:root {
  --ink: #1c2430;
  --mist: #e4eef0;
  --deep: #1e4d5c;
  --paper: #f7f8f6;
  --string: #c4a574;
  --string-soft: rgba(196, 165, 116, 0.35);
  --line: rgba(28, 36, 48, 0.12);
  --muted: rgba(28, 36, 48, 0.62);
  --eng-bg: #152028;
  --eng-ink: #e8eef0;
  --eng-muted: rgba(232, 238, 240, 0.68);
  --eng-line: rgba(232, 238, 240, 0.14);
  --eng-deep: #3d8a9e;
  --radius: 14px;
  --header-h: 4rem;
  --font-display: "LXGW WenKai", "Noto Serif SC", "Songti SC", serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, monospace;
  --space: clamp(1.25rem, 3vw, 2rem);
  --measure: 40rem;
  --wide: 68rem;
}

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

html {
  scroll-behavior: smooth;
}

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

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

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-body);
  font-size: clamp(1rem, 0.95rem + 0.3vw, 1.1rem);
  line-height: 1.7;
  color: var(--ink);
  background:
    radial-gradient(120% 80% at 10% -10%, rgba(30, 77, 92, 0.08), transparent 55%),
    radial-gradient(80% 50% at 100% 0%, rgba(196, 165, 116, 0.12), transparent 45%),
    var(--paper);
  transition: background 0.45s ease, color 0.45s ease;
}

body[data-mode="engineering"] {
  color: var(--eng-ink);
  background:
    radial-gradient(100% 70% at 80% -20%, rgba(61, 138, 158, 0.22), transparent 50%),
    radial-gradient(60% 40% at 0% 30%, rgba(196, 165, 116, 0.08), transparent 40%),
    var(--eng-bg);
}

body[data-mode="visitor"] .engineering-panel,
body[data-mode="visitor"] .engineering-only {
  display: none;
}

body[data-mode="engineering"] .visitor-panel,
body[data-mode="engineering"] .visitor-only {
  display: none;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -3rem;
  z-index: 100;
  padding: 0.5rem 0.75rem;
  background: var(--deep);
  color: var(--paper);
  border-radius: 8px;
  text-decoration: none;
}

.skip-link:focus {
  top: 1rem;
}

a {
  color: var(--deep);
  text-underline-offset: 0.18em;
}

body[data-mode="engineering"] a {
  color: var(--string);
}

a:hover {
  text-decoration-thickness: 2px;
}

:focus-visible {
  outline: 2px solid var(--string);
  outline-offset: 3px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: var(--header-h);
  padding: 0.75rem var(--space);
  backdrop-filter: blur(12px);
  background: rgba(247, 248, 246, 0.82);
  border-bottom: 1px solid var(--line);
}

body[data-mode="engineering"] .site-header {
  background: rgba(21, 32, 40, 0.86);
  border-bottom-color: var(--eng-line);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  color: var(--ink);
  text-decoration: none;
  min-width: 0;
}

body[data-mode="engineering"] .brand {
  color: var(--eng-ink);
}

.brand__mark {
  flex: 0 0 auto;
  width: 2rem;
  height: 2rem;
  color: var(--deep);
}

body[data-mode="engineering"] .brand__mark {
  color: var(--eng-ink);
}

.brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
  min-width: 0;
}

.brand__name {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.brand__studio {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  font-weight: 500;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  opacity: 0.72;
}

.brand__cn {
  font-family: var(--font-display);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  opacity: 0.65;
  margin-top: 0.1rem;
}

@media (max-width: 36rem) {
  .brand__cn {
    display: none;
  }
}

.nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-end;
  gap: 0.35rem 1rem;
}

.nav a {
  color: inherit;
  text-decoration: none;
  font-size: 0.95rem;
  opacity: 0.85;
}

.nav a:hover,
.nav a:focus-visible {
  opacity: 1;
}

.mode-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-left: 0.25rem;
  padding: 0.35rem 0.7rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: transparent;
  color: inherit;
  font: inherit;
  font-size: 0.85rem;
  cursor: pointer;
  transition: border-color 0.2s ease, background 0.2s ease;
}

body[data-mode="engineering"] .mode-toggle {
  border-color: var(--eng-line);
  background: rgba(196, 165, 116, 0.12);
}

