Replace sparkle with app logo that's easier to replace (#2299)

app/frontend/src/pages/chat/Chat.tsx

@@ -2,9 +2,9 @@ import { useRef, useState, useEffect, useContext } from "react";
 import { useTranslation } from "react-i18next";
 import { Helmet } from "react-helmet-async";
 import { Panel, DefaultButton } from "@fluentui/react";
-import { SparkleFilled } from "@fluentui/react-icons";
 import readNDJSONStream from "ndjson-readablestream";
 
+import appLogo from "../../assets/applogo.svg";
 import styles from "./Chat.module.css";
 
 import {
@@ -370,7 +370,8 @@ const Chat = () => {
                 <div className={styles.chatContainer}>
                     {!lastQuestionRef.current ? (
                         <div className={styles.chatEmptyState}>
-                            <SparkleFilled fontSize={"120px"} primaryFill={"rgba(115, 118, 225, 1)"} aria-hidden="true" aria-label="Chat logo" />
+                            <img src={appLogo} alt="App logo" width="120" height="120" />
+
                             <h1 className={styles.chatEmptyStateTitle}>{t("chatEmptyStateTitle")}</h1>
                             <h2 className={styles.chatEmptyStateSubtitle}>{t("chatEmptyStateSubtitle")}</h2>
                             {showLanguagePicker && <LanguagePicker onLanguageChange={newLang => i18n.changeLanguage(newLang)} />}

app/frontend/src/pages/layout/Layout.module.css

@@ -82,11 +82,6 @@
     display: none;
 }
 
-.microsoftLogo,
-.githubLogo {
-    display: none;
-}
-
 .menuToggle {
     display: block;
     background: none;
@@ -143,14 +138,6 @@
         vertical-align: middle;
     }
 
-    .githubLogo,
-    .microsoftLogo {
-        height: 1.25rem;
-        font-weight: 600;
-        display: inline-block;
-        vertical-align: middle;
-    }
-
     .menuToggle {
         display: none;
     }