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HTML 

              
                <h1>Flex Grow, Flex Shrink and Flex Basis</h1>

<h1>Flex Basis</h1>
<p>Before we start growing or shrinking the elements, we need to should set the basis of the elements</p>
<p>The flex-basis CSS property specifies the flex basis which is the initial main size of a flex item. </p>
<p>This defines the default size of an element before the remaining space is distributed. It can be a length (e.g. 20%, 5rem, etc.) or a keyword. </p>
<p>Flex basis is similar to min-width. Try applying flex-wrap: wrap; on the flex containers.</p>

<ul class="flex-container flex-basis">
  <li class="flex-item flex-1">flex-basis: 100px;</li>
  <li class="flex-item flex-2">flex-basis: 200px;</li>
  <li class="flex-item flex-3">flex-basis: 300px;</li>
</ul>

<h1 style="margin-top: 100px;">Flex Grows</h1>
<p>When we have extra space, how should the elements be divided among everybody on the same line?</p>
<h2 class="first-h2">Even Growth</h2>
<ul class="flex-container flex-grow-1">
  <li class="flex-item flex-1">
    flex-grow: 1;<br>
  </li>
  <li class="flex-item flex-2">
    flex-grow: 1;<br>
  </li>
  <li class="flex-item flex-3">
    flex-grow: 1;<br>
  </li>
</ul>

<pre>
(700px / 3) * 1 = 233.33px
(700px / 3) * 1 = 233.33px
(700px / 3) * 1 = 233.33px
</pre>

<h2>Uneven Growth</h2>
<ul class="flex-container flex-grow-2">
  <li class="flex-item flex-1">
    flex-grow: 1;<br>
  </li>
  <li class="flex-item flex-2">
    flex-grow: 3;<br>
  </li>
  <li class="flex-item flex-3">
    flex-grow: 1;<br>
  </li>
</ul>

<pre>
(700px / 5) * 1 = 140px
(700px / 5) * 3 = 420px
(700px / 5) * 1 = 140px
</pre>

<h1 style="margin-top: 100px;">Flex Grows with Flex Basis</h1>
<p>When we have extra space, how should the elements be divided among everybody on the same line?</p>
<p>Try setting the first box's flex-grow to 0</p>
<h2 class="first-h2">Flex Grow on one flex-item</h2>
<ul class="flex-container flex-grow-3">
  <li class="flex-item flex-1">
    flex-grow: 1;<br>
    flex-basis: 100px;
  </li>
  <li class="flex-item flex-2">
    flex-grow: 0;<br>
    flex-basis: 200px;
  </li>
  <li class="flex-item flex-3">
    flex-grow: 0;<br>
    flex-basis: 300px;
  </li>
</ul>
<pre>
  width: 100px;
  width: 200px;
  width: 300px;
  
  empty-space-left: 700px - 600px = 100px;
  
  (flex-grow: 1) width: 200px (100px + 100px);
  (flex-grow: 0) width: 200px;
  (flex-grow: 0) width: 300px;
</pre>

<h2>Even Flex Growth on all flex items</h2>
<ul class="flex-container flex-grow-4">
  <li class="flex-item flex-1">
    flex-grow: 1;<br>
    flex-basis: 100px;
  </li>
  <li class="flex-item flex-2">
    flex-grow: 1;<br>
    flex-basis: 200px;
  </li>
  <li class="flex-item flex-3">
    flex-grow: 1;<br>
    flex-basis: 300px;
  </li>
</ul>

<pre>
  width: 100px;
  width: 200px;
  width: 300px;
  empty-space-left: 700px - 600px = 100px;
  
  100px / 3 = 33.33px
  (flex-grow: 1) width: 133.33px; (100 + 33.3)
  (flex-grow: 1) width: 233.33px; (200 + 33.3)
  (flex-grow: 1) width: 333.33px; (300 + 33.3)
</pre>

<h2>Uneven Flex Growth on all flex items</h2>
<ul class="flex-container flex-grow-5">
  <li class="flex-item flex-1">
    flex-grow: 1;<br>
    flex-basis: 100px;
  </li>
  <li class="flex-item flex-2">
    flex-grow: 3;<br>
    flex-basis: 200px;
  </li>
  <li class="flex-item flex-3">
    flex-grow: 1;<br>
    flex-basis: 300px;
  </li>
</ul>

<pre>
  width: 100px;
  width: 200px;
  width: 300px;
  empty-space-left: 700px - 600px = 100px;
  
