I have a button on the form that is used to upload an image. But applying the typical code does not look good...
<div class="ui segment">
<div class="field">
<input type="hidden" name="MAX_FILE_SIZE" value="100000" />
<label for="#elegir">Elige el archivo a subir: </label>
<input id="elegir" name="uploadedfile" type="file" /><br />
<input type="submit" class="ui blue inline button" value="Subir archivo" />
</div>
</div>
I searched the semantic-ui documentation but didn't find an implementation of this item...
Playing with the styles of the input to upload files is not easy, since most browsers do not allow you to style it directly, neither with JavaScript nor with CSS. Semantic UI, like most CSS frameworks, does not offer a specific style for said element.
There are many workarounds, which I would consider more like CSS and/or JavaScript "tricks" to achieve such an effect.
I leave you one of many examples that you can find on the internet:
Another example, a bit more "Bootstrap":
There is an option that can be very interesting with Materialize CSS, but maybe it is a bit out of the scope of the question, just like the previous Bootstrap one:
http://materializecss.com/forms.html#file