logseq/src/main/frontend/components/editor.css

.editor-wrapper {

}

.editor-inner {
  position: relative;
  display: flex;
}

.editor-inner textarea {
  border: none;
  border-radius: 0;
  background: transparent;
  padding: 0;
}

.non-block-editor textarea, pre {
  display: block;
  padding: 0.5rem;
  box-shadow: 0 0 0 1px rgba(0, 0, 0, .02);
  border-radius: 4px;
}

.non-block-editor textarea {
  background: #F6F8FA;
  background: var(--ls-secondary-background-color);
}