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;
}

.ProseMirror pre {
  background: #121212;
  border-radius: 0.375rem;
  border-color: rgba(var(--color-background-100));
  border: 0.5px solid;
  font-family: "JetBrainsMono", monospace;
  padding: 0.75rem 1rem;
}

.ProseMirror pre code {
  background: none;
  color: inherit;
  font-size: 0.8rem;
  padding: 0;
}

.ProseMirror-icon {
  display: inline-block;
  line-height: 0.8;
  vertical-align: -2px;
  color: #666;
  cursor: pointer;
  margin: 0 3px;
  padding: 3px 8px;
  border-radius: 3px;
  border: 1px solid transparent;
  transition: background 50ms ease-in-out;
  -moz-user-select: none;
  -webkit-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

.ProseMirror-menu-disabled.ProseMirror-icon {
  opacity: 0.3;
  cursor: default;
  pointer-events: none;
}

.ProseMirror-icon svg {
  fill: currentColor;
  height: 1em;
}

.ProseMirror-icon span {
  vertical-align: text-top;
}

.remirror-editor-wrapper .remirror-editor {
  min-height: 150px;
}

.issue-comments-section .remirror-editor-wrapper .remirror-editor,
.page-block-section .remirror-editor-wrapper .remirror-editor {
  min-height: 50px;
}

.remirror-section .remirror-editor-wrapper .remirror-editor {
  min-height: 0 !important;
}

.remirror-editor-wrapper {
  padding-top: 8px;
}

.MuiButtonBase-root {
  border: none !important;
  border-radius: 0.25rem !important;
  padding: 0.25rem !important;
}

.MuiButtonBase-root svg {
  fill: rgb(var(--color-text-100)) !important;
}

.MuiButtonBase-root.Mui-selected,
.MuiButtonBase-root:hover {
  background-color: rgb(var(--color-background-100)) !important;
}