GoSquared released some flags. This CSS lets you use them similarly to Bootstrap's icons!

flags.css

.flag {
	display: inline-block;
	width: 16px;
	height: 16px;
	line-height: 16px;
	vertical-align: text-top;
}

.flag-AD {background: url(img/flags-iso/16/AD.png) no-repeat top left transparent;}
.flag-AE {background: url(img/flags-iso/16/AE.png) no-repeat top left transparent;}
.flag-AF {background: url(img/flags-iso/16/AF.png) no-repeat top left transparent;}
.flag-AG {background: url(img/flags-iso/16/AG.png) no-repeat top left transparent;}
.flag-AI {background: url(img/flags-iso/16/AI.png) no-repeat top left transparent;}
.flag-AL {background: url(img/flags-iso/16/AL.png) no-repeat top left transparent;}
.flag-AM {background: url(img/flags-iso/16/AM.png) no-repeat top left transparent;}
.flag-AN {background: url(img/flags-iso/16/AN.png) no-repeat top left transparent;}
.flag-AO {background: url(img/flags-iso/16/AO.png) no-repeat top left transparent;}
.flag-AQ {background: url(img/flags-iso/16/AQ.png) no-repeat top left transparent;}
.flag-AR {background: url(img/flags-iso/16/AR.png) no-repeat top left transparent;}
.flag-AS {background: url(img/flags-iso/16/AS.png) no-repeat top left transparent;}
.flag-AT {background: url(img/flags-iso/16/AT.png) no-repeat top left transparent;}
.flag-AU {background: url(img/flags-iso/16/AU.png) no-repeat top left transparent;}
.flag-AW {background: url(img/flags-iso/16/AW.png) no-repeat top left transparent;}
.flag-AX {background: url(img/flags-iso/16/AX.png) no-repeat top left transparent;}
.flag-AZ {background: url(img/flags-iso/16/AZ.png) no-repeat top left transparent;}
.flag-BA {background: url(img/flags-iso/16/BA.png) no-repeat top left transparent;}
.flag-BB {background: url(img/flags-iso/16/BB.png) no-repeat top left transparent;}
.flag-BD {background: url(img/flags-iso/16/BD.png) no-repeat top left transparent;}
.flag-BE {background: url(img/flags-iso/16/BE.png) no-repeat top left transparent;}
.flag-BF {background: url(img/flags-iso/16/BF.png) no-repeat top left transparent;}
.flag-BG {background: url(img/flags-iso/16/BG.png) no-repeat top left transparent;}
.flag-BH {background: url(img/flags-iso/16/BH.png) no-repeat top left transparent;}
.flag-BI {background: url(img/flags-iso/16/BI.png) no-repeat top left transparent;}
.flag-BJ {background: url(img/flags-iso/16/BJ.png) no-repeat top left transparent;}
.flag-BL {background: url(img/flags-iso/16/BL.png) no-repeat top left transparent;}
.flag-BM {background: url(img/flags-iso/16/BM.png) no-repeat top left transparent;}
.flag-BN {background: url(img/flags-iso/16/BN.png) no-repeat top left transparent;}
.flag-BO {background: url(img/flags-iso/16/BO.png) no-repeat top left transparent;}
.flag-BR {background: url(img/flags-iso/16/BR.png) no-repeat top left transparent;}
.flag-BS {background: url(img/flags-iso/16/BS.png) no-repeat top left transparent;}
.flag-BT {background: url(img/flags-iso/16/BT.png) no-repeat top left transparent;}
.flag-BW {background: url(img/flags-iso/16/BW.png) no-repeat top left transparent;}
.flag-BY {background: url(img/flags-iso/16/BY.png) no-repeat top left transparent;}
.flag-BZ {background: url(img/flags-iso/16/BZ.png) no-repeat top left transparent;}
.flag-CA {background: url(img/flags-iso/16/CA.png) no-repeat top left transparent;}
.flag-CD {background: url(img/flags-iso/16/CD.png) no-repeat top left transparent;}
.flag-CF {background: url(img/flags-iso/16/CF.png) no-repeat top left transparent;}
