Hallo,
ich habe diesen Code, damit wird ein grüner Button für "Erweiterungen" angezeigt.
CSS
#category-extension .category-icon {
list-style-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAAACXBIWXMAAAsTAAALEwEAmpwYAAAKT2lDQ1BQaG90b3Nob3AgSUNDIHByb2ZpbGUAAHjanVNnVFPpFj333vRCS4iAlEtvUhUIIFJCi4AUkSYqIQkQSoghodkVUcERRUUEG8igiAOOjoCMFVEsDIoK2AfkIaKOg6OIisr74Xuja9a89%2BbN%2FrXXPues852zzwfACAyWSDNRNYAMqUIeEeCDx8TG4eQuQIEKJHAAEAizZCFz%2FSMBAPh%2BPDwrIsAHvgABeNMLCADATZvAMByH%2Fw%2FqQplcAYCEAcB0kThLCIAUAEB6jkKmAEBGAYCdmCZTAKAEAGDLY2LjAFAtAGAnf%2BbTAICd%2BJl7AQBblCEVAaCRACATZYhEAGg7AKzPVopFAFgwABRmS8Q5ANgtADBJV2ZIALC3AMDOEAuyAAgMADBRiIUpAAR7AGDIIyN4AISZABRG8lc88SuuEOcqAAB4mbI8uSQ5RYFbCC1xB1dXLh4ozkkXKxQ2YQJhmkAuwnmZGTKBNA%2Fg88wAAKCRFRHgg%2FP9eM4Ors7ONo62Dl8t6r8G%2FyJiYuP%2B5c%2BrcEAAAOF0ftH%2BLC%2BzGoA7BoBt%2FqIl7gRoXgugdfeLZrIPQLUAoOnaV%2FNw%2BH48PEWhkLnZ2eXk5NhKxEJbYcpXff5nwl%2FAV%2F1s%2BX48%2FPf14L7iJIEyXYFHBPjgwsz0TKUcz5IJhGLc5o9H%2FLcL%2F%2Fwd0yLESWK5WCoU41EScY5EmozzMqUiiUKSKcUl0v9k4t8s%2BwM%2B3zUAsGo%2BAXuRLahdYwP2SycQWHTA4vcAAPK7b8HUKAgDgGiD4c93%2F%2B8%2F%2FUegJQCAZkmScQAAXkQkLlTKsz%2FHCAAARKCBKrBBG%2FTBGCzABhzBBdzBC%2FxgNoRCJMTCQhBCCmSAHHJgKayCQiiGzbAdKmAv1EAdNMBRaIaTcA4uwlW4Dj1wD%2FphCJ7BKLyBCQRByAgTYSHaiAFiilgjjggXmYX4IcFIBBKLJCDJiBRRIkuRNUgxUopUIFVIHfI9cgI5h1xGupE7yAAygvyGvEcxlIGyUT3UDLVDuag3GoRGogvQZHQxmo8WoJvQcrQaPYw2oefQq2gP2o8%2BQ8cwwOgYBzPEbDAuxsNCsTgsCZNjy7EirAyrxhqwVqwDu4n1Y8%2BxdwQSgUXACTYEd0IgYR5BSFhMWE7YSKggHCQ0EdoJNwkDhFHCJyKTqEu0JroR%2BcQYYjIxh1hILCPWEo8TLxB7iEPENyQSiUMyJ7mQAkmxpFTSEtJG0m5SI%2BksqZs0SBojk8naZGuyBzmULCAryIXkneTD5DPkG%2BQh8lsKnWJAcaT4U%2BIoUspqShnlEOU05QZlmDJBVaOaUt2ooVQRNY9aQq2htlKvUYeoEzR1mjnNgxZJS6WtopXTGmgXaPdpr%2Bh0uhHdlR5Ol9BX0svpR%2BiX6AP0dwwNhhWDx4hnKBmbGAcYZxl3GK%2BYTKYZ04sZx1QwNzHrmOeZD5lvVVgqtip8FZHKCpVKlSaVGyovVKmqpqreqgtV81XLVI%2BpXlN9rkZVM1PjqQnUlqtVqp1Q61MbU2epO6iHqmeob1Q%2FpH5Z%2FYkGWcNMw09DpFGgsV%2FjvMYgC2MZs3gsIWsNq4Z1gTXEJrHN2Xx2KruY%2FR27iz2qqaE5QzNKM1ezUvOUZj8H45hx%2BJx0TgnnKKeX836K3hTvKeIpG6Y0TLkxZVxrqpaXllirSKtRq0frvTau7aedpr1Fu1n7gQ5Bx0onXCdHZ4%2FOBZ3nU9lT3