F35;
  --color-sketch-blue: #8FCBDA;
  --color-ink: #2F3237;
  --color-muted: #82868D;
  --color-success: #3FA76E;
  --color-warning: #D99A2B;
  --color-error: #C23F35;
  --color-sketch: #D9DBDE;
  --color-sidebar: #3A3D42;
  --color-sidebar-text: #C9CCD1;
  --color-white-soft: #FFFFFF;
  --color-overlay: rgba(47, 50, 55, 0.28);
  --color-sidebar-active: rgba(255, 255, 255, 0.09);
  --color-shadow-near: rgba(47, 50, 55, 0.07);
  --color-shadow-far: rgba(47, 50, 55, 0.12);
  --color-shadow-button: rgba(223, 83, 71, 0.24);
  --color-shadow-toggle: rgba(47, 50, 55, 0.25);
  --font-display: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-code: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --radius-pill: 999px;
  --radius-xs: 8px;
  --radius-sm: 10px;
  --radius-md: 14px;
  --radius-card: 18px;
  --radius-window: 22px;
  --radius-large: 24px;
  --shadow-chip: 0 1px 2px var(--color-shadow-near);
  --shadow-card: 0 6px 18px var(--color-shadow-near), 0 22px 54px var(--color-shadow-near);
  --shadow-float: 0 6px 18px var(--color-shadow-near), 0 32px 80px var(--color-shadow-far);
  --shadow-button: 0 3px 10px var(--color-shadow-button), 0 14px 34px var(--color-shadow-button);
  --content-width: 1120px;
  --wide-width: 1280px;
  --reading-width: 780px;
  --gutter: clamp(16px, 4vw, 32px);
  --section-space: clamp(76px, 11vw, 150px);
  --header-height: 78px;
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
}

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

html {
  scroll-behavior: smooth;
  background: var(--color-page);
}

html.nav-open {
  overflow: hidden;
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--color-page);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.72;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-wrap: break-word;
}

body,
main,
section,
article,
header,
footer,
nav,
div,
aside {
  min-width: 0;
}

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

button,
input,
select,
textarea {
  color: inherit;
  font: inherit;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

button {
  border: 0;
}

a {
  color: var(--color-brand-deep);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

a:hover {
  color: var(--color-brand);
}

p,
ul,
ol,
blockquote,
pre,
table {
  margin-top: 0;
}

p:last-child,
ul:last-child,
ol:last-child,
blockquote:last-child,
pre:last-child {
  margin-bottom: 0;
}

h1,
h2,
h3,
h4 {
  margin: 0 0 0.55em;
  color: var(--color-ink);
  font-family: var(--font-display);
  line-height: 1.2;
  text-wrap: balance;
}

h1,
.hero-title {
  font-size: clamp(34px, 3.4vw, 48px);
  font-weight: 800;
  letter-spacing: 0.005em;
}

h2 {
  font-size: clamp(28px, 3vw, 40px);
  font-weight: 800;
}

h3 {
  font-size: clamp(20px, 2vw, 26px);
  font-weight: 750;
}

h4 {
  font-size: 18px;
  font-weight: 700;
}

small,
.text-muted {
  color: var(--color-muted);
}

strong {
  font-weight: 700;
}

code,
kbd,
samp {
  font-family: var(--font-code);
}

:not(pre) > code {
  padding: 0.14em 0.4em;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-xs);
  background: var(--color-panel);
  color: var(--color-ink);
  font-size: 0.88em;
  overflow-wrap: anywhere;
}

pre {
  max-width: 100%;
  padding: 20px;
  overflow-x: auto;
  overscroll-behavior-inline: contain;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-sidebar);
  color: var(--color-white-soft);
  font: 13.5px/1.75 var(--font-code);
  -webkit-overflow-scrolling: touch;
}

pre code {
  color: inherit;
  white-space: pre;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th,
td {
  padding: 14px 16px;
  border: 1px solid var(--color-line);
  text-align: left;
  vertical-align: top;
}

th {
  background: var(--color-panel);
  color: var(--color-ink);
  font-weight: 700;
}

.wrap,
.wide-wrap,
.reading-wrap {
  width: 100%;
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.wrap {
  max-width: calc(var(--content-width) + var(--gutter) * 2);
}

.wide-wrap {
  max-width: min(100%, calc(var(--wide-width) + var(--gutter) * 2));
}

.reading-wrap {
  max-width: calc(var(--reading-width) + var(--gutter) * 2);
}

.section {
  padding-top: var(--section-space);
  padding-bottom: var(--section-space);
}

.section-compact {
  padding-top: clamp(54px, 8vw, 96px);
  padding-bottom: clamp(54px, 8vw, 96px);
}

.center {
  text-align: center;
}

.nowrap-term {
  display: inline-block;
  white-space: nowrap;
}

.panel,
.card {
  border: 1px solid var(--color-line);
  background: var(--color-page);
  color: var(--color-ink);
}

