Improved lighthouse performance score through inlining CSS

src/Program.cs

@@ -6,6 +6,7 @@ using Berufsschule_HAM.Services;
 using Berufsschule_HAM.Models;
 using Berufsschule_HAM.HealthChecks;
 using System.Text.Json.Serialization;
+using Microsoft.AspNetCore.ResponseCompression;
 var builder = WebApplication.CreateBuilder(args);
 
 // Bind options
@@ -50,6 +51,8 @@ builder.Services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationSc
 builder.Services.AddResponseCompression(options =>
 {
     options.EnableForHttps = true;
+    options.Providers.Add<GzipCompressionProvider>();
+    options.Providers.Add<BrotliCompressionProvider>();
     options.MimeTypes =
     [
         "text/plain",

src/Views/Settings/Admin.cshtml

@@ -16,8 +16,8 @@
 }
 
 <form id="updateSettings" style="margin-bottom: 4rem !important" method="post" asp-controller="Settings" asp-action="Admin">
-    <div class="row g-3">
     <h4 class="fw-bold">@T["General settings"]</h4>
+    <div class="row g-3">
         <div class="col-md-3">
             <label class="form-label" for="updateHashAlgorithm">@T["Default hash algorithm"]</label>
             <select type="text" name="DefaultHashAlgorithm" id="updateHashAlgorithm" class="form-control">

src/Views/Shared/_Layout.cshtml

@@ -12,14 +12,26 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>@ViewData["Title"] - Berufsschule_HAM</title>
     <script type="importmap"></script>
-    @* <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.min.css" asp-append-version="true"/> *@
+    <style>
+        @if (Context.Request.Path.Value is not null)
+        {
+            string path = System.IO.Path.Combine("CriticalCSS", Context.Request.Path.Value.Trim('/').Replace("/", ".") + ".css");
+            if (File.Exists(path))
+            {
+                @Html.Raw(File.ReadAllText(path));
+            }
+        } else {
+            @Html.Raw(File.ReadAllText("CriticalCSS/_Layout.css"));
+        }
+    </style>
+    <link rel="preload" href="~/lib/bootstrap/dist/css/bootstrap.min.css" as="style"/>
     <link rel="stylesheet"
-      href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css"
-      crossorigin="anonymous">
+      href="~/lib/bootstrap/dist/css/bootstrap.min.css"
+      media="print"
+      onload="this.media='all'">
     @* <link rel="stylesheet" href="~/css/site.css" asp-append-version="true" /> *@
     <link rel="preload" href="~/css/site.css" as="style" onload="this.onload=null;this.rel='stylesheet'">
-    <noscript><link rel="stylesheet" href="~/css/site.css"></noscript>
-    <link rel="stylesheet" href="~/Berufsschule_HAM.styles.css" asp-append-version="true" />
+    <noscript><link fetchpriority="high" rel="stylesheet" href="~/css/site.css"></noscript>
     <script>
         window.appTranslations = {
             selectLocation: '@T["Select location"]',
@@ -38,7 +50,7 @@
     </script>
     <header>
         <nav class="navbar navbar-expand-sm navbar-toggleable-sm navbar bg border-bottom box-shadow mb-3">
-            <a href="#main-content" class="skip-link btn btn-primary">@T["Jump to content"]</a>
+            <a href="#main-content" class="skip-link btn btn-primary" style="position: fixed; left: -10000px; z-index: 1000;">@T["Jump to content"]</a>
             <div class="container-fluid">
                 <a class="" asp-area="" asp-controller="Home" asp-action="Index"><img fetchpriority="high" src="/HAM_Banner_xs.png" alt="Logo" width="123" height="40" style="width: 123px; height: 40px;"></a>
                 <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target=".navbar-collapse" aria-controls="navbarSupportedContent"

src/Views/Shared/_Layout.cshtml.css

@@ -46,14 +46,3 @@ button.accept-policy {
   white-space: nowrap;
   line-height: 60px;
 }
-
-.skip-link {
-  position: fixed;
-  left: -10000px;
-  z-index: 1000;
-}
-.skip-link:focus {
-  left: 10px;
-  top: 10px;
-  outline: none;
-}

