KNACSS/sass/_library/_base.scss

/* ----------------------------- */
/* ==Base (basic styles)         */
/* ----------------------------- */

/* switching to border-box model for all elements */
html {
  box-sizing: border-box;
}

* {
  box-sizing: inherit;
}

html {
  /* set base font-size to equiv "10px", which is adapted to rem unit */
  font-size: 62.5%;
  /* IE9-IE11 math fixing. See http://bit.ly/1g4X0bX */
  /* thanks to @guardian, @victorbritopro and @eQRoeil */
  font-size: calc(1em * 0.625);
}

body {
  font-size: $base-font-size;
  @if variable_exists(base-font-size-l) and $base-font-size-l != $base-font-size {
    @include respond-to("tiny-up") {
      font-size: $base-font-size-l;
    }
  }
  background-color: $background-base;
  color: $color-base;
  font-family: $font-stack-common;
  line-height: $line-height;
  @if variable_exists(line-height-l) and $line-height-l != $line-height {
    @include respond-to("tiny-up") {
      line-height: $line-height-l;
    }
  }
}

a {
  color: $color-link;

  // No styling on focus/hover if there's no effect. Avoids to then have to
  // override it countless times. See Issue #232
  @if variable_exists(color-link-hover) and
      ( null == index( ($color-link, null, false), $color-link-hover) ) {
    &:focus,
    &:hover,
    &:active {
      color: $color-link-hover;
    }
  }
}

ul,
ol {
  padding-left: 2em;
}

img {
  vertical-align: middle;
}

blockquote,
figure {
  margin-left: 0;
  margin-right: 0;
}

/* font-sizing for content */
p,
.p-like,
ul,
ol,
dl,
blockquote,
pre,
td,
th,
label,
textarea,
caption,
details,
figure {
  margin-top: 0.75em;
  margin-bottom: 0;
  line-height: $line-height;
}

h1, .h1-like {
  font-size: $h1-size;
  @if variable_exists(h1-size-l) and $h1-size-l != $h1-size {
    @include respond-to("tiny-up") {
      font-size: $h1-size-l;
    }
  }
  @if variable_exists(font-stack-headings) and $font-stack-headings != $font-stack-common {
    font-family: $font-stack-headings;
  }
}

h2, .h2-like {
  font-size: $h2-size;
  @if variable_exists(h2-size-l) and $h2-size-l != $h2-size {
    @include respond-to("tiny-up") {
      font-size: $h2-size-l;
    }
  }
  @if variable_exists(font-stack-headings) and $font-stack-headings != $font-stack-common {
    font-family: $font-stack-headings;
  }
}

h3, .h3-like {
  font-size: $h3-size;
  @if variable_exists(h3-size-l) and $h3-size-l != $h3-size {
    @include respond-to("tiny-up") {
      font-size: $h3-size-l;
    }
  }
}

h4, .h4-like {
  font-size: $h4-size;
  @if variable_exists(h4-size-l) and $h4-size-l != $h4-size {
    @include respond-to("tiny-up") {
      font-size: $h4-size-l;
    }
  }
}

h5, .h5-like {
  font-size: $h5-size;
  @if variable_exists(h5-size-l) and $h5-size-l != $h5-size {
    @include respond-to("tiny-up") {
      font-size: $h5-size-l;
    }
  }
}

h6, .h6-like {
  font-size: $h6-size;
  @if variable_exists(h6-size-l) and $h6-size-l != $h6-size {
    @include respond-to("tiny-up") {
      font-size: $h6-size-l;
    }
  }
}

/* alternate font-sizing */
.smaller {
  font-size: 0.6em;
}

.small {
  font-size: 0.8em;
}

.big {
  font-size: 1.2em;
}

.bigger {
  font-size: 1.5em;
}

.biggest {
  font-size: 2em;
}

code,
pre,
samp,
kbd {
  /* IE fix */
  white-space: pre-line;
  white-space: pre-wrap;
  font-family: $font-stack-monospace;
  line-height: normal;
}

em,
.italic,
address,
cite,
i,
var {
  font-style: italic;
}

/* avoid top margins on first content element */
p,
.p-like,
ul,
ol,
dl,
blockquote,
pre,
h1,
.h1-like,
h2,
.h2-like,
h3,
.h3-like,
h4,
.h4-like,
h5,
.h5-like,
h6,
.h6-like {
  &:first-child {
    margin-top: 0;
  }
}

/* avoid margins on nested elements */
li p,
li .p-like,
li ul,
li ol {
  margin-top: 0;
  margin-bottom: 0;
}

/* max values */
img,
table,
td,
blockquote,
code,
pre,
textarea,
input,
video,
svg {
  max-width: 100%;
}

img {
  height: auto;
}