Bleeding master cylinder

Just reconditioned and refitted a seized caliper and am enveloped in a warm feeling of contentment.

However! This feeling is also accompanied by a faint murmur of despair - despite bleeding my brakes, the pedal is still very soft. It doesn't touch the floor and pumps-up hard if the ignition is off, but it just doesn't feel right.

I lost a lot of fluid when I removed the calipers - is there a chance there might be air in the master cylinder? If so, where are the valves to bleed it and how do I get to them? The engine bay is full of other things...

Your advice will be rewarded with a Briskoda how-to on caliper piston seal renewal!