ghost/core/client/assets/sass/modules/base.scss

/*
 * Global styles for Ghost which are used throughout the admin interface
 * Utility classes defined here to keep other libraries (Normalize) from
 * being modified, preventing upgrade later.
 *
 * Table of Contents
 *
 * Box Sizing
 * Text Selection
 * Colour Classes
 * Focus Styles
 */

/* ==========================================================================
   Box Sizing
   ---
   Apple `border-box` globally
   ========================================================================== */

*,
*:before,
*:after {
    @include box-sizing(border-box);
}


/* ==========================================================================
   Text Selection
   ---
   These colours do not differ much from browser defaults, but
   this makes it consistent & predicable.
   ========================================================================== */

::-moz-selection {
    color: $darkgrey;
    background: lighten($blue, 20%);
    text-shadow: none;
}

::selection {
    color: $darkgrey;
    background: lighten($blue, 20%);
    text-shadow: none;
}


/* ==========================================================================
   Color Classes
   ---
   Pragmatically generate classes for background & text colour, based on
   `$list-colours` in `variables.scss`
   ========================================================================== */

@each $colour in $list-colours {
    .#{nth($colour, 1)}-bg {
        background: nth($colour, 2);
    }
    .#{nth($colour, 1)} {
        color: nth($colour, 2);
    }
}


/* ==========================================================================
   Focus Styles
   ---
   These are applied globally, to everything except images
   ========================================================================== */

*:not(img):focus {
    outline: 0;
    outline-width: 0;
}