Explanation

You can specify the background color of an element using a valid color name (e.g., “red”), a HEX value (e.g., “#ff0000”), an RGB (red, green, blue) value (e.g., “rgb(255, 0, 0)”) or an RGBA (red, green, blue, alpha) color value. Here are some examples:

HTML

<div class="demo-container">
  <p>background-color: #FFFFFF;</p> 
  <p>background-color: rgb(255, 255, 255);</p>
  <p>background-color: rgba(255, 255, 255, 1.0);</p>
  <p>background-color: rgba(255, 255, 255, 0.64);</p> 
  </div>

CSS

.demo-container {
  padding: 1.4rem;
  background-image: url("bg.jpg");
  background-repeat: no-repeat;
  background-size: cover;
  background-position: center;
  padding: 2rem; 
}

.demo-container p {
  padding: 1rem;
  margin-bottom: 1rem;
  border-radius: 4px;
}

.demo-container p:nth-child(1)  {
/* HEX value (white ) */
  background-color: #FFFFFF;s
}

.demo-container p:nth-child(2)  {
/* white RGB background color */
  background-color: rgb(255, 255, 255);
}

.demo-container p:nth-child(3)  {
/* white RGBA background color without transperancy */
  background-color: rgba(255, 255, 255, 1.0);
}

.demo-container p:nth-child(4)  {
/* white RGBA background color with 64% transperancy */
  background-color: rgba(255, 255, 255, 0.64);
}

HTML and CSS

Background color

Explanation