html - 图标栏汉堡不起作用，只显示一条水平线

Question

我正在尝试创建一个如下所示的响应式布局按钮:

但问题是我无法创建三条水平线，只能创建其中一条。保持这种状态:

我的代码:

HTML

<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarResponsive" aria-controls="navbarResponsive" aria-expanded="false" aria-label="Toggle navigation">
   <span class="navbar-toggler-icon"></span>
</button>

CSS

.navbar-toggler {
  position: relative;
  float: right;
  width: 40px;
  height: 40px;
  margin-top: 5px;
  margin-right: 5px;
  cursor: pointer;
  z-index: 99999;
}

.navbar-toggler span {
  height: 4px;
  background: #545454;
  transition: 0.2s all;
}

.navbar-toggler span:before, .navbar-toggler span:after {
  content: "";
  display: block;
}

Answer 1

您可以将 HTML unicode ☰ 用于汉堡包图标

您可以在此处找到更多信息:https://www.w3schools.com/charsets/ref_utf_symbols.asp

.navbar-toggle
{
font-size:25px; 
background:none; 
border:none;
}

<button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#myNavbar">&#9776;                 
</button>

您还可以为图标设置动画，请参阅:https://www.w3schools.com/howto/tryit.asp?filename=tryhow_css_menu_icon_js