:root {
  --bg: #f8fafc;
  --bg-card: #ffffff;
  --fg: #0f172a;
  --fg-muted: #475569;
  --accent: #0e7490;
  --accent-soft: #cffafe;
  --callout-bg: #fef3c7;
  --callout-border: #f59e0b;
  --border: #e2e8f0;
  --code-bg: #f1f5f9;
  --table-row-alt: #f8fafc;

  /* infographic palette */
  --bar-pavegen: #0e7490;
  --bar-piezo: #7c3aed;
  --bar-teng: #16a34a;
  --bar-track: #e2e8f0;

  --badge-commercial-bg: #d1fae5;
  --badge-commercial-fg: #065f46;
  --badge-pilot-bg: #dbeafe;
  --badge-pilot-fg: #1e40af;
  --badge-lab-bg: #fef3c7;
  --badge-lab-fg: #92400e;
  --badge-concept-bg: #f1f5f9;
  --badge-concept-fg: #475569;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  color: var(--fg);
  background: var(--bg);
}

/* ========== HERO ========== */
.hero {
  background: linear-gradient(135deg, #0f172a 0%, #134e4a 100%);
  color: #fff;
  padding: 4rem 2rem 3rem;
  text-align: center;
}
.top-nav {
  margin-bottom: 2rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1.5rem;
}
.top-nav a {
  color: var(--accent-soft);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  transition: background 0.15s;
}
.top-nav a:hover { background: rgba(255,255,255,0.1); }
.hero h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin: 0 0 0.5rem;
  letter-spacing: -0.02em;
}
.hero .kicker {
  font-size: 1rem;
  color: var(--accent-soft);
  margin: 0 0 1.5rem;
  font-weight: 500;
}
.hero .lede {
  max-width: 720px;
  margin: 0 auto 1.5rem;
  font-size: 1.05rem;
  color: rgba(255,255,255,0.88);
  text-align: left;
}
.hero .meta {
  font-size: 0.85rem;
  color: rgba(255,255,255,0.65);
  margin: 0;
}
.hero .meta a { color: var(--accent-soft); }
.hero code {
  background: rgba(255,255,255,0.1);
  padding: 0.1rem 0.4rem;
  border-radius: 3px;
  font-size: 0.85em;
}

/* ========== MAIN ========== */
main {
  max-width: 880px;
  margin: 0 auto;
  padding: 3rem 2rem;
}
section {
  margin-bottom: 3rem;
  background: var(--bg-card);
  padding: 2rem;
  border-radius: 8px;
  border: 1px solid var(--border);
}
section h2 {
  margin-top: 0;
  margin-bottom: 1.25rem;
  font-size: 1.6rem;
  border-bottom: 2px solid var(--accent);
  padding-bottom: 0.4rem;
  color: var(--fg);
}
section h3 {
  margin-top: 1.5rem;
  margin-bottom: 0.75rem;
  font-size: 1.2rem;
  color: var(--accent);
}
section p { margin: 0 0 1rem; color: var(--fg); }
section ul, section ol { padding-left: 1.5rem; }
section li { margin-bottom: 0.5rem; }

.section-lede {
  font-size: 0.95rem;
  color: var(--fg-muted);
  margin-top: -0.5rem;
  margin-bottom: 1.25rem;
  font-style: italic;
}

.callout {
  background: var(--callout-bg);
  border-left: 4px solid var(--callout-border);
  padding: 1rem 1.25rem;
  margin: 1.25rem 0;
  border-radius: 4px;
}
.callout strong { color: #92400e; }

/* ========== INFOGRAPHICS: stat cards ========== */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}
.stat-card {
  background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem 1rem;
  text-align: center;
  border-top: 4px solid var(--accent);
}
.stat-card.stat-pavegen { border-top-color: var(--bar-pavegen); }
.stat-card.stat-piezo { border-top-color: var(--bar-piezo); }
.stat-card.stat-teng { border-top-color: var(--bar-teng); }
.stat-card.stat-efficiency { border-top-color: var(--callout-border); }
.stat-number {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--fg);
  line-height: 1;
  margin-bottom: 0.4rem;
}
.stat-label {
  font-size: 0.85rem;
  color: var(--fg);
  margin-bottom: 0.5rem;
  min-height: 2.5em;
}
.stat-source {
  font-size: 0.7rem;
  color: var(--fg-muted);
  font-style: italic;
}

