>>6871686the gradient is there at the top as a placeholder more than anything. i've had that as a "feature" since 2014 (pic related). the intention is to put your own image there, or alternatively a solid colour, or the original banner images 4chan uses
and i do agree gradients need to be executed well; good examples:
https://webgradients.com/thoughts, personally, i think it breaks the visually hierarchy a tad too much. if it is too gradual or subtle, you're better off just using a solid colour to save the browser rendering a gradient every single time. i also find that the dark blue background doesn't create enough contrast when the gradient turns purple. also why isn't it applied to every post? and is the 1px bottom border gradient intentional? it's an interesting concept, and that's half the fun. keep at it for sure!