That was cool! The momentum-based movement was engaging and satisfying; repairing bridge segments as quickly as possible was a fun and fair challenge. The art is also quite polished, especially in regards to the beautiful transition to night!
The repair noise is considerably louder than the music. Also, spamming the repair button creates an unpleasant continuous ringing that peaks the audio above +0.0 dB.
I might have missed something, but I didn't notice any increase in the frequency of blocks becoming unstable. It's an interesting artistic decision to have the primary mode of difficulty be the reduction of contrast and value between the foreground and background (it getting darker). Although, it does limit your primary audience to people with above-average graphics decoding skills and an increased tolerance for straining their eyes (this is a valid design choice). Still, I think it would've made the game more replayable and engaging if the difficulty also increased materially (subtly, of course), rather than it simply being an endurance and visual distinction challenge.
All-in-all, great work!