/* =====================================================
   ConstructAI Labs — Design Tokens
   Palette: blueprint navy, structural blue, cyanotype
   line-blue, steel gray, hi-vis amber (signal accent)
   ===================================================== */
:root {
  --bg: #F6F8FA;
  --paper: #FFFFFF;
  --ink: #0B1F33;
  --blue: #123C5E;
  --blue-deep: #0A2A45;
  --blue-line: #6FA8DC;
  --steel: #5B6B7C;
  --steel-light: #8FA0B3;
  --signal: #F5A623;
  --hairline: rgba(11, 31, 51, 0.12);

  --font-display: 'Space Grotesk', sans-serif;
  --font-body: 'IBM Plex Sans', sans-serif;
  --font-mono: 'IBM Plex Mono', monospace;

  --container: 1180px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.15;
  margin: 0 0 0.5em;
  letter-spacing: -0.01em;
}

p { margin: 0 0 1em; color: var(--steel); }

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

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--signal);
  margin: 0 0 0.9em;
  font-weight: 500;
}

.section-head { max-width: 640px; margin: 0 auto 3.5rem; text-align: center; }
.section-head h2 { font-size: clamp(1.6rem, 3vw, 2.3rem); color: var(--ink); }
.section-head.light .eyebrow { color: #FFC876; }
.section-head.light h2 { color: #fff; }

/* ============ Buttons ============ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.85rem 1.7rem;
  border-radius: 3px;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  letter-spacing: 0.03em;
  font-weight: 500;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, background 0.2s ease, border-color 0.2s ease;
}
.btn-primary { background: var(--signal); color: var(--blue-deep); }
.btn-primary:hover { transform: translateY(-1px); background: #ffb840; }
.btn-ghost { border-color: var(--hairline); color: var(--ink); }
.btn-ghost:hover { border-color: var(--blue); }
.btn-full { width: 100%; }

/* ============ Nav ============ */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(246, 248, 250, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--hairline);
}
.nav-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
  height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); font-family: var(--font-display); font-weight: 600; font-size: 1.05rem; }
.brand-mark { width: 26px; height: 26px; color: var(--blue); }
.brand em { color: var(--signal); font-style: normal; }
.nav-links { display: flex; align-items: center; gap: 2rem; }
.nav-links a { font-size: 0.92rem; color: var(--steel); }
.nav-links a:hover { color: var(--ink); }
.nav-cta {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  padding: 0.5rem 1rem;
  border: 1px solid var(--blue);
  border-radius: 3px;
  color: var(--ink) !important;
}
.nav-cta:hover { background: var(--blue); color: #fff !important; }
.nav-toggle { display: none; }

/* ============ Hero ============ */
.hero {
  position: relative;
  overflow: hidden;
  background: var(--blue-deep);
  color: #fff;
  padding-top: 2rem;
}
.blueprint-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(111,168,220,0.14) 1px, transparent 1px),
    linear-gradient(90deg, rgba(111,168,220,0.14) 1px, transparent 1px);
  background-size: 42px 42px;
  mask-image: radial-gradient(ellipse 90% 70% at 50% 30%, black 40%, transparent 100%);
}
.hero-inner {
  position: relative;
  max-width: var(--container);
  margin: 0 auto;
  padding: 4.5rem 24px 3rem;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 2rem;
  align-items: center;
}
.hero-copy h1 {
  font-size: clamp(2.1rem, 4.4vw, 3.3rem);
  color: #fff;
  max-width: 15ch;
}
.hero-sub { color: #B9C6D4; max-width: 46ch; font-size: 1.02rem; }
.hero-actions { display: flex; gap: 1rem; margin-top: 1.6rem; flex-wrap: wrap; }
.hero .btn-ghost { color: #fff; border-color: rgba(255,255,255,0.25); }
.hero .btn-ghost:hover { border-color: var(--blue-line); }

.hero-visual { display: flex; justify-content: center; }
.wireframe { width: 100%; max-width: 380px; height: auto; overflow: visible; }
.wireframe .draw {
  fill: none;
  stroke: var(--blue-line);
  stroke-width: 1.4;
  stroke-linecap: round;
  stroke-dasharray: 1400;
  stroke-dashoffset: 1400;
  animation: draw 2.6s ease forwards;
}
.wireframe .crane { stroke: #FFC876; animation-delay: 0.4s; }
.wireframe .grid-lines line { animation-duration: 1.8s; }
.callout circle { fill: var(--signal); }
.callout line { stroke: rgba(255,255,255,0.35); stroke-width: 1; }
.callout text {
  font-family: var(--font-mono);
  font-size: 10px;
  fill: #B9C6D4;
  letter-spacing: 0.05em;
}
@keyframes draw { to { stroke-dashoffset: 0; } }

.marquee {
  position: relative;
  border-top: 1px solid rgba(255,255,255,0.1);
  overflow: hidden;
  padding: 0.9rem 0;
  background: rgba(0,0,0,0.15);
}
.marquee-track {
  display: flex;
  gap: 0.8rem;
  white-space: nowrap;
  width: max-content;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  color: var(--blue-line);
  animation: scroll-left 28s linear infinite;
}
.marquee-track span:nth-child(2n) { color: #FFC876; }
@keyframes scroll-left {
  from { transform: translateX(0); }
  to { transform: translateX(-50%); }
}

