TfsWebCompact neatens up the look-and-feel of your Azure DevOps web backlog and task board. See also http://www.szalapski.com/2014/05/a-compact-layout-for-tfs-web-work-items.html .

TfsWebCompact.bookmarklet.js

/* The following is a bookmarklet. 
	To actually use it, it is easier to drag-and-drop starting with my blog post:
	http://www.szalapski.com/2014/05/a-compact-layout-for-tfs-web-work-items.html */
/* version 2024-09-11 */
javascript:(function () {     
const s = document.createElement('style');     
s.innerText = `
/* version 2024-09-11 */
 
/* draw attention to button when full-screen */
.full-screen-mode button.bolt-button.subtle#__bolt-full-screen { background-color: var(--palette-primary-darken-6);      color: white; }
.full-screen-mode button.bolt-button.subtle#__bolt-full-screen:after{ content: 'Show navigation'; }

/* for backlog list */
#header-row {display: none;}
.header-section .hubs-section {left:300px; top:-5px;}

.bolt-page .page-content-top,
.board-wrapper .kanban-board .kanban-board-column-header,
.vss-FilterBar,
.bolt-page .padding-16,
.boards-tabbar-tabs
{margin-top:0; padding-top:0; margin-bottom:0; padding-bottom:0;}

.nav-separated .hub-groups-section, 
.nav-separated .search-box
{margin-top:0; padding-top:0;}

.bolt-page > .bolt-header { margin-inline: 0; }

.board-wrapper >.kanban-board.padding-horizontal-16,
.bolt-page .page-content-top.page-content
{ padding-inline:4px; }


.header-post11 .hub-groups-section li,
.kanban-board-column-header-container.margin-bottom-4,
.bolt-page .page-content-bottom 
{margin-bottom:0; padding-bottom:0;}

.bolt-header-title.title-m { font-size: 1.1em;}

.bolt-button.icon-only.subtle {padding:2px}
.header-post11 #navWrapper {height:20px;}
.header-post11 + .content-section {top:20px;}
.header-post11 .hub-groups-section {padding-bottom: 0;} 
.hub-title {padding-top:9px; padding-bottom:9px;}
.hub-content .right-hub-content .hub-pivot { margin-left:300px; margin-right:340px;}
.hub-view.explorer .right-hub-content {top:3px;}
.backlog-header .toolbar .menu-bar > .menu-item{margin-top:0; margin-bottom:0; padding-top:0; padding-bottom:0; }
.backlog-header .toolbar .menu-bar > .menu-item.text-filter-box {margin-top: 0 !important;}
.backlog-header .toolbar .menu-bar > .menu-item.toggle-filter-bar {padding-bottom:0; padding-top: 0 !important;}
.backlog-header .toolbar .menu-bar > .menu-item.toggle {margin-top: 0 !important;}
.backlog-header .toolbar { height:25px; margin-bottom:0;}
.backlog-header { height:auto; margin-bottom:0;}
.productbacklog-grid-results.sprint-backlog.grid {margin-top:0;}
.grid-focus {height: 0;}
.bolt-tabbar-tabs.compact .bolt-tab {height: 20px;}
.bolt-filterbar-white {border: 1px solid lightgray;}
.grid-header-column > .title {padding-top: 0; }
.grid-row.closed-item-tfsWebCompact {color:green;}
.grid-row.closed-item-tfsWebCompact .grid-cell:nth-child(3) {text-decoration:line-through;}


/* for board  */

.wit-card:focus{ background-color: #bfb; }
.wit-card:focus:hover{ background-color: #cfc; }
.wit-card:hover{ background-color: #efe; }
.wit-card .card-context-menu { opacity: 50%; top:0; right:0; }


.id-title-container,
.board-content-details .task-list .add-task-container,
.agile-board .board-tile .board-tile-content .child-tasks-summary, 
.board-content-details .task-list .task,
.tags.field-container,
.wit-card.boards-card .fields .field-container,
.wit-card.boards-card .work-item-state-container,
.card-content .annotations.margin-top-8,
.additional-field.lastAdditionalField,
.board-tile .container,
.taskboard-cell .id-title-container,
.taskboard-cell .witExtra ,
.wit-card.taskboard-card .fields .field-container,
.wit-card .editable-card-identity-picker .card-assigned-to,
.wit-card.taskboard-card .work-item-state-container
{ margin:0 }


.add-task-container,
.vss-Hub .vss-HubPivotBar,
.vss-PivotBar .vss-PivotBar--bar.tall .vss-PivotBar--commandBar,
.bolt-page > .bolt-header,
.flex.flex-column.rhythm-horizontal-4.padding-top-16
{padding:0;}

.repos-pr-header.bolt-header,
.repos-pr-title input,
.pr-secondary-title-row,
.repos-compare-toolbar,
.vss-Hub .vss-HubPivotBar:not(.shadowStyle),
#taskboard-table-header th.taskboard-cell,
.bolt-tabbar-tabs.tall .bolt-tab, .bolt-button
{ padding-block: 0; margin-block: 0; height: auto; }

.repos-changes-viewer .sticky,
.repos-compare-toolbar .margin-vertical-8,
.repos-changes-viewer.is-folder > :first-child
{ padding-block : 2px; margin-block: 2px; }

.wit-card .card-content{padding: 4px 6px;}
.wit-card .editable-field.is-identity{min-height: 20px; margin-top: 2px; }
.taskboard-card {margin: 3px; }
.navigation-container .flex-column {width: 32px;}
.project-navigation .navigation-icon {width: 30px;}

.vss-PivotBar .vss-PivotBar--pivots.tall .vss-PivotBar--button,
.vss-PivotBar .vss-PivotBar--bar.tall .vss-PivotBar--commandBar
{ height: auto; }