acKpxZNPTr1ri6qa6UbobtEd79up%2B6Ynr5egJ5Mb6feeb3n%2Bhx9L%2F1U%2FW36p%2FVHDFgGswwkBtsMzhg8xTVxbzwdL8fb8VFDXcNAQ6VhlWGX4YSRudE8o9VGjUYPjGnGXOMk423GbcajJgYmISZLTepN7ppSTbmmKaY7TDtMx83MzaLN1pk1mz0x1zLnm%2Beb15vft2BaeFostqi2uGVJsuRaplnutrxuhVo5WaVYVVpds0atna0l1rutu6cRp7lOk06rntZnw7Dxtsm2qbcZsOXYBtuutm22fWFnYhdnt8Wuw%2B6TvZN9un2N%2FT0HDYfZDqsdWh1%2Bc7RyFDpWOt6azpzuP33F9JbpL2dYzxDP2DPjthPLKcRpnVOb00dnF2e5c4PziIuJS4LLLpc%2BLpsbxt3IveRKdPVxXeF60vWdm7Obwu2o26%2FuNu5p7ofcn8w0nymeWTNz0MPIQ%2BBR5dE%2FC5%2BVMGvfrH5PQ0%2BBZ7XnIy9jL5FXrdewt6V3qvdh7xc%2B9j5yn%2BM%2B4zw33jLeWV%2FMN8C3yLfLT8Nvnl%2BF30N%2FI%2F9k%2F3r%2F0QCngCUBZwOJgUGBWwL7%2BHp8Ib%2BOPzrbZfay2e1BjKC5QRVBj4KtguXBrSFoyOyQrSH355jOkc5pDoVQfujW0Adh5mGLw34MJ4WHhVeGP45wiFga0TGXNXfR3ENz30T6RJZE3ptnMU85ry1KNSo%2Bqi5qPNo3ujS6P8YuZlnM1VidWElsSxw5LiquNm5svt%2F87fOH4p3iC%2BN7F5gvyF1weaHOwvSFpxapLhIsOpZATIhOOJTwQRAqqBaMJfITdyWOCnnCHcJnIi%2FRNtGI2ENcKh5O8kgqTXqS7JG8NXkkxTOlLOW5hCepkLxMDUzdmzqeFpp2IG0yPTq9MYOSkZBxQqohTZO2Z%2Bpn5mZ2y6xlhbL%2BxW6Lty8elQfJa7OQrAVZLQq2QqboVFoo1yoHsmdlV2a%2FzYnKOZarnivN7cyzytuQN5zvn%2F%2FtEsIS4ZK2pYZLVy0dWOa9rGo5sjxxedsK4xUFK4ZWBqw8uIq2Km3VT6vtV5eufr0mek1rgV7ByoLBtQFr6wtVCuWFfevc1%2B1dT1gvWd%2B1YfqGnRs%2BFYmKrhTbF5cVf9go3HjlG4dvyr%2BZ3JS0qavEuWTPZtJm6ebeLZ5bDpaql%2BaXDm4N2dq0Dd9WtO319kXbL5fNKNu7g7ZDuaO%2FPLi8ZafJzs07P1SkVPRU%2BlQ27tLdtWHX%2BG7R7ht7vPY07NXbW7z3%2FT7JvttVAVVN1WbVZftJ%2B7P3P66Jqun4lvttXa1ObXHtxwPSA%2F0HIw6217nU1R3SPVRSj9Yr60cOxx%2B%2B%2Fp3vdy0NNg1VjZzG4iNwRHnk6fcJ3%2FceDTradox7rOEH0x92HWcdL2pCmvKaRptTmvtbYlu6T8w%2B0dbq3nr8R9sfD5w0PFl5SvNUyWna6YLTk2fyz4ydlZ19fi753GDborZ752PO32oPb%2B%2B6EHTh0kX%2Fi%2Bc7vDvOXPK4dPKy2%2BUTV7hXmq86X23qdOo8%2FpPTT8e7nLuarrlca7nuer21e2b36RueN87d9L158Rb%2F1tWeOT3dvfN6b%2FfF9%2FXfFt1%2Bcif9zsu72Xcn7q28T7xf9EDtQdlD3YfVP1v%2B3Njv3H9qwHeg89HcR%2FcGhYPP%2FpH1jw9DBY%2BZj8uGDYbrnjg%2BOTniP3L96fynQ89kzyaeF%2F6i%2FsuuFxYvfvjV69fO0ZjRoZfyl5O%2FbXyl%2FerA6xmv28bCxh6%2ByXgzMV70VvvtwXfcdx3vo98PT%2BR8IH8o%2F2j5sfVT0Kf7kxmTk%2F8EA5jz%2FGMzLdsAAAAgY0hSTQAAeiUAAICDAAD5%2FwAAgOkAAHUwAADqYAAAOpgAABdvkl%2FFRgAABPRJREFUeNrEl01oXFUUx3%2