Every icon is one vivid colour behind a pane of frosted glass with a white glyph on top, and the glyph does the work: JSON is { }, Markdown is M↓, a certificate is a rosette, a Dockerfile is a stack of crates, and from 48px a short label spells out the exact type. The top-bar microphone turns orange while it is in use. It also corrects what GNOME thinks your files are: out of the box, go.mod is a tracker-music module.