@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap');

*, *::before, *::after { margin:0; padding:0; box-sizing:border-box; }

:root {
  --bg:      #09090b;
  --surface: #111113;
  --card:    #18181b;
  --border:  #27272a;
  --text:    #fafafa;
  --muted:   #71717a;
  --accent:  #6366f1;
  --accent2: #8b5cf6;
  --nav-bg:  rgba(9,9,11,.85);
  --shadow:  rgba(0,0,0,.4);
}

/* ── LIGHT THEME ── */
html.light {
  --bg:      #ffffff;
  --surface: #f9fafb;
  --card:    #f3f4f6;
  --border:  #e5e7eb;
  --text:    #111827;
  --muted:   #6b7280;
  --accent:  #4f46e5;
  --accent2: #7c3aed;
  --nav-bg:  rgba(255,255,255,.9);
  --shadow:  rgba(0,0,0,.08);
}

/* ── THEME TOGGLE ── */
.theme-toggle {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 99px;
  width: 52px; height: 28px;
  cursor: pointer;
  position: relative;
  transition: background .2s, border-color .2s;
  flex-shrink: 0;
}
.theme-toggle::after {
  content: '';
  position: absolute;
  top: 3px; left: 3px;
  width: 20px; height: 20px;
  border-radius: 50%;
  background: var(--muted);
  transition: transform .25s cubic-bezier(.4,0,.2,1), background .2s;
}
html.light .theme-toggle::after {
  transform: translateX(24px);
  background: var(--accent);
}
.theme-toggle-icon {
  position: absolute;
  top: 50%; transform: translateY(-50%);
  font-size: .7rem; pointer-events: none;
  transition: opacity .2s;
}
.theme-toggle-icon.moon { left: 6px; }
.theme-toggle-icon.sun  { right: 5px; opacity: 0; }
html.light .theme-toggle-icon.moon { opacity: 0; }
html.light .theme-toggle-icon.sun  { opacity: 1; }

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', system-ui, sans-serif;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

/* NAV */
nav {
  position: sticky; top: 0; z-index: 50;
  background: var(--nav-bg);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 2rem; height: 60px;
  display: flex; align-items: center; justify-content: space-between;
}
.nav-logo {
  font-size: 1.1rem; font-weight: 700;
  color: var(--text); text-decoration: none;
  display: flex; align-items: center; gap: .5rem;
}
.nav-logo span {
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
}
.nav-links { display: flex; gap: 1.8rem; }
.nav-links a {
  color: var(--muted); text-decoration: none;
  font-size: .875rem; font-weight: 500; transition: color .15s;
}
.nav-links a:hover, .nav-links a.active { color: var(--text); }

/* PAGE HEADER */
.page-header {
  max-width: 1100px; margin: 0 auto;
  padding: 4rem 2rem 2.5rem;
  border-bottom: 1px solid var(--border);
}
.page-header .breadcrumb {
  font-size: .78rem; color: var(--muted);
  margin-bottom: 1rem; display: flex; align-items: center; gap: .4rem;
}
.page-header .breadcrumb a { color: var(--muted); text-decoration: none; }
.page-header .breadcrumb a:hover { color: var(--text); }
.page-header h1 {
  font-size: 2.2rem; font-weight: 800;
  letter-spacing: -.6px; margin-bottom: .5rem;
}
.page-header p { color: var(--muted); font-size: .95rem; line-height: 1.6; }

/* SECTION */
.section { max-width: 1100px; margin: 0 auto; padding: 3rem 2rem; }
.section-header { margin-bottom: 2rem; }
.section-header h2 { font-size: 1.2rem; font-weight: 700; margin-bottom: .3rem; }
.section-header p  { color: var(--muted); font-size: .875rem; }

