:root {
  --bg: #eef4f7;
  --paper: #ffffff;
  --ink: #101927;
  --muted: #5d6d7f;
  --line: #d8e4ec;
  --soft: #e8f0f5;
  --accent: #0f7c8c;
  --accent-2: #2256d8;
  --accent-3: #17a7b8;
  --success: #2e7d5b;
  --radius: 8px;
  --shadow: 0 22px 60px rgba(16, 25, 39, 0.12);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "Segoe UI", "Microsoft JhengHei", Arial, sans-serif;
  line-height: 1.65;
}

a {
  color: inherit;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 72px;
  padding: 12px clamp(18px, 4vw, 56px);
  background: rgba(250, 253, 255, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-weight: 800;
  white-space: nowrap;
}

.brand img {
  width: 42px;
  height: 42px;
  border-radius: 8px;
  object-fit: cover;
  border: 1px solid var(--line);
}

.site-nav {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 6px;
  flex-wrap: wrap;
}

.site-nav a {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  padding: 0 12px;
  color: var(--muted);
  text-decoration: none;
  border-radius: 6px;
  font-size: 14px;
}

.lang-toggle {
  min-height: 34px;
  padding: 0 12px;
  color: var(--accent);
  background: #ffffff;
  border: 1px solid var(--line);
  border-radius: 6px;
  font: inherit;
  font-size: 14px;
  font-weight: 850;
  cursor: pointer;
}

.site-nav a:hover,
.site-nav a.active,
.site-nav a[aria-current="page"],
.lang-toggle:hover {
  color: var(--accent);
  background: #e4f3f6;
}

.intro-section {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1.02fr) minmax(360px, 0.98fr);
  align-items: center;
  gap: clamp(28px, 4vw, 64px);
  min-height: calc(100vh - 72px);
  padding: clamp(42px, 7vw, 86px) clamp(18px, 5vw, 72px) 34px;
  background:
    radial-gradient(circle at 82% 12%, rgba(23, 167, 184, 0.16), transparent 30%),
    linear-gradient(135deg, #ffffff 0%, #f4f8fb 54%, #edf5f8 100%);
  border-bottom: 1px solid var(--line);
  overflow: hidden;
}

.intro-section::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(15, 124, 140, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(15, 124, 140, 0.06) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: linear-gradient(90deg, transparent, #000 42%, #000 100%);
}

.intro-copy {
  position: relative;
  z-index: 1;
  max-width: 780px;
}

.section-label {
  margin: 0 0 10px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 800;
  text-transform: uppercase;
}

h1,
h2,
h3,
h4,
p {
  letter-spacing: 0;
}

h1 {
  margin: 0;
  max-width: 820px;
  font-size: clamp(38px, 6vw, 76px);
  line-height: 1.02;
  font-weight: 850;
}

h2 {
  margin: 0;
  font-size: clamp(28px, 4vw, 44px);
  line-height: 1.12;
}

h3 {
  margin: 0 0 12px;
  font-size: 22px;
  line-height: 1.25;
}

h4 {
  margin: 0 0 10px;
  font-size: 17px;
}

.intro-copy p:not(.section-label),
.section-head p,
.split-block p,
.references p,
.author-preview p,
.author-shell p {
  color: var(--muted);
  font-size: 17px;
}

.intro-actions,
.author-preview {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 0 18px;
  color: var(--ink);
  text-decoration: none;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--paper);
  font: inherit;
  font-weight: 750;
  cursor: pointer;
}

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

.button.primary {
  color: #fff;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border-color: transparent;
}

.button.primary:hover {
  background: #155963;
  color: #fff;
}

.button.disabled {
  opacity: 0.6;
  pointer-events: none;
}

.app-showcase {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 16px;
}

.app-showcase::before {
  content: "";
  position: absolute;
  inset: 28px -12px -18px 42px;
  z-index: -1;
  border-radius: 18px;
  background: linear-gradient(135deg, rgba(15, 124, 140, 0.12), rgba(34, 86, 216, 0.1));
  border: 1px solid rgba(15, 124, 140, 0.14);
}

