ElectronMCLauncher/app/overlay.ejs

<style type="text/css">

    #overlayContainer {
        position: absolute;
        top: 22px;
        display: flex;
        align-items: center;
        justify-content: center;
        width: 100%;
        height: calc(100% - 22px);
        background: rgba(0, 0, 0, 0.50);
    }

    #overlayContent {
        position: relative;
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: space-between;
        width: 300px;
        height: 35%;
        box-sizing: border-box;
        padding: 15px 0px;
        /* background-color: #424242; */
        text-align: center;
    }

    #overlayTitle {
        font-family: 'Avenir Medium';
        font-size: 20px;
        color: #fff;
        font-weight: bold;
        letter-spacing: 1px;
    }

    #overlayDesc {
        font-family: 'Avenir Book';
        font-size: 12px;
        color: #fff;
        font-weight: bold;
    }

    #overlayAcknowledge {
        background: none;
        border: 1px solid #ffffff;
        color: white;
        font-family: 'Avenir Medium';
        font-weight: bold;
        border-radius: 2px;
        width: 75px;
        cursor: pointer;
        transition: 0.25s ease;
    }
    #overlayAcknowledge:hover,
    #overlayAcknowledge:focus {
        box-shadow: 0px 0px 10px 0px #fff;
        outline: none;
    }
    #overlayAcknowledge:active {
        border-color: rgba(255, 255, 255, 0.75);
        color: rgba(255, 255, 255, 0.75);
    }
</style>
<div id="overlayContainer" style="display: none;">
    <div id="overlayContent">
        <span id="overlayTitle">LOGIN FAILED:<br>INVALID CREDENTIALS</span>
        <span id="overlayDesc">Either the email or password you supplied is invalid. Please ensure everything is correct and try again.</span>
        <button id="overlayAcknowledge">Try Again</button>
    </div>
</div>