My Atom.app configuration

style.css

atom-text-editor,
atom-workspace {
  font-family: "OperatorSSm-Light";
  font-size: 13px;
  line-height: 1.6;
}

atom-text-editor {
  background-color: hsl(243, 26%, 12%) !important;
}

.welcome,
atom-workspace atom-workspace-axis.vertical {
  font-family: -apple-system, BlinkMacSystemFont, sans-serif !important;
}

.line-numbers > div {
  font-family: Menlo, Consolas, 'DejaVu Sans Mono', monospace;
  background: #181727 !important;
}

atom-text-editor .syntax--attribute-name {
  font-family: "OperatorSSm-LightItalic";
  font-style: italic;
}

atom-panel-container,
atom-pane .tab-bar {
  font-family: -apple-system, BlinkMacSystemFont, sans-serif;
  font-size: 12px;
}

atom-pane .tab-bar .tab.active {
  font-weight: 300;
  font-style: italic;
}

atom-pane-container atom-pane {
  border: 0;
}

atom-pane-container .tree-view {
  background: #222037;
}

.tree-view .project-root.project-root.selected > .header .name {
  color: #FFA053;
}

.list-tree.has-collapsable-children .list-nested-item.collapsed > .list-item::before {
  vertical-align: middle;
  color: #FFA053;
}

.list-tree.has-collapsable-children .list-nested-item > .list-item::before {
  top: 1px;
}

.list-group .selected::before,
.list-tree .selected::before {
  background: #963700;
  height: 28px;
}

.expanded .header span,
.expanded .list-item:before {
  color: #FFA053;
}

.project-root.expanded > .directory .header .name {
  color: #A2C2BD !important;
}

.list-tree.file.selected span {
  color: #FFA053;
}

.list-group li.list-nested-item > .list-item,
.list-group li:not(.list-nested-item),
.list-tree li.list-nested-item > .list-item,
.list-tree li:not(.list-nested-item) {
  line-height: 28px;
}

.list-group li.list-nested-item.selected > .list-item,
.list-group li:not(.list-nested-item).selected,
.list-tree li.list-nested-item.selected > .list-item,
.list-tree li:not(.list-nested-item).selected {
  color: #FFA053;
}

//Remove the new tab appearance on the left tree view
.left .panes .tab-bar {
  display: none;
}

.tab .title {
  background: transparent !important;
}

.tab.texteditor.active::before {
  bottom: 1px !important;
  top: 0 !important;
  width: 1px;
}

.tab.texteditor.active::after {
  border-bottom-color: transparent !important;
  box-shadow: none !important;
}

.tab-bar .tab .close-icon {
  border-radius: 50rem;
}

.tab-bar .tab .close-icon:hover {
  color: #fff;
  background-color: rgba(0, 0, 0, .5);
}

.header.tool-panel.panel-header {
  border-color: rgba(0, 0, 0, .2);
}