:root {
  color-scheme: light;
  --background: #f3f3f1;
  --background-strong: #fafaf8;
  --surface: rgb(255 255 255 / 0.62);
  --surface-strong: rgb(255 255 255 / 0.86);
  --surface-muted: rgb(255 255 255 / 0.44);
  --border: rgb(24 24 27 / 0.12);
  --border-strong: rgb(24 24 27 / 0.2);
  --text-primary: #171717;
  --text-secondary: #5d5d5d;
  --text-muted: #858585;
  --button-bg: #171717;
  --button-text: #f8f8f6;
  --button-hover: #2a2a2a;
  --success: #17603a;
  --shadow-image: 0 30px 80px rgb(24 24 27 / 0.12);
  --radius: 14px;
  --radius-lg: 28px;
  --radius-pill: 999px;
  --page: min(1120px, calc(100vw - 48px));
  --font: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --background: #111111;
    --background-strong: #171717;
    --surface: rgb(35 35 35 / 0.62);
    --surface-strong: rgb(38 38 38 / 0.86);
    --surface-muted: rgb(255 255 255 / 0.07);
    --border: rgb(255 255 255 / 0.12);
    --border-strong: rgb(255 255 255 / 0.2);
    --text-primary: #f3f3f1;
    --text-secondary: #c4c4c0;
    --text-muted: #8f8f8b;
    --button-bg: #f3f3f1;
    --button-text: #151515;
    --button-hover: #ffffff;
    --success: #8fe0b6;
    --shadow-image: 0 34px 90px rgb(0 0 0 / 0.4);
  }
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --background: #111111;
  --background-strong: #171717;
  --surface: rgb(35 35 35 / 0.62);
  --surface-strong: rgb(38 38 38 / 0.86);
  --surface-muted: rgb(255 255 255 / 0.07);
  --border: rgb(255 255 255 / 0.12);
  --border-strong: rgb(255 255 255 / 0.2);
  --text-primary: #f3f3f1;
  --text-secondary: #c4c4c0;
  --text-muted: #8f8f8b;
  --button-bg: #f3f3f1;
  --button-text: #151515;
  --button-hover: #ffffff;
  --success: #8fe0b6;
  --shadow-image: 0 34px 90px rgb(0 0 0 / 0.4);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  min-width: 320px;
  margin: 0;
  color: var(--text-primary);
  background: var(--background);
  font-family: var(--font);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: inherit;
  text-decoration: none;
}

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

button {
  color: inherit;
  font: inherit;
}

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

::selection {
  color: var(--button-text);
  background: var(--button-bg);
}

.skip-link:not(:focus) {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 12px;
  left: 12px;
  padding: 10px 14px;
  color: var(--button-text);
  background: var(--button-bg);
  border-radius: 10px;
}

.site-header {
  position: fixed;
  z-index: 20;
  top: 0;
  left: 0;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  width: 100%;
  min-height: 72px;
  padding: 12px max(24px, calc((100vw - 1120px) / 2));
  background: linear-gradient(180deg, var(--surface-strong), var(--surface));
  backdrop-filter: blur(24px) saturate(160%);
  -webkit-backdrop-filter: blur(24px) saturate(160%);
  transition: min-height 180ms ease, box-shadow 180ms ease, background-color 180ms ease;
}

.site-header::after {
  position: absolute;
  right: 0;
  bottom: -16px;
  left: 0;
  height: 16px;
  content: "";
  pointer-events: none;
  background: linear-gradient(180deg, rgb(0 0 0 / 0.035), transparent);
  opacity: 0;
  transition: opacity 180ms ease;
}

.site-header.is-scrolled {
  min-height: 64px;
  box-shadow: inset 0 1px rgb(255 255 255 / 0.14);
}

.site-header.is-scrolled::after {
  opacity: 1;
}

.brand,
.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
}

.brand {
  justify-self: start;
  min-width: 0;
}

.brand img,
.footer-brand img {
  flex: 0 0 auto;
  border-radius: 10px;
}

.brand > span {
  display: grid;
  min-width: 0;
}

.brand strong {
  overflow: hidden;
  font-size: 14px;
  font-weight: 660;
  letter-spacing: -0.01em;
  line-height: 1.2;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.brand small {
  margin-top: 2px;
  overflow: hidden;
  color: var(--text-muted);
  font-size: 10px;
  letter-spacing: 0.01em;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 28px;
  justify-self: center;
}

