Step 1 － Navigate to Theme Options > Header and set a color for the Header Background Color field. Any color is fine, but it’s required to populate this field.
Step 2 － In the Header Transparency field, put 0.
The Transparency field accepts values from 0 – 1. “0“ is fully transparent, while “1” is fully opaque. For a semi-transparent header, enter “0.5.”
If your header hasn’t changed, check the settings on your page, under the section Theme Header. See theme settings.