I'm trying to "clone" the TOC from this google-codelabs page here: https://codelabs.developers.google.com/codelabs/cloud-app-engine-aspnetcore
So far, it works perfectly in Google-Chrome and Firefox. 
But Internet Explorer (11)...
Juddging from Item 3, it seems like IE doesn't properly align the bullet vertically in the middle. 
Why  ?
How can I properly align the bullet and the text vertically in the middle in IE 11 ? 
This is what I have (or see fiddle):
<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
    <meta http-equiv="cache-control" content="max-age=0" />
    <meta http-equiv="cache-control" content="no-cache" />
    <meta http-equiv="expires" content="0" />
    <meta http-equiv="expires" content="Tue, 01 Jan 1980 1:00:00 GMT" />
    <meta http-equiv="pragma" content="no-cache" />
    <meta charset="utf-8" />
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <meta http-equiv="Content-Language" content="en" />
    <meta name="viewport" content="width=device-width,initial-scale=1" />
    <meta name="google" value="notranslate" />
    <title>Simple Page</title>
    <style type="text/css" media="all">
        html, body
        {
            width: 100%; height:100%;
            margin: 0px; padding: 0px;
        }
        body
        {
            background-color: #0c70b4;
            color: #546775;
            font: normal 400 18px "PT Sans", sans-serif;
            -webkit-font-smoothing: antialiased;
        }
        .googleblue
        {
            background-color:#1E88E5;
        }
        .bgLeft
        {
            background-color: #F5F5F5;
        }
        .bgRight
        {
            background-color: #E0E0E0;
        }
        .googlefontgray_line
        {
            color: #777777;
        }
    </style>
</head>
<body class="bgLeft">
    <style>
        .paper-item-0
        {
            display: -ms-flexbox;
            display: -webkit-flex;
            display: flex;
            -ms-flex-direction: row;
            -webkit-flex-direction: row;
            flex-direction: row;
            -ms-flex-align: center;
            -webkit-align-items: center;
            align-items: center;
            font-family: 'Roboto', 'Noto', sans-serif;
            -webkit-font-smoothing: antialiased;
            font-size: 16px;
            font-weight: 400;
            line-height: 24px;
            position: relative;
            min-height: 48px;
            padding: 0px 16px;
            border: 1px solid hotpink;
        }
        .toc-item
        {
            font-size: 14px;
            color: #9e9e9e;
            overflow: hidden;
            border-radius: 4px;
            padding: 6px 16px;
            box-sizing: content-box;
        }
        .bulletStyle
        {
            display: inline-block;
            font-style: normal;
            width: 24px;
            min-width: 24px;
            background-color: #fff;
            border-radius: 50%;
            text-align: center;
            height: 24px;
            vertical-align: middle;
            line-height: 24px;
            border: 2px solid #bdbdbd;
            margin-right: 8px;
            font-weight: 400;
        }
        .lineAbove::before
        {
            position: absolute;
            top: 0px;
            left: 30px;
            bottom: calc(50% + 12px);
            content: '';
            display: block;
            border-left: 1px solid #bdbdbd;
            #width: 0;
            #height: 44px;
            z-index: 1;
            #margin-top: 1px;
            #margin-left: 11px;
        }
        .lineBelow::after
        {
            position: absolute;
            top: calc(50% + 12px);
            left: 30px;
            bottom: 0px;
            content: '';
            display: block;
            border-left: 1px solid #bdbdbd;
            #width: 0;
            #height: 44px;
            z-index: 1;
            #margin-top: 1px;
            #margin-left: 11px;
        }
        /*
        .lineAbove::before
        {
            border-color: #2196f3;
        }
        */
        .tocText
        {
            font-size: 14px;
            color: #9e9e9e;
            padding: 6px 16px;
        }
    </style>
    <paper-item class="toc-item paper-item-0" role="option" tabindex="0" aria-disabled="false" aria-selected="true">
        <i class="bulletStyle #lineAbove lineBelow">1</i>
        <span class="tocText">Overview</span>
    </paper-item>
    <paper-item class="toc-item paper-item-0" role="option" tabindex="-1" aria-disabled="false">
        <i class="bulletStyle lineAbove lineBelow">2</i>
        <span class="tocText">Setup and requirements
            <br />Line 1
            <br />Line 2
            <br />Line 3
            <br />Line 4
            <br />Line 5
            <br />Line 6
        </span>
    </paper-item>
    <paper-item class="toc-item paper-item-0" role="option" tabindex="-1" aria-disabled="false">
        <i class="bulletStyle lineAbove lineBelow">3</i>
        <span class="tocText">foo</span>
    </paper-item>
    <a class="toc-item paper-item-0" role="option" tabindex="-1" aria-disabled="false">
        <i class="bulletStyle lineAbove #lineBelow">4</i>
        <span class="tocText">foo</span>
    </a>
</body>
</html>

 
     
     
    