make font size of grid captcha scale roughly to the current ratio of 20-30:120

lib/captcha/generators/grid.js

@@ -30,6 +30,8 @@ module.exports = async (captchaOptions) => {
 
 	//divide the space by grid size, accounting for padding
 	const spaceSize = (width-padding)/size;
+	const fontMinSize = Math.floor(width*0.16);
+	const fontMaxSize = Math.floor(width*0.25);
 	for(let j = 0; j < size; j++) { //for each row
 
 		//x offset for whole row (not per character or it gets way too difficult to solve)
@@ -44,7 +46,7 @@ module.exports = async (captchaOptions) => {
 			} else {
 				character = falses[(await randomRange(0, falses.length))];
 			}
-			captcha.fontSize((await randomRange(20, 30)));
+			captcha.fontSize((await randomRange(fontMinSize, fontMaxSize)));
 			captcha.drawText(
 				(spaceSize * i) + cxOffset,
 				(spaceSize * (j + 1)) + cyOffset,

lib/captcha/generators/grid2.js

@@ -92,11 +92,13 @@ module.exports = async (captchaOptions) => {
 		.font(__dirname+'/../font.ttf');
 
 	const spaceSize = (width-padding)/size;
+	const fontMinSize = Math.floor(width*0.16);
+	const fontMaxSize = Math.floor(width*0.25);
 	for (let row = 0; row < size; row++) {
 		let cxOffset = Math.floor(spaceSize * 1.5);
 		for (let col = 0; col < size; col++) {
 			const cyOffset = captchaOptions.grid.iconYOffset;
-			captcha.fontSize((await randomRange(20, 30)));
+			captcha.fontSize((await randomRange(fontMinSize, fontMaxSize)));
 			captcha.drawText(
 				(spaceSize * col) + cyOffset,
 				(spaceSize * row) + cxOffset,