  100px / 5 = 20px
  (flex-grow: 1) width: 120px; (100 + 20)
  (flex-grow: 3) width: 260px; (200 + 20*3)
  (flex-grow: 1) width: 320px; (300 + 20)
</pre>


<h2>Calculate the width of each of the flexboxes!</h2>
<p>Check the dimensions on Chrome DevTools to see if you got it right</p>
<ul class="flex-container flex-grow-6">
  <li class="flex-item flex-1">
    flex-grow: 1;<br>
    flex-basis: 300px;
  </li>
  <li class="flex-item flex-2">
    flex-grow: 3;<br>
    flex-basis: 100px;
  </li>
  <li class="flex-item flex-3">
    flex-grow: 2;<br>
    flex-basis: 350px;
  </li>
</ul>
<button class="js-flex-grow-show">show calculation</button>
<pre class="js-flex-grow-answer hide">
  width: 300px
  width: 100px
  width: 350px
  empty-space-left: 900px - 750px = 150px
  
  150px / 6 = 25px
  (flex-grow: 1) width: 325px; (300 + 25)
  (flex-grow: 3) width: 175px; (100 + 25*3)
  (flex-grow: 2) width: 400px; (350 + 25*2)
</pre>


<h1 style="margin-top: 100px;">Flex Shrinks</h1>
<p>What do we do if we don't have space?</p>

<p>The flex-shrink CSS property specifies the flex shrink factor of a flex item. Flex items will shrink to fill the container according to the flex-shrink number, when the default width of flex items is wider than the flex container.</p>
<p>If the parent has flex-wrap: wrap; flex-shrink won't work;</p>

<h2 class="first-h2">No Shrink</h2>
<ul class="flex-container flex-shrink-0">
  <li class="flex-item flex-1">
    flex-shrink: 0;<br>
    flex-basis: 200px; 
  </li>
  <li class="flex-item flex-2">
    flex-shrink: 0;<br>
    flex-basis: 200px; 
  </li>
  <li class="flex-item flex-3">
    flex-shrink: 0;<br>
    flex-basis: 200px; 
  </li>
</ul>

<h2>Even Shrink</h2>
<ul class="flex-container flex-shrink-1">
  <li class="flex-item flex-1">
    flex-shrink: 1;<br>
    flex-basis: 200px; 
  </li>
  <li class="flex-item flex-2">
    flex-shrink: 1;<br>
    flex-basis: 200px; 
  </li>
  <li class="flex-item flex-3">
    flex-shrink: 1;<br>
    flex-basis: 200px; 
  </li>
</ul>
<p>What if we give the flex-container a max-width of 300px?</p>

<pre>
/*Method 1*/
(300px / 3) * 1 = 100px
(300px / 3) * 1 = 100px
(300px / 3) * 1 = 100px
</pre>

<pre>
/*Method 2*/
total-flex-basis: 600px
container-size: 300px
space-remaining: -300px (300 - 600)
total-size: (1 * 200) + (1 * 200) + (1 * 200) = 600

How much each container shrinks?
(1 * 200) / 600 * -300 = -100px
(1 * 200) / 600 * -300 = -100px
(1 * 200) / 600 * -300 = -100px

Final Width
200 - 100 = 100px;
200 - 100 = 100px;
200 - 100 = 100px;
</pre>

<h2>Uneven Shrink</h2>
<ul class="flex-container flex-shrink-2">
  <li class="flex-item flex-1">
    flex-shrink: 1;<br>
    flex-basis: 200px;
  </li>
  <li class="flex-item flex-2">
    flex-shrink: 3;<br>
    flex-basis: 200px;
  </li>
  <li class="flex-item flex-3">
    flex-shrink: 1;<br>
    flex-basis: 200px;
  </li>
</ul>
<p>How about this one? What if we give it a width of 500px?</p>
<pre>
  total-flex-basis: 600px
  container-size: 500px
  space-remaining: -100px
  total-size: (1 * 200) + (3 * 200) + (1 * 200) = 1000

  How much each container shrinks?
  (1 * 200) / 1000 * -100 = -20px
  (3 * 200) / 1000 * -100 = -60px
  (1 * 200) / 1000 * -100 = -20px