.tbTile{width: 200px; margin: 5px;}
.tbTile.parentTbTile{width: 140px;}
.taskboard-parent{min-width:auto; width:140px; padding-right:0;}
.taskboard-expander { width: 12px;}
.taskboardTableHeaderScrollContainer .taskboard-parent{min-width:146px; width:140px; padding-right:0;}
.taskboard-cell { padding: 2px;}
.taskboard-cell .id-title-container{ padding-right:0; }
.taskboard-cell .witExtra { margin-bottom: 3px;}
.taskboard-cell:not(.taskboard-parent) .field-container.additional-field .field-label:first-child { display:none; }
.sprint-view-container .vss-PivotBar .vss-PivotBarItem.customPadding { padding-inline: 5px;}
.field-container.additional-field {padding-left: 4px;}

.wit-card.boards-card .annotations .annotation-expanded {position: relative;}
.wit-card.boards-card .annotations .annotation-expanded .annotation-button.checklist{
    margin-top: 0;
    position: absolute;
    top:-18px;
    right: 0;
    padding-inline: 40px;
}

/* make the Closed column really compact */
td[axis="taskboard-table-body_s2"] .tbTile {font-size:10.5px;}
td[axis="taskboard-table-body_s2"] .tbTile .id {line-height:10px;}
td[axis="taskboard-table-body_s2"] .tbTile .title {line-height:12px;}
td[axis="taskboard-table-body_s2"] .tbTile .id-title-container {line-height: 10px;}
td[axis="taskboard-table-body_s2"] .tbTile .tbTileContent .container.witExtra { max-height: 12px; }
td[axis="taskboard-table-body_s2"] .witExtra {height:18px;}
td[axis="taskboard-table-body_s2"] .witExtra .user-picture-resolved { display:none;}
td[axis="taskboard-table-body_s2"] .witExtra .element-height-medium {line-height:unset;}
td[axis="taskboard-table-body_s2"] .work-item-type-icon-host { display:none;}
.kanban-board-content > div:nth-child(3) .wit-card { margin-top:1px; font-size:10.5px; line-height:11px; }
.kanban-board-content > div:nth-child(3) .wit-card .editable-field.is-identity { min-height: unset; }
.kanban-board-content > div:nth-child(3) .wit-card .card-content { padding-block: 3px; }
.kanban-board-content > div:nth-child(3) .wit-ui-control.identity-view .identity-avatar {display:none;}

/* "make need analyst testing" column narrower */
table.sticky-table colgroup col:nth-child(5){
    width: 12.5% !important;
}

/* row numbers on task board */
table.sticky-table{
    counter-reset: number;
}
table.sticky-table td .taskboard-expand-collapse-button{
    position:relative;
    counter-increment: number;
}
table.sticky-table td .taskboard-expand-collapse-button:after{ 
    position: absolute;
    writing-mode: vertical-rl; /* fallback for browsers that don't support sideways-lr */
    writing-mode: sideways-lr;
    white-space: nowrap;
    font-size: 120%;
    content:"ROW " counter(number);
    top: 30px; 
}
table.sticky-table td.taskboard-collapsed-row .taskboard-expand-collapse-button:after{ 
    /* smaller and tighter on collapsed rows */
    top: 0; left: 14px; font-size: 80%; writing-mode: unset; content:counter(number);
    
} 

/* relative card number labels on story board */
.kanban-board-content {
    counter-reset: backlog upnext hold active testing closed;
}
.kanban-board-content .main-column-container .boards-card,
.kanban-board-row-container .kanban-board-column-container .kanban-board-column .boards-card{
    position:relative;
}
.kanban-board-content .main-column-container .boards-card:after,
.kanban-board-row-container .kanban-board-column-container .kanban-board-column .boards-card:after{
    position: absolute;
    writing-mode: vertical-rl; /* fallback for browsers that don't support sideways-lr */
    writing-mode: sideways-lr;
    white-space: nowrap;
    left: -13px;
    top: 8px;
}

.kanban-board-content .main-column-container:nth-child(1) .boards-card { counter-increment: backlog; }
.kanban-board-content .main-column-container:nth-child(1) .boards-card:after { content:"BACKLOG " counter(backlog); }

.kanban-board-row-container .kanban-board-column-container .kanban-board-column:nth-child(1) .boards-card { counter-increment: upnext; }
.kanban-board-row-container .kanban-board-column-container .kanban-board-column:nth-child(1) .boards-card:after { content:"UP NEXT " counter(upnext); }

.kanban-board-row-container .kanban-board-column-container .kanban-board-column:nth-child(2) .boards-card { counter-increment: hold; }
.kanban-board-row-container .kanban-board-column-container .kanban-board-column:nth-child(2) .boards-card:after { content:"ON HOLD " counter(hold); }

.kanban-board-row-container .kanban-board-column-container .kanban-board-column:nth-child(3) .boards-card { counter-increment: active; }
.kanban-board-row-container .kanban-board-column-container .kanban-board-column:nth-child(3) .boards-card:after { content:"ACTIVE " counter(active); }

.kanban-board-row-container .kanban-board-column-container .kanban-board-column:nth-child(4) .boards-card { counter-increment: testing;}
.kanban-board-row-container .kanban-board-column-container .kanban-board-column:nth-child(4) .boards-card:after { content:"IN TEST " counter(testing); }

.kanban-board-content .main-column-container:nth-child(3) .boards-card { counter-increment: closed; }
.kanban-board-content .main-column-container:nth-child(3) .boards-card:after { content:"CLOSED " counter(closed); }
`;     
document.head.appendChild(s); 
document.getElementById('__bolt-full-screen')?.click();					 
})();

Easier to use if you start from the blog post.