:root {
  color-scheme: light dark;

  --bg-light: #f6f5f0;
  --bg-alt-light: #eeece4;
  --surface-light: #ffffff;
  --surface-subtle-light: #f1efe8;
  --text-light: #14171a;
  --text-muted-light: #4a515c;
  --border-light: #c8c4b8;
  --accent-light: #0d6e58;
  --accent-hover-light: #095645;
  --accent-ink-light: #ffffff;
  --accent-soft-light: #e0f2ec;
  --danger-light: #b42318;

  --bg-dark: #0b0f14;
  --bg-alt-dark: #111720;
  --surface-dark: #161d28;
  --surface-subtle-dark: #1c2432;
  --text-dark: #eef2f6;
  --text-muted-dark: #aab4c2;
  --border-dark: #334054;
  --accent-dark: #4fd1a5;
  --accent-hover-dark: #72e0bb;
  --accent-ink-dark: #072219;
  --accent-soft-dark: #14332a;
  --danger-dark: #ff8a80;

  --bg: var(--bg-light);
  --bg-alt: var(--bg-alt-light);
  --surface: var(--surface-light);
  --surface-subtle: var(--surface-subtle-light);
  --text: var(--text-light);
  --text-muted: var(--text-muted-light);
  --border: var(--border-light);
  --accent: var(--accent-light);
  --accent-hover: var(--accent-hover-light);
  --accent-ink: var(--accent-ink-light);
  --accent-soft: var(--accent-soft-light);
  --danger: var(--danger-light);

  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  --radius-sm: 0.5rem;
  --radius-md: 0.875rem;
  --radius-lg: 1.125rem;
  --container-max: 70rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: var(--bg-dark);
    --bg-alt: var(--bg-alt-dark);
    --surface: var(--surface-dark);
    --surface-subtle: var(--surface-subtle-dark);
    --text: var(--text-dark);
    --text-muted: var(--text-muted-dark);
    --border: var(--border-dark);
    --accent: var(--accent-dark);
    --accent-hover: var(--accent-hover-dark);
    --accent-ink: var(--accent-ink-dark);
    --accent-soft: var(--accent-soft-dark);
    --danger: var(--danger-dark);
  }
}

@supports (color: light-dark(white, black)) {
  :root {
    --bg: light-dark(var(--bg-light), var(--bg-dark));
    --bg-alt: light-dark(var(--bg-alt-light), var(--bg-alt-dark));
    --surface: light-dark(var(--surface-light), var(--surface-dark));
    --surface-subtle: light-dark(var(--surface-subtle-light), var(--surface-subtle-dark));
    --text: light-dark(var(--text-light), var(--text-dark));
    --text-muted: light-dark(var(--text-muted-light), var(--text-muted-dark));
    --border: light-dark(var(--border-light), var(--border-dark));
    --accent: light-dark(var(--accent-light), var(--accent-dark));
    --accent-hover: light-dark(var(--accent-hover-light), var(--accent-hover-dark));
    --accent-ink: light-dark(var(--accent-ink-light), var(--accent-ink-dark));
    --accent-soft: light-dark(var(--accent-soft-light), var(--accent-soft-dark));
    --danger: light-dark(var(--danger-light), var(--danger-dark));
  }
}

:root {
  accent-color: var(--accent);
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}

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

html {
  scroll-behavior: smooth;
}

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

body {
  margin: 0;
  background-color: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  text-align: start;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 {
  margin: 0;
  line-height: 1.24;
  letter-spacing: -0.015em;
  text-wrap: balance;
}

p, li, dd {
  text-wrap: pretty;
  overflow-wrap: break-word;
}

p {
  margin: 0;
  max-inline-size: 65ch;
}

ul, ol {
  margin: 0;
  padding: 0;
}

a {
  color: var(--accent);
  text-underline-offset: 0.2em;
}

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

:where(a:any-link, button, summary, input):focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
}

