:root {
  --bg: #f6f3ec;
  --bg-elevated: #fffdf8;
  --text: #1d2b26;
  --muted: #65716b;
  --line: rgba(29, 43, 38, 0.14);
  --green: #1f5b43;
  --green-deep: #173f31;
  --green-soft: #dbe8dc;
  --orange: #df6d39;
  --yellow: #ebc85a;
  --shadow: 0 28px 80px rgba(29, 43, 38, 0.11);
  --radius-lg: 32px;
  --radius-md: 20px;
  --content-width: 1160px;
}

[data-theme="dark"] {
  --bg: #111915;
  --bg-elevated: #17211c;
  --text: #edf2ed;
  --muted: #aab5ae;
  --line: rgba(237, 242, 237, 0.14);
  --green: #8fc8a7;
  --green-deep: #d7ebdd;
  --green-soft: #243b30;
  --orange: #f08a57;
  --yellow: #ebc85a;
  --shadow: 0 28px 80px rgba(0, 0, 0, 0.28);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 88px;
}

body {
  margin: 0;
  min-width: 320px;
  color: var(--text);
  background:
    radial-gradient(circle at 78% 8%, rgba(235, 200, 90, 0.1), transparent 28rem),
    var(--bg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

button,
a {
  color: inherit;
}

a {
  text-decoration: none;
}

button {
  font: inherit;
}

svg {
  display: block;
}

::selection {
  color: #fff;
  background: var(--green);
}

.skip-link {
  position: fixed;
  z-index: 1000;
  top: 12px;
  left: 12px;
  padding: 10px 14px;
  color: #fff;
  background: var(--green-deep);
  border-radius: 8px;
  transform: translateY(-160%);
  transition: transform 180ms ease;
}

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

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.site-header {
  position: fixed;
  z-index: 100;
  top: 0;
  left: 0;
  width: 100%;
  border-bottom: 1px solid transparent;
  transition: background-color 200ms ease, border-color 200ms ease, box-shadow 200ms ease;
}

.site-header.is-scrolled {
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  border-color: var(--line);
  box-shadow: 0 8px 28px rgba(29, 43, 38, 0.04);
  backdrop-filter: blur(16px);
}

.header-inner {
  width: min(calc(100% - 40px), var(--content-width));
  height: 76px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  font-size: 17px;
  font-weight: 750;
  letter-spacing: 0.02em;
}

.brand-mark {
  width: 35px;
  height: 35px;
  flex: 0 0 auto;
  object-fit: cover;
  border-radius: 50% 50% 46% 54% / 55% 45% 55% 45%;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 30px;
}

.site-nav > a {
  position: relative;
  color: var(--muted);
  font-size: 14px;
  font-weight: 600;
  transition: color 160ms ease;
}

.site-nav > a::after {
  position: absolute;
  bottom: -7px;
  left: 0;
  width: 100%;
  height: 2px;
  content: "";
  background: var(--orange);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 180ms ease;
}

.site-nav > a:hover,
.site-nav > a:focus-visible {
  color: var(--text);
}

.site-nav > a:hover::after,
.site-nav > a:focus-visible::after {
  transform: scaleX(1);
  transform-origin: left;
}

.theme-toggle,
.menu-toggle {
  border: 0;
  cursor: pointer;
}

.theme-toggle {
  width: 38px;
  height: 38px;
  display: grid;
  place-items: center;
  color: var(--text);
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  border-radius: 50%;
}

.theme-toggle svg {
  width: 18px;
  height: 18px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 1.7;
}

.moon-icon,
[data-theme="dark"] .sun-icon {
  display: none;
}

[data-theme="dark"] .moon-icon {
  display: block;
}

.menu-toggle {
  display: none;
  padding: 8px;
  background: transparent;
}

.menu-toggle span:not(.sr-only) {
  width: 22px;
  height: 2px;
  display: block;
  margin: 5px 0;
  background: var(--text);
  border-radius: 2px;
}

.hero {
  position: relative;
  min-height: 760px;
  overflow: hidden;
  display: grid;
  align-items: center;
  padding: 132px 0 80px;
}

.hero::after {
  position: absolute;
  right: -80px;
  bottom: 0;
  width: 46%;
  height: 1px;
  content: "";
  background: var(--line);
  transform: rotate(-8deg);
  transform-origin: right;
}

.hero-inner {
  position: relative;
  z-index: 2;
  width: min(calc(100% - 40px), var(--content-width));
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.04fr 0.96fr;
  align-items: center;
  gap: 60px;
}

.eyebrow,
.section-index {
  margin: 0;
  color: var(--green);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.eyebrow {
  display: flex;
  align-items: center;
  gap: 10px;
}

.eyebrow span {
  width: 24px;
  height: 2px;
  display: inline-block;
  background: var(--orange);
}

