:root {
  --bg: #edf0ea;
  --bg-strong: #dfe6dd;
  --panel: rgba(249, 250, 246, 0.86);
  --panel-strong: rgba(255, 255, 255, 0.94);
  --text: #122029;
  --muted: #53616b;
  --line: rgba(18, 32, 41, 0.12);
  --accent: #0f6a76;
  --accent-strong: #0a4b58;
  --accent-soft: rgba(15, 106, 118, 0.12);
  --hot: #d86f45;
  --hot-soft: rgba(216, 111, 69, 0.14);
  --shadow: 0 20px 48px rgba(20, 28, 36, 0.12);
  --radius-xl: 28px;
  --radius-lg: 22px;
  --radius-md: 18px;
  --radius-sm: 14px;
  --shell: min(1180px, calc(100vw - 32px));
  --font-ui: "Avenir Next", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-display: "Iowan Old Style", "Georgia", "Source Han Serif SC", serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  font-family: var(--font-ui);
  background:
    radial-gradient(circle at top right, rgba(15, 106, 118, 0.14), transparent 24%),
    radial-gradient(circle at 10% 22%, rgba(216, 111, 69, 0.1), transparent 20%),
    linear-gradient(180deg, #f3f5ef 0%, #edf0ea 42%, #e6ebe4 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.05), rgba(255, 255, 255, 0.05)),
    radial-gradient(circle, rgba(18, 32, 41, 0.05) 1px, transparent 1px);
  background-size: auto, 18px 18px;
  opacity: 0.35;
}

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

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

strong {
  color: var(--text);
}

code {
  padding: 0.16rem 0.44rem;
  border-radius: 999px;
  background: var(--accent-soft);
  font-family: "SFMono-Regular", "Menlo", monospace;
  font-size: 0.92em;
}

.shell {
  width: var(--shell);
  margin: 0 auto;
}

.site-noise {
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0.02)),
    radial-gradient(circle at 20% 80%, rgba(15, 106, 118, 0.08), transparent 18%);
  z-index: -1;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(18px);
  background: rgba(237, 240, 234, 0.82);
  border-bottom: 1px solid rgba(18, 32, 41, 0.08);
}

.site-header__inner,
.site-footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}

.site-header__inner {
  min-height: 72px;
}

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

.brand__mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 15px;
  background: linear-gradient(135deg, var(--accent-strong), var(--accent));
  color: #f3f7f6;
  font-family: var(--font-display);
  font-size: 1.15rem;
  box-shadow: 0 12px 30px rgba(10, 75, 88, 0.26);
}

.brand__text {
  color: var(--muted);
  font-size: 0.96rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.top-nav {
  display: inline-flex;
  align-items: center;
  gap: 20px;
  color: var(--muted);
  font-size: 0.95rem;
}

.top-nav a {
  position: relative;
}

.top-nav a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -6px;
  height: 1px;
  background: var(--text);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 180ms ease;
}

.top-nav a:hover::after,
.top-nav a:focus-visible::after {
  transform: scaleX(1);
}

.hero,
.article-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(320px, 0.92fr);
  gap: 30px;
  padding: 44px 0 24px;
}

.hero__copy,
.article-hero__copy {
  padding-top: 14px;
}

.eyebrow {
  margin: 0 0 14px;
  color: var(--accent);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  margin: 0;
  line-height: 1.08;
}

.hero h1,
.article-hero h1 {
  font-family: var(--font-display);
  font-weight: 600;
  letter-spacing: -0.05em;
}

.hero h1 {
  font-size: clamp(3.1rem, 6vw, 5.4rem);
  max-width: 11ch;
}

.article-hero h1 {
  font-size: clamp(2.6rem, 5vw, 4.5rem);
  max-width: 12ch;
}

.hero__lead,
.hero__visual figcaption,
.summary-panel p,
.feature-band__copy p,
.article-hero__summary,
.quick-card p,
.source-panel p,
.card p,
.timeline-item p,
.article-section p,
.article-section li,
.sidebar-fact p,
.caveat-panel li {
  color: var(--muted);
}

.hero__lead,
.article-hero__summary {
  margin-top: 20px;
  font-size: 1.08rem;
  line-height: 1.9;
  max-width: 40rem;
}

.hero--product {
  align-items: center;
  gap: 36px;
  padding-top: 52px;
}

.hero--product h1 {
  max-width: 10ch;
}

.hero-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 18px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  padding: 0 12px;
  border: 1px solid rgba(15, 106, 118, 0.12);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.52);
  color: var(--accent-strong);
  font-size: 0.84rem;
  font-weight: 700;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.hero-proof {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin-top: 28px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 50px;
  padding: 0 20px;
  border-radius: 999px;
  border: 1px solid transparent;
  font-weight: 700;
  transition:
    transform 180ms ease,
    box-shadow 180ms ease,
    background-color 180ms ease,
    border-color 180ms ease;
}