.flag-CG {background: url(img/flags-iso/16/CG.png) no-repeat top left transparent;}
.flag-CH {background: url(img/flags-iso/16/CH.png) no-repeat top left transparent;}
.flag-CI {background: url(img/flags-iso/16/CI.png) no-repeat top left transparent;}
.flag-CL {background: url(img/flags-iso/16/CL.png) no-repeat top left transparent;}
.flag-CM {background: url(img/flags-iso/16/CM.png) no-repeat top left transparent;}
.flag-CN {background: url(img/flags-iso/16/CN.png) no-repeat top left transparent;}
.flag-CO {background: url(img/flags-iso/16/CO.png) no-repeat top left transparent;}
.flag-CR {background: url(img/flags-iso/16/CR.png) no-repeat top left transparent;}
.flag-CS {background: url(img/flags-iso/16/CS.png) no-repeat top left transparent;}
.flag-CU {background: url(img/flags-iso/16/CU.png) no-repeat top left transparent;}
.flag-CV {background: url(img/flags-iso/16/CV.png) no-repeat top left transparent;}
.flag-CY {background: url(img/flags-iso/16/CY.png) no-repeat top left transparent;}
.flag-CZ {background: url(img/flags-iso/16/CZ.png) no-repeat top left transparent;}
.flag-DE {background: url(img/flags-iso/16/DE.png) no-repeat top left transparent;}
.flag-DJ {background: url(img/flags-iso/16/DJ.png) no-repeat top left transparent;}
.flag-DK {background: url(img/flags-iso/16/DK.png) no-repeat top left transparent;}
.flag-DM {background: url(img/flags-iso/16/DM.png) no-repeat top left transparent;}
.flag-DO {background: url(img/flags-iso/16/DO.png) no-repeat top left transparent;}
.flag-DZ {background: url(img/flags-iso/16/DZ.png) no-repeat top left transparent;}
.flag-EC {background: url(img/flags-iso/16/EC.png) no-repeat top left transparent;}
.flag-EE {background: url(img/flags-iso/16/EE.png) no-repeat top left transparent;}
.flag-EG {background: url(img/flags-iso/16/EG.png) no-repeat top left transparent;}
.flag-EH {background: url(img/flags-iso/16/EH.png) no-repeat top left transparent;}
.flag-ER {background: url(img/flags-iso/16/ER.png) no-repeat top left transparent;}
.flag-ES {background: url(img/flags-iso/16/ES.png) no-repeat top left transparent;}
.flag-ET {background: url(img/flags-iso/16/ET.png) no-repeat top left transparent;}
.flag-EU {background: url(img/flags-iso/16/EU.png) no-repeat top left transparent;}
.flag-FI {background: url(img/flags-iso/16/FI.png) no-repeat top left transparent;}
.flag-FJ {background: url(img/flags-iso/16/FJ.png) no-repeat top left transparent;}
.flag-FK {background: url(img/flags-iso/16/FK.png) no-repeat top left transparent;}
.flag-FM {background: url(img/flags-iso/16/FM.png) no-repeat top left transparent;}
.flag-FO {background: url(img/flags-iso/16/FO.png) no-repeat top left transparent;}
.flag-FR {background: url(img/flags-iso/16/FR.png) no-repeat top left transparent;}
.flag-GA {background: url(img/flags-iso/16/GA.png) no-repeat top left transparent;}
.flag-GB {background: url(img/flags-iso/16/GB.png) no-repeat top left transparent;}
.flag-GD {background: url(img/flags-iso/16/GD.png) no-repeat top left transparent;}
.flag-GE {background: url(img/flags-iso/16/GE.png) no-repeat top left transparent;}
.flag-GG {background: url(img/flags-iso/16/GG.png) no-repeat top left transparent;}
.flag-GH {background: url(img/flags-iso/16/GH.png) no-repeat top left transparent;}
.flag-GL {background: url(img/flags-iso/16/GL.png) no-repeat top left transparent;}
.flag-GM {background: url(img/flags-iso/16/GM.png) no-repeat top left transparent;}
