Help w header, menu bar and white space

1. Use:

body {
  margin: 0;
}

#menu {
  margin-top: 0;
}

2. Use:

.page h1.entry-title {
  display: none;
}

3. These are only seen by you, the admin and are for your convenience. Would you still like to hide them?

If you’re not familiar with adding CSS, please see:

https://startupwp.com/topic/customizing-your-theme/