:root {
  --bg: #0b1220;
  --panel: #121a2b;
  --line: #243049;
  --text: #e8eefc;
  --muted: #93a0b8;
  --accent: #3dd6c6;
  --danger: #ff6b7a;
  --font: "Segoe UI", system-ui, sans-serif;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: var(--font);
  background: radial-gradient(1200px 600px at 10% -10%, #1a2a4a, var(--bg));
  color: var(--text);
  min-height: 100vh;
}
.hidden { display: none !important; }
.muted { color: var(--muted); }
.error { color: var(--danger); min-height: 1.2em; }
.panel {
  max-width: 380px;
  margin: 12vh auto;
  padding: 1.5rem;
  background: color-mix(in srgb, var(--panel) 92%, transparent);
  border: 1px solid var(--line);
  border-radius: 14px;
}
.login-panel h1 { margin: 0 0 .25rem; font-size: 1.6rem; }
.login-panel label, .compose label, .create-box label {
  display: block;
  margin: .75rem 0;
  font-size: .9rem;
}
input, textarea, button {
  width: 100%;
  margin-top: .35rem;
  padding: .65rem .75rem;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: #0d1524;
  color: var(--text);
}
button {
  cursor: pointer;
  background: linear-gradient(180deg, #2a9f94, #1f7f78);
  border: none;
  font-weight: 600;
}
button.linkish {
  width: auto;
  background: transparent;
  color: var(--muted);
  border: 1px solid var(--line);
  padding: .25rem .5rem;
  font-size: .75rem;
}
.app {
  display: grid;
  grid-template-columns: 260px 1fr;
  min-height: 100vh;
}
.sidebar {
  border-right: 1px solid var(--line);
  background: color-mix(in srgb, var(--panel) 88%, transparent);
  padding: 1rem;
  overflow: auto;
}
.brand {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}
.sidebar h2 {
  font-size: .75rem;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--muted);
  margin: 1rem 0 .4rem;
}
.sidebar ul { list-style: none; padding: 0; margin: 0; }
.sidebar li button {
  text-align: left;
  background: transparent;
  border: 1px solid transparent;
  margin: .15rem 0;
}
.sidebar li button.active,
.sidebar li button:hover {
  border-color: var(--line);
  background: #182338;
}
.main { display: flex; flex-direction: column; min-width: 0; }
.toolbar {
  display: flex;
  gap: .5rem;
  align-items: center;
  padding: .75rem 1rem;
  border-bottom: 1px solid var(--line);
}
.toolbar button { width: auto; }
#current-box { flex: 1; font-weight: 600; }
.split {
  display: grid;
  grid-template-columns: minmax(280px, 38%) 1fr;
  flex: 1;
  min-height: 0;
}
.msg-list {
  border-right: 1px solid var(--line);
  overflow: auto;
}
.msg-item {
  display: block;
  width: 100%;
  text-align: left;
  background: transparent;
  border: none;
  border-bottom: 1px solid var(--line);
  border-radius: 0;
  padding: .85rem 1rem;
}
.msg-item:hover, .msg-item.active { background: #182338; }
.msg-item .sub { font-weight: 600; }
.msg-item .meta { color: var(--muted); font-size: .8rem; margin-top: .2rem; }
.msg-view { padding: 1.25rem; overflow: auto; white-space: pre-wrap; }
.msg-view h3 { margin-top: 0; }
.create-box { margin-top: 1rem; color: var(--muted); }
dialog {
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--panel);
  color: var(--text);
  padding: 0;
  width: min(520px, 92vw);
}
.compose { padding: 1rem 1.25rem 1.25rem; }
.compose .row { display: flex; gap: .5rem; }
.compose .row button { width: auto; flex: 1; }
@media (max-width: 860px) {
  .app { grid-template-columns: 1fr; }
  .split { grid-template-columns: 1fr; }
  .sidebar { max-height: 40vh; }
}