/* ====================================================
   MNotation — Project Website
   Style inspired by academic project pages (e.g. CMU MuFIN)
   ==================================================== */

:root {
  --c-bg: #ffffff;
  --c-bg-alt: #f7f8fb;
  --c-bg-soft: #eef1f7;
  --c-text: #1f2330;
  --c-text-mute: #5b6273;
  --c-text-soft: #8a91a3;
  --c-border: #e2e6ef;
  --c-border-strong: #cdd3e0;

  --c-primary: #1a3d8f;        /* HKU-inspired deep blue */
  --c-primary-dark: #122a66;
  --c-primary-light: #e8eefc;
  --c-accent: #d4a017;         /* warm gold accent */
  --c-accent-light: #fff6dc;

  --c-mode-1: #1a3d8f;         /* Manual = blue */
  --c-mode-2: #7a3fb0;         /* LLM = purple */
  --c-mode-3: #2f9e7a;         /* Active = green */

  --radius: 14px;
  --radius-sm: 8px;
  --shadow-sm: 0 1px 2px rgba(20, 30, 60, 0.05);
  --shadow-md: 0 4px 18px rgba(20, 30, 60, 0.08);
  --shadow-lg: 0 12px 36px rgba(20, 30, 60, 0.12);

  --font-sans: "Inter", "Helvetica Neue", -apple-system, BlinkMacSystemFont,
    "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", sans-serif;
  --font-serif: "Source Serif Pro", "Iowan Old Style", "Apple Garamond",
    "Times New Roman", Georgia, serif;

  --container-w: 1120px;
  --container-narrow: 820px;
}

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  color: var(--c-text);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: var(--c-primary);
  text-decoration: none;
  transition: color 0.15s ease, opacity 0.15s ease;
}
a:hover { color: var(--c-primary-dark); text-decoration: underline; }

button { font: inherit; cursor: pointer; }

h1, h2, h3, h4 {
  font-family: var(--font-serif);
  color: var(--c-text);
  line-height: 1.25;
  margin: 0 0 0.6em;
  font-weight: 600;
  letter-spacing: -0.01em;
}

p { margin: 0 0 1em; }

/* ---------- Layout helpers ---------- */
.container {
  width: 100%;
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 0 24px;
}
.container.narrow { max-width: var(--container-narrow); }

.section-title {
  font-size: 1.85rem;
  margin-bottom: 0.4em;
}
.section-title.centered { text-align: center; }
.section-sub {
  color: var(--c-text-mute);
  font-size: 1.05rem;
  margin-bottom: 2.5em;
}
.section-sub.centered { text-align: center; }

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--c-border);
}
.header-inner {
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  gap: 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--c-text);
}
.brand:hover { text-decoration: none; color: var(--c-primary); }
.brand-logo { width: 38px; height: 38px; }
.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}
.brand-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.brand-sub {
  font-size: 0.78rem;
  color: var(--c-text-soft);
  letter-spacing: 0.02em;
}
.brand-accent { color: var(--c-accent); font-weight: 600; }

.site-nav {
  display: flex;
  gap: 4px;
  margin-left: auto;
  align-items: center;
}
.nav-link {
  background: transparent;
  border: none;
  color: var(--c-text-mute);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  transition: background 0.15s ease, color 0.15s ease;
  position: relative;
}
.nav-link:hover { color: var(--c-primary); background: var(--c-primary-light); }
.nav-link.active {
  color: var(--c-primary);
  background: var(--c-primary-light);
}
.nav-link.active::after {
  content: "";
  position: absolute;
  left: 14px;
  right: 14px;
  bottom: 4px;
  height: 2px;
  background: var(--c-primary);
  border-radius: 2px;
}

.nav-toggle {
  display: none;
  margin-left: auto;
  background: transparent;
  border: 1px solid var(--c-border);
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  flex-direction: column;
  gap: 4px;
}
.nav-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--c-text);
  border-radius: 1px;
}