.site-nav a {
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 560;
  transition: color 120ms ease;
}

.site-nav a:hover {
  color: var(--text-primary);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  justify-self: end;
}

.language-toggle,
.donation-link,
.header-cta {
  height: 38px;
  border-radius: var(--radius-pill);
}

.language-toggle {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 0 12px;
  color: var(--text-secondary);
  background: transparent;
  border: 0;
  cursor: pointer;
}

.language-toggle i {
  width: 1px;
  height: 12px;
  background: var(--border-strong);
}

.lang-option {
  font-size: 11px;
  font-style: normal;
  font-weight: 650;
}

:lang(zh-CN) .lang-option-zh,
:lang(en) .lang-option-en {
  color: var(--text-primary);
}

.donation-link {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 0 13px;
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 620;
  border: 1px solid var(--border);
}

.donation-link img {
  width: 20px;
  height: 20px;
  object-fit: contain;
}

.header-cta {
  display: inline-flex;
  align-items: center;
  padding: 0 17px;
  color: var(--button-text);
  background: var(--button-bg);
  font-size: 12px;
  font-weight: 650;
}

.language-toggle:active,
.donation-link:active,
.header-cta:active,
.button:active,
.screenshot-tabs button:active,
.nav-toggle:active {
  transform: scale(0.97);
  transition: transform 100ms ease-out;
}

.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  padding: 0;
  background: transparent;
  border: 0;
  border-radius: 50%;
}

.nav-toggle span {
  display: block;
  width: 17px;
  height: 1.5px;
  margin: 5px auto;
  background: currentColor;
  transition: transform 180ms ease;
}

.nav-toggle[aria-expanded="true"] span:first-child {
  transform: translateY(3.25px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] span:last-child {
  transform: translateY(-3.25px) rotate(-45deg);
}

.hero,
.section,
.final-cta,
.site-footer {
  width: var(--page);
  margin-inline: auto;
}

.hero {
  padding-top: clamp(160px, 18vw, 230px);
  text-align: center;
}

.hero-copy {
  max-width: 900px;
  margin-inline: auto;
}

.hero h1,
.section h2,
.final-cta h2 {
  margin: 0;
  font-weight: 690;
  letter-spacing: -0.045em;
  text-wrap: balance;
}

.hero h1 {
  font-size: clamp(3.6rem, 8vw, 6.8rem);
  line-height: 0.96;
}

:lang(en) .hero h1 {
  font-size: clamp(3.3rem, 7.4vw, 6.4rem);
}

.marker {
  color: var(--text-secondary);
}

.hero-lede {
  max-width: 720px;
  margin: 34px auto 0;
  color: var(--text-secondary);
  font-size: clamp(1.05rem, 1.7vw, 1.24rem);
  line-height: 1.75;
  text-wrap: pretty;
}

.hero-lede em {
  color: var(--text-primary);
  font-style: normal;
}

.hero-actions,
.final-cta-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
}

.hero-actions {
  margin-top: 36px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  min-height: 52px;
  padding: 0 23px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-size: 14px;
  font-weight: 640;
}

.button-primary {
  color: var(--button-text);
  background: var(--button-bg);
}

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

.button-secondary {
  background: var(--surface-muted);
  border-color: var(--border);
}

.button-secondary:hover {
  background: var(--surface-strong);
}

.micro-proof {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 18px 0 0;
  color: var(--text-muted);
  font-size: 12px;
}

.status-dot {
  width: 6px;
  height: 6px;
  background: var(--success);
  border-radius: 50%;
}

.hero-demo {
  aspect-ratio: 16 / 10;
  margin: clamp(70px, 9vw, 110px) 0 0;
  overflow: hidden;
  background: var(--background-strong);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-image);
}

.hero-demo img,
.screenshot-frame img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.section {
  padding: clamp(110px, 13vw, 170px) 0;
  border-top: 1px solid var(--border);
  scroll-margin-top: 72px;
}

.section-heading {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 0.7fr);
  gap: 64px;
  align-items: end;
}

.section-heading h2,
.privacy h2,
.final-cta h2 {
  font-size: clamp(2.7rem, 5.6vw, 5rem);
  line-height: 1.02;
}

.section-heading > p,
.privacy-copy > p {
  margin: 0;
  color: var(--text-secondary);
  font-size: 16px;
  line-height: 1.75;
}