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

.button--primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #f3f7f6;
  box-shadow: 0 14px 28px rgba(10, 75, 88, 0.24);
}

.button--ghost {
  background: rgba(255, 255, 255, 0.42);
  border-color: var(--line);
}

.panel,
.card,
.timeline-item,
.article-section,
.sidebar-fact {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.58), rgba(255, 255, 255, 0.18)),
    var(--panel);
  box-shadow: var(--shadow);
}

.panel::before,
.card::before,
.timeline-item::before,
.article-section::before {
  content: "";
  position: absolute;
  inset: auto -15% 78% auto;
  width: 160px;
  height: 160px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(15, 106, 118, 0.12), transparent 70%);
  pointer-events: none;
}

.hero__visual,
.summary-panel,
.feature-band__visual,
.cta,
.source-panel,
.caveat-panel,
.toc-card {
  padding: 24px;
}

.hero__visual img,
.feature-band__visual img {
  width: 100%;
  border-radius: 18px;
}

.hero__visual figcaption {
  margin-top: 14px;
  font-size: 0.95rem;
  line-height: 1.7;
}

.hero__stats,
.article-meta,
.tag-row,
.card-grid,
.quick-grid,
.sidebar-facts {
  display: grid;
  gap: 16px;
}

.stat-card {
  padding: 18px;
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.46);
  border: 1px solid rgba(18, 32, 41, 0.08);
}

.stat-card strong,
.meta-card strong {
  display: block;
  font-size: 1.08rem;
}

.stat-card span,
.meta-card span {
  display: block;
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.9rem;
}

.section {
  padding: 24px 0;
}

.section-heading {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 18px;
}

.section-heading h2,
.feature-band__copy h2,
.cta h2,
.article-section h2 {
  font-family: var(--font-display);
  font-weight: 600;
  letter-spacing: -0.04em;
}

.section-heading h2 {
  max-width: 16ch;
  font-size: clamp(2rem, 4vw, 3.1rem);
}

.summary-panel p,
.feature-band__copy p,
.article-section p,
.article-section li,
.source-panel p,
.quick-card li,
.caveat-panel li {
  line-height: 1.85;
}

.tag-row {
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin-top: 22px;
}

.tag-pill {
  padding: 14px 16px;
  border-radius: 14px;
  background: rgba(15, 106, 118, 0.08);
  color: var(--accent-strong);
  font-size: 0.92rem;
  font-weight: 700;
}

.product-window {
  padding: 0;
  overflow: hidden;
  background:
    radial-gradient(circle at top right, rgba(15, 106, 118, 0.18), transparent 28%),
    linear-gradient(180deg, #eef3f2 0%, #e7eceb 100%);
}

.product-window__chrome {
  display: flex;
  align-items: center;
  gap: 8px;
  min-height: 54px;
  padding: 0 20px;
  background: rgba(18, 32, 41, 0.92);
  color: rgba(243, 247, 246, 0.7);
}

.product-window__chrome span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.product-window__chrome span:nth-child(1) {
  background: #ff7d66;
}

.product-window__chrome span:nth-child(2) {
  background: #f5c252;
}

.product-window__chrome span:nth-child(3) {
  background: #32c371;
}

.product-window__chrome p {
  margin: 0 0 0 10px;
  font-size: 0.92rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.product-window__body {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(250px, 0.75fr);
  gap: 0;
}

.product-window__screen {
  min-height: 100%;
  padding: 22px;
  border-right: 1px solid rgba(18, 32, 41, 0.08);
}

.product-window__screen img {
  width: 100%;
  border-radius: 18px;
  box-shadow: 0 16px 38px rgba(17, 29, 36, 0.14);
}

.product-window__aside {
  display: grid;
  gap: 14px;
  padding: 22px;
  align-content: start;
}

.hero-panel {
  padding: 16px 16px 18px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.6);
  border: 1px solid rgba(18, 32, 41, 0.08);
}

.hero-panel strong {
  display: block;
  margin-bottom: 10px;
  color: var(--accent-strong);
  font-size: 0.88rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero-panel p {
  margin: 0;
  color: var(--muted);
  font-size: 0.98rem;
  line-height: 1.75;
}

.product-promise {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(280px, 0.9fr);
  gap: 28px;
  padding: 28px;
}

.product-promise__copy h2 {
  max-width: 14ch;
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 600;
  letter-spacing: -0.04em;
}

.product-promise__copy p:last-child {
  margin: 18px 0 0;
  line-height: 1.9;
}

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

.card {
  padding: 22px;
}

.card h3 {
  margin-bottom: 12px;
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: -0.03em;
}

