Investment and Saving taxed higher than expected - Not as long term capital gains

When I finish the Investment and Saving tab of turbo tax it gives me a summary. $26k in capital gains and $4.8k in taxes due to these gains. I know that about $24k of these gains are long term capital gains, while the rest is short term/dividend income. Since my AGI is in the $40k - $445k range, this should be taxed at 15%. However it is taxed at 18%, which is the same as my total taxes/taxable income. 

 

I feel like the correct amount should be $24k*15% +$2k*18% ~= $4k. If the $24k is taxed at 15% then the dividends are being taxed at 60%, which makes no sense. 

Turbotax has explanation boxes that are very helpful in other sections of the application. It would be really nice to have a detailed breakdown here.