Hi, Dorayh,
Here is some general background. Both .jpg and .png files are bit-maps (like graph paper, if you ever used that). If they are resized, say down to 20%, 5 dots have to be squeezed into a single space. If the dots are monochrome, as text often is, any curves in the text are turned to blocky stair steps. Colored images tend to average the color values, and so internally look smoother, if chromatically duller. The edges are chunky also if the images had curved edges.
Most software at this time will add in intermediate tones along the edges so they don't appear so jagged. But as the size decreases, that effect adds a distinct blur at the edges.
That blur is minimized if vector objects such as fonts are turned to bit maps at good resolution, 300 dpi. If you export a large font, but tell the software to scale it down, it appears that the font is rasterized, and that is then scaled down, leading to excessive blurriness. So re-size the fonts to a smaller size before exporting the .jpg. While the text is still in vector format, the export will result in a fairly clean bit map.
Note, modern browser displays do not need .jpg or .png. They display .svg at whatever size is appropriate as cleanly as possible.
Hopefully I inferred what you are doing correctly. The processes of scaling bitmaps has been a problem forever, and often there are no good solutions.
