<?php 
function blogus_custom_style()
{
  $blogus_theme_sidebar_width = get_theme_mod('blogus_theme_sidebar_width'); 
  if($blogus_theme_sidebar_width)
  {
  ?>
  <style>
  .sidebar-right, .sidebar-left
  {
    flex: 100;
    width:<?php echo esc_attr(get_theme_mod('blogus_theme_sidebar_width',280)).'px'; ?> !important;
  }

  .content-right
  {
    width: calc((1130px - <?php echo esc_attr(get_theme_mod('blogus_theme_sidebar_width',280)).'px'; ?>)) !important;
  }

  </style>
  <?php } 
} add_action('wp_head','blogus_custom_style',10,0);