spacing on website

@media screen and (min-width: 48em) {
.page.page-one-column .entry-header, .twentyseventeen-front-page.page-one-column .entry-header {
   margin-bottom: 1em;
  }
}

To add or override CSS: use the “Additional CSS” option in the customizer. https://codex.ww.wp.xz.cn/CSS#Custom_CSS_in_WordPress

Learn to use the Chrome Developer Tools to help you see and test changes to your CSS.