/* ============================================================
   LV · Audio & Acoustic Lab
   Design: Instrument-grade · Black/Silver/Copper
   ============================================================ */

/* ---- Custom Properties ---- */
:root {
  --bg-base:       #121212;
  --bg-surface:    #181818;
  --bg-card:       #1c1c1c;
  --bg-card-hover: #222222;
  --text-primary:  #d4d4d4;
  --text-secondary:#989898;
  --text-muted:    #6a6a6a;
  --accent-copper: #b8860b;
  --accent-silver: #a8a8a8;
  --border-subtle: #2a2a2a;
  --border-mid:    #3a3a3a;
  --border-accent: rgba(184, 134, 11, 0.2);

  --font-sans:    'IBM Plex Sans', -apple-system, sans-serif;
  --font-serif:   'Source Serif 4', Georgia, 'Times New Roman', serif;
  --font-mono:    'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;

  --content-max: 960px;
  --content-wide:1080px;
  --section-gap: 100px;
}

/* ---- Reset ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background: var(--bg-base);
}

body {
  font-family: var(--font-serif);
  background: var(--bg-base);
  color: var(--text-primary);
  line-height: 1.75;
  font-size: 16px;
  font-weight: 400;
  overflow-x: hidden;
}

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

.text-copper { color: var(--accent-copper); }
.text-silver  { color: var(--accent-silver); }

/* Selection */
::selection {
  background: rgba(184, 134, 11, 0.25);
  color: var(--text-primary);
}

/* ---- Scrollbar ---- */
::-webkit-scrollbar { width: 4px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-mid); border-radius: 0; }

/* ============================================================
   HEADER — Instrument Panel Style
   ============================================================ */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(18, 18, 18, 0.92);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-subtle);
}

.header-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: 0 28px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* Logo */
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--accent-silver);
  transition: color 0.2s;
}
.logo:hover { color: var(--text-primary); }

.logo-mark { color: var(--accent-silver); }

.logo-text {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.04em;
}
.logo-amp { color: var(--accent-copper); font-weight: 400; }

/* Nav */
.nav-links { display: flex; gap: 28px; align-items: center; }

.nav-link {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-secondary);
  transition: color 0.2s;
}
.nav-link:hover { color: var(--accent-copper); }
.nav-link--rss { color: var(--text-muted); }
.nav-link--rss:hover { color: var(--accent-copper); }

/* Mobile toggle — two bars, instrument style */
.mobile-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none; border: none;
  cursor: pointer; padding: 4px;
}
.mobile-toggle span {
  display: block;
  width: 20px; height: 1.5px;
  background: var(--accent-silver);
  transition: transform 0.25s, opacity 0.25s;
}

/* ============================================================
   HERO
   ============================================================ */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 120px 28px 80px;
  max-width: var(--content-max);
  margin: 0 auto;
  position: relative;
}

.hero-rule {
  width: 48px; height: 1px;
  background: var(--accent-copper);
  margin-bottom: 48px;
}

.hero-label {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.hero-headline {
  font-family: var(--font-sans);
  font-size: clamp(2.25rem, 4.5vw, 3rem);
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin-bottom: 32px;
  max-width: 960px;
}

.hero-subline {
  font-family: var(--font-serif);
  font-size: 1.0625rem;
  line-height: 1.8;
  color: var(--text-secondary);
  max-width: 600px;
  margin-bottom: 64px;
}

.hero-scroll {
  display: flex;
  align-items: center;
  gap: 10px;
}

.hero-scroll-text {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  text-transform: uppercase;
}

.hero-scroll-arrow {
  color: var(--accent-copper);
  font-size: 0.875rem;
  animation: arrow-bob 2s ease-in-out infinite;
}
@keyframes arrow-bob {
  0%, 100% { transform: translateY(0); opacity: 0.5; }
  50% { transform: translateY(4px); opacity: 1; }
}

