/* -----------------------------
   Afshar Sanam AI Lab — styles.css
------------------------------ */

:root{
  --bg: #ffffff;
  --ink: #0b1220;
  --muted: #5a6475;
  --soft: #eef2f6;
  --soft2: #f6f8fb;
  --line: #e5e9f0;
  --accent: #1f6feb;
  --accent2: #0b4cc2;
  --shadow: 0 10px 30px rgba(11,18,32,.08);
  --radius: 14px;
  --radius2: 18px;
  --max: 1120px;
}

*{ box-sizing: border-box; }
html, body{ height: 100%; }
html{ scroll-behavior: smooth; }

body{
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  line-height: 1.5;
  padding-top: 74px; /* IMPORTANT: space for fixed topbar */
}

/* Accessibility */
.skip-link{
  position: absolute;
  left: -999px;
  top: 10px;
  padding: 10px 12px;
  background: var(--ink);
  color: #fff;
  border-radius: 10px;
  text-decoration: none;
  z-index: 9999;
}
.skip-link:focus{ left: 10px; }

/* Layout */
.wrap{
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 22px;
}

.section{
  padding: 34px 0;
}

.section__head{
  margin-bottom: 16px;
}
.section__head h2{
  font-size: 26px;
  margin: 0 0 8px 0;
  letter-spacing: -0.02em;
}
.sublead{
  margin: 0;
  color: var(--muted);
  max-width: 78ch;
}

/* Topbar */
.topbar{
  position: fixed;
  top: 0; left: 0;
  width: 100%;
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
  z-index: 9999;
}
.topbar__inner{
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 0;
  gap: 16px;
}

/* Brand */
.brand{
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 260px;
}
.brand__mark{
  width: 38px;
  height: 38px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  background: var(--ink);
  color: #fff;
  font-weight: 700;
  letter-spacing: .02em;
}
.brand__name{
  font-weight: 700;
  letter-spacing: -0.01em;
}
.brand__tag{
  color: var(--muted);
  font-size: 12px;
  margin-top: 2px;
}

/* Nav */
.nav{
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  justify-content: flex-end;
}
.nav a{
  color: var(--ink);
  text-decoration: none;
  font-size: 14px;
  padding: 8px 10px;
  border-radius: 10px;
}
.nav a:hover{
  background: var(--soft2);
}
.nav__cta{
  background: var(--accent);
  color: #fff !important;
  border: 1px solid rgba(31,111,235,.15);
}
.nav__cta:hover{
  background: var(--accent2) !important;
}

/* Hero */
.hero{
  display: grid;
  grid-template-columns: 1.3fr 0.9fr;
  gap: 18px;
  padding: 34px 0 12px 0;
  align-items: start;
}
.kicker{
  display: inline-block;
  margin: 0 0 10px 0;
  padding: 6px 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 12px;
  color: var(--muted);
  background: var(--soft2);
}
.hero h1{
  margin: 0 0 10px 0;
  font-size: 44px;
  line-height: 1.08;
  letter-spacing: -0.03em;
}
.lead{
  margin: 0 0 18px 0;
  font-size: 16px;
  color: var(--muted);
  max-width: 72ch;
}
.note{
  margin: 14px 0 0 0;
  color: var(--muted);
  font-size: 13px;
}

/* Buttons */
.cta{
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}
.cta--compact{ margin-top: 12px; }
.btn{
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 11px 14px;
  border-radius: 12px;
  font-weight: 600;
  font-size: 14px;
  text-decoration: none;
  border: 1px solid rgba(31,111,235,.18);
  background: var(--accent);
  color: #fff;
}
.btn:hover{ background: var(--accent2); }
.btn--secondary{
  background: #fff;
  color: var(--ink);
  border: 1px solid var(--line);
}
.btn--secondary:hover{
  background: var(--soft2);
}

/* Cards */
.card{
  border: 1px solid var(--line);
  border-radius: var(--radius2);
  background: #fff;
  box-shadow: var(--shadow);
  padding: 18px 18px;
}
.card--tight{ padding: 16px; }
.card h3{
  margin: 0 0 10px 0;
  font-size: 18px;
  letter-spacing: -0.02em;
}
.card__title{
  margin: 0 0 12px 0;
  font-size: 16px;
  letter-spacing: -0.02em;
}
.card p{ margin: 0 0 10px 0; }
.card p:last-child{ margin-bottom: 0; }

.muted{ color: var(--muted); }

/* Equation blocks */
.eq{
  padding: 12px 12px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--soft2);
  margin-top: 10px;
}
.eq__label{
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 6px;
}
.eq__expr{
  font-size: 13px;
  line-height: 1.35;
  color: var(--ink);
}
.mono{
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  font-size: 12.5px;
  padding: 1px 6px;
  border-radius: 10px;
  background: rgba(11,18,32,.06);
}

/* Pills/tags */
.pillrow{
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 12px;
}
.pill{
  font-size: 12px;
  color: var(--ink);
  border: 1px solid var(--line);
  background: #fff;
  padding: 6px 10px;
  border-radius: 999px;
}
.tag{
  font-size: 12px;
  color: var(--muted);
  border: 1px solid var(--line);
  background: var(--soft2);
  padding: 6px 10px;
  border-radius: 999px;
}
.meta{
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 12px;
}

/* Lists */
.list{
  margin: 0;
  padding-left: 18px;
  color: var(--ink);
}
.list li{
  margin: 8px 0;
}
.list--big li{
  margin: 10px 0;
}

/* Grid layouts */
.grid{
  display: grid;
  gap: 16px;
}
.grid--2{ grid-template-columns: 1fr 1fr; }
.grid--3{ grid-template-columns: 1fr 1fr 1fr; }

/* Callout */
.callout{
  display: flex;
  gap: 10px;
  align-items: flex-start;
  margin-top: 14px;
  padding: 12px;
  border-radius: 16px;
  border: 1px solid var(--line);
  background: var(--soft2);
}
.callout__dot{
  width: 10px;
  height: 10px;
  margin-top: 6px;
  border-radius: 50%;
  background: var(--accent);
}
.callout__title{
  font-weight: 700;
  font-size: 13px;
  margin-bottom: 2px;
}
.callout__text{
  font-size: 13px;
  color: var(--muted);
}

/* About links */
.aboutlinks{
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 12px;
}
.link{
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
  font-size: 14px;
}
.link:hover{ text-decoration: underline; }

/* Footer */
.footer{
  margin-top: 26px;
  padding: 18px 0 30px 0;
  border-top: 1px solid var(--line);
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.footer__right{
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-end;
}
.footer__fine{
  margin-top: 6px;
  font-size: 13px;
}

/* Responsive */
@media (max-width: 980px){
  body{ padding-top: 74px; }

  .hero{
    grid-template-columns: 1fr;
  }
  .grid--3{
    grid-template-columns: 1fr;
  }
  .grid--2{
    grid-template-columns: 1fr;
  }
  .topbar__inner{
    align-items: flex-start;
    flex-direction: column;
  }
  .nav{
    justify-content: flex-start;
  }
  .hero h1{
    font-size: 38px;
  }
}

@media (prefers-reduced-motion: reduce){
  *{ scroll-behavior: auto !important; }
}