:root {
  --bg: #f5f6f8;
  --surface: #ffffff;
  --text: #1b2130;
  --muted: #5d6679;
  --border: #dde1e8;
  --accent: #2f5bea;
  --accent-text: #ffffff;
  --ok: #1f8a4c;
  --warn: #b7791f;
  --bad: #c53030;
  --box: rgba(47, 91, 234, 0.15);
  --pad-ink: #14203c;
  --radius: 10px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12151c;
    --surface: #1b1f29;
    --text: #e6e9ef;
    --muted: #9aa3b5;
    --border: #2d3342;
    --accent: #6d8dff;
    --accent-text: #0d1020;
    --ok: #4ac27d;
    --warn: #e0a84a;
    --bad: #f07070;
    --box: rgba(109, 141, 255, 0.2);
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.45 system-ui, -apple-system, "Segoe UI", sans-serif;
}
h3 { margin: 0 0 12px; font-size: 15px; }

.topbar {
  display: flex; align-items: center; gap: 24px;
  padding: 12px 24px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.brand { font-weight: 700; font-size: 18px; letter-spacing: -0.02em; }
.tabs { display: flex; gap: 4px; }
.tab {
  background: none; border: 0; color: var(--muted);
  padding: 8px 14px; border-radius: 8px; cursor: pointer; font: inherit;
}
.tab.active { background: var(--bg); color: var(--text); font-weight: 600; }

main { padding: 24px; max-width: 1280px; margin: 0 auto; }
.panel { display: none; }
.panel.active { display: block; }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 16px;
}
label { display: block; font-size: 13px; color: var(--muted); margin-bottom: 10px; }
label.check { display: flex; gap: 8px; align-items: center; color: var(--text); }
input[type=text], input[type=email], input[type=password], input:not([type]), select {
  display: block; width: 100%; margin-top: 4px;
  padding: 8px 10px; font: inherit; color: var(--text);
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
}
button, .button {
  font: inherit; cursor: pointer; border-radius: 8px;
  padding: 8px 14px; border: 1px solid var(--border);
  background: var(--surface); color: var(--text); text-decoration: none; display: inline-block;
}
button.primary { background: var(--accent); color: var(--accent-text); border-color: var(--accent); width: 100%; padding: 11px; font-weight: 600; }
button:disabled { opacity: 0.5; cursor: not-allowed; }
button.link { border: 0; background: none; color: var(--accent); padding: 4px 0; }

.hint { color: var(--muted); font-size: 13px; margin: 0 0 12px; }
.msg { font-size: 13px; min-height: 1.2em; margin: 10px 0 0; }
.msg.error { color: var(--bad); }
.msg.ok { color: var(--ok); }

.dropzone {
  display: flex; align-items: center; justify-content: center;
  min-height: 90px; padding: 16px; margin-bottom: 16px;
  border: 2px dashed var(--border); border-radius: var(--radius);
  background: var(--surface); color: var(--muted); cursor: pointer; text-align: center;
}
.dropzone.over { border-color: var(--accent); color: var(--accent); }

.sign-layout { display: grid; grid-template-columns: 1fr 340px; gap: 24px; align-items: start; }
.side { position: sticky; top: 80px; }
.viewer { display: flex; flex-direction: column; align-items: center; gap: 16px; }
.page {
  position: relative; background: #fff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.2);
  cursor: crosshair; user-select: none; max-width: 100%;
}
.page canvas { display: block; max-width: 100%; height: auto; }
.page-label { position: absolute; top: -18px; left: 0; font-size: 11px; color: var(--muted); }
.sig-box {
  position: absolute; border: 2px dashed var(--accent); background: var(--box);
  pointer-events: none; border-radius: 4px;
}

.seg { display: flex; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; margin-bottom: 10px; }
.seg-btn { flex: 1; border: 0; border-radius: 0; background: var(--surface); color: var(--muted); }
.seg-btn.active { background: var(--accent); color: var(--accent-text); }
#pad {
  width: 100%; height: auto; aspect-ratio: 3 / 1; display: block;
  background: #fff; border: 1px solid var(--border); border-radius: 8px; touch-action: none; cursor: crosshair;
}
#typed-name { margin: 8px 0 0; }

.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; align-items: start; }
.identity { display: flex; justify-content: space-between; gap: 12px; }
.identity .meta { font-size: 12px; color: var(--muted); word-break: break-all; }

.result { border-left: 4px solid var(--border); }
.result.valid { border-left-color: var(--ok); }
.result.untrusted, .result.modified { border-left-color: var(--warn); }
.result.invalid { border-left-color: var(--bad); }
.badge { font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.04em; }
.valid .badge { color: var(--ok); }
.untrusted .badge, .modified .badge { color: var(--warn); }
.invalid .badge { color: var(--bad); }
.result dl { display: grid; grid-template-columns: 140px 1fr; gap: 4px 12px; margin: 12px 0 0; font-size: 13px; }
.result dt { color: var(--muted); }
.result dd { margin: 0; word-break: break-word; }
details pre { font-size: 11px; white-space: pre-wrap; color: var(--muted); max-height: 300px; overflow: auto; }

@media (max-width: 860px) {
  main { padding: 16px; }
  .sign-layout, .two-col { grid-template-columns: 1fr; }
  .side { position: static; }
  .result dl { grid-template-columns: 1fr; }
}