/* ---------- Main / Tab panel ---------- */
.site-main {
  min-height: 60vh;
}
.tab-panel {
  display: none;
  padding: 0 0 80px;
  animation: fadeIn 0.35s ease;
}
.tab-panel.active { display: block; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ---------- Hero (overview) ---------- */
.hero {
  background:
    radial-gradient(1200px 500px at 20% 0%, var(--c-primary-light), transparent 70%),
    radial-gradient(900px 400px at 90% 10%, var(--c-accent-light), transparent 70%),
    linear-gradient(180deg, #fbfcff 0%, #ffffff 100%);
  border-bottom: 1px solid var(--c-border);
  padding: 80px 0 70px;
}
.hero-inner {
  max-width: var(--container-narrow);
  margin: 0 auto;
  padding: 0 24px;
  text-align: center;
}
.eyebrow {
  display: inline-block;
  text-transform: uppercase;
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  color: var(--c-text-soft);
  background: var(--c-bg-soft);
  padding: 6px 14px;
  border-radius: 999px;
  margin: 0 0 24px;
  font-weight: 600;
}
.hero-title {
  font-size: clamp(2.4rem, 5vw, 3.6rem);
  font-weight: 700;
  line-height: 1.05;
  margin: 0 0 18px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.hero-title-main {
  background: linear-gradient(135deg, var(--c-primary) 0%, var(--c-mode-2) 65%, var(--c-accent) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}
.hero-title-sub {
  font-size: 0.42em;
  font-family: var(--font-sans);
  font-weight: 500;
  color: var(--c-text-mute);
  letter-spacing: 0.02em;
}
.hero-title-sub em {
  color: var(--c-accent);
  font-style: normal;
  font-weight: 700;
}
.hero-lede {
  font-size: 1.15rem;
  color: var(--c-text-mute);
  max-width: 680px;
  margin: 0 auto 32px;
  line-height: 1.7;
}
.hero-lede strong { color: var(--c-text); font-weight: 600; }

.hero-cta {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  padding: 12px 22px;
  border-radius: 999px;
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  text-decoration: none;
  transition: all 0.18s ease;
  border: 1.5px solid transparent;
  cursor: pointer;
}
.btn-primary {
  background: var(--c-primary);
  color: #fff;
  border-color: var(--c-primary);
}
.btn-primary:hover {
  background: var(--c-primary-dark);
  border-color: var(--c-primary-dark);
  color: #fff;
  text-decoration: none;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}
.btn-ghost {
  background: transparent;
  color: var(--c-primary);
  border-color: var(--c-border-strong);
}
.btn-ghost:hover {
  background: var(--c-primary-light);
  border-color: var(--c-primary);
  color: var(--c-primary-dark);
  text-decoration: none;
}

/* ---------- About blurb ---------- */
.about-blurb {
  padding: 70px 24px 40px;
  font-size: 1.05rem;
}
.about-blurb p { color: var(--c-text); line-height: 1.8; }

/* ---------- Mode cards ---------- */
.mode-list {
  display: flex;
  flex-direction: column;
  gap: 36px;
  margin-top: 30px;
}

.mode-card {
  display: grid;
  grid-template-columns: minmax(280px, 1fr) 1.2fr;
  gap: 36px;
  align-items: center;
  background: var(--c-bg);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}
.mode-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.mode-card-reverse {
  grid-template-columns: 1.2fr minmax(280px, 1fr);
}
.mode-card-reverse .mode-demo { order: 2; }
.mode-card-reverse .mode-body { order: 1; }

.mode-card.slim {
  grid-template-columns: 1fr;
}

.mode-demo {
  position: relative;
  background: linear-gradient(135deg, #f3f5fb 0%, #e9edf7 100%);
  border-radius: var(--radius);
  padding: 18px;
  overflow: hidden;
  aspect-ratio: 4 / 3;
  display: flex;
  align-items: center;
  justify-content: center;
}
.mode-demo img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}
.mode-badge {
  position: absolute;
  top: 12px;
  left: 12px;
  background: rgba(255,255,255,0.92);
  border: 1px solid var(--c-border);
  color: var(--c-text-mute);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  padding: 4px 10px;
  border-radius: 999px;
}

