Hide the Notion header

/* Remove Notion Header (Page Title, Cover and Icon)*/
.notion-header {
    display: none!important;
}

.super-content {
    padding-top: 60px!important; /* You can change this number */ 
}

Change the maximum page width

/* Change the max width of the page content */
:root {
    --max-width: 990px!important;
}

Turn a callout block into a button

/* Turn a single line callout block into a button (Entire block is clickable) */
 .notion-callout { 
  position: relative!important;
}

.notion-callout .notion-callout__content:first-of-type > .notion-semantic-string span .notion-link {
  position: absolute!important;
  height: 100%!important;
  width: 100%!important;
  top: 0!important;
  left: 0!important;
  right: 0!important;
  bottom: 0!important;
  padding: 15px!important;
  padding-left: 50px!important;
  border: none!important;
}

Change default text color

/* Change default text color */
:root {
	--color-text-default: #2b2b2b!important;
}

Change default background color

/* Change default background color */
:root {
	--color-bg-default: #eeeeee!important;
}

Modify Notion colors

/* Change Notion text colors */
:root {
  --color-text-blue: #2081e2!important;
  --color-text-red: #e2a79e!important;
  --color-text-green: #115e67!important;
  --color-text-pink: #fbbfe5!important;
  --color-text-yellow: #ffd140!important;
  --color-text-orange: #fba067!important;
  --color-text-purple: #80379c!important;
  --color-text-gray: #2b2b2b!important;
  --color-text-brown: #404040!important;
}

/* Change Notion background colors */
:root {
  --color-bg-blue-light: #2081e2!important;
  --color-bg-red-light: #e2a79e!important;
  --color-bg-green-light: #115e67!important;
  --color-bg-pink-light: #fbbfe5!important;
  --color-bg-yellow-light: #ffd140!important;
  --color-bg-orange-light: #fba067!important;
  --color-bg-purple-light: #80379c!important;
  --color-bg-gray-light: #2b2b2b!important;
  --color-bg-brown-light: #404040!important;
}