Flexbox - justify-content & align-items (horizontal & vertical)

SassMeister-input-HTML.haml

%header
  %h1 Flexbox - main axis alignment
%article
  %section.flex-container
    .box.flex1
      %h3 One
    .box.flex1
      %h3 Two
    .box.flex2
      %h3 Three
    .box.flex1
      %h3 Four
  %section.flex-container.column
    .box.flex1
      %h3 One
    .box.flex1
      %h3 Two
    .box.flex2
      %h3 Three
    .box.flex1
      %h3 Four
  %h1 Flexbox - cross axis alignment
  %section.flex-container.cross-axis
    .box.flex1
      %h3 One
    .box.flex1.self
      %h3 Two
    .box.flex2
      %h3 Three
    .box.flex1
      %h3 Four
  %h1 Flexbox - margins don't collapse vertically
  %section.flex-container.vertical
    .box.flex1
      %h3 One
    .box.flex1
      %h3 Two
    .box.flex2
      %h3 Three
    .box.flex1
      %h3 Four
  %h1 Flexbox - trick with margin: auto
  %section.flex-container.trick
    .box.flex1
      %h3 Column One
    .box.flex1
      %h3 Column Two
    .box.flex2
      %h3 Column Three
      %strong Fat
    .box.flex1
      %h3 Sidebar

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.2)
// Compass (v1.0.0.alpha.17)
// ----

@import "compass";
@import url(http://fonts.googleapis.com/css?family=Audiowide);

// Documentation about Flex
// http://www.w3.org/TR/css3-flexbox/

$colors: (chartreuse, royalblue, plum, teal, lightsteelblue, sienna, maroon, lime, cornflowerblue, darkviolet, dodgerblue);

@for $n from 1 through length($colors) {
  .box:nth-child(#{$n}) {
    background-color: nth($colors, $n);
  }
}

body {
  width: 80%;
  margin: 0 auto;
  padding: 2%;
  line-height: 1.6;
}

.flex-container {
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  margin: 1em 0;
  border: 1px solid #333;
  // flex-start, flex-end, space-between, space-around
  @include justify-content(space-between);
  
  // flex-flow is a shorthand for flex-direction & flex-wrap
  &.row {
    @include flex-flow(row);
  }
  
  &.column {
    @include flex-flow(column);
    height: 300px;
  }
  
  &.vertical {
    @include flex-flow(column);
    height: 400px;
    & .box {
      width: auto;
      margin: 20px;
    }
  }
  
  &.cross-axis {
    height: 200px;
    // default stretch
    // flex-start, flex-end, stretch, baseline
    @include align-items(stretch);
  }
  
  // by setting margin: auto on last child and 20px on all other
  // we fill all the space with margin before the last element
  &.trick {
    height: 200px;
    @include justify-content(flex-start);
    .box {
      margin: 20px;
      &:nth-last-child(1) {
        margin-left: auto;
      }
    }
  }
}

.box {
  font-family: 'Audiowide', cursive;
  font-size: 1.8em;
  line-height: 1;
  margin: 0 5px;
  padding: 10px 20px;
  text-align: center;
}

.flex1 {
  width: 100px;
  .column & {
    width: 100%;
  }
}

.flex2 {
  width: 200px;
  .column & {
    width: 100%;
  }
  .cross-axis & {
    margin-top: 10px;
    height: 100px;
  }
}

.self {
  @include align-self(flex-start);
}

SassMeister-output.css

.box:nth-child(1) {
  background-color: chartreuse;
}

.box:nth-child(2) {
  background-color: royalblue;
}

.box:nth-child(3) {
  background-color: plum;
}

.box:nth-child(4) {
  background-color: teal;
}

.box:nth-child(5) {
  background-color: lightsteelblue;
}

.box:nth-child(6) {
  background-color: sienna;
}

.box:nth-child(7) {
  background-color: maroon;
}

.box:nth-child(8) {
  background-color: lime;
}

.box:nth-child(9) {
  background-color: cornflowerblue;
}

.box:nth-child(10) {
  background-color: darkviolet;
}

.box:nth-child(11) {
  background-color: dodgerblue;
}

body {
  width: 80%;
  margin: 0 auto;
  padding: 2%;
  line-height: 1.6;
}

.flex-container {
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  margin: 1em 0;
  border: 1px solid #333;
  -webkit-justify-content: space-between;
  justify-content: space-between;
}
.flex-container.row {
  -webkit-flex-flow: row;
  flex-flow: row;
}
.flex-container.column {
  -webkit-flex-flow: column;
  flex-flow: column;
  height: 300px;
}
.flex-container.vertical {
  -webkit-flex-flow: column;
  flex-flow: column;
  height: 400px;
}
.flex-container.vertical .box {
  width: auto;
  margin: 20px;
}
.flex-container.cross-axis {
  height: 200px;
  -webkit-align-items: stretch;
  align-items: stretch;
}
.flex-container.trick {
  height: 200px;
  -webkit-justify-content: flex-start;
  justify-content: flex-start;
}
.flex-container.trick .box {
  margin: 20px;
}
.flex-container.trick .box:nth-last-child(1) {
  margin-left: auto;
}

.box {
  text-align: center;
}

.flex1 {
  width: 100px;
}
.column .flex1 {
  width: 100%;
}

.flex2 {
  width: 200px;
}
.column .flex2 {
  width: 100%;
}
.cross-axis .flex2 {
  margin-top: 10px;
  height: 100px;
}

.self {
  -webkit-align-self: flex-start;
  align-self: flex-start;
}

SassMeister-rendered.html

<header>
  <h1>Flexbox - main axis alignment</h1>
</header>
<article>
  <section class='flex-container'>
    <div class='box flex1'>
      <h3>One</h3>
    </div>
    <div class='box flex1'>
      <h3>Two</h3>
    </div>
    <div class='box flex2'>
      <h3>Three</h3>
    </div>
    <div class='box flex1'>
      <h3>Four</h3>
    </div>
  </section>
  <section class='flex-container column'>
    <div class='box flex1'>
      <h3>One</h3>
    </div>
    <div class='box flex1'>
      <h3>Two</h3>
    </div>
    <div class='box flex2'>
      <h3>Three</h3>
    </div>
    <div class='box flex1'>
      <h3>Four</h3>
    </div>
  </section>
  <h1>Flexbox - cross axis alignment</h1>
  <section class='flex-container cross-axis'>
    <div class='box flex1'>
      <h3>One</h3>
    </div>
    <div class='box flex1 self'>
      <h3>Two</h3>
    </div>
    <div class='box flex2'>
      <h3>Three</h3>
    </div>
    <div class='box flex1'>
      <h3>Four</h3>
    </div>
  </section>
  <h1>Flexbox - margins don't collapse vertically</h1>
  <section class='flex-container vertical'>
    <div class='box flex1'>
      <h3>One</h3>
    </div>
    <div class='box flex1'>
      <h3>Two</h3>
    </div>
    <div class='box flex2'>
      <h3>Three</h3>
    </div>
    <div class='box flex1'>
      <h3>Four</h3>
    </div>
  </section>
  <h1>Flexbox - trick with margin: auto</h1>
  <section class='flex-container trick'>
    <div class='box flex1'>
      <h3>Column One</h3>
    </div>
    <div class='box flex1'>
      <h3>Column Two</h3>
    </div>
    <div class='box flex2'>
      <h3>Column Three</h3>
      <strong>Fat</strong>
    </div>
    <div class='box flex1'>
      <h3>Sidebar</h3>
    </div>
  </section>
</article>