/* ==========================================================================
   AI Skills for Developers — landing page styles
   ========================================================================== */

:root {
  --bg: #0f1117;
  --bg-alt: #171a23;
  --surface: #1c202b;
  --border: #2a2f3d;
  --text: #e6e8ee;
  --muted: #9aa3b2;
  --accent: #6366f1;
  --accent-strong: #818cf8;
  --accent-dark: #4f46e5;
  --success: #34d399;
  --radius: 14px;
  --container: 1120px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

code {
  font-family: var(--mono);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.1em 0.4em;
  font-size: 0.9em;
}

pre {
  margin: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  overflow-x: auto;
  font-size: 0.92rem;
  line-height: 1.7;
}

pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: inherit;
}

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--accent);
  color: #fff;
  padding: 0.6rem 1rem;
  border-radius: 0 0 8px 0;
  z-index: 100;
}
.skip-link:focus { left: 0; }

/* --- Syntax highlight colors --- */
.c { color: #6b7280; font-style: italic; }
.k { color: #a5b4fc; }
.r { color: var(--success); }

/* --- Header / nav --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(15, 17, 23, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--text);
  font-weight: 800;
  font-size: 1.15rem;
  letter-spacing: -0.02em;
}
.brand:hover { text-decoration: none; }

.brand-mark {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), var(--accent-dark));
  color: #fff;
  font-weight: 900;
  font-size: 1.1rem;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 1.6rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-menu a { color: var(--muted); font-weight: 500; font-size: 0.95rem; }
.nav-menu a:hover { color: var(--text); text-decoration: none; }

.nav-cta {
  color: #fff !important;
  background: var(--accent);
  padding: 0.5rem 1rem;
  border-radius: 8px;
}
.nav-cta:hover { background: var(--accent-strong); }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}
.nav-toggle span {
  width: 24px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.2s, opacity 0.2s;
}

@media (max-width: 760px) {
  .nav-toggle { display: flex; }
  .nav-menu {
    display: none;
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: var(--bg-alt);
    border-bottom: 1px solid var(--border);
  }
  .nav-menu.open { display: flex; }
  .nav-menu li { width: 100%; }
  .nav-menu a { display: block; padding: 1rem 1.5rem; border-top: 1px solid var(--border); }
  .nav-cta { border-radius: 0; text-align: center; }
}

/* --- Hero --- */
.hero {
  padding: 5rem 0 4rem;
  background:
    radial-gradient(60rem 30rem at 80% -10%, rgba(99, 102, 241, 0.18), transparent),
    radial-gradient(40rem 20rem at 10% 10%, rgba(52, 211, 153, 0.08), transparent);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 3rem;
  align-items: center;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.8rem;
  color: var(--accent-strong);
  font-weight: 600;
  margin: 0 0 1rem;
}

h1 {
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin: 0 0 1.2rem;
}

.accent {
  background: linear-gradient(120deg, var(--accent-strong), var(--success));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.lead {
  font-size: 1.15rem;
  color: var(--muted);
  margin: 0 0 2rem;
  max-width: 34rem;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 2rem;
}

.btn {
  display: inline-block;
  padding: 0.8rem 1.5rem;
  border-radius: 10px;
  font-weight: 600;
  font-size: 1rem;
  transition: background 0.2s, transform 0.1s;
}
.btn:hover { text-decoration: none; transform: translateY(-1px); }

.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-strong); }

.btn-secondary {
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
}
.btn-secondary:hover { border-color: var(--accent); }

.hero-badges {
  list-style: none;
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  margin: 0;
  padding: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

/* --- Sections --- */
.section { padding: 4.5rem 0; }
.section-alt { background: var(--bg-alt); }

.section-head {
  max-width: 48rem;
  margin: 0 auto 3rem;
  text-align: center;
}
.section-head h2 {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  letter-spacing: -0.02em;
  margin: 0 0 1rem;
}
.section-head p { color: var(--muted); margin: 0.5rem 0; }
.section-sub { margin-top: 1rem; }
.section-sub strong { color: var(--text); }
.section-sub em { color: var(--text); font-style: normal; }