.app-shot {
  margin: 0;
  overflow: hidden;
  background: rgba(255, 255, 255, 0.86);
  border: 1px solid rgba(184, 202, 216, 0.86);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.app-shot-primary {
  transform: translateX(-10px);
}

.app-shot:not(.app-shot-primary) {
  transform: translateX(28px);
}

.app-shot img {
  display: block;
  width: 100%;
  height: auto;           /* show full screenshot, no cropping */
  aspect-ratio: 1360/820; /* matches actual webp dimensions */
  object-fit: cover;
  object-position: left top;
  background: #eaf0f5;
}

.app-shot figcaption {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 14px;
  border-top: 1px solid var(--line);
}

.app-shot figcaption strong {
  white-space: nowrap;
  color: var(--ink);
}

.app-shot figcaption span {
  color: var(--muted);
  font-size: 13px;
  text-align: right;
}

.band,
.content-section {
  padding: clamp(44px, 7vw, 82px) clamp(18px, 5vw, 72px);
  border-bottom: 1px solid var(--line);
}

.band {
  background: #f4f8fb;
}

.content-section {
  background: var(--paper);
}

.content-section.compact {
  background: #edf5f8;
}

.section-head {
  max-width: 840px;
  margin-bottom: 28px;
}

.feature-grid,
.workflow-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.feature-card,
.workflow-card,
.note-panel,
.download-row {
  background: rgba(255, 255, 255, 0.9);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.feature-card {
  padding: 24px;
}

.feature-index {
  display: block;
  margin-bottom: 18px;
  color: var(--accent-3);
  font-size: 13px;
  font-weight: 850;
}

.feature-card p,
.workflow-card li,
.note-panel li,
.download-row span,
.reference-list span {
  color: var(--muted);
}

.split-block {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(320px, 0.8fr);
  gap: 24px;
  align-items: start;
  margin-top: 26px;
}

.split-block.reverse {
  grid-template-columns: minmax(320px, 0.8fr) minmax(0, 1.2fr);
}

.split-block.reverse > div:first-child {
  order: 2;
}

.split-block.reverse > div:last-child {
  order: 1;
}

.equation-stack {
  display: grid;
  gap: 12px;
  margin: 22px 0;
}

.equation-card {
  margin: 0;
  padding: 16px 18px 14px;
  overflow-x: auto;
  color: #102033;
  background: linear-gradient(180deg, #f8fcfe, #eef7fa);
  border: 1px solid #c9e0e8;
  border-radius: var(--radius);
}

.equation-card math {
  min-width: max-content;
  color: #0f2437;
  font-family: "Cambria Math", Cambria, "Times New Roman", serif;
  font-size: 22px;
}

.equation-card figcaption {
  margin-top: 10px;
  color: var(--muted);
  font-size: 14px;
}

.note-panel {
  padding: 22px;
  background: #f8fbfd;
}

.note-panel ul,
.reference-list {
  margin: 0;
  padding-left: 20px;
}

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

.workflow-card {
  padding: 26px;
}

.workflow-card ol {
  margin: 0;
  padding-left: 22px;
}

.workflow-card li + li {
  margin-top: 9px;
}

.download-list {
  display: grid;
  gap: 12px;
}

.download-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 18px;
}

.download-row strong,
.download-row span {
  display: block;
}

.download-row span {
  margin-top: 3px;
}

.references {
  background: #f8fbfd;
}

.reference-list {
  display: grid;
  gap: 12px;
  max-width: 980px;
}

.reference-list a {
  color: var(--accent-2);
  font-weight: 800;
}

.reference-list span {
  display: block;
}

.author-preview {
  justify-content: space-between;
  background: var(--paper);
}

.site-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 20px clamp(18px, 5vw, 72px);
  color: var(--muted);
  background: #0f1722;
}

.author-page {
  display: grid;
  min-height: calc(100vh - 72px);
  padding: clamp(44px, 7vw, 90px) clamp(18px, 5vw, 72px);
  background:
    linear-gradient(180deg, #f8fbfd 0%, #ffffff 46%, #edf5f8 100%);
}