.visually-hidden:where(:not(:focus-within, :active)) {
  position: absolute !important;
  clip-path: inset(50%) !important;
  overflow: hidden !important;
  inline-size: 1px !important;
  block-size: 1px !important;
  margin: -1px !important;
  padding: 0 !important;
  border: 0 !important;
  white-space: nowrap !important;
}

.skip-link:focus-visible {
  position: fixed;
  inset-block-start: 0.75rem;
  inset-inline-start: 0.75rem;
  z-index: 100;
  padding: 0.6rem 1rem;
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: var(--accent-ink);
  font-weight: 600;
  text-decoration: none;
}

.container {
  inline-size: min(100% - 2rem, var(--container-max));
  margin-inline: auto;
}

.section {
  padding-block: clamp(3rem, 2.2rem + 3vw, 4.75rem);
}

.section-alt {
  background-color: var(--bg-alt);
  border-block: 1px solid var(--border);
}

/* Header */
.site-header {
  position: sticky;
  inset-block-start: 0;
  z-index: 20;
  background-color: color-mix(in oklab, var(--bg) 88%, transparent);
  backdrop-filter: blur(10px);
  border-block-end: 1px solid var(--border);
}

.header-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem 1.25rem;
  padding-block: 0.75rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  color: var(--text);
  text-decoration: none;
  font-weight: 700;
  min-block-size: 2.5rem;
}

.brand-mark {
  inline-size: 0.85rem;
  block-size: 0.85rem;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.brand-text {
  font-family: var(--font-mono);
  font-size: 1rem;
  letter-spacing: 0.06em;
}

.brand-sub {
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 500;
}

.site-nav {
  margin-inline-start: auto;
}

.nav-list {
  display: flex;
  flex-wrap: wrap;
  list-style: none;
  gap: 0.25rem 0.5rem;
}

.nav-list a {
  display: inline-flex;
  align-items: center;
  min-block-size: 2.5rem;
  padding-inline: 0.6rem;
  color: var(--text);
  text-decoration: none;
  font-size: 0.9375rem;
  border-radius: var(--radius-sm);
}

.nav-list a:hover {
  background-color: var(--surface-subtle);
  color: var(--accent);
}

.lang-switch {
  display: inline-flex;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  overflow: clip;
}

.lang-btn {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 600;
  min-inline-size: 2.75rem;
  min-block-size: 2.5rem;
  padding-inline: 0.7rem;
  cursor: pointer;
}

.lang-btn[aria-pressed="true"] {
  background: var(--accent);
  color: var(--accent-ink);
}

/* Hero */
.hero {
  padding-block-start: clamp(2.5rem, 1.8rem + 3vw, 4.25rem);
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
  gap: 2rem clamp(1.5rem, 3vw, 3rem);
  align-items: start;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.35rem 0.8rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text-muted);
  font-size: 0.875rem;
  margin-block-end: 1.25rem;
}

.status-dot {
  inline-size: 0.5rem;
  block-size: 0.5rem;
  border-radius: 50%;
  background: var(--accent);
  flex-shrink: 0;
}

h1 {
  font-size: clamp(1.9rem, 1.3rem + 2.4vw, 3.1rem);
  margin-block-end: 1.1rem;
}

.hero-lead {
  font-size: clamp(1.02rem, 0.96rem + 0.35vw, 1.18rem);
  color: var(--text-muted);
  margin-block-end: 1.65rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-block-size: 2.875rem;
  min-inline-size: 2.875rem;
  padding: 0.65rem 1.2rem;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  cursor: pointer;
}

.btn-primary {
  background: var(--accent);
  color: var(--accent-ink);
  border-color: var(--accent);
}

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

.btn-secondary {
  background: var(--surface);
  color: var(--text);
  border-color: var(--border);
}

.btn-secondary:hover {
  background: var(--surface-subtle);
  color: var(--text);
}

.hero-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.4rem 1.5rem;
}

.panel-label {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  margin-block-end: 1rem;
}

.principle-list {
  margin: 0;
  display: grid;
  gap: 1rem;
}

.principle-list dt {
  font-weight: 700;
  margin-block-end: 0.2rem;
}

.principle-list dd {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.9375rem;
}

