边框border(HTML、CSS)

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>边框（border）</title>
    <style>
        div {
            width: 300px;
            height: 200px;
            /*   border-width: px;      边框的粗细 一般情况下用px作为单位 */
            border-width: 5px;
            
            /*      border-style: ;   边框的样式  solid为实线边框  */
            border-style: solid;
            /*   border-style: dashed; */
            /*   dashed 为虚线 */
            /*  border-style: dotted; */
            /*  dotted 点线边框 */
            /*   border-color: ;  边框的颜色*/
            border-color: blue;

        }