纯 CSS 可点击下拉菜单？

Question

This tutorial 解释了如何使用:hover 伪类在悬停时设置 HTML 元素的样式，以及如何在纯 CSS 中悬停在特定元素上时创建下拉列表（不使用任何 JavaScript）。

是否可以在纯 CSS 中创建与以下示例中的下拉列表相同的下拉列表，但在单击元素而不是悬停在其上时？

我宁愿完全不使用 JavaScript，或者 - 如果没有 JavaScript 不可能 - 尽可能少地使用 JavaScript。下拉菜单的项目本身应该是可点击的。

示例：

.dropdown {
    position: relative;
    display: inline-block;
}

.dropbtn {
    background-color: #4CAF50;
    color: white;
    padding: 16px;
    font-size: 16px;
    border: none;
    cursor: pointer;
}

.dropdown-content {
    display: none;
    position: absolute;
    right: 0;
    background-color: #f9f9f9;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    z-index: 1;
}

.dropdown-content a {
    color: black;
    padding: 12px 16px;
    text-decoration: none;
    display: block;
}

.dropdown-content a:hover {background-color: #f1f1f1}

.dropdown:hover .dropdown-content {
    display: block;
}

.dropdown:hover .dropbtn {
    background-color: #3e8e41;
}

<div class="dropdown" style="float:left;">
  <button class="dropbtn">Left</button>
  <div class="dropdown-content" style="left:0;">
    <a href="#">Link 1</a>
    <a href="#">Link 2</a>
    <a href="#">Link 3</a>
  </div>
</div>

Answer 1

您在这里使用了一个隐藏的复选框，并在“选中”时显示菜单。

/*hide the inputs/checkmarks and submenu*/
input, ul.submenu {
  display: none;
}

/*position the label*/
label {
  position: relative;
  display: block;
  cursor: pointer;
}

/*show the submenu when input is checked*/
input:checked~ul.submenu {
  display: block;
}

<input id="check01" type="checkbox" name="menu" />
<label for="check01">Menu</label>
<ul class="submenu">
  <li><a href="#">Item 1</a></li>
  <li><a href="#">Item 2</a></li>
</ul>

取自this Codepen并简化。

Answer 2

使用单选按钮和同级选择器。

这与复选框的不同之处在于它会在单击另一个菜单项时自动关闭打开的菜单项。

.menu ul,
.menu input,
.menu .closer,
.menu input:checked~.opener {
  display: none;
}

.menu input:checked~ul,
.menu input:checked~.closer {
  display: block;
}

<ul class="menu">
  <li>
    <input type="radio" name="menuopt" id="drop1" />
    <label class="opener" for="drop1">Parent item 1</label>
    <label class="closer" for="dropclose">Parent item 1</label>
    <ul>
      <li><a href="">Menu item 1</a></li>
      <li><a href="">Menu item 2</a></li>
      <li><a href="">Menu item 3</a></li>
    </ul>
  </li>
  <li>
    <input type="radio" name="menuopt" id="drop2" />
    <label class="opener" for="drop2">Parent item 2</label>
    <label class="closer" for="dropclose">Parent item 2</label>
    <ul>
      <li><a href="">Menu item 1</a></li>
      <li><a href="">Menu item 2</a></li>
      <li><a href="">Menu item 3</a></li>
      <li><a href="">Menu item 4</a></li>
      <li><a href="">Menu item 5</a></li>
    </ul>
    <input type="radio" name="menuopt" id="dropclose" />
  </li>
</ul>

View on jsFiddle

Answer 3

可以。示例 1. 下拉菜单。纯 CSS。简约风格。
jsfiddle link

body {
  margin: 0;
  font-size: 20px;
  font-family: Times, "Times New Roman", serif;
}

/* dd container */
.dropdown {
  display: inline-block;
  position: relative;
  outline: none;
  margin: 10px;
}

/* button */
.dropbtn {
  padding: 12px 16px;
  color: white;
  background-color: #861cb9;
  cursor: pointer;
  transition: 0.35s ease-out;
}

/* dd content */
.dropdown .dropdown-content {
  position: absolute;
  top: 50%;
  background-color: #f7f7f7;
  min-width: 120%;
  box-shadow: 0px 8px 16px rgba(0, 0, 0, 0.2);
  z-index: 100000;
  visibility: hidden;
  opacity: 0;
  transition: 0.35s ease-out;
}
.dropdown-content a {
  color: black;
  padding: 12px 16px;
  display: block;
  text-decoration: none;
  transition: 0.35s ease-out;
}
.dropdown-content a:hover {
  background-color: #eaeaea;
}

/* show dd content */
.dropdown:focus .dropdown-content {
  outline: none;
  transform: translateY(20px);
  visibility: visible;
  opacity: 1;
}
.dropbtn:hover, .dropdown:focus .dropbtn {
  background-color: #691692;
}

