Server Displaying Text Instead Of HTML

I'm attempting to make a C server that will take inputs and be able to spit them back out to the user via html format where the server works as a user interface. My current issue I

Solution 1:

You need to add the response headers like this one :

for example the response header send by SO for this page is:

HTTP/2.0 200 OK
cache-control: private
content-type: text/html; charset=utf-8
content-encoding: gzip
x-frame-options: SAMEORIGIN
x-request-guid: 599a5768-3cc6-4b94-86e1-e1d1daa8acd5
strict-transport-security: max-age=15552000
content-security-policy: upgrade-insecure-requests
accept-ranges: bytes
date: Tue, 07 May 2019 13:17:15 GMT
via: 1.1 varnish
x-served-by: cache-lcy19237-LCY
x-cache: MISS
x-cache-hits: 0
x-timer: S1557235035.073229,VS0,VE89
vary: Accept-Encoding,Fastly-SSL
x-dns-prefetch-control: off
content-length: 35669
X-Firefox-Spdy: h2