:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --border: #e5e7eb;
  --text: #111827;
  --muted: #6b7280;
  --accent: #1d4ed8;
  --accent-text: #ffffff;
  --alert-bg: #fef3c7;
  --alert-text: #92400e;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115;
    --surface: #171a21;
    --border: #2a2f3a;
    --text: #e5e7eb;
    --muted: #9ca3af;
    --accent: #3b82f6;
    --alert-bg: #3f2d0a;
    --alert-text: #fcd34d;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.brand {
  font-weight: 600;
}

.user {
  display: flex;
  align-items: center;
  gap: 12px;
}

.user form {
  margin: 0;
}

.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 20px 64px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.center {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 20px;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
}

.card h1 {
  margin: 0 0 8px;
  font-size: 20px;
}

.card h2 {
  margin: 0 0 14px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}

.login {
  max-width: 380px;
  text-align: center;
}

.login .btn {
  margin-top: 8px;
}

/* La firma se previsualiza siempre sobre fondo claro: es el lienzo real de un
   correo, y sus estilos inline asumen texto oscuro. */
.preview {
  background: #ffffff;
  color: #111827;
  border: 1px dashed var(--border);
  border-radius: 8px;
  padding: 20px;
  overflow-x: auto;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
}

.btn {
  display: inline-block;
  padding: 10px 16px;
  font: inherit;
  font-weight: 500;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  text-decoration: none;
}

.btn:hover {
  border-color: var(--accent);
}

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-text);
}

.btn-ghost {
  padding: 6px 12px;
  color: var(--muted);
}

.btn.is-error {
  border-color: #dc2626;
  color: #dc2626;
  background: var(--surface);
}

.status {
  color: var(--muted);
  font-size: 13px;
}

.muted {
  color: var(--muted);
}

.small {
  font-size: 13px;
}

.alert {
  margin: 0;
  padding: 12px 14px;
  background: var(--alert-bg);
  color: var(--alert-text);
  border-radius: 8px;
  font-size: 14px;
}

details {
  border-top: 1px solid var(--border);
  padding: 10px 0 2px;
}

details:first-of-type {
  border-top: 0;
  padding-top: 0;
}

summary {
  cursor: pointer;
  font-weight: 500;
}

details p {
  margin: 8px 0 4px;
  color: var(--muted);
  font-size: 14px;
}

kbd {
  padding: 1px 5px;
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 4px;
  font-size: 12px;
  font-family: ui-monospace, monospace;
}

code {
  font-family: ui-monospace, monospace;
  font-size: 13px;
}