Things need to be know when designing a website(For Performance)
What i understand is when designing a website are mentioned below
If an image file is larger than it needs to be for its displayed dimensions, the loading speed gets lower and is not responsive for mobile-sized screens. Use responsive images to reduce conflicts when loading the website in your browser.Set an explicit width and height on image elements.
Reduce unused rules from stylesheets
Ensure text is consistently visible. Low-contrast text is difficult or impossible for many users to read.
Displayed dimensions for logos (80x80). Use responsive images.
Link text (and alternate text for images, when used as links) must unique, and focusable improves the navigation experience for screen readers.
Use " @media (max-width: 768px) {} " for your css file for mobile and deskstop reponse.