A Pen by Jake Albaugh.

index.html

<!-- TAB CONTROLLERS -->
<input id="panel-1-ctrl"
       class="panel-radios" type="radio" name="tab-radios" checked>
<input id="panel-2-ctrl"
       class="panel-radios" type="radio" name="tab-radios">
<input id="panel-3-ctrl"
       class="panel-radios" type="radio" name="tab-radios">
<input id="panel-4-ctrl"
       class="panel-radios" type="radio" name="tab-radios">
<input id="panel-5-ctrl"
       class="panel-radios" type="radio" name="tab-radios">
<input id="nav-ctrl"
       class="panel-radios" type="checkbox" name="nav-checkbox">

<header id="introduction">
  <h1>No JS: Tabs That Scale Down to Menu</h1>
</header>

<!-- TABS LIST -->
<ul id="tabs-list">
    <!-- MENU TOGGLE -->
    <label id="open-nav-label" for="nav-ctrl"></label>
    <li id="li-for-panel-1">
      <label class="panel-label"
             for="panel-1-ctrl">Radio Toggles</label>
    </li><!--INLINE-BLOCK FIX
 --><li id="li-for-panel-2">
      <label class="panel-label"
             for="panel-2-ctrl">Input :checked</label>
    </li><!--INLINE-BLOCK FIX
 --><li id="li-for-panel-3">
      <label class="panel-label"
             for="panel-3-ctrl">The Tabs</label>
    </li><!--INLINE-BLOCK FIX
 --><li id="li-for-panel-4">
      <label class="panel-label"
             for="panel-4-ctrl">Tab :hover</label>
    </li><!--INLINE-BLOCK FIX
 --><li id="li-for-panel-5">
      <label class="panel-label"
             for="panel-5-ctrl">Menu</label>
    </li>
    <label id="close-nav-label" for="nav-ctrl">Close</label>
</ul>

<!-- THE PANELS -->
<article id="panels">
  <div class="container">
    <section id="panel-1">
      <main>
        <h1>Radio Toggles</h1>
        <p>In this demo, <code>labels</code> for hidden <code>radios</code> toggle the content. This is based on the behavior in which clicked <code>labels</code> for a <code>radio</code> or <code>checkbox</code> input will check that <code>input</code>.</p> 
<pre>&lt;input id="radio-1" type="radio" name="demo-radios"&gt;
&lt;input id="radio-2" type="radio" name="demo-radios"&gt;</pre>
        #radio-1: <input id="radio-1" type="radio" name="demo-radios"> #radio-2: <input id="radio-2" type="radio" name="demo-radios">
<pre>&lt;label for="radio-1"&gt;Toggle #radio-1&lt;/label&gt;
&lt;label for="radio-2"&gt;Toggle #radio-2&lt;/label&gt;</pre>
        <label for="radio-1" class="demo-label">Toggle #radio-1</label>
        <label for="radio-2" class="demo-label">Toggle #radio-2</label>
        <p>Click one of the labels above and see its effect on the radios above it.</p>
        <p>The radios for this pen's tabs are displayed semi-transparently at the top of this demo page.</p>
      </main>
    </section>
    <section id="panel-2">
      <main>
        <h1>Input :checked</h1>
        <p>In CSS, you can query based on the <code>:checked</code> selector for <code>radios</code> and <code>checkboxes</code> to style siblings down the DOM scope. To do this, we can use the <code>~</code>. It will select same-level siblings after the given selector. Because the tab <code>labels</code> in this demo are nested and not immediate siblings, we will need to select their topmost parent that is at the same level as our <code>input</code>.</p>
        <p>To demonstrate, we will do a simplified version of this with a checkbox:</p>
        <pre><strong>&lt;!-- invisible input and its label --&gt;</strong>
&lt;input id="demo-child-toggle" type="checkbox"&gt;
&lt;label for="demo-child-toggle"&gt;Toggle #demo-child&lt;/label&gt;

