用 scss 练习编写一个样式库，有什么原则可以遵守呢？自己生成的 css 文件庞大无比

我有几个具体的问题： 1.这种在一个组件文件内分 mixin 的做法合适吗？与下一个对应，划分的一个原因是希望 mixin 内写代码，下面写嵌套结构。但是我看到有人说尽量少用 mixin。

2.从速度上来说不要嵌套结构会更快，但是嵌套的话我觉得更有助于开发的时候不乱章法，作为一个样式库，应该通过嵌套进行限制防止滥用还是样式不做嵌套，但是给出正确的示例代码，要求使用者按照示例代码来？

摘取一段代码，是用来实现右上角提醒框的。

scss：

@mixin notice(){
    padding: 1.6rem;
    border: 1px solid rgba($default-color,.3);
    width: 30rem;
    max-width: 90%;
    position: fixed;
    top: 2rem;
    right: 2rem;
    box-shadow: 0 2px 12px 0 rgba(0, 0, 0, .1);
    overflow: hidden;
    border-radius: 5px;
    z-index: 2000;
}

@mixin notice-color($background-color:$white-color,$color:$white-color){
    background-color: $background-color;
    color: $color;
}

@mixin notice-head(){
    height: 1.8rem;
    margin: 0 0 1rem 0;
    position: relative;
}

@mixin notice-title(){
    height: 1.8rem;
    overflow: hidden;
    text-overflow: ellipsis;
    position: absolute;
    word-break: keep-all;
    left: 0;
    top:0;
    right: 2rem;
    font-weight: 600;
    margin: 0 2rem 0 0;
}

@mixin notice-close(){
    font-family: 'icomoon';
    vertical-align: middle;
    position: absolute;
    right: 0;
    opacity: .5;
    &:hover{
        cursor: pointer;
    }
    &:before{
        content: "\e91e";
    }
}

@mixin notice-content(){
    font-size: 1.4rem;
    overflow: hidden;
    margin: 0;
    word-break:break-all;
}

.#{$prefix}notice {
    & {
        @include notice();
        @include notice-color($background-color:$white-color,$color:$black-color);
    }
    &.#{$prefix}notice-primary{
        @include notice-color($primary-color);
    }
    &.#{$prefix}notice-success{
        @include notice-color($success-color);
    }
    &.#{$prefix}notice-warn{
        @include notice-color($warn-color);
    }
    &.#{$prefix}notice-danger{
        @include notice-color($danger-color);
    }
    & .#{$prefix}notice-head {
        @include notice-head();
    }
    & .#{$prefix}notice-title {
        @include notice-title();
    }
    & .#{$prefix}notice-close {
        @include notice-close();
    }
    & .#{$prefix}notice-content {
        @include notice-content();
    }
}

生成的 css

.p-notice {
  padding: 1.6rem;
  border: 1px solid rgba(212, 212, 212, 0.3);
  width: 30rem;
  max-width: 90%;
  position: fixed;
  top: 2rem;
  right: 2rem;
  box-shadow: 0 2px 12px 0 rgba(0, 0, 0, 0.1);
  overflow: hidden;
  border-radius: 5px;
  z-index: 2000;
  background-color: #ffffff;
  color: #000000; }

.p-notice.p-notice-primary {
  background-color: #29B6F6;
  color: #ffffff; }

.p-notice.p-notice-success {
  background-color: #66BB6A;
  color: #ffffff; }

.p-notice.p-notice-warn {
  background-color: #FFCA28;
  color: #ffffff; }

.p-notice.p-notice-danger {
  background-color: #EF5350;
  color: #ffffff; }

.p-notice .p-notice-head {
  height: 1.8rem;
  margin: 0 0 1rem 0;
  position: relative; }

.p-notice .p-notice-title {
  height: 1.8rem;
  overflow: hidden;
  text-overflow: ellipsis;
  position: absolute;
  word-break: keep-all;
  left: 0;
  top: 0;
  right: 2rem;
  font-weight: 600;
  margin: 0 2rem 0 0; }

.p-notice .p-notice-close {
  font-family: 'icomoon';
  vertical-align: middle;
  position: absolute;
  right: 0;
  opacity: .5; }
  .p-notice .p-notice-close:hover {
    cursor: pointer; }
  .p-notice .p-notice-close:before {
    content: "\e91e"; }

.p-notice .p-notice-content {
  font-size: 1.4rem;
  overflow: hidden;
  margin: 0;
  word-break: break-all; }