Skyline CSS Architecture - this is currently a work in progress in our application. I use sass since this is a rails app, we are extending bootstrap framework, mostly I just used the grid, and I want to able to customized more the framework. My CSS architecture is based on how bootstrap structure itself, I mostly used the _variables.scss file to…

_base.scss

body {
  margin-top: $header-height;
}

.main-content-container {
  @include make-lg-column(10);
}

.main-content {
	min-height: 78vh;
}

_dashboard.scss

.dashboard {
  margin-top: 30px;
  margin-bottom: 30px;
  
  .tabs-menu {
    padding-left: 0;

    .tabs-menu-item {
      display: table-cell;
      width: 1%;
      border-top: $border-tabs-blue;
      border-right: $border-tabs-blue;
      border-bottom: $border-tabs-blue;
      padding: $border-tabs-padding;
      text-align: center;
      text-transform: uppercase;

      &:first-child { border-left: $border-tabs-blue; }
      &.tab-active { background: $base-blue; }
      &.tab-active a { color: $base-white; }
      &:hover { background: $base-gray; }
      &.tab-active:hover { background: $base-blue; }

      a { text-decoration: none; }
    }
  }

  .tabs-menu-content {
    border: 1px solid $base-blue;
    margin-top: 30px;
    @include clearfix;
  }

  .tabs-content-wrapper {
    float: left;
    width: 50%;
    padding: 15px;
  }

  .tab-content {
    overflow: hidden;
    border: $border-tabs-blue;
    border-width: 3px;
    background: $base-white;
    border-top-left-radius: 6px;
    border-bottom-right-radius: 6px;
    cursor: pointer;

    .tab-title {
      color: $base-blue;
      font-size: $font-size-h4;
      text-align: center;
      @include clearfix;
      text-transform: uppercase;
      font-weight: $font-bold;

    }

    .stats-title,
    .stats-value {
      color: $base-blue;
      font-size: $font-size-h6;
      text-transform: uppercase;
      font-weight: $font-bold;
    }

    .stats-container {
      float: left;
      width: 33.33%;
      text-align: center;
    }

    &.tab-content-inactive {
      border: 3px solid $base-blue-light;
    
      > .tab-title {
        color: $base-blue-light;
      }

      .stats-title,
      .stats-value {
        color: $base-blue-light;
      }
    }
  }

  .tabs-content-stages-wrapper {
    padding: 0px 15px;
    overflow: hidden;
  }

  .tabs-content-stages {
    float: left;
    width: 33.333333%;

    .stage-title {
      border-top: 3px solid $base-blue;
      border-right: 3px solid $base-blue;
      border-bottom: 3px solid $base-blue;
      font-size: $font-size-h4;
      color: $base-blue;
      text-transform: uppercase;
      text-align: center;
      padding: 5px;
      margin-top: 0;
    }

    &:first-child > .stage-title {
      border-left: 3px solid $base-blue;
    }

    .stage-stats {
      background: $base-gray;
      margin:10px;
      padding: 10px;
      font-size: $font-size-h6;

    }

    .stage-stats-count {
      @extend .pull-right;
    }
  }
}

_footer.scss

.app-main-footer {
  position: fixed;
  bottom: 0;
  left: 0;
  padding: $gutter;
  font-size: 0.8em;
  z-index: 0;
  max-width: 120px;
  width: 20%;

  .logo{ 
    background-image: url( asset_path('logo.png') );
    background-position: top left;
    background-repeat: no-repeat;
    background-size: contain;
    height: 40px;

    @media screen and ( max-width: $breakpoint-medium ) {
      width: $gutter * 3;
    }
  }
}

_header.scss

header {
  padding: 20px 0;
  border-bottom: 3px solid #009B87;
  @extend .navbar;
  @extend .navbar-default;
  @extend .navbar-fixed-top;
}

.header-container {
  @extend .container;
}

.header-container--contents {
  @include make-row;
  .contents-logo {
    @include make-lg-column(3);
    @include make-md-column(3);
    @include make-sm-column(3);

    img {
      width: 100%;
    }
  }

  .contents-links {
    @include make-lg-column(9);
    @include make-md-column(9);
    @include make-sm-column(9);

    .contents-nav {
      @extend .nav;
      @extend .navbar-nav;
      @extend .navbar-right;

      .contents-nav-item {
        @extend .text-center;
      }
    }
  }
}

_sidebar.scss

.sidebar-container {
  @include make-lg-column(2);
}

.sidebar-nav {
  margin-top: 30px;
}

.nav-menu {
  list-style: none;
  padding-left: 0;

  .nav-menu-item {
    border-bottom: 1px solid $base-blue;
    border-left: 1px solid $base-blue;
    border-right: 1px solid $base-blue;
    padding: 5px;
    @extend .text-center;
    cursor: pointer;
    
    a {
      text-transform: uppercase;
    }

    i {
      @extend .icon-36;
    }
    
    &:first-child {
     border-top: 1px solid $base-blue;
    }

    &.active {
      background: $base-blue;
    }

    &.active a {
      color: $base-white;
      background: none;
    }

    &.active a:hover,
    a {
      text-decoration: none;
    }

    &:hover {
      background: $base-gray;
    }

   &.active:hover {
     background: $base-blue;
   }

  }

}

_sm.scss

@media (max-width: 1024px) {
	.nav-menu-item {
		display: table-cell;
		width: 1%;

		border-top: $border-tabs-blue !important;
		border-left: none !important;
		border-right: $border-tabs-blue !important;
		border-bottom: $border-tabs-blue !important;

		&:first-child {
			border-left: $border-tabs-blue !important;
		}
	}
}

_utilities.scss

.icon-24 {
  font-size: 24px;
}
.icon-36 {
  font-size: 36px;
}

_variables.scss

// Colors
$base-blue: #0068A0;
$base-gray: #F6F6F6;
$base-white: #FEFFFF;
$base-green: #009B87;
$base-black: #02174A;
$base-blue-light: #4097D3;

// Scaffolding
$body-bg: $base-white;
$text-color: $base-black;
$link-color: $base-blue;

// Typography
$font-family-sans-serif: "Source Sans Pro", Helvetica, Arial, sans-serif;
$font-size-base: 16px;
// font scale using 3:4 proportion
$font-size-h1: 67px;
$font-size-h2: 50px;
$font-size-h3: 37px;
$font-size-h4: 28px;
$font-size-h5: 21px;
$font-size-h6: 16px; // same as $font-size-base

$font-normal: 400;
$font-bold: 700;
$font-semi-bold: 600;

// Navbar
$navbar-default-color: $base-black;
$navbar-default-bg: $base-white;

$navbar-default-link-color: $base-blue;
$navbar-default-link-active-color: $base-black;
$navbar-default-link-hover-color: $base-blue;
$navbar-default-link-hover-bg: transparent;
$navbar-default-link-active-bg: transparent;


// Dropdowns
$dropdown-bg: $base-white;
$dropdown-border: $base-blue;
$dropdown-divider-bg: $base-blue;
$dropdown-link-color: $base-blue;

// Base Variables
$header-height: 121px;
$border-tabs-blue: 1px solid $base-blue;
$border-tabs-padding: 20px;

skyline.css.scss

// Bootstrap overrides & mixins
@import "skyline/variables";

// Core Bootstrap
@import "bootstrap-sprockets";
@import "bootstrap";

// Layouts
@import "skyline/base";
@import "skyline/utilities";
@import "skyline/layouts/header";
@import "skyline/layouts/sidebar";
@import "skyline/layouts/footer";

// Individual pages
@import "skyline/dashboard";

// Breakpoints
@import "skyline/breakpoints/sm";