display only category label on axis for multicategory plots

I would like to display only the category, and not the specific tick labels on the axis. For example, in this example https://codepen.io/plotly/pen/bOByWR I would like to only display 'SF Zoo' and 'LA Zoo'. I've tried several hacks such as setting tick labels to empty string, but in my case the plot still leaves room for the tick labels and it looks weird. See what I mean:

Is there a way to accomplish this? I think I might have to use the idea of subcategory axis instead.

首先复现链接的 CodePen 多类别图，并将其与提供的截图进行比较。调查 Plotly.js 如何渲染类别标签和刻度标签，然后确定是否只显示“SF Zoo”和“LA Zoo”也能移除为具体刻度标签预留的空间。当类别标签在没有未使用的刻度标签空间的情况下仍保持可读时，即表示完成。