/* ============================================================
   SECTION COMMON
   ============================================================ */
.section {
  padding: var(--section-gap) 28px;
  max-width: var(--content-max);
  margin: 0 auto;
}

.section-rule {
  width: 48px; height: 1px;
  background: var(--border-mid);
  margin-bottom: 20px;
}

.section-title {
  font-family: var(--font-sans);
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.section-desc {
  font-family: var(--font-serif);
  font-size: 0.9375rem;
  color: var(--text-muted);
  margin-bottom: 48px;
}

.section-cta {
  margin-top: 40px;
  text-align: left;
}

/* ============================================================
   ABOUT
   ============================================================ */
.about { max-width: var(--content-max); }

.about-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  margin-bottom: 48px;
}

.about-block { }

.about-heading {
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--accent-silver);
  margin-bottom: 12px;
  letter-spacing: 0.02em;
}

.about-block p {
  font-size: 0.875rem;
  line-height: 1.75;
  color: var(--text-secondary);
}

.about-contact {
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 20px 0;
  border-top: 1px solid var(--border-subtle);
  border-bottom: 1px solid var(--border-subtle);
}

.contact-prefix {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}

.contact-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-secondary);
  transition: color 0.2s;
}
.contact-item:hover { color: var(--accent-copper); }

/* ============================================================
   THE LAB (三列)
   ============================================================ */
.lab-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.lab-category {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.lab-cat-title {
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--accent-silver);
  margin-bottom: 8px;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px;
}

.lab-cat-num {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  color: var(--accent-copper);
  font-weight: 500;
}

.lab-cat-sub {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--text-muted);
}

/* ============================================================
   NOTE CARDS
   ============================================================ */
.note-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 2px;
  padding: 20px;
  transition: border-color 0.2s, background 0.2s;
}
.note-card:hover {
  border-color: var(--border-mid);
  background: var(--bg-card-hover);
}

.note-card--seed {
  border-left: 2px solid var(--accent-copper);
}

.note-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.625rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 2px;
  margin-bottom: 12px;
}

.note-badge--seed {
  color: var(--accent-copper);
  background: rgba(184, 134, 11, 0.1);
  border: 1px solid rgba(184, 134, 11, 0.2);
}

.note-title {
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  line-height: 1.45;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.note-excerpt {
  font-family: var(--font-serif);
  font-size: 0.8125rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: 12px;
  display: -webkit-box;
  -webkit-line-clamp: 4;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.note-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  color: var(--text-muted);
}

.note-tag {
  display: inline-block;
  color: var(--text-muted);
  background: rgba(152, 152, 152, 0.06);
  padding: 1px 6px;
  border-radius: 2px;
  letter-spacing: 0.03em;
}

time {
  color: var(--accent-copper);
}

/* ============================================================
   SYSTEM THINKING
   ============================================================ */
.system-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.system-block {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.system-heading {
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--accent-silver);
  margin-bottom: 4px;
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.system-cn {
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--text-muted);
}

/* ============================================================
   CASE STUDIES
   ============================================================ */
.cases-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
}

.cases-block {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.cases-heading {
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--accent-silver);
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.cases-cn {
  font-size: 0.8125rem;
  font-weight: 400;
  color: var(--text-muted);
}

.cases-intro {
  font-family: var(--font-serif);
  font-size: 0.8125rem;
  color: var(--text-muted);
  font-style: italic;
  margin-bottom: 4px;
}

/* ============================================================
   PERSPECTIVES
   ============================================================ */
.views-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.view-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 2px;
  padding: 24px;
  transition: border-color 0.2s, background 0.2s;
}
.view-card:hover {
  border-color: var(--border-mid);
  background: var(--bg-card-hover);
}

.view-label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-copper);
  margin-bottom: 14px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-subtle);
}

.view-title {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.4;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.view-excerpt {
  font-family: var(--font-serif);
  font-size: 0.8125rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