.mode-title {
  font-size: 1.5rem;
  margin-bottom: 6px;
}
.mode-subtitle {
  font-style: italic;
  color: var(--c-text-mute);
  margin-bottom: 14px;
  font-size: 1rem;
}
.mode-features {
  margin: 14px 0 0;
  padding-left: 0;
  list-style: none;
}
.mode-features li {
  position: relative;
  padding: 6px 0 6px 26px;
  color: var(--c-text);
  border-bottom: 1px dashed var(--c-border);
}
.mode-features li:last-child { border-bottom: none; }
.mode-features li::before {
  content: "✓";
  position: absolute;
  left: 0;
  top: 6px;
  color: var(--c-mode-3);
  font-weight: 700;
}

/* Per-mode color hint on the demo background */
.mode-card:nth-child(1) .mode-demo { background: linear-gradient(135deg, #eef3ff 0%, #dfe7ff 100%); }
.mode-card:nth-child(2) .mode-demo { background: linear-gradient(135deg, #f4ecff 0%, #e8d8ff 100%); }
.mode-card:nth-child(3) .mode-demo { background: linear-gradient(135deg, #e7f7f0 0%, #d3eee0 100%); }

/* ---------- Use cases ---------- */
.use-cases {
  margin-top: 50px;
  padding-top: 50px;
  border-top: 1px solid var(--c-border);
}
.usecase-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin-top: 24px;
}
.usecase {
  background: var(--c-bg-alt);
  padding: 22px;
  border-radius: var(--radius);
  border: 1px solid var(--c-border);
}
.usecase h4 {
  margin: 0 0 8px;
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 600;
  color: var(--c-primary);
}
.usecase p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--c-text-mute);
  line-height: 1.55;
}

/* ---------- Page header (sub-pages) ---------- */
.page-header {
  padding: 60px 0 30px;
  text-align: center;
}
.page-eyebrow {
  display: inline-block;
  background: var(--c-accent-light);
  color: #8a6a08;
  padding: 5px 14px;
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  margin-bottom: 14px;
}
.page-title {
  font-size: clamp(2rem, 4vw, 2.8rem);
  margin: 0 0 14px;
}
.page-sub {
  color: var(--c-text-mute);
  font-size: 1.08rem;
  max-width: 720px;
  margin: 0 auto;
  line-height: 1.7;
}

/* ---------- People ---------- */
.people-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 22px;
  margin-top: 28px;
}
.person-card {
  background: var(--c-bg);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 26px;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 16px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.person-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}
.person-avatar {
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--c-primary) 0%, var(--c-mode-2) 100%);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.4rem;
  letter-spacing: 0.02em;
  box-shadow: var(--shadow-sm);
}
.person-avatar.avatar-pi {
  background: linear-gradient(135deg, var(--c-accent) 0%, #b07a00 100%);
}
.person-name {
  font-size: 1.25rem;
  margin: 0 0 4px;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.person-tag {
  font-family: var(--font-sans);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  background: var(--c-accent-light);
  color: #8a6a08;
  padding: 3px 10px;
  border-radius: 999px;
}
.person-role {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--c-primary);
  margin: 0;
}
.person-affil {
  font-size: 0.88rem;
  color: var(--c-text-mute);
  margin: 0 0 8px;
}
.person-bio {
  font-size: 0.95rem;
  color: var(--c-text);
  line-height: 1.65;
  margin: 0;
}
.person-links {
  font-size: 0.88rem;
  margin: 6px 0 0;
}

.lab-callout {
  margin-top: 50px;
  background: linear-gradient(135deg, var(--c-primary-light) 0%, var(--c-accent-light) 100%);
  border-radius: var(--radius);
  padding: 32px;
  border: 1px solid var(--c-border);
}
.lab-callout h3 {
  margin: 0 0 10px;
  font-size: 1.3rem;
}
.lab-callout p {
  margin: 0 0 16px;
  color: var(--c-text);
  line-height: 1.75;
}

