RazorSvelte/Pages/Shared/_Layout.cshtml

﻿@using System.Security.Claims
@using Microsoft.IdentityModel.JsonWebTokens
@{
    var user = JsonSerializer.Serialize(new
    {
        isSigned = User.Identity?.IsAuthenticated,
        name = User.Claims.FirstOrDefault(c => c.Type == ClaimTypes.NameIdentifier)?.Value,
        email = User.Claims.FirstOrDefault(c => c.Type == ClaimTypes.Email)?.Value,
        timezone = User.Claims.FirstOrDefault(c => c.Type == "timezone")?.Value,
        timestamp = User.Claims.FirstOrDefault(c => c.Type == JwtRegisteredClaimNames.AuthTime)?.Value
    });
}
<html lang="en">
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>@ViewData["Title"] - @Consts.Title</title>
    <link href="~/style.css" asp-append-version="true" rel="stylesheet" />
    @await RenderSectionAsync("HeadSection", required: false)
    <script>
    (function() {
        var theme = localStorage.getItem("@Consts.ThemeKey");
        if (!theme) {
            theme = window.matchMedia && window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
            localStorage.setItem("@Consts.ThemeKey", theme);
        }
        document.getElementsByTagName("html")[0].dataset.bsTheme = theme;
    })();
    </script>
</head>
<body class="d-flex flex-column h-100">
    @*
        These hiddens are needed by the header component on each page.
        Display basic login info in the header and make urls available to the client.
    *@
    <input id="user" type="hidden" value='@Html.Raw(user)' />
    <input id="theme-key" type="hidden" value='@Consts.ThemeKey' />
    <input id="error-key" type="hidden" value='@Consts.ErrorKey' />
    <input id="title" type="hidden" value='@Consts.Title' />
    @RenderBody()
</body>
</html>