iridium-c/src/iridium.css

GtkSourceView#source-view {
  font-family: "Fira Mono", monospace;
  font-size: 1.05em;
}

GtkEntry#title-entry {
  border: none;
  background: none;
  font-size: x-large;
  font-weight: bold;
}

GtkPaned#main-pane {
  background: white;
  border: 1px solid #ccc;
}

.list-box > IridiumNoteRow:not(:last-child) {
  border-bottom: 1px solid #ccc;
}

GtkBox#tags GtkLabel {
  color: #aaa;
}