(CA) - Buying a place with girlfriend - Uneven downpayment, equal monthly payments?

Hi folks, I'm looking to purchase a new home with my girlfriend.

We are likely going to be putting down an uneven amount for a downpayment where I'm likely going to be contributing 70% and she will be contributing 30% so that would mean the home would have a 70/30 split in ownership.

However, we'd like to split the monthly fees 50/50 as I would not be able to take on 70% of the mortgage, strata etc. We've discussed this and agreed that this would be the best solution. What's the best way to approach this? I understand that this would mean our ownership % will change over time as we'll be putting in equal amounts towards the monthly payments.