.panel {
  padding: clamp(20px, 4vw, 34px);
  border-radius: var(--radius-large);
  background: var(--color-panel);
  color: var(--color-ink);
}

.card {
  padding: 24px;
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-card);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
}

.button-row.center {
  justify-content: center;
}

.button {
  display: inline-flex;
  min-height: 46px;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 12px 28px;
  border: 1.5px solid transparent;
  border-radius: var(--radius-pill);
  font-family: var(--font-display);
  font-size: 15.5px;
  font-weight: 700;
  line-height: 1;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
  transition: transform 160ms var(--ease-out), border-color 160ms var(--ease-out), background-color 160ms var(--ease-out), box-shadow 160ms var(--ease-out);
}

.button svg {
  width: 17px;
  height: 17px;
  flex-shrink: 0;
}

.button-primary {
  background: var(--color-brand);
  color: var(--color-white-soft);
  box-shadow: var(--shadow-button);
}

.button-primary:hover {
  background: var(--color-brand-deep);
  color: var(--color-white-soft);
  transform: translateY(-1px);
}

.button-secondary {
  border-color: var(--color-line);
  background: var(--color-page);
  color: var(--color-ink);
}

.button-secondary:hover {
  border-color: var(--color-muted);
  color: var(--color-ink);
  transform: translateY(-1px);
}

.button:focus-visible,
.site-nav a:focus-visible,
.language-button:focus-visible,
.menu-toggle:focus-visible {
  outline: 3px solid var(--color-sketch-blue);
  outline-offset: 3px;
}

.button[disabled],
.button.is-disabled {
  border-color: var(--color-line);
  background: var(--color-panel-strong);
  color: var(--color-muted);
  box-shadow: none;
  cursor: not-allowed;
  transform: none;
}

.keyword-mark {
  position: relative;
  display: inline-block;
  white-space: nowrap;
}

.keyword-mark::after {
  position: absolute;
  right: -2%;
  bottom: -0.12em;
  left: -2%;
  height: 0.2em;
  border-bottom: 3px solid var(--color-brand);
  border-radius: 50%;
  content: "";
  transform: rotate(-1deg);
}

.blue-tick {
  position: relative;
}

.blue-tick::before {
  position: absolute;
  top: -8px;
  left: 48%;
  width: 22px;
  border-top: 2px solid var(--color-sketch-blue);
  content: "";
  transform: rotate(-7deg);
}

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 620ms var(--ease-out), transform 620ms var(--ease-out);
}

.reveal.shown {
  opacity: 1;
  transform: none;
}

.site-header {
  position: relative;
  z-index: 50;
  background: var(--color-page);
  color: var(--color-ink);
}

.site-header-inner {
  display: flex;
  min-height: var(--header-height);
  align-items: center;
  gap: 24px;
  width: 100%;
  max-width: min(100%, calc(1280px + var(--gutter) * 2));
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.site-brand {
  display: inline-flex;
  flex-shrink: 0;
  align-items: center;
  gap: 10px;
  color: var(--color-ink);
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 750;
  text-decoration: none;
}

.site-brand:hover {
  color: var(--color-ink);
}

.site-brand img {
  width: 34px;
  height: 34px;
  flex-shrink: 0;
}

.desktop-nav {
  display: flex;
  align-items: center;
  gap: 13px;
  margin-left: auto;
  white-space: nowrap;
}

.desktop-nav a {
  color: var(--color-ink);
  font-size: 14.5px;
  font-weight: 550;
  text-decoration: none;
}

.desktop-nav a:hover,
.desktop-nav a.is-current {
  color: var(--color-brand-deep);
}

.nav-separator {
  color: var(--color-sketch);
  font-size: 13px;
  user-select: none;
}

.header-tools {
  position: relative;
  display: flex;
  flex-shrink: 0;
  align-items: center;
  gap: 8px;
}

.language-button,
.menu-toggle {
  min-height: 44px;
  border: 1px solid var(--color-line);
  background: var(--color-page);
  color: var(--color-ink);
  cursor: pointer;
}

.language-button {
  display: inline-flex;
  min-width: 116px;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding-inline: 14px;
  border-radius: var(--radius-pill);
  font-size: 13.5px;
}

.language-short {
  display: none;
}

.language-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: 70;
  display: none;
  width: 170px;
  padding: 7px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-page);
  color: var(--color-ink);
  box-shadow: var(--shadow-card);
}

.language-menu.is-open {
  display: block;
}

.language-menu a {
  display: flex;
  min-height: 42px;
  align-items: center;
  width: 100%;
  padding: 8px 11px;
  border-radius: var(--radius-xs);
  color: var(--color-ink);
  text-decoration: none;
}

.language-menu a:hover,
.language-menu a[aria-current="true"] {
  background: var(--color-panel);
  color: var(--color-brand-deep);
}

