Sincerely its not much more that technicall interface demo, there is not really a game loop, for example you have a button to start and a slider to set the temperture right(the temperature wasn't clear), you simply push the button and move the slider until is in the correct position aand win(the value of the heat is not even randomized), itself don't produce any sensation, you not feel stress to loss, or satisfaction add win, it not a idle were the point is be relaxing or work as a fidget toy.
For example there is a thing you could do to create a game loop, , instead of 2 minutes make it 20 seconds, don't let the player, know beforehand the heat , and don't let they control the slider until press the button, so they have to set in the correct positon counter clock. and each they release it display the value of for how much they miss (if 70 and the player put on 69 or 71 show a 1 ) with a second of delay, plus make the values of the slider don't go from 1 to 100 instead 2 randomized values(there are tricks to make it consistent there is a lot of youtube tutorials on the mather). And this is only one of the multiple paths you can go from here
The end level interface is confusing, to begin with the "won" message cover all, and there is 2 buttonss that quick you out of the game, I recomend to make it turn back to main screen, and put there the exit button(at least for demos and prototypes, these have errors and it's better don't frustrate the player with closing the game accidentally)
For the good side you have a solid interface, that can be reutilize to make quick demos. And a recomentation, learn how to export to html, more people gonna try you game if not have to download.
The dark mode, not a bad idea it look better but you are darkening all, generally it mean to change the shader or "theme", to key elements, generally the background and fontss, but shouldn't be applied to the cheffor the bread