/* --- Cards --- */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.card {
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  transition: transform 0.2s, border-color 0.2s;
}
.card:hover { transform: translateY(-4px); border-color: var(--accent); }

.card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.chip {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.3rem 0.7rem;
  border-radius: 999px;
}
.chip-auth { background: rgba(129, 140, 248, 0.15); color: #a5b4fc; }
.chip-api { background: rgba(52, 211, 153, 0.15); color: var(--success); }
.chip-upload { background: rgba(251, 191, 36, 0.15); color: #fbbf24; }

.card-stack { font-size: 0.8rem; color: var(--muted); }

.card h3 { margin: 0 0 0.75rem; font-size: 1.3rem; letter-spacing: -0.01em; }
.card > p { color: var(--muted); font-size: 0.95rem; margin: 0 0 1rem; }

.card-list {
  list-style: none;
  margin: 0 0 1.5rem;
  padding: 0;
  display: grid;
  gap: 0.5rem;
  flex: 1;
}
.card-list li { padding-left: 1.4rem; position: relative; color: var(--muted); font-size: 0.9rem; }
.card-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--success);
  font-weight: 700;
}

.card-foot {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  border-top: 1px solid var(--border);
  padding-top: 1.25rem;
}

.trigger { font-size: 0.78rem; color: var(--muted); }

.btn-link { color: var(--accent-strong); font-weight: 600; font-size: 0.9rem; }

/* --- Features --- */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.feature {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
}
.feature-icon { font-size: 1.6rem; }
.feature h3 { margin: 0.75rem 0 0.5rem; font-size: 1.1rem; }
.feature p { color: var(--muted); font-size: 0.92rem; margin: 0; }

/* --- Skill structure --- */
.structure-grid {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 2.5rem;
  align-items: start;
}

.structure-code pre { font-size: 0.85rem; }

.structure-copy {
  display: grid;
  gap: 1.25rem;
}

.structure-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
}
.structure-item h3 { margin: 0 0 0.5rem; font-size: 1.05rem; }
.structure-item h3 code { font-size: 0.9em; }
.structure-item p { color: var(--muted); font-size: 0.92rem; margin: 0; }

@media (max-width: 900px) {
  .structure-grid { grid-template-columns: 1fr; }
}

/* --- Tabs --- */
.tabs {
  display: flex;
  gap: 0.5rem;
  justify-content: center;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.tab {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 0.6rem 1.2rem;
  border-radius: 999px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s, color 0.2s, border-color 0.2s;
}
.tab:hover { border-color: var(--accent); color: var(--text); }
.tab.active { background: var(--accent); border-color: var(--accent); color: #fff; }

.tab-panel { display: none; max-width: 44rem; margin: 0 auto; }
.tab-panel.active { display: block; }

.install-note { text-align: center; color: var(--muted); margin-top: 1.5rem; }

/* --- Contribute --- */
.center { text-align: center; }

/* --- Footer --- */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-alt);
  padding: 3.5rem 0 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2.5rem;
}
.footer-grid p { color: var(--muted); font-size: 0.9rem; }
.footer-grid h4 { margin: 0 0 0.75rem; font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--muted); }
.footer-grid ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.4rem; }
.footer-grid a { color: var(--muted); font-size: 0.9rem; }
.footer-grid a:hover { color: var(--text); }

.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 1.5rem;
  color: var(--muted);
  font-size: 0.85rem;
}
.footer-bottom p { margin: 0; }

@media (max-width: 900px) {
  .hero-grid { grid-template-columns: 1fr; gap: 2.5rem; }
  .hero { padding: 3.5rem 0; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 520px) {
  .footer-grid { grid-template-columns: 1fr; }
  .hero-badges { gap: 0.6rem 1.5rem; }
}