/* ────────────────────────────────────────────────────────────
   Cosmo-Edu-Lab — base stylesheet
   Plain, standard layout for an educational/software project site.
   System fonts only: no external font requests, fast & simple.
   ──────────────────────────────────────────────────────────── */

:root {
  --bg:        #ffffff;
  --bg-alt:    #f6f8fa;
  --border:    #d8dee4;
  --text:      #1f2328;
  --text-muted:#59636e;
  --accent:    #1f5fbf;
  --accent-dark:#163f80;
  --radius:    6px;
  --max-width: 880px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

img { max-width: 100%; }

h1, h2, h3, h4 {
  line-height: 1.25;
  font-weight: 600;
  margin: 1.6em 0 0.6em;
}
h1 { font-size: 1.9rem; margin-top: 0; }
h2 { font-size: 1.45rem; }
h3 { font-size: 1.15rem; }

p { margin: 0 0 1em; }
ul, ol { margin: 0 0 1em; padding-left: 1.4em; }
li { margin-bottom: 0.4em; }
ul:not(.home-gallery):not(.grid):not(.columns) li::marker { content: "- "; color: var(--text-muted); }

code { font-family: var(--font-mono); background: var(--bg-alt); padding: 0.15em 0.4em; border-radius: 4px; font-size: 0.9em; }

hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 2.5rem 0;
}

/* ── NAV ── */
.site-nav {
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 10;
}
.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.9rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}
.brand:hover { text-decoration: none; }
.brand-logo {
  display: block;
  width: auto;
  height: 72px;
  flex-shrink: 0;
}
.brand-logo-uni {
  height: 56px;
}

.nav-links { display: flex; gap: 1.5rem; margin-left: 2rem; }
.nav-links a {
  color: var(--text);
  font-size: 0.95rem;
  font-weight: 600;
}
.nav-links a:hover { color: var(--accent); text-decoration: none; }
.nav-links a.active { color: var(--text); font-weight: 600; }

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 32px;
  height: 32px;
  background: none;
  border: none;
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  height: 2px;
  background: var(--text);
  border-radius: 1px;
}

@media (max-width: 640px) {
  .nav-toggle { display: flex; }
  .brand-logo { height: 48px; }
  .brand-logo-uni { height: 38px; }
  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    margin-left: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    gap: 0;
    padding: 0.5rem 0;
    display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 0.7rem 1.5rem; }
}

/* ── LAYOUT ── */
.content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2.5rem 1.5rem 4rem;
  min-height: 60vh;
}

.page-header { margin-bottom: 0.5rem; }
.page-header h1 { margin-bottom: 0; }

/* ── HERO (home page only) ── */
.hero {
  padding: 2.5rem 0 3rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2.5rem;
}
.eyebrow {
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.8rem;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 2.7rem);
  margin: 0 0 1rem;
}
.lead {
  font-size: 1.1rem;
  color: var(--text-muted);
  max-width: 620px;
  margin-bottom: 1.8rem;
}
.hero-actions { display: flex; gap: 0.9rem; flex-wrap: wrap; }

.home-gallery {
  display: flex;
  flex-wrap: nowrap;
  gap: 0.6rem;
  margin: 0 0 1.6rem;
  list-style: none;
  padding: 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
.home-gallery li {
  margin: 0;
  flex: 0 0 calc((100% - 2.4rem) / 5);
}
.home-gallery img {
  width: 100%;
  aspect-ratio: 5 / 3;
  object-fit: cover;
  display: block;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  max-height: 120px;
}
@media (max-width: 900px) {
  .home-gallery li { flex-basis: 180px; }
}

/* ── BUTTONS ── */
.btn {
  display: inline-block;
  padding: 0.6rem 1.3rem;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 500;
  border: 1px solid var(--border);
  color: var(--text);
  background: var(--bg);
}
.btn:hover { text-decoration: none; border-color: var(--accent); color: var(--accent); }
.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.btn-primary:hover { background: var(--accent-dark); border-color: var(--accent-dark); color: #fff; }

/* ── CARD GRID (used via {: .grid} on a list) ── */
.grid {
  list-style: none;
  margin: 1.5rem 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}
.grid li {
  background: var(--bg);
  padding: 1.2rem 1.3rem;
  margin: 0;
}
.grid li p:last-child { margin-bottom: 0; }
.grid li strong { display: block; margin-bottom: 0.3rem; font-size: 1rem; }

/* Fixed 3-card row variant (used on home quick links) */
.grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}
@media (max-width: 900px) {
  .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 640px) {
  .grid-3 { grid-template-columns: 1fr; }
}

/* ── TWO-COLUMN LIST (used via {: .columns} on a list of links) ── */
.columns {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0 2.5rem;
  list-style: none;
  padding: 0;
}
@media (max-width: 640px) {
  .columns { grid-template-columns: 1fr; }
}

/* ── PANEL (used via {: .panel} on a block, e.g. a sub-section) ── */
.panel {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem 1.6rem;
  margin: 1.5rem 0;
  background: var(--bg-alt);
}
.panel h3:first-child { margin-top: 0; }

/* ── INLINE IMAGES BESIDE TEXT (used via {: .float-left} / {: .float-right} on an image) ── */
.float-left, .float-right {
  max-width: 42%;
  height: auto;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  margin-bottom: 0.4rem;
}
.float-left  { float: left;  margin-right: 1.6rem; }
.float-right { float: right; margin-left: 1.6rem; }

/* clearfix so floated images don't bleed into the next heading/section */
h2, h3, .grid, .columns, .panel, hr { clear: both; }

/* Opt-out for pages/sections where heading flow should ignore float height. */
.no-float-clear { clear: none; }

@media (max-width: 640px) {
  .float-left, .float-right {
    float: none;
    display: block;
    max-width: 100%;
    margin: 0 0 1rem;
  }
}

/* ── PAGE IMAGE (optional, set via `image:` in front matter) ── */
.page-image {
  margin: 1.4rem 0 2.2rem;
}
.page-image img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 380px;
  object-fit: cover;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}
.page-image figcaption {
  margin-top: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ── FOOTER ── */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-alt);
}
.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.8rem 1.5rem;
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}
.footer-inner p { margin: 0.2rem 0; }
.footer-links a { color: var(--text-muted); }

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