.mode-toggle:hover,
.mode-toggle:focus-visible {
  border-color: var(--string);
}

.mode-toggle__code {
  font-family: var(--font-mono);
  font-weight: 500;
  color: var(--deep);
}

body[data-mode="engineering"] .mode-toggle__code {
  color: var(--string);
}

.mode-toggle__label {
  opacity: 0.8;
}

@media (max-width: 640px) {
  .mode-toggle__label {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
  }
}

main {
  padding: 0 var(--space) 4rem;
}

.hero {
  max-width: var(--wide);
  margin: 0 auto;
  padding: clamp(2.5rem, 8vw, 5rem) 0 2rem;
}

.eyebrow {
  margin: 0 0 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

body[data-mode="engineering"] .eyebrow {
  color: var(--eng-muted);
}

h1,
h2,
h3 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: 0.01em;
}

h1 {
  margin: 0 0 1.25rem;
  font-size: clamp(2.2rem, 1.4rem + 3.5vw, 3.6rem);
  max-width: 16ch;
}

h1 em,
h2 em {
  font-style: italic;
  color: var(--deep);
}

body[data-mode="engineering"] h1 em,
body[data-mode="engineering"] h2 em {
  color: var(--string);
}

.lede {
  max-width: 36rem;
  margin: 0 0 1.5rem;
  font-size: 1.08rem;
  color: var(--muted);
}

body[data-mode="engineering"] .lede {
  color: var(--eng-muted);
}

.hero-actions {
  margin: 0 0 2.5rem;
}

.text-link,
.as-button {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0;
  border: 0;
  background: none;
  color: var(--deep);
  font: inherit;
  text-decoration: underline;
  text-underline-offset: 0.18em;
  cursor: pointer;
}

body[data-mode="engineering"] .text-link,
body[data-mode="engineering"] .as-button {
  color: var(--string);
}

.signature {
  position: relative;
  margin-top: 1rem;
  border-radius: var(--radius);
  overflow: hidden;
  background: linear-gradient(180deg, rgba(228, 238, 240, 0.7), rgba(228, 238, 240, 0.15));
  border: 1px solid var(--line);
}

body[data-mode="engineering"] .signature {
  background: linear-gradient(180deg, rgba(30, 77, 92, 0.35), rgba(21, 32, 40, 0.2));
  border-color: var(--eng-line);
}

#shoreline {
  display: block;
  width: 100%;
  height: clamp(72px, 14vw, 120px);
}

.signature__caption {
  position: absolute;
  right: 0.9rem;
  bottom: 0.55rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  color: var(--muted);
}

body[data-mode="engineering"] .signature__caption {
  color: var(--eng-muted);
}

.section {
  max-width: var(--wide);
  margin: 0 auto;
  padding: clamp(2.5rem, 6vw, 4.5rem) 0;
  border-top: 1px solid var(--line);
}

body[data-mode="engineering"] .section {
  border-top-color: var(--eng-line);
}

.section-head {
  margin-bottom: 2rem;
}

.section-head h2 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.8rem, 1.2rem + 2vw, 2.6rem);
  max-width: 14ch;
}

.section-lead {
  max-width: var(--measure);
  margin: 0;
  color: var(--muted);
}

body[data-mode="engineering"] .section-lead {
  color: var(--eng-muted);
}

.project {
  max-width: 40rem;
  margin: 0 0 3rem;
  padding: 1.5rem 0;
}

.project__index {
  margin: 0 0 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.project h3 {
  margin: 0 0 0.5rem;
  font-size: 1.85rem;
}

.project__tagline {
  margin: 0 0 1rem;
  font-family: var(--font-display);
  font-size: 1.25rem;
  line-height: 1.45;
  color: var(--deep);
}

body[data-mode="engineering"] .project__tagline {
  color: var(--string);
}

.project__meta {
  margin: 1rem 0 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--muted);
}

.project__links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  margin: 0.75rem 0 0;
}

.ideas {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1.25rem;
}

.ideas li {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1rem;
  padding: 1.25rem 1.35rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.35);
}

body[data-mode="engineering"] .ideas li {
  border-color: var(--eng-line);
  background: rgba(255, 255, 255, 0.03);
}

