Blocking bad bots that don’t access CSS can be beneficial for various reasons. CSS (Cascading Style Sheets) is a crucial component of web design, responsible for styling and layout. If a bot doesn’t access CSS, it might not interpret and display the web content as intended. Blocking such bots ensures that your content is presented in the desired format, improving user experience.

Search engines often consider the visual presentation and user experience of a website when determining search rankings. Ensuring that bots access CSS can contribute to better search engine optimization (SEO) by providing a more accurate representation of your site.

Bots that access CSS contribute to more accurate user analytics. Blocking bots that ignore CSS can help in obtaining more reliable data about user interactions and behavior on your website.

Some bots that ignore CSS might be malicious or attempting to scrape content without adhering to the intended structure. Blocking such bots can enhance the security of your website.

Bots that ignore CSS may still consume bandwidth by crawling through your pages. Blocking them can help reduce unnecessary server load and bandwidth usage.

Here’s a general idea using .htaccess to block bots that don’t request CSS files:


IfModule mod_rewrite.c
RewriteEngine On

SetEnvIfNoCase Referer ".css$" allow_css
Order Allow,Deny
Allow from env=allow_css
Deny from all
IfModule


This code checks if the Referer header contains ".css". It assumes that most browsers requesting CSS files will include a Referer header. Always test thoroughly and consider using a more sophisticated solution, such as a web application firewall or a bot management system, for more effective bot detection and blocking.

It’s essential to balance these considerations with ensuring that legitimate bots, such as search engine crawlers, can access your content appropriately. Always be cautious when implementing bot-blocking measures to avoid negatively impacting your site’s visibility or functionality.

You may proceed with the method, but you should also know that modern browsers request CSS files to properly render and display web pages, so relying solely on this aspect to identify good bots is not reliable.

Bots may have varying behaviors, and some may choose not to load CSS for specific reasons, such as conserving bandwidth or focusing on extracting content. To differentiate between good and bad bots more effectively, it’s recommended to use a combination of techniques, including analyzing User-Agent headers, IP addresses, behavior patterns, and implementing solutions like CAPTCHA, rate limiting, or using specialized bot management tools.