  Final Width
  200 - 20 = 180px;
  200 - 60 = 140px;
  200 - 20 = 180px;
</pre>


<h2>flex-shrink and flex-basis</h2>
<ul class="flex-container flex-shrink-3">
  <li class="flex-item flex-1">
    flex-shrink: 2;<br>
    flex-basis: 400px; 
  </li>
  <li class="flex-item flex-2">
    flex-shrink: 1;<br>
    flex-basis: 100px; 
  </li>
  <li class="flex-item flex-3">
    flex-shrink: 3;<br>
    flex-basis: 150px; 
  </li>
</ul>
<p>Final one! What are the width values for each flex-item if we were to shrink the flex-container to 450px?</p>
<pre>
  total-flex-basis: 650px
  container-size: 450px
  space-remaining: -200px
  total-size: (2 * 400) + (1 * 100) + (3 * 150) = 1350

  How much each container shrinks?
  (2 * 400) / 1350 * -200 = -118.50px
  (1 * 100) / 1350 * -200 = -14.80px
  (3 * 150) / 1350 * -200 = -66.67px

  Final Width
  400 - 118.50 = 281.50px;
  100 - 14.80 = 85.20px;
  150 - 66.67 = 83.33px;
</pre>

<p>Sidenote: Add flex-wrap: wrap to see how the layout changes</p>
<a href="https://madebymike.com.au/writing/understanding-flexbox/" target="_blank">Extra Read</a>
!

CSS 

              
                h2 {
  margin: 80px 0px 20px;
  
  &.first-h2 {
    margin: 20px 0px;
  }
}

pre {
  margin: 30px 0px;
}
.flex-container {
  margin: 0;
  margin-bottom: 30px;
  padding: 0;
  list-style: none;
  display: flex;
  position: relative;
  justify-content: flex-start;
  background-color: beige;
  padding: 10px 0px;
  max-width: 700px;
  box-sizing: border-box;
  outline: 1px solid black;
  
  &:after {
    content:"700px";
    font-style: italic;
    font-size: 12px;
    padding: 3px 10px;
    position: absolute;
    background-color: #8e44ad;
    color: white;
    bottom: -20px;
    right: 50%;
    transform: translateX(50%);
  }
  
  &:before {
    content: "";
    height: 2px;
    width: 100%;
    background-color: #8e44ad;
    bottom: -10px;
    position: absolute;
  }
}

.flex-1 { background-color: #e74c3c;}
.flex-2 { background-color: #e67e22;}
.flex-3 { background-color: #3498db;}

.flex-item {
  width: 100px;
  height: 100px;
  color: black;
  font-size: 18px;
  text-align: center;
}

.flex-1 {flex-basis: 100px;}
.flex-2 {flex-basis: 200px;}
.flex-3 {flex-basis: 300px;}

/*Flex Grows*/
.flex-grow-1 {
  .flex-item {
    flex-grow: 1;
    flex-basis: 0;
  }
}

.flex-grow-2 {
  .flex-item {
    flex-basis: 0;
  }
  .flex-1 {flex-grow: 1;}
  .flex-2 {flex-grow: 3;}
  .flex-3 {flex-grow: 1;}
}

.flex-grow-3 {
  .flex-1 {flex-grow: 1;}
}

.flex-grow-4 {
  .flex-item {flex-grow: 1;}
}

.flex-grow-5 {
  .flex-1 {flex-grow: 1;}
  .flex-2 {flex-grow: 3;}
  .flex-3 {flex-grow: 1;}
}

.flex-grow-6 {
  max-width: 900px;
  &:after {
    content:"900px"
  }
  .flex-1 {flex-basis: 300px; flex-grow: 1;}
  .flex-2 {flex-basis: 100px; flex-grow: 3;}
  .flex-3 {flex-basis: 350px; flex-grow: 2;}
}

.js-flex-grow-show {
  margin-top: 0px;
}

.js-flex-grow-answer {
  &.hide {
    display: none;
  }
}

.flex-shrink-0 {
  .flex-item {
    flex-basis: 200px;
    flex-shrink: 0;
  }
}

.flex-shrink-1 {
  .flex-item {
    flex-basis: 200px;
    flex-shrink: 1;
  }
}

.flex-shrink-2 {
  .flex-item {
    flex-basis: 200px;
    flex-shrink: 1;
  }
  .flex-2 {
    flex-shrink: 3;
  }
}

.flex-shrink-3 {
  .flex-1 {
    flex-basis: 400px;
    flex-shrink: 2;
  }
  .flex-2 {
    flex-basis: 100px;
    flex-shrink: 1;
  }
  .flex-3 {
    flex-basis: 150px;
    flex-shrink: 3;
  }
}
!

JS
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