Center Header V2

Hallo,

i have a problem. I am using Agama Theme (1.5.1) and I want to center my Header Title and the Header Subtitle. I tried a few codes in CSS, but cannot solve the problem.

I tried :

.site-header h1,.site-header h2 {
text-align: center;
}
but this code only works for the subtitle.

My Css Knowledge is bad, can anybody give me the right css code?
Thank You Very Much

Lg, Andreas

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