arduino-ide/arduino-ide-extension/src/browser/style/main.css

#theia-bottom-content-panel
    .p-TabBar[data-orientation="horizontal"].theia-app-bottom {
    background: var(--theia-editorGroupHeader-tabsBackground);
}

/* Avoid the Intellisense widget may be cover by the bottom panel partially.
   TODO: This issue may be resolved after monaco-editor upgrade */
#theia-main-content-panel {
    z-index: auto;
}

#theia-main-content-panel div[id^="code-editor-opener"] {
    z-index: auto;
}

.p-TabBar-toolbar .item.arduino-tool-item {
    margin-left: 0;
}

.p-TabBar-toolbar .item.arduino-tool-item .toggle-serial-monitor,
.p-TabBar-toolbar .item.arduino-tool-item .arduino-save-sketch--toolbar,
.p-TabBar-toolbar .item.arduino-tool-item .arduino-open-sketch--toolbar,
.p-TabBar-toolbar .item.arduino-tool-item .arduino-new-sketch--toolbar {
    border-radius: 1px;
}

.p-TabBar-toolbar .item.arduino-tool-item > div {
    display: flex;
    justify-content: center;
    align-items: center;
    height: var(--arduino-button-height);
    width: var(--arduino-button-height);
}

.p-TabBar-toolbar .item.arduino-tool-item .arduino-upload-sketch--toolbar,
.p-TabBar-toolbar .item.arduino-tool-item .arduino-verify-sketch--toolbar,
.p-TabBar-toolbar .item.arduino-tool-item .arduino-start-debug {
    background: var(--theia-arduino-toolbar-button-background);
}

.p-TabBar-toolbar .item.arduino-tool-item.enabled:hover > div {
    background: var(--theia-arduino-toolbar-button-hoverBackground);
}

.p-TabBar-toolbar
    .item.arduino-tool-item.enabled:hover
    > div.toggle-serial-monitor,
.p-TabBar-toolbar
    .item.arduino-tool-item.enabled:hover
    > div.toggle-serial-plotter {
    background-color: var(
        --theia-arduino-toolbar-button-secondary-hoverBackground
    );
    border-radius: 14px;
}

.arduino-verify-sketch--toolbar,
.arduino-upload-sketch--toolbar,
.arduino-start-debug {
    border-radius: 14px;
}

.item.arduino-tool-item.toggled {
    background-color: unset;
    opacity: 1;
    border: none;
}

.item.arduino-tool-item.toggled .arduino-verify-sketch--toolbar,
.item.arduino-tool-item.toggled .arduino-upload-sketch--toolbar {
    background-color: var(--theia-arduino-toolbar-toggleBackground) !important;
}

.arduino-tool-icon {
    height: var(--arduino-button-height);
    width: var(--arduino-button-height);
}

.arduino-verify-sketch--toolbar-icon {
    -webkit-mask: url(../icons/verify.svg) center no-repeat;
    background-color: var(--theia-titleBar-activeBackground);
}

.arduino-upload-sketch--toolbar-icon {
    -webkit-mask: url(../icons/upload.svg) center no-repeat;
    background-color: var(--theia-titleBar-activeBackground);
}

.toggle-serial-monitor-icon {
    -webkit-mask: url(../icons/monitor.svg) center no-repeat;
    background-color: var(--theia-arduino-toolbar-button-secondary-label);
}

.toggle-serial-plotter-icon {
    -webkit-mask: url(../icons/plotter.svg) center no-repeat;
    background-color: var(--theia-arduino-toolbar-button-secondary-label);
}

.arduino-start-debug-icon {
    -webkit-mask: url("../icons/debug-dark.svg") 50% 60%;
    -webkit-mask-size: 70%;
    -webkit-mask-repeat: no-repeat;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: var(--theia-titleBar-activeBackground);
}

#arduino-toolbar-container {
    display: flex;
    width: 100%;
    justify-content: space-between;
}

.p-TabBar-toolbar.theia-arduino-toolbar {
    align-items: center;
    gap: 8px;
    margin: 0 12px;
    padding: 0;
    z-index: 0;
}

.p-TabBar-toolbar .item > div {
    text-align: center;
}

:root {
    --theia-private-menubar-height: 40px; /* set the topbar height */
}

#theia-top-panel .p-TabBar-toolbar.theia-arduino-toolbar.right {
    justify-content: flex-start;
}

#theia-top-panel .p-TabBar-toolbar.theia-arduino-toolbar.left {
    min-width: 398px;
    justify-content: flex-end;
}

.arduino-toolbar-tooltip {
    display: flex;
    align-items: center;
    color: var(--theia-titleBar-activeForeground);
}

.arduino-open-boards-control-icon {
    mask: none;
    -webkit-mask: none;
    background: none;
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--theia-titleBar-activeBackground);
}
.p-TabBar.theia-app-sides .p-TabBar-tabIcon.fa-arduino-folder,
.p-TabBar.theia-app-sides .p-TabBar-tabIcon.fa-arduino-boards {
    font-size: 21px;
}

.monaco-editor .margin {
    border-right: 2px solid var(--theia-sideBar-background);
    box-sizing: border-box;
}

.noWrapInfo {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.theia-sidepanel-toolbar .theia-sidepanel-title {
    margin-left: 10px;
}

/* Output */
.theia-output .editor-container {
    background-color: var(--theia-terminal-background);
}

.theia-output .monaco-editor .lines-content.monaco-editor-background {
    background-color: var(--theia-terminal-background);
}

.theia-output
    .monaco-editor
    .lines-content.monaco-editor-background
    .view-lines
    .view-line
    .mtk1:not(.theia-output-error):not(.theia-output-warning) {
    color: var(--theia-terminal-foreground);
}

.theia-output .monaco-editor .margin {
    border-right: none;
    background-color: var(--theia-terminal-background);
}

.monaco-hover .hover-row.markdown-hover:first-child p {
    margin-top: 8px;
}
.monaco-hover .hover-row.markdown-hover:first-child .monaco-tokenized-source {
    margin-top: 8px;
}