<strong>&lt;-- parent to select first via "~" --&gt;</strong>
&lt;div id="demo-parent"&gt;
  <strong>&lt;-- child to select through parent --&gt;</strong>
  &lt;div id="demo-child"&gt;#demo-child&lt;/div&gt;
&lt;/div&gt;</pre>
        <p>and in our CSS:</p>
        <pre><strong>/* hiding our checkbox */</strong>
#demo-child-toggle {
  display: none;  
}
<strong>/* selecting the child */</strong>
#demo-child-toggle:checked ~ #demo-parent #demo-child {
  color: #c0392b;
  font-weight: bold;
  text-transform: uppercase;
}</pre>
        <hr>
        <input id="demo-child-toggle" type="checkbox">
        <label class="demo-label" for="demo-child-toggle">Toggle #demo-child</label>
        <div id="demo-parent">
          <div id="demo-child">#demo-child</div>
        </div>
        <hr>
        <p>As you can see, we can control the style of content that comes after a hidden input by toggling it via its label.</p>
        <p>At this point you can probably get the picture for how we can conditionally display the tabbed panel content in this pen.</p>
      </main>
    </section>
    <section id="panel-3">
      <main>
        <h1>The Tabs</h1>
        <p>Here is the basic form of a tab in this demo:</p>
<pre>&lt;li id="li-for-panel-1"&gt;
  &lt;label class="panel-label" for="panel-1-ctrl"&gt;CSS Radio Toggles&lt;/label&gt;
&lt;/li&gt;</pre>
        <p>For the "active" tab to cover the bottom border, the child <code>label</code> gets an additional 2 pixels of <code>padding-top</code> while its parent <code>li</code> gets a <code>translateY(1px)</code>. This not only covers the bottom border, but gives an ever-so-subtle "moving toward you" effect by shifting the title down <code>1px</code>.</p>
        
<pre>#panel-1-ctrl:checked ~ #tabs-list #li-for-panel-1 {
  transform: translate(0, 1px);
}
#panel-1-ctrl:checked ~ #tabs-list #li-for-panel-1 label.panel-label {
  padding-top: 26px; <strong>/* instead of "24px" */</strong>
}</pre>
      </main>
    </section>
    <section id="panel-4">
      <main>
        <h1>Tab :hover</h1>
        <p>When designing the <code>:hover</code> and "active" states I had a dilemma.</p>
<pre>&lt;li id="li-for-panel-1"&gt;
  &lt;label class="panel-label" for="panel-1-ctrl"&gt;CSS Radio Toggles&lt;/label&gt;
&lt;/li&gt;</pre>
        <p>Each tab <code>li</code> has a <code>border-right</code>. But when the additional <code>border-top</code> appears, we dont want the lighter <code>border-right</code> to be shown all the way to the top. The fix for this is to cancel the <code>border-right</code> on both the <code>:hover</code> and "active" state as well as style the <code>li</code>'s next sibling's <code>border-left</code>.</p>
        <p>To do this, we can use a combination of the siblings after <code>~</code> and sibling next <code>+</code> selectors:</p>
        <pre><strong>/* remove the right border on "active" state */</strong>
#panel-1-ctrl:checked ~ #tabs-list #li-for-panel-1 {
  border-right: none;
}
<strong>/* override that if the last child (we still want the border) */</strong>
#panel-1-ctrl:checked ~ #tabs-list #li-for-panel-1:last-child {
  border-right: 1px solid #dfdfdf;
}
<strong>/* add left to next sibling */</strong>
#panel-1-ctrl:checked ~ #tabs-list #li-for-panel-1 + li {
  border-left: 1px solid #dfdfdf;
}</pre>
      </main>
    </section>
    <section id="panel-5">
      <main>
        <h1>Menu</h1>
        <p>On small screens, the tabs fold down into an expandable menu. To trigger the menu, I use a <code>checkbox</code> (note that it appears at the top of the screen on smaller screen sizes). There are two labels that trigger this checkbox. One opens and the other closes the menu. The one that opens is absolutely positioned invisibly over the "active" menu item. The closing label is at the bottom of the open menu.</p>
        <p>The best way I have found to show and hide content without using absolute positioning is to use a combination of <code>max-height</code> and <code>opacity</code>. When "inactive", the content has a <code>max-height: 0</code> and <code>opacity: 0</code>.</p>
        <p>It also has a <code>transition: opacity</code> when I don't know the future height (this panel's content for example) and <code>transition: opacity, max-height</code> when I do know the future height (like the menu). When "active", the <code>max-height</code> and <code>opacity</code> get positive values and the content will transition in. I'm sure flexbox could get me around this hack, but this works for now.</p>   
      </main>
    </section>
  </div>
</article>

No-JS:-Tabs-that-scale-down-to-menu.markdown

No JS: Tabs that scale down to menu

A tab-to-menu layout that doesn't use javascript. Modern browser compatible.

