我使用html css和bootstrap创建了一个页面。我遇到水平线标签的问题。当窗口大小变得特别小时，需要帮助来解决这个问题
当我给hr标签400px它在全屏幕上运行良好但是当屏幕尺寸减小到低于500px的移动尺寸时它看起来不太好所以我尝试了90％宽度然后它适用于超小屏幕但是当屏幕很小或者更高时，它会占据更多的水平空间，这是我不想要的。
body {
color: white;
font-family: Lato;
background: url(purrfectimage.jpg);
background-repeat: no-repeat;
background-size: cover;
background-position: center;
background-attachment: fixed;
}
#content {
text-align: center;
padding-top: 25%;
text-shadow: 0px 4px 3px rgba(0, 0, 0, 0.4), 0px 8px 13px rgba(0, 0, 0, 0.1), 0px 18px 23px rgba(0, 0, 0, 0.1);
}
hr {
width: 400px;
border-top: 1px solid #f8f8f8;
border-bottom: 1px solid rgba(0, 0, 0, 0.2);
}
h1 {
font-weight: 700;
font-size: 5em;
}
html {
height: 100%;
width: 100%;
}
.custom-toggler.navbar-toggler {
border-color: rgb(255, 255, 255);
}<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width,initial-scale=1,shrink-to-fit=no;">
<title>Purrfect Match</title>
<link href="https://fonts.googleapis.com/css?family=Lato:400,700" rel="stylesheet">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
<link rel="stylesheet" href="
https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
<link rel="stylesheet" type="text/css" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<link rel="stylesheet" type="text/css" href="purr.css">
</head>
<body>
<div class="container">
<div class="row">
<div class="col-lg-12">
<div id="content">
<h1>Purrfect Match</h1>
<h3>The Only Human-Feline Dating App</h3>
<hr>
<button type="button" class="btn btn-light btn-lg"><i class="fa fa-paw" aria-hidden="true"></i> Get Started!</button>
</div>
</div>
</div>
</div>
</body>
</html>我实际上想要当我调整窗口大小时，水平线应该看起来与出现在完整窗口或甚至是小断点时相同。
您好，欢迎来到Stackoverflow。试试看看这个网站，在那里你可以阅读有关vw和vh的信息，它们是响应屏幕大小的单位:)