The ceilings are shares of adjusted gross income
The deduction for charitable contributions generally cannot be more than 60% of adjusted gross income, and inside that overall limit the categories are capped separately: 60% for cash to a 50%-limit organization, 50% for property that is not capital gain property, 30% for capital gain property, and 20% for capital gain property given to an organization that is not a 50%-limit organization. On top of those ceilings, 2026 adds a floor: an itemizer deducts only what is more than 0.5% of adjusted gross income, so the first 0.5% of giving does not count at all.
The lower ceilings are what is left after the higher ones are used, which is why the order matters. A page that added three independent 50% ceilings together would promise three times the deduction the law allows; this one works down the ceilings the way the form does, so the effective cap for a year is a single surviving number. The floor runs the other way: it is taken once off the total that survives the ceilings, not off each category in turn.