increase width of large-ecreen breakpoint

otherwise on westmisnter the top menu doesn't fit into the space
only use single column layout for mobile

may need to revisit this once we have a better idea of how in page nav
will work on mobile
reduce height of hero banner on all but desktop

in order to avoid pushing the start of the real content below the fold
push hamburger menu left to avoid overlaying mysoc branding on tablets
split constituency and party over two lines on tablet and  narrower

also left align as it ends up looking a bit neater
requires some margin's etc to line things up with other page elements
and each other
make MP speech search box as wide as cell

Tidies things, especially the alignement with the party and constituency
details on tablet screens