.author-shell {
  width: min(1120px, 100%);
  margin: 0 auto;
}

.author-hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(300px, 0.42fr);
  gap: clamp(22px, 4vw, 46px);
  align-items: center;
  margin-bottom: 28px;
}

.author-summary h1 {
  max-width: 760px;
}

.author-lead {
  max-width: 780px;
}

.tag-list,
.publication-links,
.author-footer-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.tag-list span,
.publication-links a {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  padding: 0 12px;
  color: var(--accent);
  background: #e4f3f6;
  border: 1px solid #c9e0e8;
  border-radius: 6px;
  font-size: 14px;
  font-weight: 800;
  text-decoration: none;
}

.author-contact-card {
  display: grid;
  justify-items: center;
  gap: 14px;
  padding: 22px;
  text-align: center;
  background: #ffffff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.profile-logo {
  width: 82px;
  height: 82px;
  object-fit: cover;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.profile-name strong,
.profile-name span {
  display: block;
}

.profile-name span,
.contact-list span,
.achievement-item span,
.publication-list span {
  color: var(--muted);
}

.profile-qr {
  width: min(180px, 100%);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.contact-list {
  display: grid;
  gap: 10px;
  width: 100%;
  margin: 0;
  padding: 0;
  list-style: none;
  text-align: left;
}

.contact-list li {
  display: grid;
  gap: 2px;
  padding-top: 10px;
  border-top: 1px solid var(--line);
}

.contact-list a,
.publication-list a {
  color: var(--accent-2);
  font-weight: 800;
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.info-card {
  padding: 24px;
  background: rgba(255, 255, 255, 0.94);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.info-card.wide {
  grid-column: 1 / -1;
}

.info-card h2 {
  font-size: clamp(24px, 3vw, 34px);
}

.info-card ul,
.publication-list {
  margin: 14px 0 0;
  padding-left: 22px;
}

.info-card li + li,
.publication-list li + li {
  margin-top: 8px;
}

.achievement-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-top: 18px;
}

.achievement-item {
  padding: 16px;
  background: #f8fbfd;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.achievement-item strong,
.achievement-item span {
  display: block;
}

.achievement-item strong {
  color: var(--accent);
  font-size: 22px;
}

.project-card .button {
  margin-top: 8px;
}

.publication-links {
  margin-top: 8px;
}

.author-footer-actions {
  margin-top: 22px;
}

@media (max-width: 980px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .site-nav {
    justify-content: flex-start;
  }

  .intro-section,
  .split-block,
  .split-block.reverse,
  .feature-grid,
  .workflow-grid,
  .author-hero,
  .achievement-grid {
    grid-template-columns: 1fr;
  }

  .split-block.reverse > div:first-child,
  .split-block.reverse > div:last-child {
    order: initial;
  }

  .intro-section {
    min-height: auto;
  }

  .app-shot-primary,
  .app-shot:not(.app-shot-primary) {
    transform: none;
  }
}

@media (max-width: 640px) {
  .site-nav a,
  .lang-toggle {
    padding: 0 9px;
  }

  .download-row,
  .author-preview,
  .site-footer {
    align-items: flex-start;
    flex-direction: column;
  }

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

  .info-card.wide {
    grid-column: auto;
  }

  h1 {
    font-size: 38px;
  }
}

/* Download version tag + changelog */
.version-tag {
  font-style: normal;
  font-size: 0.78em;
  font-weight: 700;
  color: #2563eb;
  background: rgba(37, 99, 235, 0.1);
  border-radius: 999px;
  padding: 2px 10px;
  margin-left: 8px;
  vertical-align: middle;
}
.changelog {
  margin-top: 28px;
  border: 1px solid rgba(148, 163, 184, 0.35);
  border-radius: 14px;
  padding: 18px 22px;
}
.changelog h3 { margin: 0 0 10px; font-size: 1.05rem; }
.changelog-entry strong { display: block; margin-bottom: 6px; font-size: 0.95rem; }
.changelog-entry ul { margin: 0; padding-left: 20px; }
.changelog-entry li { margin: 4px 0; font-size: 0.92rem; line-height: 1.55; }

