Please try
header image apply manually
Add style.css bottom
/* No4. Lessons */
.page-id-191 #header-image{
background-image:url('https://example.com/your-header-image.jpg');
}
/* No5. Contact */
.page-id-22 #header-image{
background-image:url('https://example.com/your-header-image.jpg');
}
/* No6. Schedule */
.page-id-113 #header-image{
background-image:url('https://example.com/your-header-image.jpg');
}
/* No7. Testimonials */
.page-id-18 #header-image{
background-image:url('https://example.com/your-header-image.jpg');
}
/* No8. Gallery */
.page-id-20 #header-image{
background-image:url('https://example.com/your-header-image.jpg');
}
/* No9. Links */
.page-id-26 #header-image{
background-image:url('https://example.com/your-header-image.jpg');
}
By the way
Now default sidebar set display none for maybe create 1 column
You can use Raindrops magic rule
Try
Add editor content below with text mode
<!--[raindrops color_type="dark" col="1"]-->