Creating accessible CSS is an essential aspect of web development. It ensures that people with disabilities can access and navigate your website effectively. Here are some tips and techniques for creating accessible CSS:

Use color with care
Color plays a vital role in CSS, but it can also pose accessibility issues. Ensure that your text and background colors have enough contrast to make them easy to read. A minimum contrast ratio of 4.5:1 is recommended for text, and 3:1 for larger text and graphical elements.

h1 {
  color: #000;
  background-color: #fff;
}

p {
  color: #666;
  background-color: #f2f2f2;
}

In this example, the colors for the heading and paragraph elements have been chosen to ensure they have sufficient contrast.

Use semantic HTML
Semantic HTML helps users with screen readers or other assistive technologies to understand the content and context of the page. CSS can enhance the layout and design, but it's important to ensure that it doesn't interfere with the structure of the HTML.

<nav>
  <ul>
    <li><a href="#">Home</a></li>
    <li><a href="#">About</a></li>
    <li><a href="#">Contact</a></li>
  </ul>
</nav>

In this example, the navigation menu is structured using semantic HTML, which makes it easier for users with assistive technologies to navigate.

Provide alternative text for images
Images can be challenging for users with visual impairments or those who use screen readers. Providing alternative text for images can help these users understand the content of the image.

<img src="image.jpg" alt="A person walking in a park">

In this example, the alternative text describes the content of the image, which helps users with visual impairments or screen readers understand what the image represents.

Use meaningful link text
Link text should be meaningful and descriptive to help users understand the context of the link. Avoid using generic text like "click here" or "read more" and instead use descriptive text that gives context about the linked page.

<a href="https://example.com/about">Learn more about our company</a>

In this example, the link text provides context about the page it links to, which helps users understand the content of the linked page.

Use ARIA attributes
Accessible Rich Internet Applications (ARIA) attributes are a set of HTML attributes that provide additional information to assistive technologies. They can be used to indicate the role, state, or properties of an element.

<button aria-label="Play video">
  <svg class="svg-inline--fa fa-play fa-w-14" aria-hidden="true" focusable="false" data-prefix="fa" data-icon="play" role="img" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512" data-fa-i2svg=""><path fill="currentColor" d="M424.4 214.7L72.4 6.6C43.8-10.3 0 6.1 0 47.9V464c0 37.5 40.7 60.1 72.4 41.3l352-208c31.4-18.5 31.5-64.1 0-82.6z"></path></svg>
</button>

In this example, the aria-label attribute provides additional information about the button, which helps users with assistive technologies understand its purpose.

In summary, creating accessible CSS is critical for ensuring that all users can access and navigate your website effectively. By using color with care, using semantic HTML, providing alternative text for images, using meaningful link text, and using ARIA attributes, you can create a website that is accessible to all users.