mq

$BASE_FONT_SIZE = 15px
$MIN_WIDTH = 320px
$MAX_WIDTH = 540px

px2rem($px)
	($px / $BASE_FONT_SIZE)rem


html
	// 在元素的before伪类上写上当前真实的font-size的大小，以便JS获取
	// 原因：JS在获取CSS字体大小时候某些内核会直接将字体转为整数
	setAccurateFontSize($font-size)
		&:before
			content 'Accurate font size:' + $font-size
			display none

	font-size $BASE_FONT_SIZE
	setAccurateFontSize($BASE_FONT_SIZE)
	$break-point-size = ()
	$break-point-step = 20
	$step-num = floor(unit(($MAX_WIDTH - $MIN_WIDTH) / $break-point-step, ''))
	if $step-num > 1
		for i in (1 ... $step-num + 1)
			$width = $MIN_WIDTH + (i * $break-point-step)
			$font-size = ($width / $MIN_WIDTH) * $BASE_FONT_SIZE
			@media screen and (min-width: $width)
				font-size $font-size
				setAccurateFontSize($font-size)

	else
		$min-width = $break-point-size['min-width']
		$font-size = $break-point-size['font-size']
		@media screen and (min-width: $min-width)
			font-size $font-size