いままでは余白は自分でクラスを設定していたが、Bootsrtap4では既にマージンやパディングが用意されている。
公式: https://getbootstrap.com/docs/4.1/utilities/spacing/
Where property is one of:
m– for classes that setmarginp– for classes that setpadding
Where sides is one of:
t– for classes that setmargin-toporpadding-topb– for classes that setmargin-bottomorpadding-bottoml– for classes that setmargin-leftorpadding-leftr– for classes that setmargin-rightorpadding-rightx– for classes that set both*-leftand*-righty– for classes that set both*-topand*-bottom- blank – for classes that set a
marginorpaddingon all 4 sides of the element
Where size is one of:
0– for classes that eliminate themarginorpaddingby setting it to01– (by default) for classes that set themarginorpaddingto$spacer * .252– (by default) for classes that set themarginorpaddingto$spacer * .53– (by default) for classes that set themarginorpaddingto$spacer4– (by default) for classes that set themarginorpaddingto$spacer * 1.55– (by default) for classes that set themarginorpaddingto$spacer * 3auto– for classes that set themarginto auto
