Usability - off switch for transparency

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Is your feature request related to a problem? Please describe.

I am unable to use Nextcloud on older hardware. The rendering of the web UI is so slow that it becomes unusable. This is also true for VMs without hardware acceleration.

Describe the solution you'd like

Nextcloud should consider adding an off switch for UI effects (like transparency/animations).

Describe alternatives you've considered

I was able to fix the problem by using custom CSS.

If an off switch is not feasible maybe something like this can be added to the docs?

[data-theme-dark] {
  --color-main-background:#171717;
  --color-main-background-rgb:23,23,23;
  --color-main-background-translucent:#171717;
  --color-main-background-blur:#171717;
  --filter-background-blur:none;
  --gradient-main-background:none;
  --color-background-hover:#212121;
  --color-background-dark:#292929;
  --color-background-darker:#3b3b3b;
  --color-placeholder-light:#313131;
  --color-placeholder-dark:#4a4a4a;
  --color-main-text:#D8D8D8;
  --color-text-maxcontrast:#8c8c8c;
  --color-text-maxcontrast-default:#8c8c8c;
  --color-text-maxcontrast-background-blur:#919191;
  --color-text-light:#bfbfbf;
  --color-text-lighter:#a5a5a5;
  --color-scrollbar:#3d3d3d;
  --color-error:#e9322d;
  --color-error-rgb:233,50,45;
  --color-error-hover:#ed5a56;
  --color-warning:#eca700;
  --color-warning-rgb:236,167,0;
  --color-warning-hover:#efb832;
  --color-success:#46ba61;
  --color-success-rgb:70,186,97;
  --color-success-hover:#6ac780;
  --color-loading-light:#777;
  --color-loading-dark:#CCC;
  --color-box-shadow-rgb:0,0,0;
  --color-box-shadow:#000000;
  --color-border:#292929;
  --color-border-dark:#3b3b3b;
  --color-border-maxcontrast:#646464;
  --font-face:-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen-Sans, Cantarell, Ubuntu, 'Helvetica Neue', Arial, sans-serif, 'Noto Color Emoji', 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';
  --default-font-size:15px;
  --animation-quick:100ms;
  --animation-slow:300ms;
  --border-radius:3px;
  --border-radius-large:10px;
  --border-radius-pill:100px;
  --default-clickable-area:44px;
  --default-line-height:24px;
  --default-grid-baseline:4px;
  --header-height:50px;
  --navigation-width:300px;
  --sidebar-min-width:300px;
  --sidebar-max-width:500px;
  --list-min-width:200px;
  --list-max-width:300px;
  --header-menu-item-height:44px;
  --header-menu-profile-item-height:66px;
  --breakpoint-mobile:1024px;
  --background-invert-if-dark:invert(100%);
  --background-invert-if-bright:no;
  --background-image-invert-if-bright:no;
  --image-background:no;
  --image-background-default:no;
  --color-background-plain:#00070B;
  --primary-invert-if-bright:no;
  --color-primary:#00070B;
  --color-primary-default:#00304A;
  --color-primary-text:#ffffff;
  --color-primary-hover:#040a0d;
  --color-primary-light:#141515;
  --color-primary-light-text:#999b9d;
  --color-primary-light-hover:#1d1e1e;
  --color-primary-text-dark:#ededed;
  --color-primary-element:#00070B;
  --color-primary-element-default-hover:#042b3f;
  --color-primary-element-text:#ffffff;
  --color-primary-element-hover:#040a0d;
  --color-primary-element-light:#141515;
  --color-primary-element-light-text:#999b9d;
  --color-primary-element-light-hover:#1d1e1e;
  --color-primary-element-text-dark:#ededed;
  --gradient-primary-background:none;
}

[data-theme-light] {
  --color-main-background: #ffffff;
  --color-main-background-rgb: 255,255,255;
  --color-main-background-translucent: #ffffff;
  --color-main-background-blur: #ffffff;
  --filter-background-blur: none;
  --gradient-main-background: none;
  --color-background-hover: #f5f5f5;
  --color-background-dark: #ededed;
  --color-background-darker: #dbdbdb;
  --color-placeholder-light: #e6e6e6;
  --color-placeholder-dark: #cccccc;
  --color-main-text: #222222;
  --color-text-maxcontrast: #767676;
  --color-text-maxcontrast-default: #767676;
  --color-text-maxcontrast-background-blur: #646464;
  --color-text-light: #222222;
  --color-text-lighter: #767676;
  --color-scrollbar: rgba(34,34,34, .15);
  --color-error: #e9322d;
  --color-error-rgb: 233,50,45;
  --color-error-hover: #ed5a56;
  --color-warning: #eca700;
  --color-warning-rgb: 236,167,0;
  --color-warning-hover: #efb832;
  --color-success: #46ba61;
  --color-success-rgb: 70,186,97;
  --color-success-hover: #6ac780;
  --color-loading-light: #cccccc;
  --color-loading-dark: #444444;
  --color-box-shadow-rgb: 77,77,77;
  --color-box-shadow: #777777;
  --color-border: #ededed;
  --color-border-dark: #dbdbdb;
  --color-border-maxcontrast: #949494;
  --font-face: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen-Sans, Cantarell, Ubuntu, 'Helvetica Neue', Arial, sans-serif, 'Noto Color Emoji', 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';
  --default-font-size: 15px;
  --animation-quick: 100ms;
  --animation-slow: 300ms;
  --border-radius: 3px;
  --border-radius-large: 10px;
  --border-radius-pill: 100px;
  --default-clickable-area: 44px;
  --default-line-height: 24px;
  --default-grid-baseline: 4px;
  --header-height: 50px;
  --navigation-width: 300px;
  --sidebar-min-width: 300px;
  --sidebar-max-width: 500px;
  --list-min-width: 200px;
  --list-max-width: 300px;
  --header-menu-item-height: 44px;
  --header-menu-profile-item-height: 66px;
  --breakpoint-mobile: 1024px;
  --background-invert-if-dark: no;
  --background-invert-if-bright: invert(100%);
  --background-image-invert-if-bright: no;
  --image-background: no;
  --image-background-default: no;
  --color-background-plain: #9c4236;
  --primary-invert-if-bright: no;
  --color-primary: #9c4236;
  --color-primary-default: #00304A;
  --color-primary-text: #ffffff;
  --color-primary-hover: #af675e;
  --color-primary-light: #f5ecea;
  --color-primary-light-text: #3e1a15;
  --color-primary-light-hover: #eae1df;
  --color-primary-text-dark: #ededed;
  --color-primary-element: #9c4236;
  --color-primary-element-default-hover: #32596e;
  --color-primary-element-text: #ffffff;
  --color-primary-element-hover: #af675e;
  --color-primary-element-light: #f5ecea;
  --color-primary-element-light-text: #3e1a15;
  --color-primary-element-light-hover: #eae1df;
  --color-primary-element-text-dark: #ededed;
  --gradient-primary-background: none;
}

No implementation files, tests, or entry points are identified in the issue. First determine whether the scope is a UI setting or documentation of the supplied CSS workaround; done means the chosen behavior is available and verified on older hardware, or the workaround is documented.