Answers for "how to make a line shadow in html"

css box shadow

#example1 {
  box-shadow: 10px 10px 8px #888888;
}

adding shadow to a div

/* CSS box shadow look like paper lift up*/
/* provide shadow to all four corners */
/* source - W3Schools.com */
 box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);

change button shaddow css

button{
  2.5px 2.5px 2px #888;
}