When hovering over a building button on the bonfire tab, a red line is shown on all resources that would be used to indicate how much you'll have after clicking the button, but the space tab doesn't have this feature. For that matter, the religion tab could use it as well, for buying religious upgrades and sacrificing unicorns/alicorns or refining tears. The workshop and science tabs too, for research/upgrades/crafting.
When hovering over a building button on the bonfire tab, a red line is shown on all resources that would be used to indicate how much you'll have after clicking the button, but the space tab doesn't have this feature. For that matter, the religion tab could use it as well, for buying religious upgrades and sacrificing unicorns/alicorns or refining tears. The workshop and science tabs too, for research/upgrades/crafting.