問題：如果indesign裏字號是默認的12px(點)，輸出epub後，css裏樣式爲1em，在chrome裏計算爲16px
原因：indesign在輸出epub過程中將每12px轉爲1em，與chrome、ibooks的規則不同，chrome的em默認值對應16px
參考：https://helpx.adobe.com/in/indesign/using/export-content-epub-cc.html
https://books.google.com/books?id=dEbaAgAAQBAJ&pg=PT155&lpg=PT155&dq=indesign+epub+font-size+12+1em&source=bl&ots=awIv8RNaDa&sig=ACfU3U025uyRsyVujmyMi-HtDU60aNKyNA&hl=en&sa=X&ved=2ahUKEwjwz_fgu_PlAhVzyjgGHTsXAWEQ6AEwDHoECAkQAQ#v=onepage&q=indesign%20epub%20font-size%2012%201em&f=false
https://www.lynda.com/InDesign-tutorials/Adjusting-type-sizes-screen/385429/422858-4.html