Preview screenshot uses:
- Input Mono - Programming font
- Seti - Icon theme
Minor custom styling done using, custom css and js extension.
.monaco-icon-label > .monaco-icon-label-description-container > .label-name {
  letter-spacing: -1px;
  font-family: "Input Mono";
  font-weight: 400;
}
.monaco-workbench
  > .activitybar
  > .content
  .monaco-action-bar
  .action-item
  .action-label {
  background-color: #313071 !important;
}
.monaco-workbench
  > .activitybar
  > .content
  .monaco-action-bar
  .action-item.checked
  .action-label {
  background-color: #185b90 !important;
}MIT

