Stylesheet to make Mastodon more macOS-like

mastodon-macos.css

body.app-body.layout-multiple-columns.theme-mastodon-light,
body.app-body.layout-multiple-columns.theme-default,
body.app-body.layout-multiple-columns.theme-contrast {
  overflow: hidden !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .columns-area,
body.app-body.layout-multiple-columns.theme-default .columns-area,
body.app-body.layout-multiple-columns.theme-contrast .columns-area {
  margin: 0 -1px !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .column,
body.app-body.layout-multiple-columns.theme-mastodon-light .drawer,
body.app-body.layout-multiple-columns.theme-default .column,
body.app-body.layout-multiple-columns.theme-default .drawer,
body.app-body.layout-multiple-columns.theme-contrast .column,
body.app-body.layout-multiple-columns.theme-contrast .drawer {
  padding: 0 !important;
  margin: -1px 0 0 -1px !important;
  flex: 1 1 auto !important;
  min-width: 300px !important;
  max-width: 450px !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .drawer,
body.app-body.layout-multiple-columns.theme-default .drawer,
body.app-body.layout-multiple-columns.theme-contrast .drawer {
  flex: 0.5 0 300px !important;
  border-left: 1px solid #c0cdd9 !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .drawer__header,
body.app-body.layout-multiple-columns.theme-default .drawer__header,
body.app-body.layout-multiple-columns.theme-contrast .drawer__header {
  border-top: none !important;
  border-left: none !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .search,
body.app-body.layout-multiple-columns.theme-default .search,
body.app-body.layout-multiple-columns.theme-contrast .search {
  padding: 10px 20px !important;
  margin: 10px 0 !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .search__input,
body.app-body.layout-multiple-columns.theme-default .search__input,
body.app-body.layout-multiple-columns.theme-contrast .search__input {
  border-radius: 10px !important;
  font-size: inherit !important;
  padding: 10px !important;
  background: inherit !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .search__icon .fa,
body.app-body.layout-multiple-columns.theme-default .search__icon .fa,
body.app-body.layout-multiple-columns.theme-contrast .search__icon .fa {
  top: 20px !important;
  right: 30px !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .drawer__header,
body.app-body.layout-multiple-columns.theme-default .drawer__header,
body.app-body.layout-multiple-columns.theme-contrast .drawer__header {
  margin: 0 !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .drawer,
body.app-body.layout-multiple-columns.theme-default .drawer,
body.app-body.layout-multiple-columns.theme-contrast .drawer {
  padding: 0 !important;
  margin: 0 !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .drawer__inner,
body.app-body.layout-multiple-columns.theme-default .drawer__inner,
body.app-body.layout-multiple-columns.theme-contrast .drawer__inner {
  border: none !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .navigation-bar,
body.app-body.layout-multiple-columns.theme-mastodon-light .compose-form,
body.app-body.layout-multiple-columns.theme-default .navigation-bar,
body.app-body.layout-multiple-columns.theme-default .compose-form,
body.app-body.layout-multiple-columns.theme-contrast .navigation-bar,
body.app-body.layout-multiple-columns.theme-contrast .compose-form {
  padding: 10px 20px !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .status__prepend,
body.app-body.layout-multiple-columns.theme-default .status__prepend,
body.app-body.layout-multiple-columns.theme-contrast .status__prepend {
  font-size: 90% !important;
  line-height: 140% !important;
  padding-bottom: 0 !important;
  margin-bottom: -5px !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .status,
body.app-body.layout-multiple-columns.theme-default .status,
body.app-body.layout-multiple-columns.theme-contrast .status {
  padding-top: 10px !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .status > *,
body.app-body.layout-multiple-columns.theme-default .status > *,
body.app-body.layout-multiple-columns.theme-contrast .status > * {
  font-size: 108% !important;
  line-height: 140% !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .status__display-name,
body.app-body.layout-multiple-columns.theme-default .status__display-name,
body.app-body.layout-multiple-columns.theme-contrast .status__display-name {
  font-size: 100% !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .muted .status__content,
body.app-body.layout-multiple-columns.theme-default .muted .status__content,
body.app-body.layout-multiple-columns.theme-contrast .muted .status__content {
  max-height: 4em !important;
  position: relative !important;
}

