# Presentation Layer Architecture

This section discusses the structure and purpose of the SCSS files and how to customize the application using Bootstrap theming.

# SCSS Directory Structure

# `bmc` Directory

The bmc directory contains Sass helpers and default styles for customizing the OpenBMC Web UI.

.
├─ src
   ├─ assets
      ├─ styles
         ├─ bmc
            ├─ custom
            └─ helpers
         ├─ bootstrap
         └─ _obmc-custom.scss

# `custom` Directory

The custom Directory imports all the styles needed to customize the UI. These are small changes used to reach parity with the OpenBMC Design Workgroup's agreed-upon design. The file naming convention closely follows the Bootstrap or Boostrap-vue library file naming since most of the ruleset selectors in these files are based on these two libraries.

.
├─ src
   ├─ assets
      ├─ styles
         ├─ bmc
            ├─ custom
               ├─ alert.scss
               ├─ _badge.scss
               ├─ _base.scss
               ├─ _bootstrap-grid.scss
               ├─ _buttons.scss
               ├─ _calendar.scss
               ├─ _card.scss
               ├─ _dropdown.scss
               ├─ _forms.scss
               ├─ _index.scss
               ├─ _kvm.scss
               ├─ _modal.scss
               ├─ _pagination.scss
               ├─ _sol.scss
               ├─ _tables.scss
               └─ _toasts.scss
         ├─ helpers
         ├─ bootstrap
         └─ _obmc-custom.scss

# `helpers` Directory

The helpers directory contains a set of Sass helper files containing Sass variables that establish the custom theme of the application.

.
├─ src
   ├─ assets
      ├─ styles
         ├─ bmc
         ├─ helpers
                ├─ _colors.scss
                ├─ _functions.scss
                ├─ _index.scss
                ├─ _motion.scss
                └─ _variables.scss
         ├─ bootstrap
         └─ _obmc-custom.scss

# `_colors.scss`

The _colors.scss file sets all the SASS variables and color maps for the OpenBMC Web UI. Any color settings needed to meet company brand guidelines will happen in this file.

# Sass Color Variables

$black: #000;
$white: #fff;

$blue-500: #2d60e5;
$green-500: #0a7d06;
$red-500: #da1416;
$yellow-500: #efc100;

$gray-100: #f4f4f4;
$gray-200: #e6e6e6;
$gray-300: #d8d8d8;
$gray-400: #cccccc;
$gray-500: #b3b3b3;
$gray-600: #999999;
$gray-700: #666666;
$gray-800: #3f3f3f;
$gray-900: #161616;

# Custom Color Variables

// Sass Base Color Variables
$blue: $blue-500;
$green: $green-500;
$red: $red-500;
$yellow: $yellow-500;

# Custom Colors Map

$colors: (
  "blue": $blue,
  "green": $green,
  "red": $red,
  "yellow": $yellow,
);

# Custom Theme Color Variables

// Sass Theme Color Variables
// Can be used as variants
$danger: $red;
$dark: $gray-900;
$info: $blue;
$light: $gray-100;
$primary: $blue;
$secondary: $gray-800;
$success: $green;
$warning: $yellow;

# Custom Theme Colors Map

$theme-colors: (
  "primary": $primary,
  "secondary": $secondary,
  "dark": $dark,
  "light": $light,
  "danger": $danger,
  "info": $info "success": $success "warning": $warning,
);

# Color Resources

# `_functions.scss`

Two functions provide a customized way to set color highlights. The theme-color-light and theme-color-dark are custom functions used to create colors for the alert, badge, card, and toast components. They have also set color highlights for some pseudo-elements like : hover.