/* ========== INFOGRAPHICS: bar chart ========== */
.chart-heading {
  margin-top: 2.5rem !important;
}
.chart-caption {
  font-size: 0.85rem;
  color: var(--fg-muted);
  margin-bottom: 1rem;
}
.bar-chart {
  margin: 1rem 0 1.5rem;
}
.bar-row {
  display: grid;
  grid-template-columns: 180px 1fr 80px;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.6rem;
}
.bar-label {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--fg);
  text-align: right;
}
.bar-track {
  background: var(--bar-track);
  height: 28px;
  border-radius: 4px;
  overflow: hidden;
  position: relative;
}
.bar-fill {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  padding-right: 0.5rem;
  color: #fff;
  font-size: 0.75rem;
  font-weight: 600;
  transition: width 0.3s ease-out;
  border-radius: 4px;
  white-space: nowrap;
  overflow: visible;
}
.bar-fill span {
  text-shadow: 0 1px 2px rgba(0,0,0,0.3);
}
.bar-fill-pavegen { background: linear-gradient(90deg, var(--bar-pavegen) 0%, #0891b2 100%); }
.bar-fill-piezo { background: linear-gradient(90deg, var(--bar-piezo) 0%, #a855f7 100%); }
.bar-fill-teng { background: linear-gradient(90deg, var(--bar-teng) 0%, #22c55e 100%); }
.bar-value {
  font-size: 0.85rem;
  color: var(--fg);
  font-weight: 600;
}

/* ========== INFOGRAPHICS: readiness pills ========== */
.readiness-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin: 1rem 0;
}
.readiness-pill {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}
.readiness-label {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
}
.readiness-tech {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--fg);
}
.readiness-detail {
  font-size: 0.8rem;
  color: var(--fg-muted);
}

/* ========== TABLES ========== */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.25rem 0;
  font-size: 0.9rem;
}
th {
  background: var(--fg);
  color: #fff;
  text-align: left;
  padding: 0.6rem 0.75rem;
  font-weight: 600;
}
td {
  padding: 0.6rem 0.75rem;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}
tbody tr:nth-child(even) { background: var(--table-row-alt); }

.brand-table .row-commercial { border-left: 3px solid var(--bar-pavegen); }
.brand-table .row-pilot { border-left: 3px solid var(--bar-piezo); }
.brand-table .row-lab { border-left: 3px solid var(--bar-teng); }
.brand-table .row-concept { border-left: 3px solid var(--badge-concept-fg); }
.flag {
  font-size: 1.1rem;
  margin-right: 0.2rem;
}
.badge {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  border-radius: 12px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}
.badge-commercial { background: var(--badge-commercial-bg); color: var(--badge-commercial-fg); }
.badge-pilot { background: var(--badge-pilot-bg); color: var(--badge-pilot-fg); }
.badge-lab { background: var(--badge-lab-bg); color: var(--badge-lab-fg); }
.badge-concept { background: var(--badge-concept-bg); color: var(--badge-concept-fg); }

/* ========== PROJECT CARDS ========== */
.project-list {
  list-style: none;
  padding-left: 0;
}
.project-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: 6px;
  padding: 1.25rem 1.5rem;
  margin-bottom: 1.25rem;
  transition: box-shadow 0.15s;
}
.project-card:hover {
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.08);
}
.project-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  font-size: 0.75rem;
  margin-bottom: 0.6rem;
  color: var(--fg-muted);
  align-items: center;
}
.project-year {
  background: var(--accent);
  color: #fff;
  padding: 0.15rem 0.55rem;
  border-radius: 4px;
  font-weight: 600;
}
.project-loc { font-weight: 500; }
.project-tag {
  background: var(--code-bg);
  padding: 0.15rem 0.55rem;
  border-radius: 4px;
  font-weight: 500;
}
.project-card h3 {
  margin: 0.5rem 0 0.5rem;
  font-size: 1.05rem;
  color: var(--fg);
}
.project-body {
  font-size: 0.9rem;
  color: var(--fg-muted);
  margin-bottom: 0.75rem;
}
.project-source {
  font-size: 0.85rem;
  margin: 0;
}
.project-source a {
  word-break: break-all;
}

/* ========== SOURCE LIST ========== */
.source-list { padding-left: 1.5rem; }
.source-list li { font-size: 0.9rem; margin-bottom: 0.6rem; }
.caveats-heading { color: var(--accent); margin-top: 2rem; }
.caveats { font-size: 0.85rem; color: var(--fg-muted); }

