Customise Color Section background image position & responsive Overlay

Hi
I’d like to say how much I am enjoying using the Enfold theme, and how impressive your tech support is!

I’m trying to do two customisations on the Color Selection with a back ground Image. Unrtunately I’m developing locally, so can’t provide access.
Here’s the element from the page
<div id="castiletop" class="avia-section header_color avia-section-small avia-no-border-styling av-section-color-overlay-active avia-bg-style-scroll avia-builder-el-0 el_before_av_section avia-builder-el-first myname av-minimum-height av-minimum-height-custom container_wrap fullsize" style="background-repeat: no-repeat; background-image: url(https://tcs-japan-new:8888/wp-content/uploads/2016/11/The-Camel-Soap-Factory-Pure-and-Natural-Camel-Milk-Soap-1-4.jpg); background-attachment: scroll; background-position: center left; " data-section-bg-repeat="no-repeat"><div class="av-section-color-overlay-wrap"><div class="av-section-color-overlay" style="opacity: 0.5; background-color: #ffffff; "></div><div class="container" style="height:500px"><main role="main" itemprop="mainContentOfPage" class="template-page content av-content-full alpha units"><div class="post-entry post-entry-type-page post-entry-39"><div class="entry-content-wrapper clearfix">

I ‘ve implemented avia_template_builder_custom_css and have given it a name (myname) as well as giving the id (castiletop)
So, two questions:
1. I’d like to ‘nudge’ the background image say 20px to the right – as a temporary solution I’ve added whitespace to the actual image, but this is not suitable on smaller screens. can this be done ?
2. The code shows that I have a white overlay @ 50%, however I would like this overlay to appear only on smaller screens (mobile ..> )

With Thanks
Dave