:root {
  color-scheme: light;
  --bg: #f5f7f8;
  --panel: #ffffff;
  --text: #1f2933;
  --muted: #667085;
  --line: #d7dde3;
  --accent: #0f766e;
  --accent-hover: #0b5f59;
  --danger: #b42318;
  --ok-bg: #edf7f4;
  --warn-bg: #fff6e6;
  --err-bg: #fff0f0;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
}
.shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}
.panel {
  width: min(560px, 100%);
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 28px;
  box-shadow: 0 10px 28px rgba(31, 41, 51, 0.08);
}
h1 {
  margin: 0 0 22px;
  font-size: 24px;
  line-height: 1.25;
  font-weight: 700;
}
label {
  display: block;
  margin-bottom: 8px;
  color: var(--muted);
  font-size: 14px;
}
.input-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
  margin-bottom: 14px;
}
input {
  width: 100%;
  min-width: 0;
  height: 44px;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 0 12px;
  font-size: 15px;
  color: var(--text);
}
input:focus {
  outline: 2px solid rgba(15, 118, 110, 0.18);
  border-color: var(--accent);
}
button {
  height: 44px;
  border: 0;
  border-radius: 6px;
  padding: 0 16px;
  font-size: 15px;
  cursor: pointer;
}
#toggle-key {
  background: #eef2f4;
  color: var(--text);
}
#submit-button {
  width: 100%;
  background: var(--accent);
  color: #fff;
  font-weight: 650;
}
#submit-button:hover { background: var(--accent-hover); }
#submit-button:disabled { opacity: 0.65; cursor: not-allowed; }
.result {
  margin-top: 18px;
  border-radius: 6px;
  padding: 14px;
  border: 1px solid var(--line);
  line-height: 1.55;
  word-break: break-word;
}
.result.ok { background: var(--ok-bg); }
.result.warn { background: var(--warn-bg); }
.result.err { background: var(--err-bg); color: var(--danger); }
.hidden { display: none; }
.meta {
  margin-top: 8px;
  color: var(--muted);
  font-size: 13px;
}
@media (max-width: 520px) {
  .shell { padding: 14px; align-items: start; }
  .panel { padding: 20px; margin-top: 24px; }
  .input-row { grid-template-columns: 1fr; }
  #toggle-key { width: 100%; }
}