Fix/landing page vs learn page (#38085)

* fix: Use template literals for welcome conditional on /learn page

* fix: Make sign in button on /learn page same width as landing page

client/src/components/Intro/index.js

@@ -42,9 +42,7 @@ function Intro({
           <Col sm={10} smOffset={1} xs={12}>
             <Spacer />
             <h1 className='text-center big-heading'>
-              {name
-                ? 'Welcome back, ' + name + '.'
-                : 'Welcome to freeCodeCamp.org'}
+              {name ? `Welcome back, ${name}.` : `Welcome to freeCodeCamp.org`}
             </h1>
             <Spacer />
           </Col>

client/src/components/Intro/intro.css

@@ -29,7 +29,6 @@
 
 #learn-app-wrapper h2.medium-heading {
   margin-bottom: 50px;
-  margin-top: 0px;
   text-align: center;
 }
 

client/src/components/layouts/global.css

@@ -12,6 +12,7 @@ body {
   max-height: 100%;
   font-size: 27px;
   white-space: normal;
+  width: 100%;
 }
 
 .default-layout {