.benefit-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: clamp(34px, 6vw, 72px);
  margin-top: clamp(70px, 8vw, 100px);
}

.benefit-icon {
  display: grid;
  width: 48px;
  height: 48px;
  place-items: center;
  color: var(--text-primary);
  background: var(--surface-muted);
  border: 1px solid var(--border);
  border-radius: 14px;
}

.benefit-icon svg,
.privacy-mark svg {
  width: 24px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 1.6;
}

.benefit h3,
.steps h3 {
  margin: 25px 0 10px;
  font-size: 18px;
  font-weight: 660;
  letter-spacing: -0.015em;
}

.benefit p,
.steps p {
  margin: 0;
  color: var(--text-secondary);
  font-size: 14px;
  line-height: 1.7;
}

.workflow .section-heading {
  display: block;
  max-width: 720px;
}

.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: clamp(30px, 6vw, 72px);
  padding: 0;
  margin: clamp(60px, 8vw, 96px) 0 0;
  list-style: none;
}

.step-index {
  display: grid;
  width: 32px;
  height: 32px;
  place-items: center;
  color: var(--button-text);
  background: var(--button-bg);
  border-radius: 50%;
  font-size: 12px;
  font-weight: 700;
}

.steps h3 {
  margin-top: 22px;
}

.screenshot-stage {
  margin-top: clamp(70px, 9vw, 110px);
}

.screenshot-tabs {
  display: flex;
  width: max-content;
  max-width: 100%;
  padding: 4px;
  margin: 0 auto 24px;
  overflow-x: auto;
  background: var(--surface-muted);
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
}

.screenshot-tabs button {
  flex: 0 0 auto;
  min-height: 38px;
  padding: 0 17px;
  color: var(--text-secondary);
  background: transparent;
  border: 0;
  border-radius: var(--radius-pill);
  font-size: 12px;
  font-weight: 610;
  cursor: pointer;
}

.screenshot-tabs button[aria-selected="true"] {
  color: var(--text-primary);
  background: var(--surface-strong);
  box-shadow: 0 1px 4px rgb(0 0 0 / 0.08);
}

.screenshot-frame {
  aspect-ratio: 16 / 10;
  overflow: hidden;
  background: var(--background-strong);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-image);
}

.screenshot-frame img {
  opacity: 1;
  transition: opacity 180ms ease;
}

.screenshot-frame img.is-changing {
  opacity: 0;
}

.screenshot-stage > p {
  margin: 18px 0 0;
  color: var(--text-muted);
  font-size: 12px;
  text-align: center;
}

.privacy {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 200px;
  gap: 80px;
  align-items: center;
}

.privacy-copy {
  max-width: 760px;
}

.privacy-copy > p {
  max-width: 680px;
  margin-top: 28px;
}

.privacy-copy > a {
  display: inline-flex;
  gap: 8px;
  margin-top: 28px;
  font-size: 14px;
  font-weight: 640;
}

.privacy-mark {
  display: grid;
  width: 160px;
  height: 160px;
  place-items: center;
  justify-self: end;
  color: var(--text-primary);
  background: var(--surface-muted);
  border: 1px solid var(--border);
  border-radius: 42px;
}

.privacy-mark svg {
  width: 60px;
  stroke-width: 1.25;
}

.final-cta {
  padding: clamp(110px, 14vw, 180px) 0;
  text-align: center;
  border-top: 1px solid var(--border);
}

.final-cta h2 {
  max-width: 900px;
  margin-inline: auto;
}

.final-cta-actions {
  margin-top: 36px;
}

.final-cta-actions > a:not(.button) {
  padding: 12px;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 610;
}

.site-footer {
  display: grid;
  grid-template-columns: 1fr auto auto;
  gap: 28px;
  align-items: center;
  padding: 34px 0 42px;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  font-size: 12px;
}

.footer-brand strong {
  color: var(--text-primary);
  font-size: 13px;
  font-weight: 640;
}

.footer-links {
  display: flex;
  gap: 22px;
}

.footer-links a:hover,
.final-cta-actions > a:not(.button):hover,
.privacy-copy > a:hover {
  color: var(--text-primary);
}

.site-footer p {
  margin: 0;
}

.reveal {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 520ms ease, transform 520ms cubic-bezier(0.2, 0.75, 0.2, 1);
}

.reveal-delay-1 {
  transition-delay: 70ms;
}

.reveal-delay-2 {
  transition-delay: 140ms;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 940px) {
  .site-header {
    grid-template-columns: 1fr auto;
  }

