/* =========================================================
   ARCSTONE — CORE SITE STYLES
   Minimal • Institutional • Long-horizon
========================================================= */

/* ========== RESET ========== */

*,
*::before,
*::after {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
}

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

/* ========== ROOT TOKENS ========== */

:root {
  --bg-main: #f4f6f8;
  --bg-soft: #eef1f4;

  --text-main: #0f172a;
  --text-dim: #475569;

  --border-subtle: rgba(0,0,0,0.08);

  --link: #3b82f6;

  --heading-strong: #1e3a8a;
  --heading-main: #2563eb;
  --heading-soft: #3b82f6;
}

/* ========== BODY ========== */

body {
  background:
    radial-gradient(circle at top, var(--bg-soft) 0%, var(--bg-main) 60%);
  color: var(--text-main);

  font-family:
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Roboto,
    Helvetica,
    Arial,
    sans-serif;

  line-height: 1.65;
  font-size: 16px;

  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* ========== LINKS ========== */

a {
  color: var(--link);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

a:focus-visible {
  outline: 2px solid var(--link);
  outline-offset: 2px;
}

/* ========== NAV BAR ========== */

nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;

  background: rgba(244,246,248,0.85);
  backdrop-filter: blur(6px);

  border-bottom: 1px solid var(--border-subtle);
  z-index: 1000;
}

.nav-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 14px 28px;

  display: flex;
  gap: 28px;
  align-items: center;
}

nav a {
  font-size: 0.95rem;
  white-space: nowrap;

  color: var(--heading-main);
  opacity: 0.85;
}

nav a:hover {
  opacity: 1;
  text-decoration: underline;
}

nav a:first-child {
  font-weight: 600;
  letter-spacing: 0.4px;
  opacity: 1;
  color: var(--heading-strong);
}

nav a.active {
  color: var(--heading-strong);
  opacity: 1;
  text-decoration: underline;
  text-underline-offset: 4px;
}

/* ========== MAIN LAYOUT ========== */

main {
  max-width: 1080px;
  margin: 0 auto;
  padding: 140px 28px 120px;
}

/* ========== HERO ========== */

.hero {
  max-width: 720px;
}

.hero p {
  font-size: 1.05rem;
}

/* ========== HEADINGS ========== */

h1 {
  font-size: 3.1rem;
  font-weight: 600;
  letter-spacing: -0.03em;
  margin: 0 0 1.4rem;
  color: var(--text-main);   /* BLACK */
}

h2 {
  font-size: 1.75rem;
  font-weight: 600;
  margin-top: 3.4rem;
  margin-bottom: 1rem;
  color: var(--text-main);   /* BLACK */
}

h2 + p {
  margin-top: 0.4rem;
}

h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-top: 2.2rem;
  margin-bottom: 0.6rem;
  color: var(--text-main);   /* BLACK */
}


/* ========== TEXT ========== */

p {
  margin: 0 0 1.15rem;
  max-width: 72ch;
  color: var(--text-main);
}

em {
  color: var(--text-dim);
  font-style: italic;
}

/* ========== LISTS ========== */

ul {
  margin-top: 0.6rem;
  margin-bottom: 1.6rem;
  padding-left: 1.2rem;
  max-width: 72ch;
}

li {
  margin-bottom: 0.45rem;
}

/* ========== DIVIDERS ========== */

hr {
  border: none;
  height: 1px;
  background: linear-gradient(
    to right,
    transparent,
    var(--border-subtle),
    transparent
  );
  margin: 4rem 0;
}

/* ========== FOOTER ========== */

.site-footer {
  margin-top: 6rem;
  padding: 3rem 1.5rem 3.5rem;

  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.4rem;

  font-size: 0.75rem;
  color: var(--text-dim);
  opacity: 0.85;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  justify-content: center;
}

.footer-nav a {
  color: var(--text-dim);
  text-decoration: none;
  font-size: 0.75rem;
}

.footer-nav a:hover {
  color: var(--link);
  text-decoration: underline;
}

.site-footer p {
  margin: 0;
  text-align: center;
  max-width: 72ch;
}

/* ========== RESPONSIVE ========== */

@media (max-width: 720px) {

  h1 {
    font-size: 2.4rem;
  }

  main {
    padding-top: 120px;
  }

  .nav-inner {
    gap: 18px;
    flex-wrap: wrap;
  }
}