Check out example codes for "how to split a background into two color in css". It will help you in understanding the concepts better.

Code Example 1

background: linear-gradient(<angle>, color1 color1-stop-at, color2 color2-start-at);

Code Example 2

.logindiv {
  height: 200px;
  width: 200px;
  background: linear-gradient(to bottom, #1F4E79 0%, #1F4E79 50%, #ddd 50%, #ddd 100%);
}

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