Just out of curiosity, why bootstrap uses -15px left and right margins which going to cancel the 15px left and right padding on .container and .container-fluid classes.
Why set padding and then cancel it with a negative margin on the child?
出于好奇，为什么bootstrap使用-15px左右边距来取消。container和。container-fluid类上的15px左右边距。为什么要设置填充，然后在子对象上使用负的空白来取消它?
2 个解决方案
#1
1
As in Official Bootstrap Website said:
正如在官方引导网站上所说:
Rows are wrappers for columns. Each column has horizontal
padding(called a gutter) for controlling the space between them. Thispaddingis then counteracted on the rows with negativemargins. This way, all the content in your columns is visually aligned down the left side.行是列的包装器。每一列都有水平填充(称为排水沟)来控制它们之间的空间。然后，在具有负边距的行上抵消这种填充。这样，列中的所有内容在视觉上都沿着左侧对齐。
#2
1
A negative margin on row avoids the blank space that would be left because of padding of first column. In its absence the whole layout will look a little indented.
行上的负边距避免了由于第一列的填充而留下的空白空间。如果没有它，整个布局看起来会有点缩进。
#1
1
As in Official Bootstrap Website said:
正如在官方引导网站上所说:
Rows are wrappers for columns. Each column has horizontal
padding(called a gutter) for controlling the space between them. Thispaddingis then counteracted on the rows with negativemargins. This way, all the content in your columns is visually aligned down the left side.行是列的包装器。每一列都有水平填充(称为排水沟)来控制它们之间的空间。然后，在具有负边距的行上抵消这种填充。这样，列中的所有内容在视觉上都沿着左侧对齐。
#2
1
A negative margin on row avoids the blank space that would be left because of padding of first column. In its absence the whole layout will look a little indented.
行上的负边距避免了由于第一列的填充而留下的空白空间。如果没有它，整个布局看起来会有点缩进。