:root {
  --bg: #f6f8fb;
  --surface: #ffffff;
  --surface-elevated: #eef2f8;
  --border: #dfe6f0;
  --border-strong: #c6d0e0;
  --text: #101828;
  --text-dim: #46536b;
  --text-faint: #64748b;
  --accent: #1e3a8a;
  --accent-bright: #2a4bab;
  --accent-soft: rgba(30, 58, 138, 0.06);
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --max: 1080px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

.wrap {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 24px;
}

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

a { color: inherit; }

h1, h2, h3, h4, h5 {
  font-family: var(--sans);
  font-weight: 700;
  margin: 0 0 0.4em;
  letter-spacing: -0.015em;
}

p { margin: 0 0 0.85em; color: var(--text-dim); }

/* ---------- Header ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(246, 248, 251, 0.88);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.logo {
  font-family: var(--sans);
  font-size: 1.1rem;
  font-weight: 800;
  text-decoration: none;
  color: var(--text);
  letter-spacing: -0.02em;
}

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

.site-nav {
  display: flex;
  gap: 24px;
}

.site-nav a {
  text-decoration: none;
  color: var(--text-dim);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.15s ease;
}

.site-nav a:hover { color: var(--text); }

.header-resume {
  font-size: 0.82rem;
  padding: 6px 14px;
}

/* ---------- Buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  font-family: var(--sans);
  font-weight: 600;
  font-size: 0.9rem;
  padding: 9px 18px;
  border-radius: 7px;
  border: 1px solid transparent;
  transition: all 0.15s ease;
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent);
  color: #ffffff;
}

.btn-primary:hover { background: var(--accent-bright); }

.btn-ghost {
  background: var(--surface);
  border-color: var(--border-strong);
  color: var(--text);
}

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

/* ---------- Hero ---------- */

.hero {
  padding: 56px 0 32px;
}

.eyebrow {
  font-family: var(--mono);
  color: var(--accent);
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 12px;
}

.hero h1 {
  font-size: clamp(2rem, 4.2vw, 2.85rem);
  line-height: 1.16;
  max-width: 26ch;
  color: var(--text);
  font-weight: 800;
}

.hero-sub {
  font-size: 1.05rem;
  max-width: 64ch;
  margin-top: 14px;
  color: var(--text-dim);
  line-height: 1.5;
}

.hero-actions {
  display: flex;
  gap: 12px;
  margin-top: 22px;
  flex-wrap: wrap;
}

/* ---------- Metrics strip ---------- */

.metrics {
  padding: 4px 0 44px;
  border-bottom: 1px solid var(--border);
}

.metrics-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
}

.metric-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
}

.metric-value {
  font-family: var(--mono);
  font-size: 1.75rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: -0.02em;
  margin-bottom: 4px;
}

.metric-label {
  font-size: 0.86rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 3px;
  line-height: 1.3;
}

.metric-sub {
  font-size: 0.8rem;
  color: var(--text-faint);
  line-height: 1.4;
}

/* ---------- Section scaffolding ---------- */

section { padding: 52px 0; }

.section-kicker {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin-bottom: 8px;
}

.section-title {
  font-size: clamp(1.5rem, 2.8vw, 1.95rem);
  color: var(--text);
  max-width: 30ch;
  font-weight: 800;
}

.section-lede {
  font-size: 0.98rem;
  max-width: 64ch;
  margin-top: 8px;
}

/* ---------- Work / Case studies (grid) ---------- */

.work { border-bottom: 1px solid var(--border); }

.case-list {
  margin-top: 28px;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  align-items: start;
}

.case {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  box-shadow: 0 1px 2px rgba(16, 24, 40, 0.03);
}

.case[open] {
  grid-column: 1 / -1;
  box-shadow: 0 6px 20px rgba(16, 24, 40, 0.06);
  border-color: var(--border-strong);
}

.case summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 16px 20px;
  transition: background 0.15s ease;
}

.case summary::-webkit-details-marker { display: none; }

.case:not([open]) summary:hover { background: var(--surface-elevated); }

.case-num {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--accent);
  padding-top: 2px;
  flex-shrink: 0;
  width: 22px;
}

.case-head { flex: 1; min-width: 0; }

.case-title {
  display: block;
  font-family: var(--sans);
  font-weight: 700;
  font-size: 1.02rem;
  color: var(--text);
  line-height: 1.3;
  margin-bottom: 6px;
}

.case-teaser {
  display: block;
  font-size: 0.86rem;
  color: var(--text-dim);
  margin-bottom: 10px;
  line-height: 1.45;
}

.case[open] .case-teaser { max-width: 68ch; }

.case-tags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.tag {
  font-family: var(--mono);
  font-size: 0.68rem;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid rgba(30, 58, 138, 0.16);
  padding: 2px 8px;
  border-radius: 100px;
  white-space: nowrap;
}

.chevron {
  flex-shrink: 0;
  width: 16px;
  height: 16px;
  margin-top: 4px;
  position: relative;
}

