tildes-reextended/source/scss/scripts/_markdown-toolbar.scss

.trx-toolbar {
  > header {
    justify-content: initial;

    > select {
      font-size: 0.6rem;
      margin-left: 4px;
      margin-right: auto;
      width: auto;
    }

    .tab.tab-markdown-mode + a {
      margin-left: auto;
    }
  }
}