[SalesForce] How to give background color to button in lightning components

You can use the following CSS in your component

.THIS slds-tabs--default__nav li.slds-active{
     background: red;
}

Adjust as needed

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>