/* ============================================================
   BioLearn9 — Shared Design System
   Photosynthesis-inspired light theme
   ============================================================ */

/* ── DESIGN TOKENS ── */
:root {
  /* Greens (primary) */
  --green:   #1D9E75;
  --gl:      #E1F5EE;
  --gm:      #9FE1CB;
  --gd:      #085041;

  /* Blues */
  --blue:    #378ADD;
  --bl:      #E6F1FB;
  --bd:      #0C447C;

  /* Amber */
  --amber:   #BA7517;
  --al:      #FAEEDA;

  /* Purple */
  --purple:  #534AB7;
  --pl:      #EEEDFE;

  /* Coral */
  --coral:   #D85A30;
  --cl:      #FAECE7;

  /* Neutrals */
  --bg:      #F0F4F8;
  --surface: #F8FAFC;
  --card:    #ffffff;
  --border:  #E2E8F0;
  --text:    #1A202C;
  --muted:   #64748B;

  /* Shadows */
  --shadow:    0 2px 8px rgba(0,0,0,.07);
  --shadow-md: 0 4px 16px rgba(0,0,0,.1);
}

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

/* ── BASE ── */
body {
  font-family: 'DM Sans', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
}
h1, h2, h3, h4 { font-family: 'Syne', sans-serif; }
a { color: inherit; text-decoration: none; }

/* ── HEADER ── */
header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 1px 4px rgba(0,0,0,.06);
}

.top-bar {
  max-width: 1100px;
  margin: 0 auto;
  padding: 14px 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.logo {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: 1.05rem;
  letter-spacing: .06em;
  color: var(--gd);
  text-transform: uppercase;
  display: inline-block;
  cursor: pointer;
  text-decoration: none;
}
.logo span { color: var(--green); }

.nav-links {
  display: flex;
  gap: 0.7rem;
  flex-wrap: wrap;
  align-items: center;
}

.nav-link {
  font-family: 'Syne', sans-serif;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text);
  text-decoration: none;
  border: 1px solid var(--border);
  padding: 0.35rem 0.8rem;
  border-radius: 999px;
  transition: border-color .2s, color .2s;
}
.nav-link:hover { border-color: var(--green); color: var(--green); }

.catalog-badge, .sol-badge {
  background: linear-gradient(135deg, var(--green), var(--gm));
  color: #0b2b22;
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: .7rem;
  padding: .3rem .8rem;
  border-radius: 999px;
  letter-spacing: .08em;
  display: inline-block;
  text-decoration: none;
}

/* ── FOOTER ── */
footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 2rem;
  text-align: center;
  font-size: 0.78rem;
  color: var(--muted);
  max-width: 1100px;
  margin: 0 auto;
}

/* ── BUTTONS ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-family: 'Syne', sans-serif;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.6rem 1.1rem;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  transition: all .15s;
  text-decoration: none;
}
.btn-primary {
  background: var(--green);
  color: #fff;
}
.btn-primary:hover { background: var(--gd); transform: translateY(-1px); }

.btn-outline {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
}
.btn-outline:hover { border-color: var(--green); color: var(--green); }

/* ── SCROLLBAR ── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--muted); }

/* ── RESPONSIVE ── */
@media (max-width: 720px) {
  .top-bar { padding: 12px 1.2rem; }
}