src/critical.js

@@ -0,0 +1,145 @@
+import { generate } from 'critical';
+import fs from 'fs';
+import path from 'path';
+
+import puppeteer from 'puppeteer';
+
+const browser = await puppeteer.launch();
+const page = await browser.newPage();
+
+// Login
+await page.goto('http://localhost:5275/Home/Login');
+await page.type('#username', 'admin');
+await page.type('#password', 'Test1234.');
+await page.click('button[type=submit]');
+await page.waitForNavigation();
+
+// Extract cookies
+const cookies = await page.cookies();
+await browser.close();
+
+async function generateCriticalCSSForViews() {
+  const viewsDir = 'Views';
+  
+  // Helper function to get all .cshtml files recursively
+  function getAllCshtmlFiles(dir) {
+    let results = [];
+    const list = fs.readdirSync(dir);
+    
+    list.forEach(file => {
+      const filePath = path.join(dir, file);
+      const stat = fs.statSync(filePath);
+      
+      if (stat && stat.isDirectory()) {
+        // Recursively get files from subdirectories
+        results = results.concat(getAllCshtmlFiles(filePath));
+      } else if (file.endsWith('.cshtml')) {
+        results.push(filePath);
+      }
+    });
+    
+    return results;
+  }
+  
+  // Helper function to convert file path to URL path
+  function filePathToUrlPath(filePath) {
+    // Remove 'Views/' prefix
+    let relativePath = filePath.replace(/^Views[\/\\]/, '');
+    
+    // Remove .cshtml extension
+    relativePath = relativePath.replace(/\.cshtml$/, '');
+    
+    // Convert to URL format (replace \ with / and capitalize first letter)
+    const urlPath = relativePath
+      .split(/[\/\\]/)
+      .map((segment, index) => 
+        index === 0 ? segment : segment.charAt(0).toUpperCase() + segment.slice(1)
+      )
+      .join('/');
+    
+    // Handle the case where we have a single file (like Index.cshtml)
+    if (relativePath.includes('/')) {
+      // Convert to URL path format: Views/Home/Index.cshtml -> /Home/Index
+      return '/' + relativePath.replace(/\\/g, '/').replace(/\.cshtml$/, '');
+    } else {
+      // For files directly in Views folder (like Views/Index.cshtml)
+      return '/' + relativePath.replace(/\.cshtml$/, '');
+    }
+  }
+  
+  // Get all .cshtml files
+  const cshtmlFiles = getAllCshtmlFiles(viewsDir);
+  
+  // Create CriticalCSS directory if it doesn't exist
+  const criticalCssDir = 'CriticalCSS';
+  if (!fs.existsSync(criticalCssDir)) {
+    fs.mkdirSync(criticalCssDir, { recursive: true });
+  }
+  
+  // Process each file
+  for (const file of cshtmlFiles) {
+    try {
+      const urlPath = filePathToUrlPath(file);
+      
+      // Generate critical CSS
+      await generate({
+        src: `http://localhost:5275${urlPath}`,
+        inline: false,
+        width: 1920,
+        height: 1080,
+        penthouse: {
+          customHeaders: {
+            cookie: cookies.map(c => `${c.name}=${c.value}`).join('; ')
+          },
+          forceInclude: [
+            '[data-bs-theme="dark"]',
+            '[data-bs-theme="dark"] *',
+            'body.dark',
+            '.navbar-dark',
+            '.navbar',
+            '.navbar-collapse',
+            '.dropdown',
+            '.dropdown-toggle',
+            '.dropdown-toggle::after',
+            '.dropdown-item',
+            '.dropdown-menu',
+            '.dropdown-menu-end',
+            '.dropdown-menu.show',
+            '.me-2',
+            '.align-items-center',
+            '.d-flex',
+            '.position-fixed', // print batch
+            '.bottom-0',
+            '.start-0',
+            '.m-4',
+            '.row', // elements
+            '.g-3',
+            '.col-md-3',
+            '.text-center',
+            '.mb-3',
+            '.mt-3',
+            '.py-4',
+            '.text-center',
+            'h2',
+            '.form-control',
+            '.btn',
+            '.btn-secondary',
+            '.modal',
+          ]
+        },
+        target: {
+          css: path.join(criticalCssDir, urlPath.replace(/\//g, '.').replace(/^\./, '') + '.css')
+        }
+      });
+      
+      console.log(`Critical CSS generated for: ${urlPath}`);
+    } catch (err) {
+      console.error(`Error processing ${file}:`, err);
+    }
+  }
+  
+  console.log('All critical CSS files generated!');
+}
+
+// Run the function
+generateCriticalCSSForViews().catch(console.error);

src/wwwroot/css/site.css

@@ -72,3 +72,13 @@ h3.modal-title {
 h4.fw-bold, h4.card-title {
   font-size: 1rem;
 }
+
+.table button {
+  word-break: normal;
+}
+
+.skip-link:focus {
+  left: 10px;
+  top: 10px;
+  outline: none;
+}