can css get value of variable and store it code example

Example 1: create variable in css

:root {
  --tab-count: 5;
}

#div1 {
  width: calc(100% - var(--tab-count));
}

Example 2: css variables

:root {
  --background-color: #333;
  --text-color: #fff;
}
body {
  background-color: var(--background-color);
  color: var(--text-color);
}

Example 3: javascript use css custom properties

Values in JavaScript
To use the values of custom properties in JavaScript, it is just like standard properties.
// get variable from inline style
element.style.getPropertyValue("--my-var");

// get variable from wherever
getComputedStyle(element).getPropertyValue("--my-var");

// set variable on inline style
element.style.setProperty("--my-var", jsVar + 4);