Some useful things that I'm use not really often, but i want to keep it in one place instead of googling them every time i need it.

aria-cursor-styles.css

/* ref: https://codepen.io/HannahF/pen/wMNVbr */

/* specify the progress cursor of updating elements */
[aria-busy="true"] {
  cursor: progress;
}

/* specify the pointer cursor of trigger elements */
[aria-controls] {
  cursor: pointer;
}

/* specify the unstyled cursor of disabled, not-editable, or otherwise inoperable elements */
[aria-disabled] {
  cursor: default;
}

easings.css

/* Cubic Bezier variations, for more see here: http://easings.net */

:root {
  --ease-in-quad: cubic-bezier(0.55, 0.085, 0.68, 0.53);
  --ease-in-cubic: cubic-bezier(0.55, 0.055, 0.675, 0.19);
  --ease-in-quart: cubic-bezier(0.895, 0.03, 0.685, 0.22);
  --ease-in-quint: cubic-bezier(0.755, 0.05, 0.855, 0.06);
  --ease-in-expo: cubic-bezier(0.95, 0.05, 0.795, 0.035);
  --ease-in-circ: cubic-bezier(0.6, 0.04, 0.98, 0.335);
  --ease-out-quad: cubic-bezier(0.25, 0.46, 0.45, 0.94);
  --ease-out-cubic: cubic-bezier(0.215, 0.61, 0.355, 1);
  --ease-out-quart: cubic-bezier(0.165, 0.84, 0.44, 1);
  --ease-out-quint: cubic-bezier(0.23, 1, 0.32, 1);
  --ease-out-expo: cubic-bezier(0.19, 1, 0.22, 1);
  --ease-out-circ: cubic-bezier(0.075, 0.82, 0.165, 1);
  --ease-in-out-quad: cubic-bezier(0.455, 0.03, 0.515, 0.955);
  --ease-in-out-cubic: cubic-bezier(0.645, 0.045, 0.355, 1);
  --ease-in-out-quart: cubic-bezier(0.77, 0, 0.175, 1);
  --ease-in-out-quint: cubic-bezier(0.86, 0, 0.07, 1);
  --ease-in-out-expo: cubic-bezier(1, 0, 0, 1);
  --ease-in-out-circ: cubic-bezier(0.785, 0.135, 0.15, 0.86);
}

reset-input-number.css

/* Hides controls of default input with type number */

input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

input[type="number"] {
  -moz-appearance: textfield;
}

selection.css

/* Change styles for selected text */

:root {
  --text-selection-background: black;
  --text-selection-background: white;
}

*::selection {
  background-color: var(--text-selection-background);
  color: var(--text-selection-color);
}

system-fonts.css

/* System fonts that used by default in different OS */

:root {
  --system-fonts: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
                  Oxygen-Sans, Ubuntu, Cantarell,
                  "Helvetica Neue", Helvetica, Arial, sans-serif;
}

text-overflow-handlers.css

--word-wrap {
  overflow-wrap: break-word;
}

--ellipsis {
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
}

visually-hidden.css

/* Hides element from screen, but not from screenreaders. Also keyboard users still can access it too. */

.visually-hidden:not(:focus):not(:active) {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  border: 0;
  padding: 0;
  white-space: nowrap;
  clip-path: inset(100%);
  clip: rect(0 0 0 0);
  overflow: hidden;
}

.visually-hidden *:focus { 
    position:static; 
    width:auto; height:auto;  
}

/* Just a snippet */
--visually-hidden {
  position: absolute;
  /* Setting dimensions to 0 make it invisible for VoiceOver */
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  border: 0;
  clip: rect(0 0 0 0);
  overflow: hidden;
}