:root {
  --fg: #1b2430;
  --muted: #5a6b7b;
  --line: #d7dee6;
  --accent: #1565c0;
  --bg-code: #f6f8fa;
  --ok: #2e7d32;
  --err: #c62828;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font: 15px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--fg);
  padding: 1.25rem 1.5rem 2rem;
}
header h1 { font-size: 1.3rem; margin: 0 0 .4rem; }
header p { color: var(--muted); max-width: 70rem; margin: 0 0 1rem; }
code { background: var(--bg-code); padding: 0 .25em; border-radius: 3px; font-size: .92em; }
.toolbar {
  display: flex; align-items: center; gap: .6rem;
  padding: .6rem 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line);
  flex-wrap: wrap;
}
.toolbar label { color: var(--muted); }
select { padding: .35rem .5rem; border: 1px solid var(--line); border-radius: 6px; }
button {
  background: var(--accent); color: #fff; border: 0; border-radius: 6px;
  padding: .45rem .9rem; font-weight: 600; cursor: pointer;
}
button:hover { background: #0d4ea0; }
#status { color: var(--muted); }
#status.ok { color: var(--ok); }
#status.err { color: var(--err); }
main {
  display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin-top: 1rem;
}
section { display: flex; flex-direction: column; min-width: 0; }
h2 { font-size: .85rem; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); margin: 0 0 .4rem; }
.pane-head { display: flex; align-items: center; gap: .6rem; margin: 0 0 .4rem; flex-wrap: wrap; }
.pane-head h2 { margin: 0; }
.pane-head label { color: var(--muted); font-size: .85rem; }
.pane-head select { padding: .2rem .45rem; }
textarea, pre {
  border: 1px solid var(--line); border-radius: 8px; background: var(--bg-code);
  padding: .8rem; font: 13px/1.45 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  height: 60vh; overflow: auto; white-space: pre; tab-size: 2;
}
textarea { resize: vertical; color: var(--fg); }
pre { margin: 0; }
footer { margin-top: 1.5rem; color: var(--muted); font-size: .85rem; }
a { color: var(--accent); }
.explainer { max-width: 70rem; margin: 1.75rem 0 0; }
.explainer h2 { text-transform: none; letter-spacing: 0; font-size: 1.05rem; color: var(--fg); margin: 0 0 .4rem; }
.explainer p { margin: .55rem 0; }
@media (max-width: 800px) { main { grid-template-columns: 1fr; } textarea, pre { height: 40vh; } }