.cred-strip {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 14rem), 1fr));
  gap: 0.75rem;
  margin-block-start: 2.5rem;
  padding-block-start: 1.5rem;
  border-block-start: 1px solid var(--border);
}

.cred-strip li {
  font-size: 0.875rem;
  color: var(--text-muted);
  padding: 0.6rem 0.85rem;
  border-radius: var(--radius-sm);
  background: var(--surface);
  border: 1px solid var(--border);
}

/* Section heads & cards */
.section-head {
  margin-block-end: 2rem;
}

.section-kicker {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--accent);
  margin-block-end: 0.4rem;
}

h2 {
  font-size: clamp(1.5rem, 1.2rem + 1.3vw, 2.15rem);
  margin-block-end: 0.6rem;
}

.section-intro {
  color: var(--text-muted);
}

.card-grid {
  display: grid;
  gap: 1.25rem;
}

.card-grid-2 {
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 22rem), 1fr));
}

.card-grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 19rem), 1fr));
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.35rem 1.4rem;
  display: grid;
  grid-template-rows: auto 1fr auto;
  gap: 0.85rem;
}

@supports (grid-template-rows: subgrid) {
  .card-grid-2 .card {
    grid-row: span 3;
    grid-template-rows: subgrid;
  }
}

.card-head {
  display: grid;
  gap: 0.45rem;
}

.card-index {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 700;
  color: var(--accent);
}

h3 {
  font-size: 1.15rem;
}

.card-body {
  color: var(--text-muted);
  font-size: 0.95rem;
}

.card-deliverable {
  padding-block-start: 0.75rem;
  border-block-start: 1px solid var(--border);
  font-size: 0.8875rem;
  font-weight: 600;
  color: var(--text);
}

.tag {
  display: inline-flex;
  inline-size: fit-content;
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 700;
}

.card-meta {
  font-size: 0.85rem;
  color: var(--text-muted);
  padding-block-start: 0.65rem;
  border-block-start: 1px solid var(--border);
}

.link-list {
  list-style: none;
  display: grid;
  gap: 0.45rem;
  padding-block-start: 0.65rem;
  border-block-start: 1px solid var(--border);
}

.link-list a {
  display: inline-flex;
  align-items: center;
  min-block-size: 2.25rem;
  font-size: 0.92rem;
  font-weight: 600;
}

/* Scope builder + FAQ */
.scope-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.95fr);
  gap: 2.25rem;
  align-items: start;
}

.intake-form {
  display: grid;
  gap: 1.25rem;
  margin-block-end: 1.25rem;
}

.choice-group {
  border: 0;
  margin: 0;
  padding: 0;
}

.choice-group legend {
  font-weight: 700;
  font-size: 0.95rem;
  margin-block-end: 0.6rem;
}

.pill-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 14rem), 1fr));
  gap: 0.55rem;
}

.pill {
  position: relative;
  display: flex;
  align-items: center;
  gap: 0.55rem;
  min-block-size: 2.85rem;
  padding: 0.55rem 0.8rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  font-size: 0.8875rem;
  cursor: pointer;
}

.pill:has(input:checked) {
  border-color: var(--accent);
  background: var(--accent-soft);
  font-weight: 600;
}

.pill input {
  flex-shrink: 0;
  margin: 0;
}

.brief-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.1rem 1.2rem;
  display: grid;
  gap: 0.85rem;
}

.brief-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}

.brief-title {
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--accent);
}

.brief-text {
  margin: 0;
  padding: 0.9rem 1rem;
  border-radius: var(--radius-sm);
  background: var(--surface-subtle);
  border: 1px solid var(--border);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  line-height: 1.55;
  white-space: pre-wrap;
  overflow-x: auto;
}

.brief-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
}

/* Phases + Accordion */
.phase-list {
  list-style: none;
  display: grid;
  gap: 0.75rem;
  margin-block-end: 1.5rem;
}

.phase-list li {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.85rem 1rem;
  display: grid;
  gap: 0.25rem;
}

