/* 4thLayerLab · Shared Styles · 2026 */
:root {
  --black:#1A1C23;--charcoal:#2C2F3A;--mid:#64646B;--muted:#9696A0;
  --border:#E2E2E8;--surface:#F6F6F8;--white:#FFFFFF;
  --blue:#1D4ED8;--blue-h:#1740B8;--blue-lt:#EEF2FF;--blue-mid:#3B6FEA;
  --teal:#0D9488;--teal-lt:#F0FDFA;--amber:#D97706;--amber-lt:#FFFBEB;
  --serif:'DM Serif Display',Georgia,serif;
  --sans:'DM Sans',system-ui,sans-serif;
  --mono:'DM Mono','Courier New',monospace;
  --max:1100px;--pad:clamp(20px,5vw,56px);
}

*,*::before,*::after{margin:0;padding:0;box-sizing:border-box;}
html{scroll-behavior:smooth;}

body{
  background:var(--white);
  color:var(--black);
  font-family:var(--sans);
  font-weight:300;
  font-size:17px;
  line-height:1.7;
  -webkit-font-smoothing:antialiased;
}

h1,h2,h3{font-weight:400;letter-spacing:0.01em;}
p{font-size:17px;line-height:1.75;}

.inner{max-width:var(--max);margin:0 auto;padding:0 var(--pad);}
.eyebrow{font-family:var(--mono);font-size:11px;letter-spacing:0.2em;text-transform:uppercase;color:var(--muted);display:block;}
.eyebrow.blue{color:var(--blue);}

/* ── NAV ── */
header{
  position:sticky;top:0;z-index:200;
  background:rgba(255,255,255,0.97);
  backdrop-filter:blur(20px);
  -webkit-backdrop-filter:blur(20px);
  border-bottom:1px solid var(--border);
}

.nav-wrap{
  max-width:var(--max);margin:0 auto;
  padding:0 var(--pad);
  height:68px;
  display:flex;align-items:center;
  position:relative;
}

.nav-logo{
  text-decoration:none;flex-shrink:0;
  display:flex;flex-direction:column;
  align-items:flex-start;gap:3px;
}

.logo-main{font-family:var(--serif);font-size:24px;letter-spacing:0.01em;white-space:nowrap;line-height:1;}
.logo-main .logo-4th{color:var(--blue);}
.logo-main .logo-rest{color:var(--black);}
.logo-sub{font-family:var(--mono);font-size:8.5px;font-weight:500;letter-spacing:0.26em;text-transform:uppercase;color:var(--muted);}

/* desktop nav links */
.nav-links{display:flex;align-items:center;gap:32px;margin-left:auto;}
.nav-links a{font-family:var(--sans);font-size:15px;font-weight:400;color:var(--mid);text-decoration:none;transition:color 0.15s;white-space:nowrap;}
.nav-links a:hover{color:var(--black);}
.nav-links a.active{color:var(--black);font-weight:500;}
.nav-btn{font-size:14px !important;font-weight:500 !important;color:var(--white) !important;background:var(--blue);padding:10px 20px;border-radius:6px;transition:background 0.15s !important;}
.nav-btn:hover{background:var(--blue-h) !important;}

/* hamburger button */
.nav-hamburger{
  display:none;
  margin-left:auto;
  background:none;border:none;cursor:pointer;
  padding:8px;
  flex-direction:column;gap:5px;
  align-items:center;justify-content:center;
}
.nav-hamburger span{
  display:block;width:22px;height:2px;
  background:var(--black);border-radius:2px;
  transition:all 0.25s;
}
.nav-hamburger.open span:nth-child(1){transform:translateY(7px) rotate(45deg);}
.nav-hamburger.open span:nth-child(2){opacity:0;}
.nav-hamburger.open span:nth-child(3){transform:translateY(-7px) rotate(-45deg);}

/* mobile drawer */
.nav-drawer{
  display:none;
  position:fixed;
  top:68px;left:0;right:0;bottom:0;
  background:var(--white);
  z-index:199;
  flex-direction:column;
  padding:32px var(--pad) 48px;
  border-top:1px solid var(--border);
  overflow-y:auto;
}