/* ============================================================
   GLOSSARY
   ============================================================ */
.glossary-grid {
  max-width: 800px;
}

.glossary-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.glossary-item {
  padding: 22px 0;
  border-bottom: 1px solid var(--border-subtle);
}

.glossary-item dt {
  font-family: var(--font-mono);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.gloss-unit {
  font-family: var(--font-serif);
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--text-muted);
  font-style: italic;
}

.glossary-item dd {
  font-family: var(--font-serif);
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

/* ============================================================
   SUBSCRIBE
   ============================================================ */
.subscribe-links {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.subscribe-card {
  display: flex;
  gap: 20px;
  padding: 28px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 2px;
  transition: border-color 0.2s;
}
.subscribe-card:hover {
  border-color: var(--accent-copper);
}

.subscribe-icon {
  color: var(--accent-silver);
  flex-shrink: 0;
  padding-top: 2px;
}

.subscribe-title {
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.subscribe-desc {
  font-family: var(--font-serif);
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn-more {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--accent-copper);
  border-bottom: 1px solid var(--border-accent);
  padding-bottom: 2px;
  transition: border-color 0.2s, color 0.2s;
}
.btn-more:hover {
  border-color: var(--accent-copper);
  color: #d4a017;
}

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer {
  padding: 80px 28px 36px;
  max-width: var(--content-wide);
  margin: 0 auto;
}

.footer-rule {
  width: 100%;
  height: 1px;
  background: var(--border-subtle);
  margin-bottom: 48px;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  gap: 60px;
  margin-bottom: 48px;
}

.footer-logo {
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--accent-silver);
}

.footer-tagline {
  font-family: var(--font-serif);
  font-size: 0.8125rem;
  color: var(--text-muted);
  margin-top: 8px;
  max-width: 320px;
  font-style: italic;
}

.footer-right {
  display: flex;
  gap: 64px;
}

.footer-col h4 {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  text-transform: uppercase;
  margin-bottom: 14px;
}

.footer-col a {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-bottom: 8px;
  transition: color 0.2s;
}
.footer-col a:hover { color: var(--accent-copper); }

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 24px;
  border-top: 1px solid var(--border-subtle);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  color: var(--text-muted);
}

.footer-icp {
  color: var(--text-muted);
  transition: color 0.2s;
}
.footer-icp:hover { color: var(--text-secondary); }

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 960px) {
  .about-grid { grid-template-columns: 1fr; gap: 28px; }
  .lab-grid { grid-template-columns: 1fr; gap: 40px; }
  .system-grid { grid-template-columns: 1fr; gap: 40px; }
  .cases-grid { grid-template-columns: 1fr; gap: 40px; }
  .views-grid { grid-template-columns: 1fr; }
  .subscribe-links { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  :root { --section-gap: 64px; }

  .header-inner { padding: 0 20px; }

  .nav-links {
    display: none;
    position: fixed;
    top: 56px; left: 0; right: 0;
    background: rgba(24, 24, 24, 0.98);
    backdrop-filter: blur(12px);
    flex-direction: column;
    padding: 20px 28px;
    gap: 14px;
    border-bottom: 1px solid var(--border-subtle);
  }
  .nav-links.open { display: flex; }

  .mobile-toggle { display: flex; }

  .section, .hero { padding-left: 20px; padding-right: 20px; }

  .hero { padding-top: 100px; min-height: auto; }
  .hero-headline { font-size: 1.75rem; }

  .hero-subline { font-size: 0.9375rem; }

  .about-contact {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .footer-inner {
    flex-direction: column;
    gap: 36px;
  }
  .footer-right { gap: 48px; }
  .footer-bottom { flex-direction: column; align-items: flex-start; gap: 8px; }

  .glossary-item dt { flex-direction: column; gap: 2px; }
}

/* ============================================================
   SCROLL REVEAL (JS enhanced)
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}