Ask HN: Modern self-hosted IMAP webmail client?

In light of recent Gmail changes (see the recent prominent thread), which, like many others, I'm also not totally happy with (mostly because of being slower than before), I'd like to explore options of a self hosted webmail client that uses IMAP to receive emails at my Gmail account.

Let's say I'm not against Google/Gmail and don't mind emails going through their servers (privacy concerns etc. that many others here have), but am just not happy with their latest redesign. I'd also like to not use Thunderbird or other desktop clients because I have several laptops and desktops and don't wish to spend time downloading new emails when I don't use a laptop for a month and open it up. Webmail in concept sounds great, if I can control what client to use and have a good lightweight one.

What are some modern options for one? I did some googling around and found lists including ones like Squirrelmail which screams of late 90s web hosts to me. The ideal client is something like old school Gmail without all the Hangouts integration and such that slows it down.