F3vflMpjPpNE2aFNRS200RCv2g1iqlodhS%2FNi4UEQUl0UKgkVEWhDcWFyISFfdqHQlUmslBbGlNCgWo0GoqKVpE5u0%2BWonybz5ePPuOS5mMjPJJM2kIn1wmfvu3I%2Ff%2Bd9zzz3PqCoP8wk12%2FGV84f2A%2B8A2ypN%2FcAJ4Ptm5zh94LsHA3i599B%2BoPfJzU%2B5LbEWAPKF%2FP4f%2F%2B7bBxxcCcTCx2mmk6oe27Vpt2vCyr3CJPcKk5iwsmvzbldVj6kqzZQH3wLRbS2xOFP5CUQFYwye77Em3g6i2%2F53H1DFt6pxFUVQUMU4BiuCKvn%2FAtDcFoievj01ggBWBCkvzOjkCCr6hYrSTFlSgZfOHEgBmaUANqzbSDKZYrYwg6oABghIpdrYsG7jkcHb148sY4O5%2FxaIEg6F2bfjWWby03UjDKKWYlBgOj%2BNiC23GoNYYaYwQzqdpqujG8dxqmPmVkvGV%2FNt39fL%2B4CKIqJMeVNMzY7XpjF109XVjanAiU8p8MHMVBc1xtT57tLSNwCoKGIFK1JTwNSsqa83A2eg7CsrAbAq2DmZK4vUSzpnXbNwVpsGKBcRS2Bt3UJzk1XeDCuCK9kSKjSvQCKeJBCLqlAMfPxSgcAG83x4JXA5P8cj3Y8xdOvGOWDri1%2F2uMAA8P6ZV3%2FoBzCqyguf70uFQuFMS7yFrDdLJBKlq3M9ibYkWT9Lwc8vKX%2B90y2ECzkhErEkQcEn0boK17jkPI%2BBq%2F0%2B0PPNaxf6HAC1mi8V%2Fb3Tmcx2W7LRvJd7dHDw2tHff%2B23iWgCg4MVWyllPwkq9cDOtQnW1v631uIHPhnvLjnNMZ4d5072NhJRtm7ZHlGrx6pbcPaNiz5wqW5rhoETz53am%2FYy2XdD0TDFQnEJFRaTv%2F5UCNjaGGszrEt1o6J7lg3FKnpq5J9hwm64zkLbYO2cCkHF8qoK1d%2F5ygU2QEXzy15GKuqq1o5ng4X1TtgQD8q%2FjnFwXRdVxcHQEm2l6BVQ0f4mAHizs2s9uaKHFakusvjxa4QLuyES8SQUhdZVrRjjEng%2Bvw384gMfVAEOfva0C6R7D1%2BeqLw%2FDrwOvO0kInizmZoC94l8C%2BESsQTe2DS3hoYvAE9UmgeA472HL%2F9UHwcSoVBo%2FMCnewCIt7bQub6bUDLK1OwkxZI%2F74KqnbwFDrgALhKOMnjjL4AegPNv9d0%2FEO3oeYbJ6QkCWyLrFyhkMgRSAgyOMYTcMPFYnFg4BoBfKpIvFSgFpXIoXQAHZgWhWGEsM8bo5EjDnjrGEIm0ko61UbjrMTJ6E4D2rg5Wr0kzY6bJFXMogtHaUS3fhs2E4mriWM52yjoqpgLvhiKk4kmuXbnqA0eBrwBuDQ49zyAfb9q5JV70i%2FjWn%2BcP5ZRtJdexCqIKKGgteMQiMfy7eVT0OPBJ3fiTQCI%2F5X0USUTJe4WacgqqdtktKAeicp6JCBWIMrmoIiJEI1Hu3BwB5RQVvrpycnRwmGgkilSudKnkjVZ0ft%2FlFSiXsgFadSbXuPj5IsDEInNkAz%2FAMS6iMk85odmMqELYkV6L4zTmj%2B1tHQw71xArcWhIw%2BOO69C%2Bei2K1kUBaE%2B1c12b%2BS5QJfBL9J%2FrW7TTEH%2FOVROLACQksFw5e6lh3CB%2FLJvyG1XFGNP5f38F7%2F1w59jF935eHOBhPv8OAEOcPbuQAd%2BWAAAAAElFTkSuQmCC) !important;
-moz-image-region: auto !important;
}
Ich hätte das grüne Symbol auch gern für about:addons, da ist es nämlich Blau.
Desweiteren soll das alte Symbol auch als Favicon für https://addons.mozilla.org gelten, die neue "Palme" soll weg.