How to fix a death trap stair window?

[MariaDingbat]

We moved into a new house last year and the builders decided that it would be a great idea to build a stairs across the gable window which leaves a huge gap. I've attached a photo. We have a toddler who is now learning to climb stairs and we need to get it safe asap. Any ideas on what would be a good way to cover it over?

a banister on that portion of the window

Can you have a piece of clear Perspex cut and fit across the opening so you still get light through but it closes the gap? It only needs to be a temp fix until toddler is a bit older.

We were thinking that perspex might work but I have no idea how to fix it safely. We've another baby on the way so it will have to last a few years.

Just put a gate on top and bottom of stairs, and don't let him use the stairs unsupervised? I think that is what I would do.

Or you could get a pressure fit stairgate for the window frame, I suppose.

To be honest, it's a double glazed window so unless there's a huge gap between the stairs and the window that the toddler is going to fall through, the window isn't dangerous.

Someone tried to break in to my place by smashing a shovel repeatedly against the double window in my living room. They managed to chip it a bit, that's all.

Could you just fit a piece of wood across the window? It doesn't look a massive gap, so I would think a bit of 1" by 2" would do it.

Rawl plug in either side of the window, pilot hole through the wood, screw in on the diagonal. Wouldn't look great but super easy to do, cheap and easy to remove (just unscrew and paint over the rawl plugs).