index.css

html,
input,
textarea {
  font-family: 'Roboto', sans-serif;
  line-height: 1.4;
  background: #eee;
}

body {
  margin: 0;
}

p {
  margin: 0;
}

pre {
  padding: 10px;
  background-color: #eee;
  white-space: pre-wrap;
}

:not(pre) > code {
  font-family: monospace;
  background-color: #eee;
  padding: 3px;
}

img {
  max-width: 100%;
  max-height: 20em;
}

blockquote {
  border-left: 2px solid #ddd;
  margin-left: 0;
  margin-right: 0;
  padding-left: 10px;
  color: #aaa;
  font-style: italic;
}

blockquote[dir='rtl'] {
  border-left: none;
  padding-left: 0;
  padding-right: 10px;
  border-right: 2px solid #ddd;
}

table {
  border-collapse: collapse;
}

td {
  padding: 10px;
  border: 2px solid #ddd;
}

input {
  box-sizing: border-box;
  font-size: 0.85em;
  width: 100%;
  padding: 0.5em;
  border: 2px solid #ddd;
  background: #fafafa;
}

input:focus {
  outline: 0;
  border-color: blue;
}

[data-slate-editor] > * + * {
  margin-top: 1em;
}