我只是偶然发现了overflow: hidden在html上的这种用法，这对我来说似乎不合逻辑：

* {
  all: unset;
  display: revert;
}
html {
  height: 100vh;
  overflow: hidden;
  background: black;
}
body {
  height: 50vh;
  font-size: 5rem;
  background: white;
  scroll-snap-type: y mandatory;
  scroll-behavior: smooth;
  overflow-y: scroll;
}

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这是关于将滚动框从html移动到body，但是我不明白为什么这个例子只适用于overflow: hidden？body的高度已经只有50vh了，所以html元素不应该发生溢出吗？