How to add custom font sizes to QuillJS editor

How do you add custom font sizes to the toolbar with QuillJS? I've tried two approaches:

// Initiate the editor
        let toolbarOptions = [
            ['bold', 'italic', 'underline', 'strike'],
            [{ 'align': [] }],
            [{ 'size': ['10px', '20px', '80px'] }],
            [{ 'color': ['#FFF'] }]
        ];
        this.editor = new Quill('#executive-control-editor', {
            modules: {
                toolbar: toolbarOptions
            },
            theme: 'snow'
        });

and

<div id="toolbar">
        <span class="ql-formats">
            <button class="ql-bold"></button>
            <button class="ql-italic"></button>
            <button class="ql-underline"></button>
            <button class="ql-strike"></button>
        </span>
        <span class="ql-formats">
            <select class="ql-align"></select>
        </span>
        <span class="ql-format-group">
          <select title="Size" class="ql-size">
            <option value="10px">Small</option>
            <option value="13px">Normal</option>
            <option value="18px">Large</option>
            <option value="32px">Huge</option>
          </select>
        </span>
        <span class="ql-formats">
            <button class="ql-image"></button>
        </span>
    </div>

However neither of them work. Is there something I'm missing here? I've tried removing the "px" from the value as well; still nothing.

It's a bit weird right now so I may add this into a Quill configuration. But for now, the reason it's not working is Quill uses classes by default for sizing and what you want is inline styles. You can change this with:

var Size = Quill.import('attributors/style/size');
Quill.register(Size, true);

// Rest is the same
var editor = new Quill('#editor');