.ideas__num {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--string);
}

.ideas h3 {
  margin: 0 0 0.35rem;
  font-size: 1.2rem;
}

.ideas p {
  margin: 0 0 0.5rem;
  color: var(--muted);
}

body[data-mode="engineering"] .ideas p {
  color: var(--eng-muted);
}

.chip {
  display: inline-block;
  margin: 0 !important;
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
  border: 1px solid var(--string-soft);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--deep) !important;
}

body[data-mode="engineering"] .chip {
  color: var(--string) !important;
}

.about-grid {
  display: grid;
  gap: 1.5rem;
  grid-template-columns: 1.2fr 1fr;
  max-width: 52rem;
  margin-bottom: 1.5rem;
}

@media (max-width: 720px) {
  .about-grid {
    grid-template-columns: 1fr;
  }
}

blockquote {
  margin: 0;
  padding: 1.25rem 1.35rem;
  border-left: 3px solid var(--string);
  background: rgba(228, 238, 240, 0.55);
  border-radius: 0 var(--radius) var(--radius) 0;
}

body[data-mode="engineering"] blockquote {
  background: rgba(61, 138, 158, 0.12);
}

blockquote p {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-size: 1.35rem;
  line-height: 1.4;
}

blockquote footer {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--muted);
}

body[data-mode="engineering"] blockquote footer {
  color: var(--eng-muted);
}

.lab {
  display: grid;
  gap: 1rem;
  padding: 1.25rem;
  border: 1px solid var(--eng-line);
  border-radius: var(--radius);
  background: rgba(0, 0, 0, 0.18);
}

.lab__controls {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 1.5rem;
  align-items: end;
}

.lab__controls label {
  display: grid;
  gap: 0.35rem;
  min-width: min(100%, 16rem);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--eng-muted);
}

.lab__controls input[type="range"] {
  width: 100%;
  accent-color: var(--string);
}

.lab__controls output {
  font-family: var(--font-mono);
  color: var(--string);
}

.btn-quiet {
  padding: 0.45rem 0.85rem;
  border: 1px solid var(--eng-line);
  border-radius: 999px;
  background: transparent;
  color: var(--eng-ink);
  font: inherit;
  font-size: 0.85rem;
  cursor: pointer;
}

.btn-quiet:hover,
.btn-quiet:focus-visible {
  border-color: var(--string);
}

#fft-canvas {
  width: 100%;
  height: auto;
  border-radius: 10px;
  background: rgba(0, 0, 0, 0.25);
}

.lab__formula {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--string);
}

.lab__stats {
  display: grid;
  gap: 0.75rem;
  grid-template-columns: repeat(auto-fit, minmax(12rem, 1fr));
  margin: 0;
}

.lab__stats dt {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--eng-muted);
}

.lab__stats dd {
  margin: 0.2rem 0 0;
  font-size: 0.92rem;
}

.code {
  margin: 0;
  padding: 1rem 1.1rem;
  overflow-x: auto;
  border-radius: 10px;
  border: 1px solid var(--eng-line);
  background: rgba(0, 0, 0, 0.35);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.55;
  color: rgba(232, 238, 240, 0.92);
}

.lab__status {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--eng-muted);
}

.lab__status[data-state="ok"] {
  color: #8fd4a8;
}

.reorder-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.65rem;
}

.reorder-item {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.85rem;
  align-items: start;
  padding: 0.9rem 1rem;
  border: 1px solid var(--eng-line);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.04);
  cursor: grab;
  touch-action: none;
  user-select: none;
}

.reorder-item:active {
  cursor: grabbing;
}

.reorder-item[draggable="true"]:hover {
  border-color: var(--string-soft);
}

.reorder-item.is-dragging {
  opacity: 0.45;
}

.reorder-item.is-over {
  border-color: var(--string);
  box-shadow: inset 0 0 0 1px var(--string);
}

.reorder-item__handle {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--string);
  padding-top: 0.15rem;
}

.reorder-item p {
  margin: 0;
  color: var(--eng-ink);
}

.site-footer {
  max-width: var(--wide);
  margin: 0 auto;
  padding: 2rem var(--space) 3rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.9rem;
}

body[data-mode="engineering"] .site-footer {
  border-top-color: var(--eng-line);
  color: var(--eng-muted);
}

.site-footer p {
  margin: 0 0 0.35rem;
}

.site-footer a {
  color: inherit;
}