I am trying to include button in my html emailbody. Button is rendering fine on outlook web. However, its not rendering in outlook desktop app and just shows empty space.

<a href="{{testLink}}" >
    <button style="background: #6D41D3;border: 1px solid #48179C; box-sizing: border-box; border-radius: 3px; position: static;  height: 50px; left: 45px; top: 120px; width:fit-content; cursor: pointer; ">
        <h1 style="color: #FFFFFF; font-size: 16px; max-width: 230px; position: static; align-items: center; height: 20px; left: 14px; top: 05px; margin: 0px 10px;
        overflow: hidden; text-overflow: ellipsis; white-space: nowrap; margin: 45px 0px;">
            <strong>{{testLabel}}</strong>
        </h1>
    </button>
</a>