.flag-GN {background: url(img/flags-iso/16/GN.png) no-repeat top left transparent;}
.flag-GQ {background: url(img/flags-iso/16/GQ.png) no-repeat top left transparent;}
.flag-GR {background: url(img/flags-iso/16/GR.png) no-repeat top left transparent;}
.flag-GS {background: url(img/flags-iso/16/GS.png) no-repeat top left transparent;}
.flag-GT {background: url(img/flags-iso/16/GT.png) no-repeat top left transparent;}
.flag-GU {background: url(img/flags-iso/16/GU.png) no-repeat top left transparent;}
.flag-GW {background: url(img/flags-iso/16/GW.png) no-repeat top left transparent;}
.flag-GY {background: url(img/flags-iso/16/GY.png) no-repeat top left transparent;}
.flag-HK {background: url(img/flags-iso/16/HK.png) no-repeat top left transparent;}
.flag-HN {background: url(img/flags-iso/16/HN.png) no-repeat top left transparent;}
.flag-HR {background: url(img/flags-iso/16/HR.png) no-repeat top left transparent;}
.flag-HT {background: url(img/flags-iso/16/HT.png) no-repeat top left transparent;}
.flag-HU {background: url(img/flags-iso/16/HU.png) no-repeat top left transparent;}
.flag-ID {background: url(img/flags-iso/16/ID.png) no-repeat top left transparent;}
.flag-IE {background: url(img/flags-iso/16/IE.png) no-repeat top left transparent;}
.flag-IL {background: url(img/flags-iso/16/IL.png) no-repeat top left transparent;}
.flag-IM {background: url(img/flags-iso/16/IM.png) no-repeat top left transparent;}
.flag-IN {background: url(img/flags-iso/16/IN.png) no-repeat top left transparent;}
.flag-IQ {background: url(img/flags-iso/16/IQ.png) no-repeat top left transparent;}
.flag-IR {background: url(img/flags-iso/16/IR.png) no-repeat top left transparent;}
.flag-IS {background: url(img/flags-iso/16/IS.png) no-repeat top left transparent;}
.flag-IT {background: url(img/flags-iso/16/IT.png) no-repeat top left transparent;}
.flag-JE {background: url(img/flags-iso/16/JE.png) no-repeat top left transparent;}
.flag-JM {background: url(img/flags-iso/16/JM.png) no-repeat top left transparent;}
.flag-JO {background: url(img/flags-iso/16/JO.png) no-repeat top left transparent;}
.flag-JP {background: url(img/flags-iso/16/JP.png) no-repeat top left transparent;}
.flag-KE {background: url(img/flags-iso/16/KE.png) no-repeat top left transparent;}
.flag-KG {background: url(img/flags-iso/16/KG.png) no-repeat top left transparent;}
.flag-KH {background: url(img/flags-iso/16/KH.png) no-repeat top left transparent;}
.flag-KI {background: url(img/flags-iso/16/KI.png) no-repeat top left transparent;}
.flag-KM {background: url(img/flags-iso/16/KM.png) no-repeat top left transparent;}
.flag-KN {background: url(img/flags-iso/16/KN.png) no-repeat top left transparent;}
.flag-KP {background: url(img/flags-iso/16/KP.png) no-repeat top left transparent;}
.flag-KR {background: url(img/flags-iso/16/KR.png) no-repeat top left transparent;}
.flag-KV {background: url(img/flags-iso/16/KV.png) no-repeat top left transparent;}
.flag-KW {background: url(img/flags-iso/16/KW.png) no-repeat top left transparent;}
.flag-KY {background: url(img/flags-iso/16/KY.png) no-repeat top left transparent;}
.flag-KZ {background: url(img/flags-iso/16/KZ.png) no-repeat top left transparent;}
.flag-LA {background: url(img/flags-iso/16/LA.png) no-repeat top left transparent;}
.flag-LB {background: url(img/flags-iso/16/LB.png) no-repeat top left transparent;}
.flag-LC {background: url(img/flags-iso/16/LC.png) no-repeat top left transparent;}
