_getStyle(affixType){
        if( 'undefined' === typeof affixType ) return;
  
        var style = {inner: {}, outer: {}};
        var dims = this.dimensions;
  
        switch( affixType ){
          case 'VIEWPORT-TOP':
            style.inner = {position: 'fixed', top: dims.topSpacing,
                  left: dims.sidebarLeft - dims.viewportLeft, width: dims.sidebarWidth};
            break;
          case 'VIEWPORT-BOTTOM':
            style.inner = {position: 'fixed', top: 'auto', left: dims.sidebarLeft,
                  bottom: dims.bottomSpacing, width: dims.sidebarWidth};
            break;
          case 'CONTAINER-BOTTOM':
          case 'VIEWPORT-UNBOTTOM':
            let translate = this._getTranslate(0, dims.translateY + 'px');
            
            if( translate )
              style.inner = {transform: translate};
            else 
              style.inner = {position: 'absolute', top: dims.translateY, width: dims.sidebarWidth};
            break;
        }
        
        switch( affixType ){
          case 'VIEWPORT-TOP':
          case 'VIEWPORT-BOTTOM':
          case 'VIEWPORT-UNBOTTOM':
          case 'CONTAINER-BOTTOM':
            style.outer = {height: dims.sidebarHeight, position: 'relative'};
            break;
        }
  
        style.outer = StickySidebar.extend({height: '', position: ''}, style.outer);
        style.inner = StickySidebar.extend({position: 'relative', top: '', left: '',
            bottom: '', width: '',  transform: ''}, style.inner);
  
        return style;
      }
Gets inline style of sticky sidebar wrapper and inner wrapper according 
to its affix type.
@private
@param {String} affixType - Affix type of sticky sidebar.
@return {Object}