# Functions

// This function is usually used to get a lighter
// theme variant color to use as a background color
@function theme-color-light($variant) {
  @return theme-color-level($variant, -11.3);
}

@function theme-color-dark($variant) {
  @return theme-color-level($variant, 2);
}

# Examples

.b-table-sort-icon-left {
    background-position: left calc(1.5rem / 2) center !important;
    padding-left: calc(1.2rem + 0.65em) !important;
    &:focus {
      outline: none;
      box-shadow: inset 0 0 0 2px theme-color('primary') !important;
    }
    &:hover {
      background-color: theme-color-dark('light');
    }
  }
}

&.alert-info {
border-left-color: theme-color("info");
background-color: theme-color-light("info");
fill: theme-color("info");
}

# `_motion.scss`

This bezier curves and durations in this file determine the motion styles throughout the application. These guidelines from the Cabon Design System avoid easing curves that are unnatural, distracting, or purely decorative.

# Motion Styles

$duration--fast-01: 70ms; //Micro-interactions such as button and toggle
$duration--fast-02: 110ms; //Micro-interactions such as fade
$duration--moderate-01: 150ms; //Micro-interactions, small expansion, short distance movements
$duration--moderate-02: 240ms; //Expansion, system communication, toast
$duration--slow-01: 400ms; //Large expansion, important system notifications
$duration--slow-02: 700ms; //Background dimming

$standard-easing--productive: cubic-bezier(0.2, 0, 0.38, 0.9);
$standard-easing--expressive: cubic-bezier(0.4, 0.14, 0.3, 1);
$entrance-easing--productive: cubic-bezier(0, 0, 0.38, 0.9);
$entrance-easing--expressive: cubic-bezier(0, 0, 0.3, 1);
$exit-easing--productive: cubic-bezier(0.2, 0, 1, 0.9);
$exit-easing--expressive: cubic-bezier(0.4, 0.14, 1, 1);

# Example

.link-skip-nav {
  position: absolute;
  top: -60px;
  left: 0.5rem;
  z-index: $zindex-popover;
  transition: $duration--moderate-01 $exit-easing--expressive;
  &:focus {
    top: 0.5rem;
    transition-timing-function: $entrance-easing--expressive;
  }
}

# Motion Resources

# `_variables.scss`

This file contains all the global Sass options. There are Bootstrap option overrides, Bootstrap global variable overrides, and custom BMC global variables. Read more about these in the Customization section.

# `bootstrap` Directory

The bootstrap directory contains all the import references. The references are split into multiple files to support import order based on dependency. Helper styles need to be imported before all other styles.

.
├─ src
   ├─ assets
      ├─ styles
         ├─ bmc
         ├─ bootstrap
            ├─ _helpers.scss
            └─ _index.scss
         └─ _obmc-custom.scss

# `_helpers.scss`

This file contains all the helper import references for Bootstrap.

# `_index.scss`

This file contains all the import references needed to support the base, components, and utility styles.

# `_obmc-custom.scss`

.
├─ src
   ├─ assets
      ├─ styles
         ├─ bmc
         ├─ bootstrap
         └─ _obmc-custom.scss

The obmc-custom.scss file defines all of the presentational layer dependencies.

# Component / View Styles

Some stylistic changes only apply to a single-file component or view instance. In this case, rather than adding a Sass file, the scoped styles include the styles in the component's <style> block. It is required to import the _helpers Sass file when using a BMC or Bootstrap variable in the component's <style> block. Without this import, webpack cannot compile the OpenBMC Web UI CSS styles correctly.

# Scoped style block using SASS

<style scoped lang="scss">
  ...
</style>

# Scoped style block using CSS

<style scoped>
  ...;
</style>

# Example - PageSection.vue

<style lang="scss" scoped>
  .page-section {
    margin-bottom: $spacer * 2;
  }

  h2 {
    @include font-size($h3-font-size);
    margin-bottom: $spacer;
    &::after {
      content: "";
      display: block;
      width: 100px;
      border: 1px solid $gray-300;
      margin-top: 10px;
    }
  }
</style>

TIP

You might notice that there is an HTML element, <h2>, used in the example. This is an anti-pattern in global .scss files. However, in a single file component that generates the markup it is acceptable.

Learn more about single file components (opens new window)

Customization of the application requires knowledge of Sass and CSS. It also will require becoming familiar with the Bootstrap and Bootstrap-Vue component libraries. This section outlines the global options and variables that can be removed or updated to meet organizational brand guidelines.

Theme customization →