Jagged Header Edges

I’ve been playing around with the Focus Theme by Genesis, yet when I insert my header image, 1) it has jagged edges (that are not on the original image, and I haven’t resized it) and 2) the post titles move into my header, therefore making them unclickable.

I’ve changed the positionL relative/absolute values and z-index values so my header will lay on top of the sidebar, but not the menu…but any advice would be great.

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