plane/apps/app/styles/editor.css

.ProseMirror p.is-editor-empty:first-child::before {
  content: attr(data-placeholder);
  float: left;
  color: rgb(var(--color-text-400));
  pointer-events: none;
  height: 0;
}

.ProseMirror .is-empty::before {
  content: attr(data-placeholder);
  float: left;
  color: rgb(var(--color-text-400));
  pointer-events: none;
  height: 0;
}

/* Custom image styles */

.ProseMirror img {
  transition: filter 0.1s ease-in-out;

  &:hover {
    cursor: pointer;
    filter: brightness(90%);
  }

  &.ProseMirror-selectednode {
    outline: 3px solid #5abbf7;
    filter: brightness(90%);
  }
}

/* Custom TODO list checkboxes – shoutout to this awesome tutorial: https://moderncss.dev/pure-css-custom-checkbox-style/ */

ul[data-type="taskList"] li > label {
  margin-right: 0.2rem;
  user-select: none;
}

@media screen and (max-width: 768px) {
  ul[data-type="taskList"] li > label {
    margin-right: 0.5rem;
  }
}

ul[data-type="taskList"] li > label input[type="checkbox"] {
  -webkit-appearance: none;
  appearance: none;
  background-color: rgb(var(--color-background-100));
  margin: 0;
  cursor: pointer;
  width: 1.2rem;
  height: 1.2rem;
  position: relative;
  border: 2px solid rgb(var(--color-text-100));
  margin-right: 0.3rem;
  display: grid;
  place-content: center;

  &:hover {
    background-color: rgb(var(--color-background-80));
  }

  &:active {
    background-color: rgb(var(--color-background-90));
  }

  &::before {
    content: "";
    width: 0.65em;
    height: 0.65em;
    transform: scale(0);
    transition: 120ms transform ease-in-out;
    box-shadow: inset 1em 1em;
    transform-origin: center;
    clip-path: polygon(14% 44%, 0 65%, 50% 100%, 100% 16%, 80% 0%, 43% 62%);
  }

  &:checked::before {
    transform: scale(1);
  }
}

ul[data-type="taskList"] li[data-checked="true"] > div > p {
  color: rgb(var(--color-text-200));
  text-decoration: line-through;
  text-decoration-thickness: 2px;
}

/* Overwrite tippy-box original max-width */

.tippy-box {
  max-width: 400px !important;
}

.ProseMirror {
  position: relative;
  word-wrap: break-word;
  white-space: pre-wrap;
  -moz-tab-size: 4;
  tab-size: 4;
  -webkit-user-select: text;
  -moz-user-select: text;
  -ms-user-select: text;
  user-select: text;
  outline: none;
  cursor: text;
  line-height: 1.2;
  font-family: inherit;
  font-size: 14px;
  color: inherit;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
  appearance: textfield;
  -webkit-appearance: textfield;
  -moz-appearance: textfield;
}

.fadeIn {
  opacity: 1;
  transition: opacity 0.3s ease-in;
}

.fadeOut {
  opacity: 0;
  transition: opacity 0.2s ease-out;
}

.img-placeholder {
  position: relative;
  width: 35%;

  &:before {
    content: "";
    box-sizing: border-box;
    position: absolute;
    top: 50%;
    left: 45%;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    border: 3px solid rgba(var(--color-text-200));
    border-top-color: rgba(var(--color-text-800)); 
    animation: spinning 0.6s linear infinite;
  }
}

@keyframes spinning {
  to {
    transform: rotate(360deg);
  }
}