Hello, welcome to the webring.
Here is some CSS you can use on JSchan for custom spoilers and loading bars if you so desire
:root {
--spoiler-img: url(/url on this site);
}
.post-file-src[style*='loading'] {
background:url(/url on this site.gif) no-repeat center;
background-size:150px
}
.upload-thumb[src$='/file/audio.png'] {
display:block;
-moz-box-sizing:border-box;
box-sizing:border-box;
padding-left:50px;
background:url('/url on this site');
background-size:cover;
background-repeat:no-repeat;
}
The last one is for a lil pic to display in the post form if you're uploading audio, instead of just the generic music note 🎵.
Have a lovely weekend.