/* mask to close menu by clicking on the button */
.dropdown .db2 {
  position: absolute;
  top: 0; right: 0; bottom: 0; left: 0; opacity: 0;
  cursor: pointer;
  z-index: 10;
  display: none;
}
.dropdown:focus .db2 {
  display: inline-block;
}
.dropdown .db2:focus .dropdown-content {
  outline: none;
  visibility: hidden;
  opacity: 0;
}

<div class="dropdown" tabindex="1">
  <i class="db2" tabindex="1"></i>
  <a class="dropbtn">Dropdown 1</a>
   <div class="dropdown-content">
      <a href="#">Home</a>
      <a href="#">About</a>
      <a href="#">Contact</a>
   </div>
</div>

<div class="dropdown" tabindex="1">
  <i class="db2" tabindex="1"></i>
  <a class="dropbtn">Dropdown 2</a>
   <div class="dropdown-content">
      <a href="#">Blog</a>
      <a href="#">Plans</a>
      <a href="#">Partners</a>
   </div>
</div>

示例 2。添加了样式。纯 CSS。没有 JS。下拉菜单/内容在点击时打开和关闭。几种关闭方式（通过同一个按钮，通过另一个按钮，通过在菜单区域外单击，通过菜单内的图标）。额外添加了:hover的子菜单。
jsfiddle link

body {
  margin: 0;
  font-size: 20px;
  font-family: Times, "Times New Roman", serif;
}

/* dd container */
.dropdown {
  display: inline-block;
  position: relative;
  outline: none;
  background-color: #861cb9;
  margin: 10px 5px;
}

/* button */
.dropbtn {
  display: inline-block;
  padding: 12px 16px;
  color: white;
  cursor: pointer;
  background-color: #861cb9;
  transition: 0.35s ease-out;
}
.dropbtn:hover, .dropbtn.c:hover, .dropbtn.r:hover {
  background-color: #691692;
}

/* dd content */
.dropdown .dropdown-content {
  position: absolute;
  top: 50%;
  visibility: hidden;
  opacity: 0;
  z-index: 100000;
  background-color: #f7f7f7;
  min-width: 120%;
  padding: 10px;
  font-size: 16px;
  box-shadow: 0px 8px 16px rgba(0, 0, 0, 0.2);
  transition: 0.35s ease-out;
}

/* center & right position menu relative to the button */
.dropdown .dropdown-content.c  {
  left: 50%;
  margin-left: calc(-60% - 10px);
}
.dropdown .dropdown-content.r  {
  right: 0;
}

/* style link menu item */
.dropdown-content .mi {
  display: block;
  color: black;
  padding: 8px 0;
  text-decoration: none;
  position: relative;
}
.dropdown-content .mi::before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background:
  linear-gradient(
  90deg,
  rgba(240, 242, 244, 0) 0%,
  rgba(223, 223, 223, 1) 30%,
  rgba(240, 242, 244, 0) 100%
  );
  opacity: 0;
  z-index: -1;
  transition: 0.4s ease-out;
}
.dropdown-content .mi:hover::before {
    opacity: 1;
}

/* style text link */
.dropdown-content .tl {
  color: #36f;
  text-decoration: none;
  border-bottom: 1px dotted #36f;
  transition: 0.35s ease-out;
}
.dropdown-content .tl:hover {
  border-bottom: 1px dotted transparent;
}

/* show dd content */
.dropdown:focus .dropdown-content {
  outline: none;
  visibility: visible;
  opacity: 1;
  transform: translateY(20px);
}

/* mask to close menu by clicking on the button */
.dropdown .db2 {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  opacity: 0;
  cursor: pointer;
  z-index: 10;
  display: none;
}
.dropdown:focus .db2 {
  display: inline-block;
}
.dropdown .db2:focus .dropdown-content, .dropdown-content .db3:focus .dropdown-content {
  outline: none;
  visibility: hidden;
  opacity: 0;
}

/* button gradient */
.dropbtn::before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  z-index: -1;
  background: radial-gradient(circle at 0 0, #fff 0%, #D59BF0 5%, #8b1dc0 35%, transparent 60%);
  background-repeat: no-repeat;
  background-color: #861cb9;
  transition: 0.35s ease-out;
}

/* class 'c' center gradient backlight */
.dropbtn.c::before {
  background: radial-gradient(circle at 50% -1px, #fff 0%, #D59BF0 5%, #8b1dc0 35%, transparent 60%);
  background-repeat: no-repeat;
  background-color: #861cb9;
}

/* class 'r' right gradient backlight */
.dropbtn.r::before {
  background: radial-gradient(circle at 100% 0, #fff 0%, #D59BF0 5%, #8b1dc0 35%, transparent 60%);
  background-repeat: no-repeat;
  background-color: #861cb9;
}

/* show gradient backlight */
.dropdown:focus .dropbtn::before, .dropdown:focus .dropbtn.c::before, .dropdown:focus .dropbtn.r::before {
background-color: #691692;
}
.dropdown:focus  {
z-index: 1;
}
.dropdown:focus .dropbtn  {
background: none;
}