.card p {
  margin: 0;
  font-size: 1rem;
}

.resource-card__foot {
  display: inline-flex;
  align-items: center;
  margin-top: 18px;
  color: var(--accent);
  font-size: 0.92rem;
  font-weight: 700;
}

.card__label,
.timeline-item__step,
.article-section__kicker,
.quick-card__label {
  display: inline-flex;
  align-items: center;
  margin-bottom: 12px;
  color: var(--hot);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.showcase-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr 1fr;
  gap: 16px;
}

.showcase-card {
  position: relative;
  overflow: hidden;
  min-height: 290px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
}

.showcase-card h3 {
  max-width: 14ch;
  margin-bottom: 12px;
  font-family: var(--font-display);
  font-size: clamp(1.65rem, 3vw, 2.2rem);
  font-weight: 600;
  letter-spacing: -0.04em;
}

.showcase-card p {
  margin: 0;
  line-height: 1.85;
}

.showcase-card__list {
  margin: 18px 0 0;
  padding-left: 1.1rem;
}

.showcase-card__list li {
  margin-bottom: 10px;
  line-height: 1.72;
}

.showcase-card--0 {
  background:
    radial-gradient(circle at top left, rgba(255, 255, 255, 0.08), transparent 28%),
    linear-gradient(145deg, #10252c, #15363e);
  color: #eff6f4;
}

.showcase-card--0 .card__label,
.showcase-card--0 h3,
.showcase-card--0 strong {
  color: #eff6f4;
}

.showcase-card--0 p,
.showcase-card--0 li {
  color: rgba(239, 246, 244, 0.82);
}

.showcase-card--1 {
  background:
    linear-gradient(180deg, rgba(15, 106, 118, 0.14), rgba(255, 255, 255, 0.45)),
    rgba(255, 255, 255, 0.82);
}

.showcase-card--2 {
  background:
    linear-gradient(180deg, rgba(216, 111, 69, 0.16), rgba(255, 255, 255, 0.52)),
    rgba(255, 255, 255, 0.82);
}

.feature-band {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(320px, 1.05fr);
  gap: 28px;
  align-items: center;
}

.feature-band__copy h2,
.cta h2 {
  font-size: clamp(2.1rem, 4vw, 3.4rem);
  max-width: 15ch;
}

.feature-band__copy p {
  margin-top: 18px;
  max-width: 38rem;
}

.timeline {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 16px;
}

.timeline-item {
  padding: 20px;
  min-height: 220px;
}

.timeline-item__step {
  margin-bottom: 14px;
}

.timeline-item h3 {
  margin-bottom: 12px;
  font-family: var(--font-display);
  font-size: 1.36rem;
  font-weight: 600;
}

.output-showcase {
  display: grid;
  grid-template-columns: minmax(0, 0.92fr) minmax(340px, 1.08fr);
  gap: 28px;
  align-items: center;
  margin-bottom: 16px;
}

.output-showcase__copy h2,
.cta h2 {
  font-size: clamp(2.1rem, 4vw, 3.4rem);
  max-width: 15ch;
}

.output-showcase__copy p {
  max-width: 36rem;
  margin-top: 18px;
  color: var(--muted);
  line-height: 1.88;
}

.output-showcase__visual {
  padding: 22px;
}

.output-showcase__visual img {
  width: 100%;
  border-radius: 18px;
}

.cta {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
}

.cta__text {
  max-width: 38rem;
  margin: 18px 0 0;
  color: var(--muted);
  line-height: 1.88;
}

.site-footer {
  padding: 40px 0 56px;
}

.site-footer__inner {
  border-top: 1px solid rgba(18, 32, 41, 0.08);
  padding-top: 18px;
  color: var(--muted);
  font-size: 0.93rem;
}

.reading-progress {
  position: fixed;
  inset: 0 0 auto;
  height: 4px;
  background: rgba(15, 106, 118, 0.08);
  z-index: 30;
}

.reading-progress span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--hot), var(--accent));
  transition: width 90ms linear;
}

.article-page {
  padding-bottom: 28px;
}

.article-meta {
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin-top: 24px;
}

.meta-card {
  padding: 16px 18px;
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.46);
  border: 1px solid rgba(18, 32, 41, 0.08);
}

.quick-grid {
  grid-template-columns: 1.1fr 0.9fr;
  margin-top: 24px;
}

.quick-card {
  padding: 22px;
}

.quick-card ul,
.caveat-panel ul {
  margin: 0;
  padding-left: 1.05rem;
}

.quick-card li,
.caveat-panel li {
  margin-bottom: 10px;
}

.article-layout {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 28px;
  align-items: start;
  padding-top: 26px;
}

.article-sidebar {
  position: sticky;
  top: 90px;
  display: grid;
  gap: 16px;
}