A Pen by Jake Albaugh on CodePen.

License.

script.js

/*
jakealbaugh.com
@jake_albaugh
*/

style.sass

@import url(http://fonts.googleapis.com/css?family=Open+Sans:300,400|Inconsolata)


  
/////////////////  
// VARIABLES
/////////////////

$tab-count: 5
$menu-item-height: 46px
  
$color-primary-light: #E74C3C
$color-primary-dark: #C0392B
$color-text: #444

$color-border: #dfdfdf
$color-border-top: $color-primary-dark

$color-label-bg-inactive: #ECF0F1
$color-label-bg-active: #fff
$color-label-active: $color-border-top
$color-label-inactive: #BDC3C7

$btn-border-top-thickness: 6px

$tab-padding: 24px
$tab-transition-duration: 200ms
$tab-base-border-style: 1px solid $color-border
  
$panel-transition-duration: 600ms
$main-padding: 48px 24px
$menu-padding: 12px 24px



/////////////////
// ELEMENTS
/////////////////

// global list style
ul#tabs-list
  list-style: none
  text-align: center
  border-bottom: $tab-base-border-style
  margin: 0
  padding: 0
  
  
  
// global label style
label.panel-label
  user-select: none
  display: block
  width: 100%
  color: $color-label-inactive
  cursor: pointer
  background-color: $color-label-bg-inactive
  transition-property: border-top, background-color, color
  transition-duration: $tab-transition-duration
  // hover style
  &:hover
    color: $color-label-active
    
    
    
// global panel style
#panels
  background-color: $color-label-bg-active
  .container
    margin: 0 auto
    width: 90%
  section
    header
      label.panel-label
        padding: $menu-padding
        box-sizing: border-box
    main
      box-sizing: border-box
      max-height: 0
      opacity: 0
      transition: opacity $panel-transition-duration
      overflow-y: hidden

        
        
/////////////////
// MIXINS
/////////////////

// tabs list style
=tabs-list-style
  text-align: center
  border-bottom: $tab-base-border-style
  // li child
  li
    display: inline-block
    text-align: center
    font-size: 0.875em
    width: (100% / $tab-count) - 2%
    box-shadow: 0px -2px 2px rgba(0, 0, 0, 0.05)
    border-top: $tab-base-border-style
    border-right: $tab-base-border-style
    transition-property: border-top
    transition-duration: $tab-transition-duration
    // hover
    &:hover
      border-top: none
      border-right: none
      &:last-of-type
        border-right: $tab-base-border-style
      & + li
        border-left: $tab-base-border-style
    // tab labels
    label.panel-label
      border-top: 0px solid $color-border-top
      padding: $tab-padding 0
      &:hover
        border-top-width: $btn-border-top-thickness
        padding-top: $tab-padding + 1
        
        
        
// global active label styles
=active-label
  background-color: $color-label-bg-active
  color: $color-border-top
  
  
  
// active tab label style
=active-tab-label
  border-top: $btn-border-top-thickness solid $color-border-top
  // add extra pixel for shifting li downward over border
  padding-top: $tab-padding + 2
  
// active tab li style
=active-tab-li-style
  pointer-events: none
  cursor: default
  // shift down over border. label has extra pixel in padding.
  transform: translate(0, 1px)
  box-shadow: none
  border-top: none
  border-right: none
  &:last-child
    border-right: $tab-base-border-style
  & + li
    border-left: $tab-base-border-style
  label.panel-label
    +active-label
    +active-tab-label
    
    
    
// active menu label style
=active-menu-label
  background-color: $color-label-active
  color: $color-label-bg-active

// active menu li style
=active-menu-li-style
  max-height: $menu-item-height
  opacity: 1
  label.panel-label
    +active-label
    +active-menu-label
  
    
    
// active panel style
=active-panel-style
  main
    max-height: initial
    opacity: 1
    padding: $main-padding
    
    
    
// panel toggling
@for $i from 1 through $tab-count
  #panel-#{$i}-ctrl:checked ~ #panels #panel-#{$i}
    +active-panel-style

    

/////////////////
// MEDIA QUERIES
/////////////////
    
// small devices
@media all and (max-width: 767px)
  // displaying menu nav
  @for $i from 1 through $tab-count
    #nav-ctrl:checked ~ #tabs-list #li-for-panel-#{$i}
      max-height: $menu-item-height
      opacity: 1

