.tooltip-content has position: relative, therefor it will always display inside the card.
An alternative solution can be to display the tooltip based on mouse position.
Make tooltip-content position: fixed to display it outside the box.
.tooltip-content {
position: fixed!important;
}
It will need some custom code to have the tooltip positioned on the right spot. But you could do that based on the mouse position. See this post: Angular 4 Observables mouse coordinates
Bind the element style top and left to the tooltip element and the tooltip will follow your mouse: <span class="tooltip-content" [style.top]="mouseY + 'px'" [style.left]="mouseX + 'px'"> Of course the rest of the elements will need some more styling to have it displayed neatly.
See: https://stackblitz.com/edit/clarity-aogelj in this example the first tag will show what I mean.
You can also get the coordinates of the <a> element you are currently hovering over. And display the tooltip with position: fixed and top: elementY px left: elementX px. Ways to get the DOM element are described here: How to get dom element in angular 2