/* ===== DARK MODE =====
   JS sets data-theme="dark" on <html> based on:
   1. localStorage saved preference, or
   2. system prefers-color-scheme on first visit.
   No CSS media query needed — all dark rules live here.
   ===================================================== */
html[data-theme="dark"] {
  --bg: #0f1722;
  --paper: #16202e;
  --ink: #e8f0f7;
  --muted: #8ba0b4;
  --line: #243044;
  --soft: #1c2a3a;
  --accent: #17a7b8;
  --accent-2: #6b9fff;
  --accent-3: #17a7b8;
  --shadow: 0 22px 60px rgba(0, 0, 0, 0.45);
}
html[data-theme="dark"] .site-header { background: rgba(15, 23, 34, 0.92); }
html[data-theme="dark"] .intro-section {
  background:
    radial-gradient(circle at 82% 12%, rgba(23, 167, 184, 0.1), transparent 30%),
    linear-gradient(135deg, #111c2c 0%, #131f2f 54%, #0f1a28 100%);
}
html[data-theme="dark"] .content-section { background: var(--paper); }
html[data-theme="dark"] .content-section.compact { background: #121d2b; }
html[data-theme="dark"] .references { background: #111a27; }
html[data-theme="dark"] .equation-card { background: linear-gradient(180deg, #192537, #111e2e); border-color: #253548; }
html[data-theme="dark"] .equation-card math { color: #c9e4f0; }
html[data-theme="dark"] .note-panel { background: #121d2b; }
html[data-theme="dark"] .feature-strip { background: #111a27; }
html[data-theme="dark"] .fcard { background: rgba(22, 32, 46, 0.9); }
html[data-theme="dark"] .dl-card { background: rgba(22, 32, 46, 0.9); border-color: var(--line); }
html[data-theme="dark"] .dl-card.dl-primary { border-color: var(--accent); }
html[data-theme="dark"] .shortcut-strip { background: #121d2b; }
html[data-theme="dark"] kbd { background: #1c2a3a; border-color: #2e4057; color: var(--ink); }
html[data-theme="dark"] .site-footer { background: #070d15; }
html[data-theme="dark"] .workflow-card,
html[data-theme="dark"] .download-row,
html[data-theme="dark"] .feature-card { background: rgba(22, 32, 46, 0.9); }
html[data-theme="dark"] .app-shot { background: rgba(22, 32, 46, 0.86); }
html[data-theme="dark"] .lang-toggle { background: #1c2a3a; color: var(--accent); }
html[data-theme="dark"] .site-nav a:hover,
html[data-theme="dark"] .lang-toggle:hover,
html[data-theme="dark"] .theme-toggle:hover { background: #1c2a3a; color: var(--accent); }

/* ===== THEME TOGGLE BUTTON ===== */
.theme-toggle {
  min-height: 34px;
  width: 34px;
  padding: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--muted);
  background: transparent;
  border: 1px solid var(--line);
  border-radius: 6px;
  cursor: pointer;
  transition: color 0.15s, background 0.15s;
  flex-shrink: 0;
}
.theme-toggle:hover { color: var(--accent); background: #e4f3f6; }
/* In light mode: show moon icon; in dark mode: show sun icon */
.theme-toggle .icon-sun  { display: none; }
.theme-toggle .icon-moon { display: block; }
html[data-theme="dark"] .theme-toggle .icon-sun  { display: block; }
html[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

/* ===== FEATURE STRIP ===== */
.feature-strip {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
  background: #f4f8fb;
  border-bottom: 1px solid var(--line);
}

.fcard {
  display: flex;
  gap: 18px;
  align-items: flex-start;
  padding: clamp(22px, 3vw, 38px) clamp(18px, 3vw, 40px);
  border-right: 1px solid var(--line);
  background: rgba(255,255,255,0.7);
  transition: background 0.15s;
}
.fcard:last-child { border-right: none; }
.fcard:hover { background: rgba(255,255,255,1); }

