debian-mirror-gitlab/app/assets/stylesheets/framework/system_messages.scss

.header-message,
.footer-message {
  padding: 0 15px;
  border: 1px solid transparent;
  border-radius: 0;
  position: fixed;
  left: 0;
  width: 100%;
  text-align: center;
  margin: 0;
  z-index: 1000;

  p {
    @include str-truncated(100%);
    margin-top: -1px;
    margin-bottom: 0;
    font-size: $gl-font-size-small;
  }
}

.header-message {
  top: 0;
  height: $system-header-height;
  line-height: $system-header-height;
}

.footer-message {
  bottom: 0;
  height: $system-footer-height;
  line-height: $system-footer-height;
}

.with-performance-bar {
  .header-message {
    top: $performance-bar-height;
  }
}

// System Footer
.with-system-footer {
  // navless pages' footer eg: login page
  // navless pages' footer border eg: login page
  &.devise-layout-html body .footer-container,
  &.devise-layout-html body hr.footer-fixed {
    bottom: $system-footer-height;
  }

  .boards-list,
  .board-swimlanes {
    height: calc(100vh - (#{$header-height} + #{$top-bar-height} + #{$performance-bar-height} + #{$system-footer-height} + #{$gl-padding-32}));
  }
}

.fullscreen-layout {
  .header-message,
  .footer-message {
    position: static;
    top: auto;
    bottom: auto;
  }
}