Simple CSS3 drop-down menu effect with underline follow effect

Brief Tutorial

This is a drop-down menu effect with underline following effect made using pure CSS3. The drop-down menu uses CSS3 transform and transition to create underline follow effects and drop-down menu effects.

Usage

HTML structure

The drop-down menu uses the

element to wrap an unordered list.

<nav>
  <ul id="main">
    <li>主页</li>
    <li>关于我们</li>
    <li>项目分类
      <ul class="drop">
        <p>
        <li>scss</li>
        <li>jquery</li>
        <li>html</li>
        </p>
      </ul>
    </li>
    <li>联系我们</li>
    <p id="marker"></p>
  </ul>
</nav>

CSS style

The entire menu ul#mian is positioned using relative positioning. display is displayed as an inline block-level element. Menu items are sized using padding, and min-width is set to 120 pixels.

#main {
  position: relative;
  list-style: none;
  background: #6BBE92;
  font-weight: 400;
  font-size: 0;
  text-transform: uppercase;
  display: inline-block;
  padding: 0;
  margin: 50px auto;
}
#main li {
  font-size: 0.8rem;
  display: inline-block;
  position: relative;
  padding: 15px 20px;
  cursor: pointer;
  z-index: 5;
  min-width: 120px;
}
li {
  margin: 0;
}

In the HTML structure, ul.drop is the drop-down menu component. Its positioning method uses absolute positioning. The p element inside it uses the translate function to move -100% on the Y axis to make it hidden (overflow:hidden is used on .drop).

.drop {
  overflow: hidden;
  list-style: none;
  position: absolute;
  padding: 0;
  width: 100%;
  left: 0;
  top: 48px;
}
.drop p {
  -webkit-transform: translate(0, -100%);
  -moz-transform: translate(0, -100%);
  -ms-transform: translate(0, -100%);
  transform: translate(0, -100%);
  -webkit-transition: all 0.5s 0.1s;
  -moz-transition: all 0.5s 0.1s;
  -ms-transition: all 0.5s 0.1s;
  transition: all 0.5s 0.1s;
  position: relative;
}
.drop li {
  display: block;
  padding: 0;
  width: 100%;
  background: #3E8760 !important;
}

#marker is an underline element. It also uses absolute positioning. And set an animation transition effect of 0.35 seconds for all animations.

#marker {
  height: 6px;
  background: #3E8760 !important;
  position: absolute;
  bottom: 0;
  width: 120px;
  z-index: 2;
  -webkit-transition: all 0.35s;
  -moz-transition: all 0.35s;
  -ms-transition: all 0.35s;
  transition: all 0.35s;
}

When the mouse slides over the menu item #main li element, use nth-child to determine which menu item the mouse currently slides over. Then restore the Y-axis position of the submenu in the menu item to 0, display the drop-down menu, and set the X-direction movement value of the translate function to move the underline according to different menu items.

#main li:nth-child(1):hover ul p {
  -webkit-transform: translate(0, 0);
  -moz-transform: translate(0, 0);
  -ms-transform: translate(0, 0);
  transform: translate(0, 0);
}
#main li:nth-child(1):hover ~ #marker {
  -webkit-transform: translate(0px, 0);
  -moz-transform: translate(0px, 0);
  -ms-transform: translate(0px, 0);
  transform: translate(0px, 0);
}
 
#main li:nth-child(2):hover ul p {
  -webkit-transform: translate(0, 0);
  -moz-transform: translate(0, 0);
  -ms-transform: translate(0, 0);
  transform: translate(0, 0);
}
#main li:nth-child(2):hover ~ #marker {
  -webkit-transform: translate(120px, 0);
  -moz-transform: translate(120px, 0);
  -ms-transform: translate(120px, 0);
  transform: translate(120px, 0);
}
 
#main li:nth-child(3):hover ul p {
  -webkit-transform: translate(0, 0);
  -moz-transform: translate(0, 0);
  -ms-transform: translate(0, 0);
  transform: translate(0, 0);
}
#main li:nth-child(3):hover ~ #marker {
  -webkit-transform: translate(240px, 0);
  -moz-transform: translate(240px, 0);
  -ms-transform: translate(240px, 0);
  transform: translate(240px, 0);
}
 
#main li:nth-child(4):hover ul p {
  -webkit-transform: translate(0, 0);
  -moz-transform: translate(0, 0);
  -ms-transform: translate(0, 0);
  transform: translate(0, 0);
}
#main li:nth-child(4):hover ~ #marker {
  -webkit-transform: translate(360px, 0);
  -moz-transform: translate(360px, 0);
  -ms-transform: translate(360px, 0);
  transform: translate(360px, 0);
}

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