Override totally SharePoint 2010 font-family (from corev4.css)

overrideLayoutFont.css

.ms-formula,
.ms-templatepicker select,
.ms-propertysheet th.ms-vh2-nofilter-notextalign,
.ms-dspadapterlist,
.ms-sectionheader,
.ms-linksectionheader,
.ms-sectionhighlight-top,
table.ms-pageinformation,table.ms-createpageinformation,
.ms-pageinformation table td,.ms-createpageinformation table td,
.ms-pageinformation h3.ms-standardheader,
.ms-vh2-nofilter,.ms-vh2-nofilter-notextalign,
tr.ms-highlight,
.ms-subsmanageheader,
.ms-subsmanagecell,
.ms-smallheader,th.ms-smallheader,
.ms-wikifieldheader,
.ms-pickerdropdown,
.ms-dialogHeaderDescription,
.ms-dialogHelpLink,.ms-dialogHelpLink a,
.ms-dialogBodyMain,
.ms-dialogButtonCell,.ms-dialogButtonCell INPUT,
.ms-create-h2,.ms-create-h2b,.ms-create-h2d,
.ms-create-h3,
.ms-create-sectionheader,
.ms-create-listitem-a,
.ms-listedit table.ms-pageinformation,.ms-listedit .ms-pageinformation table td,.ms-listedit .ms-propertysheet,.ms-listedit .ms-descriptiontext
.ms-listedit .ms-standardheader,.ms-listedit .ms-linksectionheader,.ms-listedit .ms-linksectionheader .ms-standardheader,
.ms-inputuserfield,
.ms-formlabel,
.ms-long,
.captioned-image .caption
{
	font-family: "Segoe UI",Tahoma,Verdana,sans-serif;
}

overrideV4Font.css

.ms-toolbar,
.ms-menutoolbar td a,
td.ms-menutoolbarheader,
.ms-listheaderlabel,.ms-viewselector,.ms-viewselectortext,.ms-viewselectorhover,
.ms-paging,
.ms-viewselect a:link,
select,
.ms-input,
table.ms-navitem td,span.ms-navitem,
.ms-nav,
.ms-titlearea,
.ms-pagetitle,
.ms-propertysheet th.ms-vh2,.ms-propertysheet th.ms-vh2-nofilter,
.ms-descriptiontext,
.ms-statusdescriptiontext,
.ms-webpartpagedescription,
.ms-propertysheet th.ms-linksectionheader,
.ms-propertysheet,
.ms-propertysheet th,
.ms-vh,.ms-vh2,.ms-vh-icon,.ms-vh-icon-empty,.ms-vhImage,.ms-gb,.ms-gb2,.ms-gbload,.ms-vb,.ms-vb2,.ms-vb-tall,.ms-vb-user,.ms-vh2-nograd,.ms-vh3-nograd,.ms-vh2-nograd-icon,.ms-vh2-nofilter-icon,.ms-pb,.ms-pb-selected,.ms-ph,
th.ms-vh3-nograd,
.ms-pb a,.ms-pb-selected a,
th .ms-vb,.ms-vh2-nofilter-icon,th.ms-vh2-nograd,th.ms-vh2-nograd-icon,
a.ms-addnew,
.ms-error,
.ms-WPTitle,
.ms-WPBody,
.ms-WPBody td,
table.ms-listviewtable > tbody > tr > td.ms-stylebox,
.ms-stylelabel,
.ms-styleheader,
.ms-stylebody,
.ms-pickerwait,
.ms-formvalidation,
.ms-ribbontabswitchloading span,
.ms-welcomepageheader,
div.ms-MenuUIPopupBody.ms-MenuUIPopupScreen,div.ms-MenuUIPopupBody.ms-MenuUIPopupScreen div.ms-MenuUIPopupInner,div.ms-MenuUIPopupBody.ms-MenuUIPopupScreen div.ms-MenuUIPopupInner div,
.ms-wpadder-categoryColumn,.ms-wpadder-categoryColumn TD,.ms-wpadder-items,
.ms-wpadder-upload INPUT,.ms-wpadder-upload BUTTON,
.ms-wpadder-tabTable TH,.ms-wpadder-description,.ms-wpadder-zoneArea BUTTON,
.ms-wpadder-sectionhead,
.ms-wpadder-wpname,
body,
.ms-SPLink,
.ms-siteactionsmenuinner,.ms-siteactionsmenuhover,
.ms-welcomeMenu,
.ms-socialNotif-Container,
.s4-titletable,
.ms-ltviewselectormenuheader .ms-viewselector a,.ms-ltviewselectormenuheader .ms-viewselectorhover a,
.s4-search select,
body #pageStatusBar,
.ms-rteElement-Callout4,
.ms-rteStyle-Normal,
.ms-rteFontFace-1,
.ms-rteFontFace-2,
.ms-rteFontFace-3,
.ms-rteFontFace-4,
.ms-rteFontFace-5,
.ms-rteFontFace-6,
.ms-rteFontFace-7,
.ms-rteFontFace-8,
.ms-rteFontFace-9,
.ms-rteFontFace-10,
.ms-rteFontFace-11,
.ms-rteThemeFontFace-1,
.ms-rteThemeFontFace-2,
.ms-rte-autocomplete,
.ms-rte-wpbox,
.ms-rtedialog,
.ms-dlgTitleText,
.ms-linksection-level1,
.ms-linksection-level2,
.ms-ratingPopup,
.ms-developerdashboard > table tr td,
.ms-cui-ribbon,.ms-cui-menu,.ms-cui-toolbar-toolbar,
.ms-cui-contextmenu-inner,
.ms-cui-cb-input,
.ms-cui-tb,
.ms-cui-spn-txtbx,
.ms-cui-tooltip
{
	font-family: "Segoe UI",Tahoma,Verdana,sans-serif;
}