The tax is not calculated separately on the unemployment and your salary. The tax that is withheld from your unemployment is not specifically the tax on the unemployment, and the tax withheld from your salary is not specifically the tax on your salary. Any tax that is withheld from any income is just an advance payment towards your total tax for the year.
On your tax return, all of your income is added together. The tax is calculated on your total income. All the tax that was withheld from anywhere is added together and applied towards your total tax for the year.
You can use the Tax Withholding Estimator on the IRS web site to see how you are likely to come out at the end of the year. It will also show you how your can adjust your W-4 to get the approximate refund amount that you want.
