angular/adev/shared-docs/styles/docs/_alert.scss

// Alert

@mixin docs-alert() {
  .docs-alert {
    // Default theme is purple to blue
    --alert-gradient: var(--purple-to-blue-vertical-gradient);
    --alert-accent: var(--bright-blue);
    border-width: 0;
    border-inline-start-width: 3px;
    border-style: solid;
    background: color-mix(in srgb, var(--alert-accent) 5%, transparent);
    color: var(--primary-contrast);
    border-image: var(--alert-gradient) 1;
    padding: 1.5rem;
    font-weight: 400;
    transition: color 0.3s ease;
    margin-block: 1rem;
    position: relative;

    &::before {
      font-family: var(--icons);
      // content: icon is defined in each docs-alert class below...
      position: absolute;
      margin-top: -0.05rem;
      color: var(--alert-accent);
      font-size: 1.3rem;
    }

    p, header {
      margin-inline-start: 1.65rem;
    }

    p {
      &:first-child {
        margin-block-start: 0;
      }

      &:last-child {
        margin-block-end: 0;
      }
    }

    .docs-dark-mode & {
      background: color-mix(in srgb, var(--alert-accent) 10%, transparent);
    }

    .docs-pill-row {
      margin-block-end: 0;
    }
  }

  .docs-alert-note {
    --alert-gradient: var(--blue-to-teal-vertical-gradient);
    --alert-accent: var(--bright-blue);
    &::before {
      content: 'bookmark';
    }
  }

  .docs-alert-tip {
    --alert-gradient: var(--green-to-cyan-vertical-gradient);
    --alert-accent: var(--symbolic-cyan);
    &::before {
      content: 'star';
    }
  }

  .docs-alert-todo {
    --alert-gradient: var(--black-to-gray-vertical-gradient);
    --alert-accent: var(--quaternary-contrast);
    &::before {
      content: 'error';
    }
  }

  .docs-alert-question {
    --alert-gradient: var(--blue-to-cyan-vertical-gradient);
    --alert-accent: var(--symbolic-cyan);
    &::before {
      content: 'help';
    }
  }

  .docs-alert-summary {
    --alert-gradient: var(--purple-to-light-purple-vertical-gradient);
    --alert-accent: var(--electric-violet);
    &::before {
      content: 'sms';
    }
  }

  .docs-alert-tldr {
    --alert-gradient: var(--pink-to-purple-vertical-gradient);
    --alert-accent: var(--vivid-pink);
    &::before {
      content: 'speaker_notes';
    }
  }

  .docs-alert-critical {
    --alert-gradient: var(--red-to-orange-vertical-gradient);
    --alert-accent: var(--orange-red);
    &::before {
      content: 'warning';
    }
  }

  .docs-alert-important {
    --alert-gradient: var(--red-to-pink-vertical-gradient);
    --alert-accent: var(--hot-red);
    &::before {
      content: 'priority_high';
    }
  }

  .docs-alert-helpful {
    --alert-gradient: var(--orange-to-pink-vertical-gradient);
    --alert-accent: var(--vivid-pink);
    &::before {
      content: 'check_circle';
    }
  }
}