.toc-nav {
  display: grid;
  gap: 10px;
}

.toc-link {
  display: flex;
  gap: 12px;
  align-items: baseline;
  padding: 10px 12px;
  border-radius: 14px;
  color: var(--muted);
  transition:
    background-color 180ms ease,
    color 180ms ease,
    transform 180ms ease;
}

.toc-link:hover,
.toc-link:focus-visible,
.toc-link.is-active {
  background: rgba(15, 106, 118, 0.08);
  color: var(--accent-strong);
  transform: translateX(2px);
}

.toc-link__num {
  color: var(--hot);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.1em;
}

.sidebar-facts {
  grid-template-columns: 1fr;
}

.sidebar-fact {
  padding: 18px;
}

.sidebar-fact strong {
  display: block;
  margin-bottom: 10px;
}

.article-content > * + * {
  margin-top: 22px;
}

.article-section {
  padding: 28px;
  scroll-margin-top: 98px;
}

.article-section__header {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 20px;
}

.article-section__index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 68px;
  height: 68px;
  border-radius: 20px;
  background: linear-gradient(135deg, rgba(15, 106, 118, 0.14), rgba(216, 111, 69, 0.18));
  color: var(--accent-strong);
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 600;
}

.article-section h2 {
  max-width: 14ch;
  font-size: clamp(1.9rem, 3vw, 2.7rem);
}

.article-section__summary {
  max-width: 20rem;
  color: var(--hot);
  font-size: 0.96rem;
  line-height: 1.75;
  text-align: right;
}

.article-section__body {
  max-width: 48rem;
}

.article-section__body p {
  margin: 0 0 16px;
  font-size: 1.04rem;
}

.article-section__body ul {
  margin: 0;
  padding-left: 1.1rem;
}

.article-section__body li {
  margin-bottom: 10px;
}

.formula-box,
.tip-box {
  margin-top: 20px;
  padding: 18px 20px;
  border-radius: var(--radius-md);
}

.formula-box {
  background: rgba(10, 75, 88, 0.08);
  border: 1px solid rgba(10, 75, 88, 0.12);
}

.formula-box pre,
.tip-box p {
  margin: 0;
}

.formula-box pre {
  white-space: pre-wrap;
  font-family: "SFMono-Regular", "Menlo", monospace;
  font-size: 0.96rem;
  line-height: 1.8;
}

.tip-box {
  background: rgba(216, 111, 69, 0.08);
  border: 1px solid rgba(216, 111, 69, 0.12);
}

.tip-box strong {
  display: block;
  margin-bottom: 10px;
}

.reveal {
  opacity: 0;
  transform: translateY(16px);
  animation: rise-in 700ms ease forwards;
  animation-delay: var(--delay, 0ms);
}

@keyframes rise-in {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 1199px) {
  .hero,
  .article-hero,
  .feature-band,
  .article-layout,
  .product-promise,
  .output-showcase {
    grid-template-columns: 1fr;
  }

  .card-grid--three,
  .hero-proof,
  .article-meta,
  .quick-grid,
  .tag-row,
  .sidebar-facts,
  .showcase-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

  .product-window__body {
    grid-template-columns: 1fr;
  }

  .product-window__screen {
    border-right: 0;
    border-bottom: 1px solid rgba(18, 32, 41, 0.08);
  }

  .article-sidebar {
    position: static;
  }

  .toc-nav {
    grid-auto-flow: column;
    grid-auto-columns: minmax(180px, 1fr);
    overflow-x: auto;
    padding-bottom: 4px;
  }
}

@media (max-width: 767px) {
  .site-header__inner,
  .site-footer__inner,
  .cta,
  .article-section__header {
    flex-direction: column;
    align-items: flex-start;
  }

  .top-nav {
    width: 100%;
    overflow-x: auto;
    white-space: nowrap;
    padding-bottom: 6px;
  }

  .hero,
  .article-hero {
    padding-top: 34px;
  }

  .hero-proof,
  .tag-row,
  .card-grid--three,
  .timeline,
  .article-meta,
  .quick-grid,
  .sidebar-facts,
  .showcase-grid {
    grid-template-columns: 1fr;
  }

  .panel,
  .card,
  .timeline-item,
  .article-section,
  .sidebar-fact {
    padding-left: 20px;
    padding-right: 20px;
  }

  .section-heading h2,
  .feature-band__copy h2,
  .cta h2,
  .article-section h2,
  .hero h1,
  .article-hero h1 {
    max-width: none;
  }

  .article-section__summary {
    text-align: left;
  }
}

@media (max-width: 480px) {
  :root {
    --shell: min(100vw - 18px, 100vw - 18px);
  }

  .hero h1 {
    font-size: 2.75rem;
  }

  .article-hero h1 {
    font-size: 2.2rem;
  }

  .button {
    width: 100%;
  }

  .hero__actions {
    width: 100%;
  }
}