Do not show "Balance" when scrolling the list of envelopes.

By setting a background, we effectively let it hide below the list of
envelopes, instead of letting it show up when scrolling in the space
between envelopes.
Fix mistranslation.

Hora means "time" as in "hour", but we need something similar to "date"
instead.
Make the graph background transparent.

That way, when touching it, the highlight color is shown on all of the
box instead of just on the borders.
Add some padding between the bottom axis labels and the graph.

Otherwise, if we have an envelope on a long time low level, its graph
line will overlap with the axis a bit.