BookStack/resources/sass/_editor.scss

// Common variables
:root {
  --editor-color-primary: #206ea7;
}

// Main UI elements
.editor-toolbar-main {
  display: flex;
  flex-wrap: wrap;
}

// Buttons
.editor-button {
  border: 1px solid #DDD;
  font-size: 12px;
  padding: 4px 6px;
  color: #444;
}
.editor-button:hover {
  background-color: #EEE;
  cursor: pointer;
  color: #000;
}
.editor-button-active, .editor-button-active:hover {
  background-color: #ceebff;
  color: #000;
}
.editor-button-format-preview {
  padding: 4px 6px;
  display: block;
}

// Containers
.editor-dropdown-menu-container {
    position: relative;
}
.editor-dropdown-menu {
  position: absolute;
  background-color: #FFF;
  box-shadow: 0 0 6px 0 rgba(0, 0, 0, 0.15);
  z-index: 99;
  min-width: 120px;
}
.editor-menu-list {
  display: flex;
  flex-direction: column;
}
.editor-menu-list > .editor-button {
  border-bottom: 0;
  text-align: start;
}

.editor-format-menu .editor-dropdown-menu {
  min-width: 320px;
}

// Modals
.editor-modal-wrapper {
  position: fixed;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 999;
  background-color: rgba(0, 0, 0, 0.5);
  width: 100%;
  height: 100%;
}
.editor-modal {
  background-color: #FFF;
  border: 1px solid #DDD;
  padding: 1rem;
  border-radius: 4px;
}
.editor-modal-header {
  display: flex;
  justify-content: space-between;
  margin-bottom: 1rem;
}
.editor-modal-title {
  font-weight: 700;
}

// Specific UI elements
.editor-color-select-row {
  display: flex;
}
.editor-color-select-option {
  width: 28px;
  height: 28px;
  cursor: pointer;
}
.editor-color-select-option:hover {
  border-radius: 3px;
  box-sizing: border-box;
  z-index: 3;
  box-shadow: 0 0 4px 1px rgba(0, 0, 0, 0.25);
}

// In-editor elements
.editor-image-wrap {
  position: relative;
  display: inline-flex;
}
.editor-image-decorator {
  position: absolute;
  left: 0;
  right: 0;
  width: 100%;
  height: 100%;
  display: inline-block;
  &.selected {
    border: 1px dashed var(--editor-color-primary);
  }
}
.editor-image-decorator-handle {
  position: absolute;
  display: block;
  width: 10px;
  height: 10px;
  border: 2px solid var(--editor-color-primary);
  background-color: #FFF;
  user-select: none;
  &.nw {
    inset-inline-start: -5px;
    inset-block-start: -5px;
    cursor: nw-resize;
  }
  &.ne {
    inset-inline-end: -5px;
    inset-block-start: -5px;
    cursor: ne-resize;
  }
  &.se {
    inset-inline-end: -5px;
    inset-block-end: -5px;
    cursor: se-resize;
  }
  &.sw {
    inset-inline-start: -5px;
    inset-block-end: -5px;
    cursor: sw-resize;
  }
}