A common issue that can occur with users new to installing WordPress themes is a "Broken theme and/or stylesheets missing” error message being displayed when trying to upload or activate the theme. This error message does not mean that the theme you have purchased is broken, it simply means it has been uploaded incorrectly. Luckily, there is a very easy fix.

When using Webfonts via @font-face or other CSS3 methods, some browsers like Firefox and IE will refuse to embed the font when it’s coming from a 3rd party URL because it’s a security risk. The solution is very simple, just add a few lines in your .htaccess file to permanently solve the problem.

# ----------------------------------------------------------------------
# CORS-enabled images (@crossorigin)
# ----------------------------------------------------------------------
# Send CORS headers if browsers request them; enabled by default for images.
# developer.mozilla.org/en/CORS_Enabled_Image
# blog.chromium.org/2011/07/using-cross-domain-images-in-webgl-and.html
# hacks.mozilla.org/2011/11/using-cors-to-load-webgl-textures-from-cross-domain-images/
# wiki.mozilla.org/Security/Reviews/crossoriginAttribute
<IfModule mod_setenvif.c>
  <IfModule mod_headers.c>
    # mod_headers, y u no match by Content-Type?!
    <FilesMatch "\.(gif|png|jpe?g|svg|svgz|ico|webp)$">
      SetEnvIf Origin ":" IS_CORS
      Header set Access-Control-Allow-Origin "*" env=IS_CORS
    </FilesMatch>
  </IfModule>
</IfModule>
# ----------------------------------------------------------------------
# Webfont access
# ----------------------------------------------------------------------
# Allow access from all domains for webfonts.
# Alternatively you could only whitelist your
# subdomains like "subdomain.example.com".
<IfModule mod_headers.c>
  <FilesMatch "\.(ttf|ttc|otf|eot|woff|woff2|font.css|css|js)$">
    Header set Access-Control-Allow-Origin "*" 
  </FilesMatch>
</IfModule>

Other solution is to remove www from WordPress

Source

Here we have collected plugins that we recommend to use as needed:

WPML – WPML makes it easy to build multilingual sites and run them.

Contact Form 7 – Just another contact form plugin. Simple but flexible.

TinyMCE Advanced – Enables the advanced features of TinyMCE, the WordPress WYSIWYG editor.

Yoast SEO – Improve your WordPress SEO

W3 Total Cache – Easy Web Performance Optimization (WPO) using caching

Wordfence Security – The Wordfence WordPress security plugin provides free enterprise-class WordPress security, protecting your website from hacks and malware.

Duplicate Post – Clone posts and pages.

Duplicator – Duplicate, clone, backup, move and transfer an entire site from one location to another.

Envato WordPress Toolkit – Plugin for automatic WordPress theme updates created by Envato.