Ok for the background we might need to make some style changes.. it could be interfering with your bootstrap theme...
so if you edit the themes css style sheet in themes/defult/css/reportico.css ( there are a couple of other themes folder but im assuming this is the one thats relevant to you ) ....
and look at 3 places ..
/ border: solid 1px #AAAAAA; /
/ min-width: 100vw; /
This sets the background colour to the grey .. you can change background-color to #ffffff
This should set the buttons above the output but it seems to push your report to the left when the page should appear underneath .. try changing to
width: 100% !important;
height: 36px !important;
Then finally there is
margin: 0 auto;
padding: 0px 0px;
box-shadow: 0 0 0.5cm rgba(0, 0, 0, 0.5);
/height: 100vh !important;/
Take out the box-shadow to get of a subtle shadow around the page...
Also... regarding your header.. i think the reason is that your margin property doesnt provide the measurements
margin:40mm 0 0 150;
margin:40mm 0px 0px 150mm;
and play with the 150mm to get it right
Hope that helps