<NME> main.scss
<BEF> // VARS

$color--secondary: #4bf;
$color--bg: #1a416d;

// BASE LAYOUT

// UTILS

@font-face {
  font-family: 'Exo 2';
  src: url('../fonts/Exo2-200.ttf') format('truetype');
  font-weight: 200;
}
@font-face {
  margin: 0 auto;
  font-size: 20px;
  line-height: 1.5;
  font-family: sans-serif;
  background-color: $color--bg;
  font-weight: 100;
}
* {
  box-sizing: border-box;
}

}

a {
  color: $color--secondary;
}

// TYPOGRAPHY

code {
  background: $color--secondary;
  font-size: .8em;
  padding: .2em;
}

h2 {
  color: $color--secondary;
}

small {

mark {
  background-color: $color--highlight;
  padding: .2em;
}

h1 {
}

p {
  max-width: 34em;
  margin-left: 2em;

  @media (max-width: 600px) {
    margin-left: 0em;
  }
}

h2 {
  color: $color--primary;
  margin-bottom: 0;
}

small {
  margin-bottom: 2em;
  display: block;
  font-style: italic;
  font-size: 0.75em;
}

// PREVIEW AREA

.preview-area{
  display: flex;
  flex-wrap: wrap;
  width: 100%;
  justify-content: space-between;

  .iframe-preview {
    position: relative;
    width: 49%;
    margin-bottom: 1em;

    @media (max-width: 600px) {
      width: 100%;
      display: block;
    }

    iframe {
      outline: 1px solid black;
      width: 100%;
      min-height: 40vh;
      overflow: scroll;
      background-color: white;
    }

    input {
      width: 100%;
      margin-top: 1em;
      font-size: 1em;
      padding: .4em;
      font-family: 'Exo 2';
      border: none;
    }
  }
}

.logo {
  max-width: 260px;
}

.resize-note {
  float: right;
}

.change-note {
  position: absolute;
  top: -.5em;
  left: 1em;

  .arrow-up {
    transform: rotate(180deg);
  }
}

.arrow-up {
  width: 1em;
}

// overlay area
.overlay-area {
  position: relative;
  overflow: auto;
  // width: 10px;
  min-height: $iframe-height;
  resize: both;
  cursor: nwse-resize;

  iframe {
    outline: 1px solid $color--primary;
    position: absolute;
    top: 0; left: 0;
    width: 100%;
    height: 100%;
    background-color: white;
    pointer-events: none;

    &:nth-child(2) {
      mix-blend-mode: difference;
    }
  }
}
<MSG> playing with color

<DFF> @@ -1,6 +1,9 @@
 // VARS
 
+$color--primary: #f16464;
 $color--secondary: #4bf;
+$color--tertiary: #eb6B8f;
+$color--highlight: #ffd400;
 $color--bg: #1a416d;
 
 // BASE LAYOUT
@@ -16,7 +19,7 @@ body {
   margin: 0 auto;
   font-size: 20px;
   line-height: 1.5;
-  font-family: sans-serif;
+  font-family: 'Input Serif', 'Open Sans', 'San Fransisco', sans-serif;
   background-color: $color--bg;
   font-weight: 100;
 }
@@ -27,19 +30,37 @@ footer {
 }
 
 a {
-  color: $color--secondary;
+  color: $color--primary;
 }
 
 // TYPOGRAPHY
 
+::selection {
+  background-color: $color--highlight;
+  color: black;
+}
+
 code {
-  background: $color--secondary;
+  background: $color--primary;
   font-size: .8em;
   padding: .2em;
 }
 
+mark {
+  background-color: $color--highlight;
+  padding: .2em;
+}
+
+h1 {
+}
+
+p {
+  max-width: 40em;
+  margin-left: 2em;
+}
+
 h2 {
-  color: $color--secondary;
+  color: $color--primary;
 }
 
 small {

playing with color