Although not widely supported [96% supported in 2022], you can utilize the shape-outside CSS declaration to achieve the desired effect:
Keep in mind this is just an example, not a definitive solution.
.element{
shape-outside: polygon(0 0, 0 100%, 100% 100%);
width: 20em;
height: 40em;
}
This will create a triangular region (three-sided polygon) where the text won't appear. A polyfill is available on Github for browsers lacking support for this feature.
There are several insightful articles online regarding shape-outside, particularly on sites like HTML5 Rocks and A List Apart.
Additionally, there's a similar query on Stack Overflow from a couple of years back that might be helpful.
Edit: Added code snippet - the sample seems functional only in Chrome without the polyfill
.wrapper {
width: 300px;
}
.element {
shape-outside: polygon(0 0, 100px 0, 0 100px);
width: 100px;
height: 100px;
float:left;
}
<div class="wrapper">
<div class="element"></div>
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</div>