.flag-LI {background: url(img/flags-iso/16/LI.png) no-repeat top left transparent;}
.flag-LK {background: url(img/flags-iso/16/LK.png) no-repeat top left transparent;}
.flag-LR {background: url(img/flags-iso/16/LR.png) no-repeat top left transparent;}
.flag-LS {background: url(img/flags-iso/16/LS.png) no-repeat top left transparent;}
.flag-LT {background: url(img/flags-iso/16/LT.png) no-repeat top left transparent;}
.flag-LU {background: url(img/flags-iso/16/LU.png) no-repeat top left transparent;}
.flag-LV {background: url(img/flags-iso/16/LV.png) no-repeat top left transparent;}
.flag-LY {background: url(img/flags-iso/16/LY.png) no-repeat top left transparent;}
.flag-MA {background: url(img/flags-iso/16/MA.png) no-repeat top left transparent;}
.flag-MC {background: url(img/flags-iso/16/MC.png) no-repeat top left transparent;}
.flag-MD {background: url(img/flags-iso/16/MD.png) no-repeat top left transparent;}
.flag-MG {background: url(img/flags-iso/16/MG.png) no-repeat top left transparent;}
.flag-MH {background: url(img/flags-iso/16/MH.png) no-repeat top left transparent;}
.flag-MK {background: url(img/flags-iso/16/MK.png) no-repeat top left transparent;}
.flag-ML {background: url(img/flags-iso/16/ML.png) no-repeat top left transparent;}
.flag-MM {background: url(img/flags-iso/16/MM.png) no-repeat top left transparent;}
.flag-MN {background: url(img/flags-iso/16/MN.png) no-repeat top left transparent;}
.flag-MO {background: url(img/flags-iso/16/MO.png) no-repeat top left transparent;}
.flag-MP {background: url(img/flags-iso/16/MP.png) no-repeat top left transparent;}
.flag-MR {background: url(img/flags-iso/16/MR.png) no-repeat top left transparent;}
.flag-MS {background: url(img/flags-iso/16/MS.png) no-repeat top left transparent;}
.flag-MT {background: url(img/flags-iso/16/MT.png) no-repeat top left transparent;}
.flag-MU {background: url(img/flags-iso/16/MU.png) no-repeat top left transparent;}
.flag-MV {background: url(img/flags-iso/16/MV.png) no-repeat top left transparent;}
.flag-MW {background: url(img/flags-iso/16/MW.png) no-repeat top left transparent;}
.flag-MX {background: url(img/flags-iso/16/MX.png) no-repeat top left transparent;}
.flag-MY {background: url(img/flags-iso/16/MY.png) no-repeat top left transparent;}
.flag-MZ {background: url(img/flags-iso/16/MZ.png) no-repeat top left transparent;}
.flag-NA {background: url(img/flags-iso/16/NA.png) no-repeat top left transparent;}
.flag-NE {background: url(img/flags-iso/16/NE.png) no-repeat top left transparent;}
.flag-NF {background: url(img/flags-iso/16/NF.png) no-repeat top left transparent;}
.flag-NG {background: url(img/flags-iso/16/NG.png) no-repeat top left transparent;}
.flag-NI {background: url(img/flags-iso/16/NI.png) no-repeat top left transparent;}
.flag-NL {background: url(img/flags-iso/16/NL.png) no-repeat top left transparent;}
.flag-NO {background: url(img/flags-iso/16/NO.png) no-repeat top left transparent;}
.flag-NP {background: url(img/flags-iso/16/NP.png) no-repeat top left transparent;}
.flag-NR {background: url(img/flags-iso/16/NR.png) no-repeat top left transparent;}
.flag-NZ {background: url(img/flags-iso/16/NZ.png) no-repeat top left transparent;}
.flag-OM {background: url(img/flags-iso/16/OM.png) no-repeat top left transparent;}
.flag-PA {background: url(img/flags-iso/16/PA.png) no-repeat top left transparent;}
.flag-PE {background: url(img/flags-iso/16/PE.png) no-repeat top left transparent;}
.flag-PG {background: url(img/flags-iso/16/PG.png) no-repeat top left transparent;}
