:root[data-theme="dark"] {
  --bg: #0f172a;
  --bg-elev: #0a1024;
  --bg-elev-2: #111a30;
  --border: #1e293b;
  --text: #e2e8f0;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --accent: #c0392b;
  --ok: #16a34a;
  --warn: #f59e0b;
  --err: #ef4444;
  --info: #3b82f6;
}
:root[data-theme="light"] {
  --bg: #f7f8fa;
  --bg-elev: #ffffff;
  --bg-elev-2: #f1f5f9;
  --border: #e2e8f0;
  --text: #0f172a;
  --text-muted: #475569;
  --text-dim: #94a3b8;
  --accent: #c0392b;
  --ok: #16a34a;
  --warn: #d97706;
  --err: #dc2626;
  --info: #2563eb;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; height: 100%; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Plus Jakarta Sans', system-ui, sans-serif;
  font-size: 14px;
  line-height: 1.4;
}
.mono { font-family: 'JetBrains Mono', monospace; }
.boot { padding: 40px; text-align: center; color: var(--text-muted); }

/* ---- Sign-in screen ---- */
.signin {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}
.signin__card {
  width: 100%;
  max-width: 360px;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 32px 28px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
}
.signin__title {
  margin: 0;
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.signin__sub {
  margin: -8px 0 8px;
  color: var(--text-muted);
  font-size: 13px;
}
.signin__err {
  margin: 0;
  min-height: 1.2em;
  color: var(--err);
  font-size: 13px;
}
.signin__btn {
  appearance: none;
  border: 0;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  font-weight: 600;
  padding: 11px 16px;
  font-size: 14px;
  cursor: pointer;
}
.signin__btn:disabled { opacity: 0.6; cursor: progress; }
.signin__btn:hover:not(:disabled) { filter: brightness(1.08); }
.signin__hint {
  margin: 4px 0 0;
  text-align: center;
  color: var(--text-dim);
  font-size: 11px;
}

/* ---- Form fields (reused by app shell) ---- */
.field { display: flex; flex-direction: column; gap: 6px; }
.field__label {
  font-size: 12px;
  color: var(--text-muted);
  font-weight: 500;
}
.field input {
  background: var(--bg-elev-2);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 8px;
  padding: 10px 12px;
  font-size: 14px;
  font-family: inherit;
}
.field input:focus {
  outline: 2px solid var(--accent);
  outline-offset: -1px;
  border-color: transparent;
}

/* ---- App shell (Phase 1 placeholder, expanded in Stage 3) ---- */
.app-shell { min-height: 100vh; display: flex; flex-direction: column; }
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 20px;
  background: var(--bg-elev);
  border-bottom: 1px solid var(--border);
}
.topbar__brand { font-weight: 700; letter-spacing: -0.01em; }
.topbar__user { display: flex; align-items: center; gap: 12px; }
.topbar__who { color: var(--text-muted); font-size: 13px; }
.topbar__signout {
  appearance: none;
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 12px;
  font-size: 12px;
  font-family: inherit;
  cursor: pointer;
}
.topbar__signout:hover { background: var(--bg-elev-2); }
.content { flex: 1; padding: 24px; }