:root {
  --bg: #0b0e14; --card: #10141c; --field: #141924; --border: #2a3346; --text: #d7dee9; --muted: #8b95a7; --faint: #6b7587;
  --pos: #26a69a; --neg: #ef5350; --focus: #5fb3d9; --on: #1d2433;
  color-scheme: dark;
}
:root[data-theme="light"] {
  --bg: #f3f5f8; --card: #ffffff; --field: #f6f8fb; --border: #c6cedb; --text: #18202c; --muted: #566070; --faint: #6b7483;
  --pos: #0b7d72; --neg: #c9302c; --focus: #1f74a3; --on: #e2e7ef;
  color-scheme: light;
}
* { box-sizing: border-box; }
body {
  margin: 0; min-height: 100vh; display: grid; place-items: center; padding: 16px;
  background: var(--bg); color: var(--text); font: 14px/1.5 system-ui, -apple-system, "Segoe UI", sans-serif;
}
.card { width: min(360px, 100%); background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 24px; }
.top { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 18px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 600; font-size: 17px; color: var(--pos); }
.brand span { color: var(--text); }
.prefs { display: flex; gap: 6px; align-items: center; }
.seg { display: inline-flex; border: 1px solid var(--border); border-radius: 6px; overflow: hidden; }
.prefs button {
  margin: 0; min-height: 30px; min-width: 32px; padding: 0 8px; border: 0; border-radius: 0; background: transparent;
  color: var(--muted); font: 600 11.5px ui-monospace, monospace; cursor: pointer;
}
.seg button + button { border-left: 1px solid var(--border); }
.prefs button.on { background: var(--on); color: var(--text); }
.prefs button:hover { background: var(--on); color: var(--text); }
.prefs .icon { display: inline-grid; place-items: center; border: 1px solid var(--border); border-radius: 6px; }
:root[data-theme="light"] .sun, :root:not([data-theme="light"]) .moon { display: none; }
form { display: flex; flex-direction: column; gap: 12px; }
label { display: flex; flex-direction: column; gap: 4px; font-size: 12.5px; color: var(--muted); }
input {
  background: var(--field); border: 1px solid var(--border); border-radius: 6px; color: var(--text); padding: 10px;
  font: 15px ui-monospace, monospace; min-height: 42px;
}
input:focus { outline: none; border-color: var(--focus); }
#b {
  margin-top: 4px; min-height: 44px; border: 1px solid var(--pos); border-radius: 6px; background: rgba(38, 166, 154, 0.2);
  color: var(--text); font-weight: 600; font-size: 14px; cursor: pointer;
}
#b:hover { background: rgba(38, 166, 154, 0.3); }
#b:disabled { opacity: 0.6; cursor: wait; }
button:focus-visible, input:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; }
.err { min-height: 1.5em; margin: 0; color: var(--neg); font-size: 13px; }
.foot { margin: 16px 0 0; color: var(--faint); font-size: 11.5px; }