/* ============ Services ============ */
.services { max-width: var(--container); margin: 0 auto; padding: 6rem 24px; }
.service-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--hairline);
  border: 1px solid var(--hairline);
}
.service-card {
  background: var(--paper);
  padding: 2rem 1.8rem;
  position: relative;
}
.service-card:nth-child(4), .service-card:nth-child(5) { grid-column: span 1; }
.sheet-no {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  color: var(--steel-light);
  margin-bottom: 1.2rem;
}
.service-card h3 { font-size: 1.15rem; color: var(--ink); }
.service-card p { font-size: 0.94rem; margin-bottom: 0; }

/* ============ Process ============ */
.process { background: var(--blue-deep); color: #fff; padding: 6rem 24px; }
.process-line {
  max-width: var(--container);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
  position: relative;
}
.process-line::before {
  content: '';
  position: absolute;
  top: 18px;
  left: 4%;
  right: 4%;
  height: 1px;
  background: repeating-linear-gradient(90deg, var(--blue-line) 0 6px, transparent 6px 12px);
  opacity: 0.5;
}
.process-step { position: relative; }
.step-no {
  display: block;
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--signal);
  margin-bottom: 1rem;
  background: var(--blue-deep);
  width: fit-content;
  padding-right: 0.6rem;
  position: relative;
  z-index: 1;
}
.process-step h3 { color: #fff; font-size: 1.15rem; }
.process-step p { color: #AEBECF; font-size: 0.93rem; }

/* ============ About ============ */
.about { max-width: var(--container); margin: 0 auto; padding: 6rem 24px; }
.about-inner { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 3rem; align-items: start; }
.about-copy h2 { font-size: clamp(1.5rem, 3vw, 2.1rem); }
.about-list { display: grid; gap: 0; border-top: 1px solid var(--hairline); }
.about-item {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  padding: 1rem 0;
  border-bottom: 1px solid var(--hairline);
  font-family: var(--font-display);
  font-weight: 500;
  color: var(--ink);
}
.about-item span { font-family: var(--font-mono); color: var(--steel-light); font-size: 0.85rem; }

/* ============ Contact ============ */
.contact { position: relative; background: var(--blue-deep); color: #fff; padding: 6rem 24px; overflow: hidden; }
.contact .blueprint-grid.dark { opacity: 0.6; }
.contact-inner {
  position: relative;
  max-width: var(--container);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
}
.contact-copy h2 { color: #fff; font-size: clamp(1.6rem, 3vw, 2.2rem); }
.contact-copy p { color: #B9C6D4; max-width: 42ch; }
.contact-email {
  display: inline-block;
  margin-top: 0.8rem;
  font-family: var(--font-mono);
  color: var(--signal);
  border-bottom: 1px solid rgba(245,166,35,0.4);
  padding-bottom: 2px;
}
.contact-form {
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 6px;
  padding: 2rem;
  display: grid;
  gap: 1.1rem;
}
.contact-form label {
  display: grid;
  gap: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--blue-line);
  letter-spacing: 0.04em;
}
.contact-form input, .contact-form textarea {
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.16);
  border-radius: 3px;
  padding: 0.7rem 0.8rem;
  color: #fff;
  font-family: var(--font-body);
  font-size: 0.95rem;
  resize: vertical;
}
.contact-form input:focus, .contact-form textarea:focus {
  outline: 2px solid var(--signal);
  outline-offset: 1px;
}
.form-note { font-family: var(--font-mono); font-size: 0.8rem; color: var(--blue-line); min-height: 1.2em; margin: 0; }

/* ============ Footer ============ */
.footer { border-top: 1px solid var(--hairline); padding: 2.5rem 24px; }
.footer-inner {
  max-width: var(--container);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.8rem;
}
.footer-tag { font-family: var(--font-mono); font-size: 0.82rem; color: var(--steel); margin: 0; }
.footer-copy { font-size: 0.82rem; color: var(--steel-light); margin: 0; }

/* ============ Motion & focus ============ */
@media (prefers-reduced-motion: reduce) {
  .wireframe .draw { animation: none; stroke-dashoffset: 0; }
  .marquee-track { animation: none; }
}
a:focus-visible, button:focus-visible, input:focus-visible, textarea:focus-visible {
  outline: 2px solid var(--signal);
  outline-offset: 2px;
}

/* ============ Responsive ============ */
@media (max-width: 900px) {
  .hero-inner { grid-template-columns: 1fr; }
  .hero-visual { order: -1; max-width: 280px; margin: 0 auto; }
  .service-grid { grid-template-columns: repeat(2, 1fr); }
  .process-line { grid-template-columns: repeat(2, 1fr); row-gap: 2.5rem; }
  .process-line::before { display: none; }
  .about-inner { grid-template-columns: 1fr; }
  .contact-inner { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .nav-links { position: fixed; top: 68px; left: 0; right: 0; background: var(--bg); flex-direction: column; align-items: flex-start; padding: 1.2rem 24px; border-bottom: 1px solid var(--hairline); transform: translateY(-150%); transition: transform 0.25s ease; gap: 1.1rem; }
  .nav-links.open { transform: translateY(0); }
  .nav-toggle { display: flex; flex-direction: column; gap: 5px; background: none; border: none; cursor: pointer; padding: 8px; }
  .nav-toggle span { width: 20px; height: 2px; background: var(--ink); display: block; }
  .service-grid { grid-template-columns: 1fr; }
  .process-line { grid-template-columns: 1fr; }
}