.phase-list span {
  font-size: 0.9rem;
  color: var(--text-muted);
}

.accordion {
  display: grid;
  gap: 0.65rem;
}

.accordion details {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.25rem 1rem;
}

.accordion summary {
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.65rem;
  min-block-size: 2.85rem;
  padding-block: 0.45rem;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
}

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

.accordion summary::before {
  content: "";
  inline-size: 0.55rem;
  block-size: 0.55rem;
  flex-shrink: 0;
  border-inline-end: 2px solid currentColor;
  border-block-end: 2px solid currentColor;
  transform: rotate(-45deg);
  transition: transform 0.2s ease;
}

.accordion details[open] > summary::before {
  transform: rotate(45deg);
}

@media (prefers-reduced-motion: reduce) {
  .accordion summary::before {
    transition: none;
  }
}

.faq-answer {
  padding-block-end: 0.85rem;
  color: var(--text-muted);
  font-size: 0.92rem;
}

@supports (interpolate-size: allow-keywords) {
  .accordion details::details-content {
    interpolate-size: allow-keywords;
    overflow: clip;
    contain: layout;
  }

  .accordion details:not([open])::details-content {
    block-size: 0;
  }

  @media (prefers-reduced-motion: no-preference) {
    .accordion details::details-content {
      transition: block-size 0.28s ease, content-visibility 0.28s ease allow-discrete;
    }
  }
}

/* Contact & Copy buttons */
.contact-box {
  display: grid;
  gap: 1.75rem;
}

.contact-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 17.5rem), 1fr));
  gap: 1rem;
}

.contact-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.2rem 1.25rem;
  display: grid;
  gap: 0.7rem;
  align-content: start;
}

.contact-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 600;
}

.contact-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}

.contact-value {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  overflow-wrap: anywhere;
}

.copy-wrap {
  position: relative;
  display: inline-flex;
  align-items: center;
}

.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  min-inline-size: 2.75rem;
  min-block-size: 2.5rem;
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-subtle);
  color: var(--text);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
}

.copy-btn:hover {
  border-color: var(--accent);
}

.copy-btn svg {
  inline-size: 1rem;
  block-size: 1rem;
  flex-shrink: 0;
}

.copy-btn .icon-check {
  display: none;
}

.copy-btn[data-copied] {
  border-color: var(--accent);
  background: var(--accent-soft);
  color: var(--accent);
}

.copy-btn[data-copied] .icon-copy {
  display: none;
}

.copy-btn[data-copied] .icon-check {
  display: block;
}

.copy-btn[data-failed] {
  border-color: var(--danger);
  color: var(--danger);
}

.tip {
  position: absolute;
  inset-block-end: calc(100% + 0.4rem);
  inset-inline-end: 0;
  padding: 0.22rem 0.55rem;
  border-radius: 0.35rem;
  background: var(--text);
  color: var(--bg);
  font-size: 0.78rem;
  font-weight: 600;
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.15s ease;
}

.copy-btn[data-copied] + .tip,
.copy-btn[data-failed] + .tip {
  opacity: 1;
}

@media (prefers-reduced-motion: reduce) {
  .tip {
    transition: none;
  }
}

.social-links {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 0.9rem;
}

.social-links a {
  display: inline-flex;
  align-items: center;
  min-block-size: 2.5rem;
  font-weight: 600;
}

.channels-note {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Footer */
.site-footer {
  border-block-start: 1px solid var(--border);
  padding-block: 1.5rem;
  color: var(--text-muted);
  font-size: 0.875rem;
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem 1.5rem;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
}

@media (max-width: 56rem) {
  .hero-grid,
  .scope-layout {
    grid-template-columns: minmax(0, 1fr);
  }

  .site-nav {
    order: 3;
    inline-size: 100%;
    margin-inline-start: 0;
  }
}

@media (forced-colors: active) {
  .card,
  .hero-panel,
  .brief-box,
  .contact-card,
  .pill,
  .btn,
  .copy-btn,
  .accordion details {
    border: 1px solid CanvasText;
  }

  .btn-primary,
  .lang-btn[aria-pressed="true"] {
    outline: 2px solid Highlight;
  }
}