:root {
  color-scheme: light dark;
  --bg: #0f1115;
  --card: #171a21;
  --text: #e6e8ec;
  --muted: #8b93a1;
  --accent: #ff8c00;
  --accent-fg: #0f1115;
  --border: #262a34;
  --err: #ff6b6b;
  --ok: #4ade80;
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
}
@media (prefers-color-scheme: light) {
  :root {
    --bg: #f7f8fa;
    --card: #ffffff;
    --text: #0f1115;
    --muted: #5a6473;
    --border: #e4e7ec;
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: var(--bg); color: var(--text); min-height: 100%; }
main {
  max-width: 520px;
  margin: 8vh auto;
  padding: 32px 28px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
}
h1 { font-size: 22px; margin: 0 0 4px; }
p.lede { color: var(--muted); margin: 0 0 24px; font-size: 14px; }
.tab-row { display: flex; gap: 8px; margin-bottom: 20px; border-bottom: 1px solid var(--border); }
.tab {
  padding: 10px 14px; cursor: pointer; background: transparent; border: none;
  color: var(--muted); font: inherit; border-bottom: 2px solid transparent;
}
.tab[aria-selected="true"] { color: var(--text); border-bottom-color: var(--accent); }
label { display: block; font-size: 13px; color: var(--muted); margin: 12px 0 6px; }
input, textarea {
  width: 100%; padding: 10px 12px; background: var(--bg);
  color: var(--text); border: 1px solid var(--border); border-radius: 8px;
  font: inherit; font-size: 14px; font-family: ui-monospace, monospace;
}
textarea { min-height: 84px; resize: vertical; }
button.primary {
  width: 100%; padding: 12px; margin-top: 20px;
  background: var(--accent); color: var(--accent-fg);
  border: 0; border-radius: 8px; font: inherit; font-weight: 600;
  cursor: pointer;
}
button.primary:disabled { opacity: 0.5; cursor: wait; }
.mono { font-family: ui-monospace, monospace; font-size: 12px; word-break: break-all; }
.warn { color: var(--err); font-size: 13px; margin-top: 8px; }
.ok { color: var(--ok); font-size: 13px; margin-top: 8px; }
.mnemonic-box {
  background: var(--bg); border: 1px dashed var(--border);
  border-radius: 8px; padding: 12px; margin-top: 8px;
  font-family: ui-monospace, monospace; font-size: 13px; line-height: 1.7;
}
.small { font-size: 12px; color: var(--muted); }
.hidden { display: none; }