  body.app-body.layout-multiple-columns.theme-mastodon-light .muted .status__content:after,
body.app-body.layout-multiple-columns.theme-default .muted .status__content:after,
body.app-body.layout-multiple-columns.theme-contrast .muted .status__content:after {
    content: "";
    position: absolute;
    z-index: 1;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 1.6em;
    pointer-events: none;
}

body.app-body.layout-multiple-columns.theme-mastodon-light ::-webkit-scrollbar,
body.app-body.layout-multiple-columns.theme-default ::-webkit-scrollbar,
body.app-body.layout-multiple-columns.theme-contrast ::-webkit-scrollbar {
  width: 0 !important;
  height: 0 !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .column-header,
body.app-body.layout-multiple-columns.theme-mastodon-light .column-header button,
body.app-body.layout-multiple-columns.theme-mastodon-light .drawer-header,
body.app-body.layout-multiple-columns.theme-mastodon-light .drawer__tab {
  background: #F7FAFC !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .status,
body.app-body.layout-multiple-columns.theme-mastodon-light .column-header,
body.app-body.layout-multiple-columns.theme-mastodon-light .drawer__header {
  border-bottom: 0.5px solid #B5BEC6 !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .drawer {
  background: #fff !important;
}

body.app-body.layout-multiple-columns.theme-mastodon-light .muted .status__content:after {
  background-image: linear-gradient(to bottom,
#FFF0,
#FFFF 100%);
}

body.app-body.layout-multiple-columns.theme-default .column-header,
body.app-body.layout-multiple-columns.theme-default .column-header button,
body.app-body.layout-multiple-columns.theme-default .drawer-header,
body.app-body.layout-multiple-columns.theme-default .drawer__tab,
body.app-body.layout-multiple-columns.theme-contrast .column-header,
body.app-body.layout-multiple-columns.theme-contrast .column-header button,
body.app-body.layout-multiple-columns.theme-contrast .drawer-header,
body.app-body.layout-multiple-columns.theme-contrast .drawer__tab {
  background: #444b5d !important;
}

body.app-body.layout-multiple-columns.theme-default .search__input,
body.app-body.layout-multiple-columns.theme-contrast .search__input {
  border: 0.5px solid #8B9AC0 !important;
}

body.app-body.layout-multiple-columns.theme-default .status,
body.app-body.layout-multiple-columns.theme-default .account,
body.app-body.layout-multiple-columns.theme-default .column-header,
body.app-body.layout-multiple-columns.theme-default .drawer__header,
body.app-body.layout-multiple-columns.theme-contrast .status,
body.app-body.layout-multiple-columns.theme-contrast .account,
body.app-body.layout-multiple-columns.theme-contrast .column-header,
body.app-body.layout-multiple-columns.theme-contrast .drawer__header {
  border-bottom: 1px solid #000 !important;
}

body.app-body.layout-multiple-columns.theme-default .drawer,
body.app-body.layout-multiple-columns.theme-contrast .drawer {
  background: #444b5d !important;
}

body.app-body.layout-multiple-columns.theme-default .column > .scrollable,
body.app-body.layout-multiple-columns.theme-contrast .column > .scrollable {
  border-left: 1px solid #000 !important;
}

body.app-body.layout-multiple-columns.theme-default .muted .status__content:after,
body.app-body.layout-multiple-columns.theme-contrast .muted .status__content:after {
  background-image: linear-gradient(to bottom,
#282c3700,
#282c37FF 100%);
}

Changing the second rule to:

`body.app-body.layout-multiple-columns.theme-mastodon-light .columns-area,

body.app-body.layout-multiple-columns.theme-default .columns-area,

body.app-body.layout-multiple-columns.theme-contrast .columns-area {

max-width: 100%;

min-width: 1200px;

margin-right: -1px !important;

}`

Makes the page dynamically scale to the browser window size instead of being maxed out at 1600px wide.