/* ---------- New Feature ---------- */
.feature-hero {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 40px;
  align-items: center;
  background: linear-gradient(135deg, #ffffff 0%, var(--c-bg-soft) 100%);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 36px;
  margin-bottom: 60px;
  box-shadow: var(--shadow-sm);
}
.feature-hero-text h2 {
  font-size: 1.8rem;
  margin: 0 0 14px;
}
.feature-hero-text p { color: var(--c-text); line-height: 1.75; margin-bottom: 22px; }
.feature-hero-visual {
  background: #fff;
  border-radius: var(--radius);
  padding: 10px;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--c-border);
  position: relative;
  overflow: hidden;
}
.feature-hero-visual a {
  display: block;
  position: relative;
  border-radius: 10px;
  overflow: hidden;
  transition: transform 0.25s ease;
}
.feature-hero-visual a:hover { transform: translateY(-2px); text-decoration: none; }
.feature-hero-visual img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 8px;
  border: 1px solid var(--c-border);
}
.feature-hero-visual .visual-caption {
  position: absolute;
  bottom: 10px;
  right: 10px;
  background: rgba(26, 61, 143, 0.92);
  color: #fff;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  padding: 5px 10px;
  border-radius: 999px;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
  margin: 24px 0 60px;
}
.feature-card {
  background: var(--c-bg);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 24px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.feature-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}
.feature-icon {
  font-size: 1.8rem;
  margin-bottom: 12px;
}
.feature-card h4 {
  margin: 0 0 8px;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 1.05rem;
  color: var(--c-primary);
}
.feature-card p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--c-text-mute);
  line-height: 1.6;
}

.stay-tuned {
  background: var(--c-primary);
  color: #fff;
  padding: 36px;
  border-radius: var(--radius);
  text-align: center;
  margin-top: 50px;
  background-image:
    radial-gradient(400px 200px at 10% 0%, rgba(255,255,255,0.15), transparent),
    radial-gradient(400px 200px at 90% 100%, rgba(212,160,23,0.25), transparent),
    linear-gradient(135deg, var(--c-primary) 0%, var(--c-primary-dark) 100%);
}
.stay-tuned h3 {
  color: #fff;
  font-size: 1.4rem;
  margin: 0 0 10px;
}
.stay-tuned p {
  color: rgba(255,255,255,0.88);
  margin: 0;
  font-size: 1rem;
}
.stay-tuned a { color: var(--c-accent); font-weight: 600; }
.stay-tuned a:hover { color: #ffd66b; }

/* ---------- Contact ---------- */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
  margin-top: 30px;
}
.contact-card {
  background: var(--c-bg);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.contact-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}
.contact-card h3 {
  margin: 0 0 12px;
  font-size: 1.1rem;
  color: var(--c-primary);
  font-family: var(--font-sans);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 0.85rem;
}
.contact-name {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 1.25rem;
  margin: 0 0 4px;
}
.contact-meta {
  color: var(--c-text-mute);
  font-size: 0.92rem;
  margin: 0 0 10px;
  line-height: 1.55;
}
.contact-note {
  font-size: 0.85rem;
  color: var(--c-text-soft);
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px dashed var(--c-border);
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--c-border);
  background: var(--c-bg-alt);
  padding: 28px 0;
  margin-top: 60px;
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.88rem;
  color: var(--c-text-mute);
}
.footer-dot { margin: 0 8px; color: var(--c-text-soft); }
.footer-right a { margin: 0 2px; }

/* ---------- Responsive ---------- */
@media (max-width: 880px) {
  .mode-card,
  .mode-card-reverse {
    grid-template-columns: 1fr;
  }
  .mode-card-reverse .mode-demo { order: 1; }
  .mode-card-reverse .mode-body { order: 2; }

  .feature-hero {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .nav-toggle { display: flex; }
  .site-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #fff;
    border-bottom: 1px solid var(--c-border);
    flex-direction: column;
    padding: 12px;
    gap: 4px;
    box-shadow: var(--shadow-md);
  }
  .site-nav.open { display: flex; }
  .nav-link { width: 100%; text-align: left; }
  .nav-link.active::after { display: none; }

  .header-inner { gap: 12px; }

  .hero { padding: 60px 0 50px; }
  .hero-cta { flex-direction: column; }
  .hero-cta .btn { width: 100%; }

  .mode-card { padding: 22px; gap: 22px; }
  .person-card { padding: 22px; }
}

@media (max-width: 480px) {
  .brand-sub { display: none; }
  .container { padding: 0 18px; }
}