.flag-PH {background: url(img/flags-iso/16/PH.png) no-repeat top left transparent;}
.flag-PK {background: url(img/flags-iso/16/PK.png) no-repeat top left transparent;}
.flag-PL {background: url(img/flags-iso/16/PL.png) no-repeat top left transparent;}
.flag-PN {background: url(img/flags-iso/16/PN.png) no-repeat top left transparent;}
.flag-PR {background: url(img/flags-iso/16/PR.png) no-repeat top left transparent;}
.flag-PS {background: url(img/flags-iso/16/PS.png) no-repeat top left transparent;}
.flag-PT {background: url(img/flags-iso/16/PT.png) no-repeat top left transparent;}
.flag-PW {background: url(img/flags-iso/16/PW.png) no-repeat top left transparent;}
.flag-PY {background: url(img/flags-iso/16/PY.png) no-repeat top left transparent;}
.flag-QA {background: url(img/flags-iso/16/QA.png) no-repeat top left transparent;}
.flag-RO {background: url(img/flags-iso/16/RO.png) no-repeat top left transparent;}
.flag-RS {background: url(img/flags-iso/16/RS.png) no-repeat top left transparent;}
.flag-RU {background: url(img/flags-iso/16/RU.png) no-repeat top left transparent;}
.flag-RW {background: url(img/flags-iso/16/RW.png) no-repeat top left transparent;}
.flag-SA {background: url(img/flags-iso/16/SA.png) no-repeat top left transparent;}
.flag-SB {background: url(img/flags-iso/16/SB.png) no-repeat top left transparent;}
.flag-SC {background: url(img/flags-iso/16/SC.png) no-repeat top left transparent;}
.flag-SD {background: url(img/flags-iso/16/SD.png) no-repeat top left transparent;}
.flag-SE {background: url(img/flags-iso/16/SE.png) no-repeat top left transparent;}
.flag-SG {background: url(img/flags-iso/16/SG.png) no-repeat top left transparent;}
.flag-SH {background: url(img/flags-iso/16/SH.png) no-repeat top left transparent;}
.flag-SI {background: url(img/flags-iso/16/SI.png) no-repeat top left transparent;}
.flag-SK {background: url(img/flags-iso/16/SK.png) no-repeat top left transparent;}
.flag-SL {background: url(img/flags-iso/16/SL.png) no-repeat top left transparent;}
.flag-SM {background: url(img/flags-iso/16/SM.png) no-repeat top left transparent;}
.flag-SN {background: url(img/flags-iso/16/SN.png) no-repeat top left transparent;}
.flag-SO {background: url(img/flags-iso/16/SO.png) no-repeat top left transparent;}
.flag-SR {background: url(img/flags-iso/16/SR.png) no-repeat top left transparent;}
.flag-SS {background: url(img/flags-iso/16/SS.png) no-repeat top left transparent;}
.flag-ST {background: url(img/flags-iso/16/ST.png) no-repeat top left transparent;}
.flag-SV {background: url(img/flags-iso/16/SV.png) no-repeat top left transparent;}
.flag-SY {background: url(img/flags-iso/16/SY.png) no-repeat top left transparent;}
.flag-SZ {background: url(img/flags-iso/16/SZ.png) no-repeat top left transparent;}
.flag-TC {background: url(img/flags-iso/16/TC.png) no-repeat top left transparent;}
.flag-TD {background: url(img/flags-iso/16/TD.png) no-repeat top left transparent;}
.flag-TG {background: url(img/flags-iso/16/TG.png) no-repeat top left transparent;}
.flag-TH {background: url(img/flags-iso/16/TH.png) no-repeat top left transparent;}
.flag-TJ {background: url(img/flags-iso/16/TJ.png) no-repeat top left transparent;}
.flag-TM {background: url(img/flags-iso/16/TM.png) no-repeat top left transparent;}
.flag-TN {background: url(img/flags-iso/16/TN.png) no-repeat top left transparent;}
.flag-TO {background: url(img/flags-iso/16/TO.png) no-repeat top left transparent;}
