I fired up Windows 2.03 in DOSBox, with its clock app, available on archive.org[1], and it took up 60.1 MB. This is fun! I think the OS would run fine (at least, enough for the clock) with as little as 512K of ram[2].
If you have screen of size 640*480 and rendering without AA then you can render by CPU.
Otherwise, with modern hardware and 200 ppi monitors you will need GPU rendering with the whole infrastructure.
This clock sample ( https://github.com/c-smile/sciter-sdk/blob/master/samples/gr... ) is a port of Mozilla's clock : https://codepen.io/anon/pen/vJpqOY
Chrome needs 6 separate processes to run this sample with total memory consumption of 575 Mb.