What is Cascading Style Sheets (CSS)?

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CSS (Cascading Style Sheets) is the language used to control the look and layout of web pages. It defines how elements such as text, images, and containers are displayed, including fonts, colors, spacing, and positioning.

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Why CSS matters?

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CSS is essential for separating design from content. It allows brands to maintain consistent styles across websites while making updates faster and more efficient. For ecommerce, strong CSS design improves user experience and can increase conversions.

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How CSS works?
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CSS works by applying style rules to HTML elements. These rules can be inline, embedded in a page, or stored in external stylesheets. The “cascading” principle means that when multiple rules apply, the browser follows a hierarchy of importance to decide which style is used.

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Example in ecommerce

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An online fashion retailer uses CSS to ensure product pages load with uniform typography, clear “Add to Cart” buttons, and responsive layouts that adapt to mobile screens. Good CSS ensures that shoppers have a smooth experience whether browsing on desktop or mobile, reducing bounce rates and cart abandonment.

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Common mix-ups

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CSS is often confused with HTML. HTML structures the content, while CSS handles the presentation. CSS is also different from JavaScript, which controls interactivity and dynamic behaviors on a website.

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Best practices

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• Use external stylesheets for maintainability and reusability.
  
  
• Follow a mobile-first, responsive design approach.
  
  
• Minify and compress CSS files to reduce load time.
  
  
• Remove unused CSS to avoid bloat.
  
  
• Leverage CSS frameworks (e.g., Tailwind, Bootstrap) for speed and consistency.

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Industry benchmarks

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• Ecommerce pages should load in under 3 seconds for optimal conversion.
  
  
• CSS files should ideally stay under 150 KB after minification.
  
  
• Responsive design is expected across all devices, with mobile traffic making up over half of ecommerce visits.
  
  
• Sites should maintain a 90+ score on tools like Google PageSpeed Insights for CSS performance.

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Related terms
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HTML
Responsive Design