  .site-nav {
    position: absolute;
    top: calc(100% + 8px);
    right: 24px;
    display: grid;
    gap: 4px;
    width: 210px;
    padding: 8px;
    visibility: hidden;
    background: var(--surface-strong);
    border: 1px solid var(--border);
    border-radius: 18px;
    box-shadow: 0 18px 50px rgb(0 0 0 / 0.14);
    opacity: 0;
    transform: scale(0.96) translateY(-4px);
    transform-origin: top right;
    backdrop-filter: blur(24px) saturate(160%);
    -webkit-backdrop-filter: blur(24px) saturate(160%);
    transition: opacity 160ms ease, transform 160ms ease, visibility 160ms;
  }

  .site-nav.is-open {
    visibility: visible;
    opacity: 1;
    transform: scale(1) translateY(0);
  }

  .site-nav a {
    padding: 11px 12px;
    border-radius: 10px;
  }

  .site-nav a:hover {
    background: var(--surface-muted);
  }

  .nav-toggle {
    display: block;
  }

  .section-heading {
    grid-template-columns: 1fr;
    gap: 28px;
    max-width: 760px;
  }
}

@media (max-width: 720px) {
  :root {
    --page: min(100% - 32px, 1120px);
  }

  .site-header {
    padding-inline: 16px;
  }

  .brand small {
    display: none;
  }

  .donation-link span,
  .header-cta {
    display: none;
  }

  .donation-link {
    width: 38px;
    padding: 0;
    justify-content: center;
    border: 0;
  }

  .language-toggle {
    padding-inline: 7px;
  }

  .hero {
    padding-top: 142px;
  }

  .hero h1,
  :lang(en) .hero h1 {
    font-size: clamp(3rem, 14vw, 5rem);
    line-height: 0.98;
  }

  .hero-lede {
    margin-top: 26px;
    font-size: 16px;
    line-height: 1.7;
  }

  .hero-actions,
  .final-cta-actions {
    flex-direction: column;
  }

  .hero-actions .button,
  .final-cta-actions .button {
    width: 100%;
  }

  .hero-demo {
    margin-top: 64px;
    border-radius: 18px;
  }

  .section {
    padding-block: 96px;
  }

  .section-heading h2,
  .privacy h2,
  .final-cta h2 {
    font-size: clamp(2.45rem, 11vw, 3.6rem);
  }

  .benefit-list,
  .steps {
    grid-template-columns: 1fr;
    gap: 0;
  }

  .benefit-list {
    margin-top: 62px;
  }

  .benefit,
  .steps li {
    padding: 28px 0;
    border-top: 1px solid var(--border);
  }

  .benefit:first-child,
  .steps li:first-child {
    border-top: 0;
  }

  .benefit-icon {
    width: 44px;
    height: 44px;
  }

  .steps {
    margin-top: 42px;
  }

  .screenshot-stage {
    margin-top: 62px;
  }

  .screenshot-tabs {
    width: 100%;
    justify-content: flex-start;
  }

  .screenshot-tabs button {
    flex: 1 1 0;
    min-width: 0;
    padding-inline: 10px;
    font-size: 11px;
  }

  .screenshot-frame {
    border-radius: 18px;
  }

  .privacy {
    grid-template-columns: 1fr;
    gap: 52px;
  }

  .privacy-mark {
    width: 96px;
    height: 96px;
    justify-self: start;
    border-radius: 28px;
  }

  .privacy-mark svg {
    width: 42px;
  }

  .final-cta {
    padding-block: 106px;
  }

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

  .footer-links {
    grid-column: 1 / -1;
    grid-row: 2;
    flex-wrap: wrap;
  }
}

@media (max-width: 430px) {
  .brand > span {
    display: none;
  }

  .header-actions {
    gap: 2px;
  }

  .hero h1,
  :lang(en) .hero h1 {
    font-size: clamp(2.8rem, 13.8vw, 4rem);
  }
}

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0ms !important;
  }

  .reveal {
    transform: none;
  }
}

@media (prefers-reduced-transparency: reduce) {
  .site-header,
  .site-nav {
    background: var(--background-strong);
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }
}

@media (prefers-contrast: more) {
  .site-header,
  .site-nav,
  .hero-demo,
  .screenshot-frame,
  .benefit-icon,
  .privacy-mark {
    border: 1px solid currentColor;
  }
}