substance/packages/gutter/_gutter.css

Substance is a JavaScript library for web-based content editing. It provides building blocks for realizing custom text editors and web-based publishing systems.

.sc-gutter { z-index: 200; position: absolute; }
.sc-gutter.sm-hidden { visibility: hidden; position: fixed; }

.sc-gutter.sm-theme-dark::before {
  content: '';
  display: block;
  margin: 0 auto;
  width: 0;
  height: 0;
  border-style: solid;
  border-width: 0 4px 8px 4px;
  border-color: transparent transparent #2E2E2C transparent;
}

.sc-gutter.sm-theme-dark > .se-active-tools {
  background: #2E2E2C;
  padding: 5px;
}