fix(stat): add fixed font-size for stat-title

[michaelcozzolino]

Although I don't have access to the figma files I suppose the font size of the stat title must be fixed and I encountered that, if we add a custom font size to the parent element also the stat title size changes:

<div class="stats text-3xl">
  <div class="stat">
    <div class="stat-title">Total Emails Sent</div>
    <div class="stat-value">76,250</div>
    <div class="stat-desc">18% more than last month</div>
  </div>
</div>