<!-- Serial interval label and help tooltip. -->
<label class="form-label" for="mu_{{ id }}">
  Serial interval
  <sup data-bs-toggle="tooltip" data-bs-placement="right"
       data-bs-title="The serial interval is the time between when an infected individual (the infector) becomes
                      symptomatic, to when another individual (who is infected by the infector) becomes symptomatic.">
    [?]
  </sup>
</label>
<div class="input-group">
  <!-- Serial interval input field. -->
  <input name="mu_{{ id }}" class="form-control" type="text">
  <!-- Days/weeks dropdown. -->
  <select name="mu_{{ id }}_units" class="form-select">
    <option value="Days" selected>Days</option>
    <option value="Weeks">Weeks</option>
  </select>
</div>
<!-- Warning text for incorrect values. -->
<div>
  <small id="mu_{{ id }}_warn" class="form-text text-primary shiny-text-output"></small>
</div>