.hero h1 {
  margin: 22px 0 24px;
  font-family: Georgia, "Songti SC", "STSong", serif;
  font-size: clamp(48px, 6.2vw, 78px);
  font-weight: 500;
  line-height: 1.13;
  letter-spacing: -0.045em;
}

.hero h1 em {
  position: relative;
  color: var(--green);
  font-style: normal;
}

.hero h1 em::after {
  position: absolute;
  z-index: -1;
  right: -5px;
  bottom: 5px;
  left: -5px;
  height: 13px;
  content: "";
  background: color-mix(in srgb, var(--yellow) 64%, transparent);
  transform: rotate(-1.5deg);
}

.hero-description {
  max-width: 570px;
  margin: 0;
  color: var(--muted);
  font-size: 17px;
  line-height: 1.9;
}

.hero-actions {
  margin: 34px 0 32px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.button {
  min-height: 48px;
  padding: 11px 22px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 14px;
  font-weight: 700;
  transition: transform 160ms ease, background-color 160ms ease, border-color 160ms ease;
}

.button:hover {
  transform: translateY(-2px);
}

.button-primary {
  color: #f8f4e8;
  background: var(--green-deep);
  border-color: var(--green-deep);
}

.button-ghost:hover {
  background: var(--bg-elevated);
  border-color: var(--green);
}

.hero-tags {
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 22px;
  list-style: none;
  color: var(--muted);
  font-size: 12px;
  font-weight: 650;
}

.hero-tags li::before {
  content: "✦";
  margin-right: 7px;
  color: var(--orange);
}

.hero-visual {
  position: relative;
  min-height: 500px;
  display: grid;
  place-items: center;
}

.hero-decoration {
  position: absolute;
  border: 1px solid var(--line);
  border-radius: 50%;
}

.hero-decoration-one {
  top: 120px;
  right: -120px;
  width: 500px;
  height: 500px;
}

.hero-decoration-two {
  top: 250px;
  right: 9%;
  width: 210px;
  height: 210px;
  border-color: color-mix(in srgb, var(--orange) 35%, transparent);
}

.paper-stack {
  position: relative;
  width: min(360px, 78vw);
  height: 430px;
  transform: rotate(3deg);
}

.paper {
  position: absolute;
  inset: 0;
  border: 1px solid rgba(29, 43, 38, 0.12);
  border-radius: 4px 24px 5px 18px;
  box-shadow: var(--shadow);
}

.paper-back {
  background: var(--orange);
  transform: rotate(9deg) translate(22px, 8px);
}

.paper-middle {
  background: var(--yellow);
  transform: rotate(-6deg) translate(-18px, 12px);
}

.paper-front {
  padding: 34px;
  color: #1d2b26;
  background: #fffdf8;
  transform: rotate(-1deg);
}

.paper-header,
.paper-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.paper-header {
  padding-bottom: 17px;
  border-bottom: 1px solid rgba(29, 43, 38, 0.18);
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.14em;
}

.paper-dot {
  width: 8px;
  height: 8px;
  background: var(--orange);
  border-radius: 50%;
}

.paper-label {
  margin: 48px 0 10px;
  color: #65716b;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.14em;
}

.paper-title {
  margin: 0 0 38px;
  font-family: Georgia, "Songti SC", serif;
  font-size: 27px;
  font-weight: 600;
  line-height: 1.45;
}

.paper-line {
  width: 76%;
  height: 2px;
  margin: 14px 0;
  background: rgba(29, 43, 38, 0.18);
}

.paper-line.long {
  width: 100%;
}

.paper-line.short {
  width: 52%;
}

.paper-footer {
  position: absolute;
  right: 34px;
  bottom: 30px;
  left: 34px;
  color: #65716b;
  font-size: 11px;
  font-weight: 700;
}

.float-note {
  position: absolute;
  z-index: 4;
  padding: 7px 13px;
  color: #f8f4e8;
  background: var(--green-deep);
  border-radius: 999px;
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.08em;
  box-shadow: 0 12px 24px rgba(29, 43, 38, 0.14);
}

.float-note-one { top: 12%; left: 3%; transform: rotate(-8deg); }
.float-note-two { top: 37%; right: -2%; transform: rotate(6deg); }
.float-note-three { bottom: 10%; left: 7%; transform: rotate(-3deg); }

.section {
  width: min(calc(100% - 40px), var(--content-width));
  margin: 0 auto;
  padding: 112px 0;
}

.section-heading {
  margin-bottom: 48px;
  display: grid;
  grid-template-columns: 190px 1fr;
  gap: 28px;
}

.section-heading h2,
.method-copy h2,
.about-card h2 {
  margin: 0;
  font-family: Georgia, "Songti SC", "STSong", serif;
  font-size: clamp(34px, 4vw, 50px);
  font-weight: 500;
  line-height: 1.3;
  letter-spacing: -0.025em;
}

