@inject IJSRuntime js

<TelerikEditor @bind-Value="@EditorValue" />

@* Move scripts to separate js files in production. *@
<script suppress-error="BL9992">
    function injectEditorStyleTag() {
        var doc = document.querySelector("iframe").contentWindow.document;
        var head = doc.querySelector("head");
        
        var style = doc.createElement("style");
        style.type = "text/css";
        
        var css = "body { background: #fed; font-size: 24px; }";
        
        style.appendChild(doc.createTextNode(css));
        head.appendChild(style);
    }
</script>

@code {
    private string EditorValue { get; set; } = "<p>The default font-size is 24px.</p>";

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            await js.InvokeVoidAsync("injectEditorStyleTag");
        }
    }
}