.flag-TP {background: url(img/flags-iso/16/TP.png) no-repeat top left transparent;}
.flag-TR {background: url(img/flags-iso/16/TR.png) no-repeat top left transparent;}
.flag-TT {background: url(img/flags-iso/16/TT.png) no-repeat top left transparent;}
.flag-TV {background: url(img/flags-iso/16/TV.png) no-repeat top left transparent;}
.flag-TW {background: url(img/flags-iso/16/TW.png) no-repeat top left transparent;}
.flag-TZ {background: url(img/flags-iso/16/TZ.png) no-repeat top left transparent;}
.flag-UA {background: url(img/flags-iso/16/UA.png) no-repeat top left transparent;}
.flag-UG {background: url(img/flags-iso/16/UG.png) no-repeat top left transparent;}
.flag-US {background: url(img/flags-iso/16/US.png) no-repeat top left transparent;}
.flag-UY {background: url(img/flags-iso/16/UY.png) no-repeat top left transparent;}
.flag-UZ {background: url(img/flags-iso/16/UZ.png) no-repeat top left transparent;}
.flag-VA {background: url(img/flags-iso/16/VA.png) no-repeat top left transparent;}
.flag-VC {background: url(img/flags-iso/16/VC.png) no-repeat top left transparent;}
.flag-VE {background: url(img/flags-iso/16/VE.png) no-repeat top left transparent;}
.flag-VG {background: url(img/flags-iso/16/VG.png) no-repeat top left transparent;}
.flag-VI {background: url(img/flags-iso/16/VI.png) no-repeat top left transparent;}
.flag-VN {background: url(img/flags-iso/16/VN.png) no-repeat top left transparent;}
.flag-VU {background: url(img/flags-iso/16/VU.png) no-repeat top left transparent;}
.flag-WS {background: url(img/flags-iso/16/WS.png) no-repeat top left transparent;}
.flag-YE {background: url(img/flags-iso/16/YE.png) no-repeat top left transparent;}
.flag-ZA {background: url(img/flags-iso/16/ZA.png) no-repeat top left transparent;}
.flag-ZM {background: url(img/flags-iso/16/ZM.png) no-repeat top left transparent;}
.flag-ZW {background: url(img/flags-iso/16/ZW.png) no-repeat top left transparent;}

Hey!
You saved me much time 👍
Thanks a lot
Here's the updated and missing flags.

.flag-CX {background-image: url(img/flags-iso/16/CX.png) no-repeat top left transparent;}
.flag-CC {background-image: url(img/flags-iso/16/CC.png) no-repeat top left transparent;}
.flag-CK {background-image: url(img/flags-iso/16/CK.png) no-repeat top left transparent;}
.flag-CW {background-image: url(img/flags-iso/16/CW.png) no-repeat top left transparent;}
.flag-PF {background-image: url(img/flags-iso/16/PF.png) no-repeat top left transparent;}
.flag-TF {background-image: url(img/flags-iso/16/TF.png) no-repeat top left transparent;}
.flag-GI {background-image: url(img/flags-iso/16/GI.png) no-repeat top left transparent;}
.flag-MQ {background-image: url(img/flags-iso/16/MQ.png) no-repeat top left transparent;}
.flag-YT {background-image: url(img/flags-iso/16/YT.png) no-repeat top left transparent;}
.flag-ME {background-image: url(img/flags-iso/16/ME.png) no-repeat top left transparent;}
.flag-NC {background-image: url(img/flags-iso/16/NC.png) no-repeat top left transparent;}
.flag-NU {background-image: url(img/flags-iso/16/NU.png) no-repeat top left transparent;}
.flag-MF {background-image: url(img/flags-iso/16/MF.png) no-repeat top left transparent;}
.flag-TL {background-image: url(img/flags-iso/16/TL.png) no-repeat top left transparent;}
.flag-TK {background-image: url(img/flags-iso/16/TK.png) no-repeat top left transparent;}
.flag-WF {background-image: url(img/flags-iso/16/WF.png) no-repeat top left transparent;}