.chevron::before,
.chevron::after {
  content: "";
  position: absolute;
  background: var(--text-faint);
  transition: transform 0.2s ease;
}

.chevron::before { width: 2px; height: 10px; left: 7px; top: 3px; }
.chevron::after { width: 10px; height: 2px; left: 3px; top: 7px; }

.case[open] .chevron::before { transform: scaleY(0); }

.case-body {
  padding: 0 28px 22px 28px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.case-col { min-width: 0; }

.case-body h4 {
  font-family: var(--mono);
  font-size: 0.74rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent);
  margin-top: 16px;
  margin-bottom: 6px;
}

.case-body h4:first-child { margin-top: 0; }

.case-body p, .case-body li {
  color: var(--text-dim);
  font-size: 0.92rem;
  line-height: 1.55;
}

.case-body ul { margin: 0 0 0.8em; padding-left: 18px; }
.case-body li { margin-bottom: 6px; }
.case-body strong { color: var(--text); }

/* ---------- Live-connected diagrams ---------- */

.diagram-figure {
  margin: 2px 0 20px;
}

.diagram-frame {
  background: #ffffff;
  border-radius: 8px;
  padding: 18px 16px;
  border: 1px solid var(--border);
  box-shadow: 0 2px 6px rgba(16, 24, 40, 0.03);
}

.live-diagram { position: relative; }

.diagram-overlay {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  overflow: visible;
  pointer-events: none;
  color: var(--text-faint);
}

.diagram-arrow-label { fill: var(--text-dim); font-family: var(--mono); }
.diagram-arrow-label-bg { fill: #ffffff; }

.dbox {
  position: relative;
  z-index: 1;
  background: #ffffff;
  border: 1.2px solid var(--border-strong);
  border-radius: 6px;
  padding: 8px 11px;
  font-size: 11px;
  line-height: 1.35;
  text-align: center;
  color: var(--text);
  flex: 1 1 150px;
}

.dbox-sub { display: block; font-size: 9px; color: var(--text-faint); margin-top: 2px; }

.dbox.accent { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.dbox.warn { border-color: #b45309; background: #fff7ed; color: #92400e; }
.dbox.decision { border-style: dashed; font-style: italic; }
.dbox.spacer { visibility: hidden; border: none; padding: 0; }

.dgroup {
  position: relative;
  border: 1px dashed var(--border-strong);
  border-radius: 10px;
  padding: 24px 14px 14px;
  margin-bottom: 24px;
}

.dgroup:last-child { margin-bottom: 0; }

.dgroup.accent { border-color: rgba(30, 58, 138, 0.35); background: var(--accent-soft); }

.dgroup-label {
  position: absolute;
  top: 7px;
  left: 14px;
  font-family: var(--mono);
  font-size: 8.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-faint);
}

.dgroup.accent .dgroup-label { color: var(--accent); opacity: 0.85; }

.drow { display: flex; flex-wrap: wrap; gap: 10px; }
.dstack { display: flex; flex-direction: column; gap: 10px; }
.dstack .dbox { flex-basis: auto; }

.dgroup > .drow + .drow,
.dgroup > .drow + .dstack,
.dgroup > .dstack + .drow,
.dgroup > .dstack + .dstack {
  margin-top: 16px;
}

/* ---------- About ---------- */

.about-grid {
  display: grid;
  grid-template-columns: 1.35fr 1fr;
  gap: 40px;
}

.credentials {
  display: grid;
  gap: 16px;
  align-content: start;
  padding-top: 2px;
}

.credential-block { border-top: 1px solid var(--border); padding-top: 10px; }

.credential-block h5 {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-faint);
  margin-bottom: 4px;
}

.credential-block p { color: var(--text); font-size: 0.9rem; margin: 0; }

/* ---------- Contact ---------- */

.contact { border-top: 1px solid var(--border); }

.contact-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 20px;
}

/* ---------- Footer ---------- */

.site-footer { border-top: 1px solid var(--border); padding: 22px 0; }

.footer-inner {
  display: flex;
  justify-content: space-between;
  font-size: 0.82rem;
  color: var(--text-faint);
  flex-wrap: wrap;
  gap: 8px;
}

/* ---------- Responsive ---------- */

@media (max-width: 900px) {
  .metrics-grid { grid-template-columns: repeat(2, 1fr); }
  .case-list { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .diagram-frame { padding: 14px 12px; }
}

@media (max-width: 760px) {
  .site-nav { display: none; }
  .hero { padding: 44px 0 24px; }
  section { padding: 38px 0; }
  .about-grid { grid-template-columns: 1fr; gap: 24px; }
  .case summary { padding: 14px 16px; gap: 10px; }
  .case-body { padding: 0 16px 18px 16px; }
  .case-num { width: auto; }
}

@media (max-width: 480px) {
  .hero-actions, .contact-actions { flex-direction: column; align-items: stretch; }
  .metrics-grid { grid-template-columns: 1fr 1fr; }
}