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

:root {
  --bg:       #0f1117;
  --surface:  #1a1d27;
  --border:   #2a2d3e;
  --accent:   #4f8ef7;
  --accent2:  #7c3aed;
  --text:     #e2e8f0;
  --muted:    #8892a4;
  --header-h: 56px;
}

body {
  font-family: 'Segoe UI', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* ── Header ─────────────────────────────────────────────── */
header {
  height: var(--header-h);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  gap: 2rem;
  flex-shrink: 0;
  position: relative;
  z-index: 100;
}

.logo {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: .05em;
  white-space: nowrap;
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-decoration: none;
}

nav {
  display: flex;
  align-items: center;
  gap: .25rem;
  flex: 1;
  overflow: visible;
}

/* ── Nav groups & dropdowns ──────────────────────────────── */
.nav-group {
  position: relative;
}

.nav-group-btn {
  background: none;
  border: none;
  color: var(--muted);
  font: inherit;
  font-size: .875rem;
  padding: .4rem .75rem;
  border-radius: 6px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: .35rem;
  white-space: nowrap;
  transition: color .15s, background .15s;
}
.nav-group-btn:hover,
.nav-group-btn.active {
  color: var(--text);
  background: var(--border);
}
.nav-group-btn svg { transition: transform .2s; }
.nav-group:hover .nav-group-btn svg { transform: rotate(180deg); }

.dropdown {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  padding-top: 6px;
  min-width: 180px;
}
.dropdown-inner {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: .35rem;
  box-shadow: 0 8px 24px rgba(0,0,0,.4);
}
.nav-group:hover .dropdown { display: block; }

.dropdown a {
  display: block;
  padding: .45rem .75rem;
  border-radius: 5px;
  font-size: .875rem;
  color: var(--muted);
  text-decoration: none;
  transition: color .15s, background .15s;
}
.dropdown a:hover,
.dropdown a.active {
  color: var(--text);
  background: var(--border);
}

/* ── Direct nav links ────────────────────────────────────── */
.nav-link {
  padding: .4rem .75rem;
  border-radius: 6px;
  font-size: .875rem;
  color: var(--muted);
  text-decoration: none;
  white-space: nowrap;
  transition: color .15s, background .15s;
}
.nav-link:hover,
.nav-link.active {
  color: var(--text);
  background: var(--border);
}

/* ── GitHub link ─────────────────────────────────────────── */
.github-link {
  color: var(--muted);
  display: flex;
  align-items: center;
  flex-shrink: 0;
  transition: color .15s;
}
.github-link:hover { color: var(--text); }

/* ── Content area ────────────────────────────────────────── */
#frame-wrap {
  flex: 1;
  overflow: hidden;
  position: relative;
}

iframe#tool-frame {
  width: 100%;
  height: 100%;
  border: none;
  background: var(--bg);
}