Boba Gateway - UI Tweaks

[HangingGolem]

Here are issues that really bother me at the moment

1. This blurred gradient was meant to be fixed down and work in complex with other visuals. We need to remove this gradient, since now it looks like the sidenav is broken

2. Deposit button on wallet is inconsistent with other buttons - should be linked to the same global style as other outline buttons

3. Hover states aren't presented in some places. It creates a lot of confusion in understanding what is clickable when platform is used. In general hover effects would be: default: gray -> hover: white default: white -> hover: orange

We don't have .hov on: network selector dropdown, tabs, datepicker (should have same active and .hov applied on top of that styling as the regular input), deposit/transact/stake expanders(basically all of them), transactions: more info expander (also lacks arrow icon), transactions hash code link

[CAPtheorem]

@sk-enya please tackle 1/ and 3/

[sk-enya]

@CAPtheorem shall I look into the 3/ as well? As it seems we just have to add hover effect

[sk-enya]

@CAPtheorem Please review changes here https://github.com/omgnetwork/optimism/pull/436