.nav-drawer.open{display:flex;}

.nav-drawer a{
  font-family:var(--sans);
  font-size:22px;
  font-weight:400;
  color:var(--black);
  text-decoration:none;
  padding:18px 0;
  border-bottom:1px solid var(--border);
  transition:color 0.15s;
}
.nav-drawer a:hover{color:var(--blue);}
.nav-drawer a.active{color:var(--blue);font-weight:500;}
.nav-drawer .drawer-cta{
  margin-top:32px;
  background:var(--blue);
  color:var(--white) !important;
  text-align:center;
  padding:16px 24px;
  border-radius:8px;
  font-size:16px !important;
  font-weight:500 !important;
  border-bottom:none !important;
}
.nav-drawer .drawer-cta:hover{background:var(--blue-h) !important;}

/* ── BUTTONS ── */
.btn-primary{display:inline-block;background:var(--blue);color:var(--white);font-family:var(--sans);font-size:15px;font-weight:500;padding:13px 28px;border-radius:7px;text-decoration:none;transition:background 0.15s;}
.btn-primary:hover{background:var(--blue-h);}
.btn-text{display:inline-flex;align-items:center;gap:8px;font-size:15px;color:var(--mid);text-decoration:none;transition:color 0.15s;}
.btn-text:hover{color:var(--black);}
.btn-text::after{content:'→';transition:transform 0.15s;}
.btn-text:hover::after{transform:translateX(4px);}

/* ── FOOTER ── */
footer{background:var(--black);padding:52px var(--pad) 36px;}
.footer-inner{max-width:var(--max);margin:0 auto;}
.footer-top{display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr;gap:40px;padding-bottom:40px;border-bottom:1px solid rgba(255,255,255,0.07);margin-bottom:32px;}
.footer-logo{display:flex;flex-direction:column;gap:2px;text-decoration:none;margin-bottom:16px;}
.footer-logo-main{font-family:var(--serif);font-size:20px;color:var(--white);letter-spacing:0.01em;white-space:nowrap;}
.footer-logo-main .logo-4th{color:var(--blue-mid);}
.footer-logo-sub{font-family:var(--mono);font-size:8.5px;letter-spacing:0.28em;text-transform:uppercase;color:rgba(255,255,255,0.2);}
.footer-brand p{font-size:14px;color:rgba(255,255,255,0.28);line-height:1.7;max-width:240px;}
.footer-col h4{font-family:var(--mono);font-size:9.5px;letter-spacing:0.22em;text-transform:uppercase;color:rgba(255,255,255,0.22);margin-bottom:16px;}
.footer-col a{display:block;font-size:14px;color:rgba(255,255,255,0.42);text-decoration:none;margin-bottom:10px;transition:color 0.15s;}
.footer-col a:hover{color:rgba(255,255,255,0.85);}
.footer-bottom{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:12px;}
.footer-copy,.footer-mark{font-family:var(--mono);font-size:10px;letter-spacing:0.1em;text-transform:uppercase;}
.footer-copy{color:rgba(255,255,255,0.18);}
.footer-mark{color:rgba(255,255,255,0.12);}


/* ── HEADING LEGIBILITY ── */
h1 { letter-spacing: 0.02em; }
h2 { letter-spacing: 0.02em; }
h3 { letter-spacing: 0.02em; font-weight: 500; }

.section-title,
.page-hero h1,
.section-header h2,
.about-left h2,
.engagement-left h2,
.how-inner h2,
.serve-inner h2,
.who-left h2,
.contact-left h2,
.labs-header h2,
.insights-header h2 {
  letter-spacing: 0.02em;
  font-weight: 400;
}

/* Card titles across all pages */
.tool-name,
.lab-card-body h3,
.insight-card h3,
.service-item h3,
.how-card h3,
.eng-card h3,
.belief-card h3 {
  letter-spacing: 0.02em;
  font-weight: 500;
}

/* ── RESPONSIVE ── */
@media(max-width:900px){
  .footer-top{grid-template-columns:1fr 1fr;}
}

@media(max-width:640px){
  body{font-size:16px;}
  p{font-size:16px;}
  .nav-links{display:none;}
  .nav-hamburger{display:flex;}
  .footer-top{grid-template-columns:1fr;}
  .footer-mark{display:none;}
}