前端 - css的加号是什么意思？

Question

  input.#{$prefix}-input-search + .button-search {
    border-top-left-radius: 0;
    border-bottom-left-radius: 0;
    left: -0.3em;
  }
  input.#{$prefix}-input-search:focus + .button-search {
    background: $border-focus-color;
  }

input.#{$prefix}-input-search + .button-search里面的+是什么意思？

Answer 1

Select adjacent elements. . .

Answer 2

Here is a very vivid CSS selector DEMO: http://flukeout.github.io/
This article explains it all: http://code.tutsplus.com/tutorials/the-30-css-selectors-you-must-memorize--net-16048
Here is an introduction to some commonly used selectors: https://developer.mozilla.org/zh-CN/docs/Web/Guide/CSS/Getting_started/Selectors