How do you ensure correct page rendering in outdated…

I use polyfills to fill gaps in functionality. I apply progressive enhancement, starting with basic semantic markup and gradually adding CSS and JavaScript. To track support, I use caniuse.com and tools like Modernizr. I test across different browser versions, including through services like BrowserStack.

Examples of approaches:

Polyfills: Adding missing APIs or functionality.

// Example of a polyfill for Promise
if (typeof Promise === 'undefined') {
  // Include a library or implement Promise
  // require('promise-polyfill');
}

Progressive enhancement: Basic content works everywhere, enhanced version for modern browsers.

<!-- Basic structure, accessible to all -->
<div class="container">
  <h1>Title</h1>
  <p>Description</p>
</div>

/* Fallback, works everywhere */
.container {
    margin: 0 auto;
}

/* Additional for modern browsers */
@supports (display: grid) {
    .container {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 20px;
    }
}

Graceful Degradation: Starting with a modern version, providing alternatives if support is absent.

<picture>
    <source srcset="image.webp" type="image/webp">
    <img src="image.jpg" alt="Image">
</picture>

Vendor Prefixes: Using prefixes for experimental CSS properties.

.box {
    -webkit-transition: all 0.5s; /* For older Chrome/Safari */
    -moz-transition: all 0.5s;    /* For older Firefox */
    -o-transition: all 0.5s;      /* For older Opera */
    transition: all 0.5s;         /* Standard property */
}

Applying these methods in combination with thorough testing allows providing an acceptable user experience even in outdated environments.

How do you ensure correct page rendering in outdated or limited browsers?