/* icon hamburger */
.dropbtn::after {
  content: "";
  display: inline-block;
  width: 15px;
  height: 3px;
  margin-left: 10px;
  border-top: 2px solid #fff;
  border-bottom: 7px double #fff;
}
.dropdown:focus .dropbtn::after {
  height: 0;
  border-bottom: 0;
  margin-bottom: 4px;
}

/* icon content */
.dropbtn.i2::after {
  content: "";
  display: inline-block;
  border: 0;
  width: 15px;
  height: 12px;
  margin-left: 10px;
  background:
  linear-gradient(to right, #fff, #fff) 0px 0px/11px 2px, /* left top / width height */
  linear-gradient(to right, #fff, #fff) 0px 5px/15px 2px,
  linear-gradient(to right, #fff, #fff) 0px 10px/8px 2px;
  background-repeat: no-repeat;
}
.dropdown:focus .dropbtn.i2::after {
  width: 15px;
  height: 12px;
  background: linear-gradient(to right, #fff, #fff) 0px 10px/15px 2px;
  background-repeat: no-repeat;
}

/* icon x */
.dropdown-content .db3  {
  display: inline-block;
  position: absolute;
  top: 5px;
  right: 5px;
  width: 18px;
  height: 18px;
  padding: 0;
  border-radius: 100%;
  z-index: 10;
  transition: 0.15s ease-out;
}
.dropdown-content .db3::before, .dropdown-content .db3::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  height: 60%;           /* height icon */
  width: 2px;            /* width icon  */
  background: #3c4043;   /* color icon  */
}
.dropdown-content .db3::before {
  transform: translate(-50%, -50%) rotate(45deg);
}
.dropdown-content .db3::after  {
  transform: translate(-50%, -50%) rotate(-45deg);
}
.dropdown-content .db3:hover   {
  background: #d1d1d6;
}

/* sub menu container */
.sub-dropdown {
  position: relative;
}
.sub-dropdown-content {
  position: absolute;
  visibility: hidden;
  opacity: 0;
  background-color: #f7f7f7;
  left: 100%;
  top: -10px;
  padding: 10px 5px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  z-index: 1;
  transition: 0.35s ease-out;
}
.sub-dropdown-content a {
  color: black;
  padding: 5px 12px;
  text-decoration: none;
  display: block;
  position: relative;
  white-space: nowrap;
}

/* sub menu item */
.si {
  cursor: default;
}
.si::after {
  content: "\25B8";
  margin-left: 5px;
  vertical-align: -1px;
  margin-right: 10px;
  float: right;
}
.sub-dropdown:hover .sub-dropdown-content {
  visibility: visible;
  opacity: 1;
  transform: translateY(10px);
}
.sub-dropdown-content a::before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background:
  linear-gradient(
  90deg,
  rgba(240, 242, 244, 0) 0%,
  rgba(223, 223, 223, 1) 50%,
  rgba(240, 242, 244, 0) 100%
  );
  opacity: 0;
  z-index: -1;
  transition: 0.4s ease-out;
}
.sub-dropdown-content a:hover::before {
    opacity: 1;
}

/* media queries */
@media (max-width:560px) {
.dropdown .dropdown-content.r,
.dropdown .dropdown-content.c {
  left: 0;
  margin-left: 0;
  }
.dropbtn.c::before, .dropbtn.r::before {
  background: radial-gradient(circle at 0 0, #fff 0%, #D59BF0 5%, #8b1dc0 35%, transparent 60%);
  }
}

<div class="dropdown" tabindex="1">
  <i class="db2" tabindex="1"></i><a class="dropbtn i2">Dropdown l</a>
    <div class="dropdown-content"><i class="db3" tabindex="1"></i>
      <p>Dropdown content. Left-aligned relative to the button. Text <a href="#" class="tl">link</a> ....</p>
    </div>
</div>

<div class="dropdown" tabindex="1">
  <i class="db2" tabindex="1"></i><a class="dropbtn c">MyMenu c</a>
    <div class="dropdown-content c"><i class="db3" tabindex="1"></i>
      <a href="#" class="mi">Products</a>

      <div class="sub-dropdown">
      <a class="mi si">Company</a>
          <div class="sub-dropdown-content">
            <a href="#">Sublink 1</a>
            <a href="#">Sublink 2</a>
          </div>
      </div>

      <a href="#" class="mi">Stackoverflow</a>
    </div>
</div>

<div class="dropdown" tabindex="1">
  <i class="db2" tabindex="1"></i><a class="dropbtn r i2">Dropdown r</a>
    <div class="dropdown-content r"><i class="db3" tabindex="1"></i>
      <p>Dropdown content. Right-aligned relative to the button. Text <a href="#" class="tl">link</a> ....</p>
    </div>
</div>