[web] style inputs fields to more closely match the figma

Summary: update input fields to match figma a bit closer. Currently there aren't empty field states in figma making it difficult to implement the full design.

Will update spacings, and labels in a follow up diff

Test Plan: render input fields to look like screen shot and match general design of figma https://www.figma.com/file/a1nkbWgbgjRlrOY9LVurTz/Comm-%2F-Desktop-app?node-id=1313%3A99486

Reviewers: atul, ashoat

Reviewed By: atul, ashoat

Subscribers: ashoat, palys-swm, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3035