/* ISAAC Operations — site stylesheet
   Editorial/structural direction: warm off-white + charcoal + rust accent.
   Source Serif 4 (headings) + IBM Plex Sans (body/UI). */

:root {
  --bg: #faf9f5;
  --ink: #141413;
  --ink-soft: #4a4844;
  --rule: #ddd9cf;
  --rust: #b5502e;
  --rust-dark: #8f3d21;
  --paper: #ffffff;
  --max: 1080px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "IBM Plex Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  font-family: "Source Serif 4", Georgia, "Times New Roman", serif;
  font-weight: 600;
  line-height: 1.2;
  margin: 0 0 0.5em;
  letter-spacing: -0.01em;
}

h1 { font-size: clamp(2rem, 4vw, 3.1rem); }
h2 { font-size: clamp(1.3rem, 2.4vw, 1.8rem); color: var(--ink); }
h3 { font-size: 1.25rem; }

p { margin: 0 0 1em; }
a { color: var(--rust-dark); }
a:hover { color: var(--rust); }

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

/* ---- Nav ---- */
.site-nav {
  border-bottom: 1px solid var(--rule);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 10;
}
.site-nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 18px;
  padding-bottom: 18px;
}
.site-nav .brand {
  font-family: "Source Serif 4", serif;
  font-weight: 600;
  font-size: 1.25rem;
  color: var(--ink);
  text-decoration: none;
  letter-spacing: 0.02em;
}
.site-nav ul {
  list-style: none;
  display: flex;
  gap: 28px;
  margin: 0;
  padding: 0;
}
.site-nav a {
  color: var(--ink-soft);
  text-decoration: none;
  font-size: 0.95rem;
}
.site-nav a:hover, .site-nav a.active { color: var(--rust-dark); }
.nav-toggle { display: none; }

@media (max-width: 720px) {
  .site-nav ul {
    display: none;
    flex-direction: column;
    gap: 14px;
    padding: 16px 0 4px;
  }
  .site-nav ul.open { display: flex; }
  .nav-toggle {
    display: inline-block;
    background: none;
    border: 1px solid var(--rule);
    border-radius: 6px;
    padding: 6px 10px;
    font-size: 0.9rem;
    cursor: pointer;
  }
}

/* ---- Hero / sections ---- */
.hero {
  padding: 96px 0 64px;
  border-bottom: 1px solid var(--rule);
}
.hero .eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.8rem;
  color: var(--rust-dark);
  font-weight: 600;
  margin-bottom: 18px;
}
.hero h1 { max-width: 760px; }
.hero .lede {
  font-size: 1.15rem;
  color: var(--ink-soft);
  max-width: 640px;
}

section { padding: 64px 0; }
section.alt { background: var(--paper); border-top: 1px solid var(--rule); border-bottom: 1px solid var(--rule); }

.section-head { max-width: 680px; margin-bottom: 36px; }
.section-head h2 { margin-bottom: 10px; }
.section-head p { color: var(--ink-soft); }

/* ---- Buttons ---- */
.btn {
  display: inline-block;
  padding: 13px 26px;
  border-radius: 4px;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.98rem;
  border: 1px solid transparent;
}
.btn-primary { background: var(--rust); color: #fff; }
.btn-primary:hover { background: var(--rust-dark); color: #fff; }
.btn-secondary { color: var(--ink); border-color: var(--ink); background: transparent; }
.btn-secondary:hover { border-color: var(--rust-dark); color: var(--rust-dark); }

.cta-row { display: flex; gap: 16px; flex-wrap: wrap; align-items: center; margin-top: 28px; }

/* ---- Grid / cards ---- */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}
.card {
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 28px;
}
.card h3 { margin-bottom: 10px; }
.card p { color: var(--ink-soft); margin-bottom: 0; }

.pillar {
  border-left: 3px solid var(--rust);
  padding-left: 20px;
  margin-bottom: 28px;
}
.pillar h3 { margin-bottom: 8px; }
.pillar p { color: var(--ink-soft); margin-bottom: 0; }

/* ---- Quick Scan ---- */
.qs-question {
  border: 1px solid var(--rule);
  background: var(--paper);
  border-radius: 8px;
  padding: 22px 24px;
  margin-bottom: 16px;
}
.qs-question .qs-num {
  display: inline-block;
  font-family: "Source Serif 4", serif;
  color: var(--rust-dark);
  font-weight: 600;
  margin-right: 10px;
}
.qs-question .qs-dim {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-soft);
  display: block;
  margin-bottom: 6px;
}

.callout {
  background: #f3ece2;
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 24px 28px;
}

/* ---- Footer ---- */
.site-footer {
  border-top: 1px solid var(--rule);
  padding: 48px 0;
  margin-top: 40px;
  color: var(--ink-soft);
  font-size: 0.92rem;
}
.site-footer .container {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}
.site-footer a { color: var(--ink-soft); }
.site-footer a:hover { color: var(--rust-dark); }