[SalesForce] Change background color for lightning:tab

Ok, so I had to open the .css file from the lightning design system and search for these class names. It turns out that either documentation is a bit out of whack, or whoever was writing the class names became a little lazy :).

So, in order to set a background of an icon from the custom sprite, you only need to specify the icon NUMBER and not the whole icon name. For an example if you want to use the icon custom15, the class name will be:

.slds-icon-custom-15 and not .slds-icon-custom-custom15

You need to wrap your component content like this -

<aura:component>
  <div class="slds-box slds-theme_default">
     //your component content
  </div>
</aura:component>

then your component background would be default white. For more information - https://www.lightningdesignsystem.com/utilities/themes/

or if you want some other background color then you have to write some css

.THIS .slds-theme_backgroundColor-lightblue {
    background-color: lightblue;
}

and add this class to your container div

<aura:component>
   <div class="slds-box slds-theme_default slds-theme_backgroundColor-lightblue">
         //your component content
   </div>
</aura:component>