JSFiddle - React, Tailwind, and code Playground
HTML
<div class="glass">
<div class="water"></div>
</div>
CSS
.glass {
margin: 30px auto;
height: 300px;
width: 100px;
position: relative;
border-style: none solid solid solid;
border-width: 10px;
border-color: lightgray;
border-radius: 10px;
}
.water {
width: 100%;
height: 10%;
background-color: skyblue;
position: absolute;
bottom: 0;
}
JavaScript
$(function(){
$('.water').animate({
height: '75%'
}, 1000)
})