z-index

z-index is the CSS property that helps control layout by providing a third axis to arrange content.

Several Material-UI components utilize z-index, employing a default z-index scale in Material-UI that has been designed to properly layer drawers, modals, snackbars, tooltips, and more.

这些值从任意数字开始，足够大和特别来避免冲突。

mobile stepper（移动设备起步）: 1000
speed dial: 1050
app bar（应用栏）：1100
drawer（抽屉）：1200
modal（浮层）：1300
snackbar：1400
tooltip（提示）：1500

这些值可以自定义。 You will find them in the theme under the zIndex key of the theme. Customization of individual values is discouraged; should you change one, you likely need to change them all.