luci-theme-openwrt: refining hide/show buttons

luci-theme-openwrt: refining hide/show buttons

Match "show" button style to IP table,
change border colour to match font
colour; fade it slightly: no variable for
disabled opacity like
luci-theme-bootstrap, assuming 0.7.
Remove fade when hovered.
Change mouse icon from text cursor
to pointer, restore button text weight
and font similar to indicators,
add subtle border to compliment
both states of button.
Work with existing mobile styling
for 480px and below, make
bigger buttons and fix
heading alignment.

Signed-off-by: Joshua Criss <redacted>