Python developers who ignore the frontend struggle to finish projects, because every web app ends in a browser. You do not need design mastery. You need enough HTML to structure a page, enough CSS to lay it out cleanly, and enough JavaScript to handle forms and fetch data from your own API. That minimum covers most full-stack work.
The minimum, concretely
- HTML: forms, inputs, labels, and semantic structure, since accessible forms are also easier to style and debug.
- CSS: layout with flexbox and grid, spacing, and responsive basics, so pages work on small screens too.
- JavaScript: reading form values, calling your API, and updating the page with the response, without a framework.
- Browser tools: the console and network tab, which show errors and failed requests plainly.
Learn a frontend framework only after building several pages with these basics. The framework will then feel like a shortcut, not a mystery.