/* ========== MISC ========== */
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
code {
  background: var(--code-bg);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
  font-size: 0.9em;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, monospace;
}
.meta { font-size: 0.85rem; color: var(--fg-muted); }
footer {
  text-align: center;
  padding: 2rem;
  color: var(--fg-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
  background: var(--bg-card);
}
footer a { color: var(--accent); }

/* ========== RECENT RESEARCH SECTION ========== */
.research-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 0.75rem;
  margin: 1rem 0 1.5rem;
}
.research-stat {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.9rem 0.75rem;
  text-align: center;
}
.research-stat-num {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
  margin-bottom: 0.3rem;
}
.research-stat-label {
  font-size: 0.75rem;
  color: var(--fg-muted);
}

.research-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin: 1.25rem 0;
}
@media (min-width: 900px) {
  .research-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
.research-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1rem 1.25rem;
  border-left: 4px solid var(--accent);
}
.research-card[data-tech="teng"] { border-left-color: var(--bar-teng); }
.research-card[data-tech="piezo"] { border-left-color: var(--bar-piezo); }
.research-card[data-tech="em"] { border-left-color: var(--bar-pavegen); }
.research-card[data-tech="hybrid"] { border-left-color: var(--callout-border); }
.research-year {
  display: inline-block;
  background: var(--fg);
  color: #fff;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  font-size: 0.7rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}
.research-tech-tag {
  display: inline-block;
  padding: 0.15rem 0.55rem;
  border-radius: 4px;
  font-size: 0.7rem;
  font-weight: 600;
  margin-left: 0.4rem;
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}
.tag-teng { background: #dcfce7; color: #166534; }
.tag-piezo { background: #ede9fe; color: #5b21b6; }
.tag-em { background: #cffafe; color: #155e75; }
.tag-hybrid { background: #fef3c7; color: #92400e; }
.research-card h3 {
  margin: 0.4rem 0 0.5rem;
  font-size: 0.95rem;
  line-height: 1.4;
  color: var(--fg);
}
.research-card h3 a {
  color: var(--fg);
  text-decoration: none;
  word-break: break-word;
}
.research-card h3 a:hover {
  color: var(--accent);
  text-decoration: underline;
}
.research-authors {
  font-size: 0.8rem;
  color: var(--fg-muted);
  font-style: italic;
  margin: 0.25rem 0;
}
.research-venue {
  font-size: 0.8rem;
  color: var(--fg-muted);
  margin: 0.25rem 0 0.5rem;
}
.research-finding {
  font-size: 0.85rem;
  margin: 0.5rem 0;
  color: var(--fg);
}
.research-output {
  font-size: 0.8rem;
  margin: 0.3rem 0;
  padding: 0.4rem 0.6rem;
  background: var(--code-bg);
  border-radius: 4px;
}
.research-context {
  font-size: 0.78rem;
  color: var(--fg-muted);
  font-style: italic;
  margin: 0.4rem 0 0;
}
.research-adjacent {
  margin-top: 1.25rem;
  padding: 0.75rem 1rem;
  background: var(--bg);
  border: 1px dashed var(--border);
  border-radius: 6px;
}
.research-adjacent summary {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--accent);
  cursor: pointer;
}
.research-adjacent p {
  font-size: 0.85rem;
  color: var(--fg-muted);
  margin-top: 0.6rem;
  margin-bottom: 0;
}
.research-methodology {
  font-size: 0.8rem;
  color: var(--fg-muted);
  margin-top: 1.25rem;
  padding: 0.75rem 1rem;
  background: var(--bg);
  border-left: 3px solid var(--accent-soft);
  border-radius: 4px;
}

/* ========== RESPONSIVE ========== */
@media (max-width: 640px) {
  .hero h1 { font-size: 1.8rem; }
  .hero .lede { font-size: 1rem; }
  section { padding: 1.25rem; }
  main { padding: 1.5rem 1rem; }
  .top-nav { gap: 0.75rem; }
  table { font-size: 0.8rem; }
  th, td { padding: 0.4rem 0.5rem; }
  .bar-row {
    grid-template-columns: 110px 1fr 60px;
    gap: 0.5rem;
  }
  .bar-label { font-size: 0.75rem; }
  .stat-number { font-size: 2rem; }
}