.section-heading p:not(.section-index) {
  margin: 13px 0 0;
  color: var(--muted);
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.topic-card {
  position: relative;
  min-height: 350px;
  padding: 32px;
  overflow: hidden;
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  transition: transform 200ms ease, box-shadow 200ms ease, border-color 200ms ease;
}

.topic-card::after {
  position: absolute;
  right: -50px;
  bottom: -75px;
  width: 190px;
  height: 190px;
  content: "";
  background: var(--green-soft);
  border-radius: 50%;
  opacity: 0.52;
  transition: transform 240ms ease;
}

.topic-card:hover {
  border-color: color-mix(in srgb, var(--green) 40%, transparent);
  box-shadow: 0 24px 55px rgba(29, 43, 38, 0.09);
  transform: translateY(-6px);
}

.topic-card:hover::after {
  transform: scale(1.12);
}

.topic-number {
  position: absolute;
  top: 25px;
  right: 28px;
  color: var(--muted);
  font-family: Georgia, serif;
  font-size: 13px;
}

.topic-icon {
  width: 58px;
  height: 58px;
  margin: 38px 0 32px;
  display: grid;
  place-items: center;
  color: var(--green);
  background: var(--green-soft);
  border-radius: 18px;
}

.topic-icon svg {
  width: 30px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 1.7;
}

.topic-card h3 {
  margin: 0 0 12px;
  font-family: Georgia, "Songti SC", serif;
  font-size: 25px;
  font-weight: 600;
}

.topic-card p {
  position: relative;
  z-index: 1;
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.85;
}

.topic-meta {
  position: absolute;
  z-index: 1;
  bottom: 28px;
  left: 32px;
  color: var(--green);
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.08em;
}

.method-section {
  width: 100%;
  max-width: none;
  padding: 80px 20px;
}

.method-panel {
  width: min(100%, var(--content-width));
  margin: 0 auto;
  padding: clamp(38px, 7vw, 80px);
  display: grid;
  grid-template-columns: 0.85fr 1.15fr;
  gap: clamp(50px, 8vw, 100px);
  color: #f0f4f0;
  background: var(--green-deep);
  border-radius: var(--radius-lg);
}

[data-theme="dark"] .method-panel {
  color: #173025;
  background: #b8d7c4;
}

.method-copy .section-index {
  color: var(--yellow);
}

.method-copy h2 {
  margin-top: 20px;
  color: inherit;
}

.method-copy > p:last-child {
  margin: 25px 0 0;
  color: color-mix(in srgb, currentColor 70%, transparent);
}

.method-steps {
  margin: 0;
  padding: 0;
  list-style: none;
}

.method-steps li {
  padding: 20px 0;
  display: grid;
  grid-template-columns: 52px 1fr;
  gap: 18px;
  border-bottom: 1px solid color-mix(in srgb, currentColor 18%, transparent);
}

.method-steps li:first-child {
  padding-top: 0;
}

.method-steps li:last-child {
  padding-bottom: 0;
  border-bottom: 0;
}

.method-steps > li > span {
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  color: var(--green-deep);
  background: var(--yellow);
  border-radius: 50%;
  font-family: Georgia, serif;
  font-size: 12px;
  font-weight: 700;
}

.method-steps h3 {
  margin: 0 0 3px;
  font-size: 17px;
}

.method-steps p {
  margin: 0;
  color: color-mix(in srgb, currentColor 68%, transparent);
  font-size: 13px;
}

.notes-list {
  border-top: 1px solid var(--line);
}

.note-row {
  padding: 28px 18px;
  display: grid;
  grid-template-columns: 54px 1fr 40px;
  align-items: center;
  gap: 22px;
  border-bottom: 1px solid var(--line);
  transition: background-color 160ms ease, padding 160ms ease;
}

.note-row:hover {
  padding-right: 28px;
  padding-left: 28px;
  background: var(--bg-elevated);
}

.note-mark {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  color: var(--green);
  background: var(--green-soft);
  border-radius: 50%;
  font-family: Georgia, serif;
  font-weight: 700;
}

.note-tags {
  margin-bottom: 7px;
  display: flex;
  gap: 7px;
}

.note-tags span {
  padding: 2px 8px;
  color: var(--muted);
  background: color-mix(in srgb, var(--green-soft) 58%, transparent);
  border-radius: 999px;
  font-size: 10px;
  font-weight: 700;
}

.note-content h3 {
  margin: 0 0 4px;
  font-size: 18px;
}

.note-content p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
}

.note-arrow {
  color: var(--orange);
  font-size: 20px;
}

.about-section {
  padding-top: 70px;
}

.about-card {
  padding: clamp(36px, 6vw, 70px);
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: 60px;
  background: var(--green-soft);
  border-radius: var(--radius-lg);
}

