message: Banner: fix styles to pass e2e tests
diff: position: relative;
  display: flex;
  padding: 12px;
  + padding-left: 16px;
  background-color: var(--content_tint_background);
  border-radius: 8px;
  overflow: hidden;
  }
  .Banner__before {
  - margin-right: 8px;
  + position: relative;
  + margin-right: 12px;
  + z-index: 2;
  }
  .Banner__content {
  + position: relative;
  flex: 1;
  display: flex;
  justify-content: center;
  flex-direction: column;
  min-width: 0;
  + z-index: 2;
  }
  .Banner__subheader {
  margin-top: 2px;
  }
  -/**
  - * Mode "tint"
  - */
  -.Banner--md-tint .Banner__content {
  - padding-left: 4px;
  -}
  -
  /**
  * Mode "image"
  */
  .Banner--md-image .Banner__in {
  - padding: 12px 16px;
  background-color: var(--content_tint_background);
  }
  -.Banner--md-image .Banner__before,
  -.Banner--md-image .Banner__content {
  - position: relative;
  - z-index: 2;
  -}
  -
  -.Banner--md-image .Banner__before {
  - margin-right: 12px;
  -}
  -
  .Banner--md-image .Banner__dismiss,
  .Banner--inverted {
  color: var(--white);
  opacity: .72;
  }
  +/**
  + * Size "s"
  + */
  +.Banner--sz-s .Banner__before {
  + margin-left: -4px;
  +}
  +
  /**
  * Size "m"
  */
  