index.css

html {
  --primary-color: #000000;
  --accent-color: rgb(33, 150, 243);
  /* Text primary color on the accent background */
  --text-primary-color: #fff;
  --dark-divider-opacity: 0.12;
  --arc-font-body1-font-size: 14px;
  --arc-font-body1-font-weight: 400;
  --arc-font-body1-line-height: 20px;
  --arc-font-code-family: 'Roboto Mono', 'Consolas', 'Menlo', monospace;
  --code-background-color: #f5f7f9;
  --anypoiont-menu-button-dropdown-background: #fff;
  --anypoint-listbox-background-color: #fff;
  --anypoint-item-focused-background-color: #f5f5f5;
  --anypoint-item-before-background: transparent;
  --anypoiont-dropdown-shaddow: 0 4px 5px 0 rgba(0, 0, 0, 0.14), 0 1px 10px 0 rgba(0, 0, 0, 0.12), 0 2px 4px -1px rgba(0, 0, 0, 0.4);
  --primary-color: #3F51B5;
  --anypoint-color-primary: var(--primary-color);
  --anypoint-dialog-background-color: #fff;
  --error-color: #D32F2F;
  --secondary-text-color: #9E9E9E;
  --anypoint-item-body-secondary-color: #9E9E9E;
}
html {
  font-family: 'Roboto', sans-serif;
  font-size: 15px;
  background-color: #fafafa;
  color: #5f6368;
}

body {
  display: flex;
  flex-direction: column;
}

html,
body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  height: 100%;
}

api-modeling-app {
  flex: 1;
}