/* Reset, page skeleton and shared primitives. */
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, Segoe UI, Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
}
.topbar {
  display: flex; justify-content: space-between; align-items: center;
  padding: .75rem 1.25rem; background: var(--panel); border-bottom: 1px solid var(--border);
}
.brand { font-weight: 600; }
.nav { display: flex; gap: .25rem; flex: 1; margin: 0 1rem; flex-wrap: wrap; }
.nav a {
  color: var(--muted); text-decoration: none; font-size: .9rem;
  padding: .35rem .7rem; border-radius: 6px;
}
.nav a:hover { color: var(--text); background: rgba(68, 147, 248, .12); }
.nav a.active { color: var(--text); background: rgba(68, 147, 248, .18); font-weight: 600; }
.logout { display: flex; align-items: center; gap: .5rem; margin: 0; }
.user { color: var(--muted); }
main { padding: 1.25rem; max-width: 1100px; margin: 0 auto; }
button {
  background: var(--accent); color: #fff; border: 0; border-radius: 6px;
  padding: .5rem .9rem; cursor: pointer; font-size: .9rem;
}
button:hover { filter: brightness(1.1); }
button:disabled { opacity: .6; cursor: progress; }
input {
  background: var(--code-bg); color: var(--text); border: 1px solid var(--border);
  border-radius: 6px; padding: .5rem; font-size: .9rem;
}
.grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.panel { background: var(--panel); border: 1px solid var(--border); border-radius: 10px; padding: 1rem; }
.panel:last-child { grid-column: 1 / -1; }
h2 { margin-top: 0; font-size: 1.05rem; }
.hint, .muted { color: var(--muted); font-size: .85rem; }
.actions { display: flex; flex-wrap: wrap; gap: .6rem; margin-bottom: .75rem; }
pre { white-space: pre-wrap; background: var(--code-bg); padding: .6rem; border-radius: 6px; overflow-x: auto; font-size: .82rem; }
details summary { cursor: pointer; color: var(--muted); margin: .3rem 0; }
.error { color: var(--red); }
/* 4.1 theme toggle button */
.theme-toggle { background: transparent; color: var(--muted); padding: .3rem .5rem; font-size: 1rem; }
.theme-toggle:hover { color: var(--text); }
@media (max-width: 720px) { .grid { grid-template-columns: 1fr; } }