.menu-toggle {
  display: none;
  min-width: 44px;
  padding: 10px;
  border-radius: 50%;
}

.menu-toggle-lines,
.menu-toggle-lines::before,
.menu-toggle-lines::after {
  display: block;
  width: 19px;
  height: 2px;
  border-radius: var(--radius-pill);
  background: var(--color-ink);
  content: "";
  transition: transform 160ms var(--ease-out);
}

.menu-toggle-lines {
  position: relative;
  margin-inline: auto;
}

.menu-toggle-lines::before {
  position: absolute;
  top: -6px;
}

.menu-toggle-lines::after {
  position: absolute;
  top: 6px;
}

.menu-toggle[aria-expanded="true"] .menu-toggle-lines {
  background: transparent;
}

.menu-toggle[aria-expanded="true"] .menu-toggle-lines::before {
  transform: translateY(6px) rotate(45deg);
}

.menu-toggle[aria-expanded="true"] .menu-toggle-lines::after {
  transform: translateY(-6px) rotate(-45deg);
}

.mobile-drawer {
  position: fixed;
  top: var(--header-height);
  right: 0;
  left: 0;
  z-index: 65;
  display: none;
  max-height: calc(100dvh - var(--header-height));
  padding: 10px var(--gutter) 22px;
  overflow-y: auto;
  overscroll-behavior: contain;
  border-top: 1px solid var(--color-line);
  background: var(--color-page);
  color: var(--color-ink);
}

.mobile-drawer.is-open {
  display: block;
}

.mobile-drawer a {
  display: flex;
  min-height: 48px;
  align-items: center;
  width: 100%;
  padding: 10px 12px;
  border-bottom: 1px solid var(--color-line);
  color: var(--color-ink);
  text-decoration: none;
}

.mobile-drawer a.is-current {
  color: var(--color-brand-deep);
  font-weight: 700;
}

.mobile-language-title {
  margin: 18px 12px 4px;
  color: var(--color-muted);
  font-size: 12px;
  letter-spacing: 0.12em;
}

.nav-veil {
  position: fixed;
  inset: var(--header-height) 0 0;
  z-index: 40;
  display: none;
  background: var(--color-overlay);
}

.nav-veil.is-open {
  display: block;
}

.site-footer {
  padding-top: 72px;
  padding-bottom: 28px;
  border-top: 1px solid var(--color-line);
  background: var(--color-panel);
  color: var(--color-ink);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.35fr 1fr 1.4fr 1fr;
  gap: 38px;
}

.footer-brand p {
  max-width: 28em;
  margin-top: 16px;
  color: var(--color-muted);
  font-size: 14px;
}

.footer-title {
  margin-bottom: 14px;
  color: var(--color-ink);
  font-size: 13px;
  font-weight: 750;
  letter-spacing: 0.08em;
}

.footer-links {
  display: grid;
  gap: 8px;
}

.footer-links a {
  color: var(--color-muted);
  font-size: 14px;
  text-decoration: none;
}

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

.footer-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.footer-keywords a {
  max-width: 100%;
  padding: 5px 10px;
  overflow: hidden;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-page);
  color: var(--color-ink);
  font-size: 12.5px;
  text-decoration: none;
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 14px;
  margin-top: 48px;
  padding-top: 22px;
  border-top: 1px solid var(--color-line);
  color: var(--color-muted);
  font-size: 13px;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
}

.footer-legal a {
  color: var(--color-muted);
}

.hero-area,
.decorated-section {
  position: relative;
  overflow-x: clip;
}

.tilt,
.tilt-soft {
  transform: rotate(-0.45deg);
}

@media (max-width: 1040px) {
  .desktop-nav {
    display: none;
  }

  .header-tools {
    margin-left: auto;
  }

  .menu-toggle {
    display: block;
  }

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

@media (max-width: 768px) {
  h1,
  .hero-title {
    font-size: clamp(24px, 7vw, 30px);
    line-height: 1.22;
    letter-spacing: 0;
  }

  h2 {
    font-size: clamp(25px, 7vw, 32px);
  }

  .section {
    padding-top: 76px;
    padding-bottom: 76px;
  }

  .card-grid {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr;
  }

  .language-full {
    display: none;
  }

  .language-short {
    display: inline;
  }

  .language-button {
    min-width: 56px;
    padding-inline: 10px;
  }
}

@media (max-width: 640px) {
  :root {
    --gutter: 16px;
    --header-height: 70px;
  }

  .site-brand {
    gap: 8px;
    font-size: 15px;
  }

  .site-brand img {
    width: 32px;
    height: 32px;
  }

  .button-row {
    justify-content: center;
  }

  .button {
    width: 100%;
  }

  .tilt,
  .tilt-soft {
    transform: none;
  }

  th,
  td {
    padding: 11px 12px;
  }
}

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }
}