/* GRID */
.grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1rem;
}

/* CARD */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.5rem;
  transition: border-color .15s, background .15s;
  cursor: pointer; text-decoration: none; color: var(--text);
  display: block;
}
.card:hover { border-color: #3f3f46; background: #1c1c1f; }
.card-icon { font-size: 1.6rem; margin-bottom: .8rem; display: block; }
.card h3 { font-size: 1rem; font-weight: 700; margin-bottom: .25rem; }
.card .card-type { font-size: .75rem; color: var(--muted); margin-bottom: .6rem; }
.card p { font-size: .85rem; color: var(--muted); line-height: 1.6; margin-bottom: 1rem; }

/* TAGS */
.tags { display: flex; gap: .4rem; flex-wrap: wrap; }
.tag {
  padding: .15rem .6rem; border-radius: 4px;
  font-size: .72rem; font-weight: 600;
  background: rgba(99,102,241,.1);
  color: #a5b4fc;
  border: 1px solid rgba(99,102,241,.2);
}
.tag.green  { background: rgba(16,185,129,.1);  color: #6ee7b7; border-color: rgba(16,185,129,.2); }
.tag.amber  { background: rgba(245,158,11,.1);  color: #fcd34d; border-color: rgba(245,158,11,.2); }
.tag.sky    { background: rgba(14,165,233,.1);  color: #7dd3fc; border-color: rgba(14,165,233,.2); }
.tag.violet { background: rgba(139,92,246,.1);  color: #c4b5fd; border-color: rgba(139,92,246,.2); }

/* CODE BLOCK */
.code-block {
  background: #0d0d0f;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: .9rem 1rem;
  margin-top: .8rem;
  font-family: 'Menlo','Courier New',monospace;
  font-size: .8rem; color: #86efac;
  overflow-x: auto; line-height: 1.7;
}

/* HOWTO LIST */
.howto-list { display: flex; flex-direction: column; gap: .6rem; }
.howto-item {
  display: flex; align-items: center; gap: 1rem;
  background: var(--card); border: 1px solid var(--border);
  border-radius: 10px; padding: 1rem 1.2rem;
  transition: border-color .15s; cursor: pointer;
  text-decoration: none; color: var(--text);
}
.howto-item:hover { border-color: #3f3f46; }
.howto-num {
  width: 30px; height: 30px; border-radius: 6px;
  background: rgba(99,102,241,.15);
  color: #a5b4fc;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: .8rem; flex-shrink: 0;
}
.howto-info { flex: 1; }
.howto-title { font-size: .9rem; font-weight: 600; }
.howto-meta  { font-size: .75rem; color: var(--muted); margin-top: .1rem; }
.howto-arrow { color: var(--muted); font-size: 1rem; }
.howto-item:hover .howto-arrow { color: var(--text); }

/* FILTER BAR */
.filter-bar { display: flex; gap: .5rem; flex-wrap: wrap; margin-bottom: 1.8rem; }
.filter-btn {
  background: var(--card); border: 1px solid var(--border);
  color: var(--muted); padding: .35rem .9rem; border-radius: 6px;
  font-size: .8rem; font-weight: 500; cursor: pointer;
  font-family: 'Inter', system-ui, sans-serif;
  transition: all .15s;
}
.filter-btn.active, .filter-btn:hover {
  background: rgba(99,102,241,.12);
  border-color: rgba(99,102,241,.3);
  color: #a5b4fc;
}

/* DIFFICULTY */
.difficulty {
  display: inline-block;
  padding: .1rem .5rem; border-radius: 4px;
  font-size: .7rem; font-weight: 600; margin-left: .4rem;
}
.difficulty.beginner { background: rgba(16,185,129,.1);  color: #6ee7b7; }
.difficulty.medium   { background: rgba(245,158,11,.1);  color: #fcd34d; }
.difficulty.advanced { background: rgba(239,68,68,.1);   color: #fca5a5; }

/* FOOTER */
footer {
  border-top: 1px solid var(--border);
  padding: 2rem; text-align: center;
  color: var(--muted); font-size: .82rem;
}
footer a { color: var(--muted); text-decoration: none; }
footer a:hover { color: var(--text); }

/* Logo invert in light mode */
html.light .nav-logo img,
html.light .hero-bg-logo { filter: invert(1); }