.fcard-icon {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  color: var(--accent);
}
.fcard-icon svg { width: 40px; height: 40px; }

.fcard h3 {
  margin: 0 0 6px;
  font-size: 16px;
  line-height: 1.3;
}

.fcard p {
  margin: 0;
  font-size: 13.5px;
  color: var(--muted);
  line-height: 1.55;
}

/* ===== SCROLL REVEAL ===== */
[data-reveal] {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}
[data-reveal].revealed {
  opacity: 1;
  transform: none;
}
@media (prefers-reduced-motion: reduce) {
  [data-reveal] { opacity: 1; transform: none; transition: none; }
}

/* ===== SHORTCUT STRIP ===== */
.shortcut-strip {
  margin-top: 32px;
  padding: 20px 24px;
  background: #edf5f8;
  border-radius: var(--radius);
  border: 1px solid var(--line);
}
.shortcut-label { margin: 0 0 14px; }
.shortcut-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 20px;
}
.sc-item {
  display: flex;
  align-items: center;
  gap: 5px;
  font-size: 13px;
  color: var(--muted);
}
.sc-item span { color: var(--ink); }
kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 26px;
  height: 22px;
  padding: 0 6px;
  font-family: inherit;
  font-size: 11px;
  font-weight: 700;
  background: var(--paper);
  border: 1px solid #c8d8e4;
  border-bottom-width: 2px;
  border-radius: 4px;
  color: var(--ink);
}

/* ===== DOWNLOAD CARDS ===== */
.dl-cards {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-bottom: 16px;
}

.dl-card {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 20px;
  padding: 24px;
  background: rgba(255,255,255,0.95);
  border: 1px solid var(--line);
  border-radius: 12px;
  box-shadow: 0 4px 18px rgba(15,124,140,0.07);
  transition: box-shadow 0.15s, border-color 0.15s;
}
.dl-card.dl-primary {
  border-color: rgba(15, 124, 140, 0.35);
}
.dl-card:hover {
  box-shadow: 0 8px 32px rgba(15,124,140,0.16);
  border-color: var(--accent);
}
.dl-card-top > div {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
}
.dl-card-top > div strong {
  font-size: 17px;
}
.dl-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 22px;
  font-size: 11px;
  font-weight: 900;
  background: var(--accent);
  color: #fff;
  border-radius: 5px;
  letter-spacing: 0.02em;
}
.dl-badge-3d {
  background: var(--accent-2);
}
.dl-features {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 5px;
}
.dl-features li {
  font-size: 13px;
  color: var(--muted);
  padding-left: 16px;
  position: relative;
}
.dl-features li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--accent);
  font-size: 11px;
  font-weight: 900;
}
.dl-btn {
  width: 100%;
  height: 46px;
  gap: 8px;
  font-size: 15px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent), #0a6070);
  border: none;
  border-radius: 8px;
  color: #fff;
}
.dl-btn:hover {
  background: linear-gradient(135deg, #0a6b7a, #0a6070);
  color: #fff;
}

.dl-secondary-list {
  margin-top: 0;
}

/* ===== FOOTER ===== */
.site-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 20px clamp(18px, 5vw, 72px);
  color: #8ba0b4;
  background: #0f1722;
  font-size: 13.5px;
  flex-wrap: wrap;
}
.footer-links {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}
.footer-links a {
  color: #8ba0b4;
  text-decoration: none;
  transition: color 0.15s;
}
.footer-links a:hover { color: var(--accent-3); }
.footer-copy { color: #627488; }

/* ===== RESPONSIVE: feature strip ===== */
@media (max-width: 860px) {
  .feature-strip { grid-template-columns: 1fr; }
  .fcard { border-right: none; border-bottom: 1px solid var(--line); }
  .fcard:last-child { border-bottom: none; }
  .dl-cards { grid-template-columns: 1fr; }
  .shortcut-grid { gap: 8px 14px; }
}