JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <p class="bottom int32">bottom: max int32 - 1</p>
    <p class="top int32-limit">top: max int32</p>
</div>
<div>
    <p class="bottom int32-limit">bottom: max int32</p>
    <p class="top int32-over">top: max int32 + 1</p>
</div>
<div>
    <p class="bottom int64">bottom: max int64 - 1</p>
    <p class="top int64-limit">top: max int64</p>
</div>
<div>
    <p class="bottom int64-limit">bottom: max int64</p>
    <p class="top int64-over">top: max int64 + 1</p>
</div>
<div>
    <p class="top int32-limit">top: max int32</p>
    <p class="bottom int32">bottom: max int32 - 1</p>
</div>
<div>
    <p class="top int32-over">top: max int32 + 1</p>
    <p class="bottom int32-limit">bottom: max int32ああああああああああああ</p>
</div>

CSS

div {height:4em;position:relative;}
p {
    padding:1em;
    border:0.1em solid grey;
    position:absolute;
    top:0;
    left:0;
}
.bottom {background: #d22;margin:0.5em;}
.top {background: #2d2;}
.int32 {z-index: 2147483646;}
.int32-limit {z-index: 2147483647;top:-100px}
.int32-over {z-index: 2147483648;}
.int64 {z-index: 9223372036854775806;}
.int64-limit {z-index: 9223372036854775807;}
.int64-over {z-index: 9223372036854775808;}