  // "show" open nav label when closed, hide when open
  #open-nav-label
    display: block
    position: absolute
    top: 0
    right: 0
    bottom: 0
    left: 0
    cursor: pointer
    //background: rgba(0,0,0,0.6)
  #nav-ctrl:checked ~ #tabs-list #open-nav-label
    display: none
  // "show" close nav label when open, hide when closed
  #close-nav-label
    display: block
    max-height: 0
    overflow-y: hidden
    background-color: $color-text
    color: $color-label-bg-inactive
    padding: 0px
    transition: max-height $tab-transition-duration
    cursor: pointer
    text-transform: uppercase
    font-size: 12px
    line-height: 22px
    letter-spacing: 1px
  #nav-ctrl:checked ~ #tabs-list #close-nav-label
    max-height: 36px
    opacity: 1
    padding: $menu-padding
      
  // tabs list style
  #tabs-list
    position: relative
    label.panel-label
      padding: ($tab-padding / 2) 0
    @for $i from 1 through $tab-count
      #li-for-panel-#{$i}
        max-height: 0
        overflow-y: hidden
        transition: max-height $tab-transition-duration

  // tab controller triggering menu     
  @for $i from 1 through $tab-count
    #panel-#{$i}-ctrl:checked ~ #tabs-list #li-for-panel-#{$i}
      +active-menu-li-style
      
  #panels 
    .container
      width: 100%
    section header
      display: block

        
        
// big devices
@media all and (min-width: 768px)
  // tab controller triggering tabs
  @for $i from 1 through $tab-count
    #panel-#{$i}-ctrl:checked ~ #tabs-list #li-for-panel-#{$i}
      +active-tab-li-style
  
  // tabs list style
  ul#tabs-list
    +tabs-list-style
    
  // nav label
  #open-nav-label,
  #close-nav-label
    display: none
      
  // nav checkbox
  #nav-ctrl
    display: none

        

// real big devices
@media all and (min-width: 900px)
  main
    width: 70%
    margin: 0 auto
    
    
    
/////////////////
// DEMO STYLES
/////////////////

// radios
.panel-radios
  $width: 20px
  $offset: $width / 2
  $middle: ceil($tab-count/2)
  //display: none
  position: fixed
  left: 50%
  top: 10px
  width: $width
  opacity: 0.5
  z-index: 99
  // conditionally centering at top of screen (cant have wrapper...ugh math)
  @for $i from 1 through $tab-count
    @if $i < ceil($tab-count/2)
      &:nth-child(#{$i})
        transform: translateX((-1 * ($width * ($middle - $i))) - $offset)
    @if $i == ceil($tab-count/2)
      &:nth-child(#{$i})
        transform: translateX(-1 * $offset)
    @if $i > ceil($tab-count/2)
      &:nth-child(#{$i})
        transform: translateX($width * ($i - $middle) - $offset)
  // menu checkbox
  &:nth-child(#{$tab-count+1})
    top: 30px
    transform: translateX(-1 * ($width/2))
    display: block

// body
body
  background: $color-primary-light
  color: $color-text
  font-family: 'Open Sans', 'Helvetica Neue', Helvetica, sans-serif

// banner
#introduction
  width: 90%
  margin: 0 auto
  padding: $main-padding
  color: white
  h1
    font-weight: 300
    text-align: center
      
// content text formatting
main
  h1
    margin-top: 0
    font-weight: 300
    color: $color-primary-dark
  p
    line-height: 1.8
  hr
    margin: 12px 0
    border-top: $tab-base-border-style
    
// demo styles    
label.demo-label
  background-color: $color-primary-dark
  color: $color-label-bg-active
  padding: 4px 8px
  border-radius: 2px
  cursor: pointer
  display: inline-block
  user-select: none
  &:hover
    background-color: $color-primary-light
#demo-child-toggle
  display: none
  &:checked ~ #demo-parent #demo-child
    color: $color-primary-dark
    font-weight: bold
    text-transform: uppercase
#demo-parent
  margin-top: 8px

// styling that code
code,
pre
  color: $color-primary-dark
  font-family: Inconsolata, 'Andale Mono', Andale, monowidth
  background-color: $color-label-bg-inactive
  border: $tab-base-border-style
  border-radius: 2px

code
  padding: 2px 6px
pre
  padding: 12px
  line-height: 1.6
  strong
    color: $color-text