.about-card .section-index {
  margin-bottom: 18px;
}

.about-text {
  padding-left: 40px;
  border-left: 1px solid color-mix(in srgb, var(--green) 28%, transparent);
}

.about-text p {
  margin: 0 0 14px;
  color: var(--muted);
  font-size: 15px;
}

.about-text p:last-child {
  margin-bottom: 0;
}

.site-footer {
  margin-top: 30px;
  padding: 42px 0;
  border-top: 1px solid var(--line);
}

.footer-inner {
  width: min(calc(100% - 40px), var(--content-width));
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 30px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.footer-brand strong,
.footer-brand small {
  display: block;
}

.footer-brand strong {
  font-size: 14px;
}

.footer-brand small {
  margin-top: 2px;
  color: var(--muted);
  font-size: 11px;
}

.footer-meta {
  color: var(--muted);
  text-align: right;
  font-size: 11px;
}

.footer-meta p {
  margin: 0 0 4px;
}

.record-links {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
}

.record-links a:hover,
.record-links a:focus-visible {
  color: var(--green);
  text-decoration: underline;
}

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 650ms ease, transform 650ms ease;
}

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

:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--orange) 72%, transparent);
  outline-offset: 4px;
}

@media (max-width: 900px) {
  .site-nav {
    position: fixed;
    top: 66px;
    right: 20px;
    left: 20px;
    padding: 22px;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 18px;
    background: var(--bg-elevated);
    border: 1px solid var(--line);
    border-radius: 18px;
    box-shadow: var(--shadow);
  }

  .site-nav.is-open {
    display: flex;
  }

  .site-nav .theme-toggle {
    position: absolute;
    right: 16px;
    bottom: 14px;
  }

  .menu-toggle {
    display: block;
  }

  .hero {
    padding-top: 125px;
  }

  .hero-inner {
    grid-template-columns: 1fr;
    gap: 55px;
  }

  .hero-copy {
    max-width: 680px;
  }

  .hero-visual {
    min-height: 480px;
  }

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

  .topic-card {
    min-height: 290px;
  }

  .method-panel,
  .about-card {
    grid-template-columns: 1fr;
  }

  .method-panel {
    gap: 55px;
  }

  .about-card {
    gap: 32px;
  }

  .about-text {
    padding: 30px 0 0;
    border-top: 1px solid color-mix(in srgb, var(--green) 28%, transparent);
    border-left: 0;
  }
}

@media (max-width: 640px) {
  .header-inner,
  .hero-inner,
  .section,
  .footer-inner {
    width: min(calc(100% - 30px), var(--content-width));
  }

  .header-inner {
    height: 66px;
  }

  .brand {
    font-size: 15px;
  }

  .brand-mark {
    width: 32px;
    height: 32px;
  }

  .hero {
    min-height: auto;
    padding: 108px 0 64px;
  }

  .hero h1 {
    font-size: clamp(42px, 13vw, 58px);
  }

  .hero-description {
    font-size: 15px;
  }

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

  .hero-tags {
    gap: 11px 17px;
  }

  .hero-visual {
    min-height: 410px;
  }

  .paper-stack {
    width: 270px;
    height: 360px;
  }

  .paper-front {
    padding: 26px;
  }

  .paper-label {
    margin-top: 35px;
  }

  .paper-title {
    font-size: 22px;
  }

  .paper-footer {
    right: 26px;
    left: 26px;
  }

  .float-note-two {
    right: 0;
  }

  .section {
    padding: 80px 0;
  }

  .section-heading {
    grid-template-columns: 1fr;
    gap: 14px;
    margin-bottom: 34px;
  }

  .section-heading h2,
  .method-copy h2,
  .about-card h2 {
    font-size: 34px;
  }

  .topic-card {
    min-height: 310px;
    padding: 27px;
  }

  .method-section {
    padding: 48px 15px;
  }

  .method-panel {
    padding: 36px 25px;
    border-radius: 24px;
  }

  .method-steps li {
    grid-template-columns: 44px 1fr;
    gap: 12px;
  }

  .note-row {
    padding: 24px 4px;
    grid-template-columns: 40px 1fr;
    gap: 14px;
  }

  .note-row:hover {
    padding-right: 4px;
    padding-left: 4px;
  }

  .note-mark {
    width: 36px;
    height: 36px;
  }

  .note-content h3 {
    font-size: 16px;
  }

  .note-content p {
    display: none;
  }

  .note-arrow {
    display: none;
  }

  .about-card {
    padding: 34px 26px;
    border-radius: 24px;
  }

  .footer-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .footer-meta {
    text-align: left;
  }

  .record-links {
    justify-content: flex-start;
    flex-direction: column;
    gap: 2px;
  }
}

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }

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