[常用图标的css实现]

icons.scss

// 正方形
#square {
  width: 100px;
  height: 100px;
  background: red;
}

// 长方形
#rectangle {
  width: 200px;
  height: 100px;
  background: red;
}

// 圆形
#circle {
  width: 100px;
  height: 100px;
  background: red;
  border-radius: 50%
}

// 椭圆
#oval {
  width: 200px;
  height: 100px;
  background: red;
  border-radius: 100px / 50px;
}

// 上三角形
#triangle-up {
  width: 0;
  height: 0;
  border-left: 50px solid transparent;
  border-right: 50px solid transparent;
  border-bottom: 100px solid red;
}

// 左上角
#triangle-topleft {
  width: 0;
  height: 0;
  border-top: 100px solid red;
  border-right: 100px solid transparent;
}

// 箭头
#curvedarrow {
  position: relative;
  width: 0;
  height: 0;
  border-top: 9px solid transparent;
  border-right: 9px solid red;
  transform: rotate(10deg);
}
#curvedarrow:after {
  content: "";
  position: absolute;
  border: 0 solid transparent;
  border-top: 3px solid red;
  border-radius: 20px 0 0 0;
  top: -12px;
  left: -9px;
  width: 12px;
  height: 12px;
  transform: rotate(45deg);
}

// 梯形
#trapezoid {
  border-bottom: 100px solid red;
  border-left: 25px solid transparent;
  border-right: 25px solid transparent;
  height: 0;
  width: 100px;
}

// 平行四边形
#parallelogram {
  width: 150px;
  height: 100px;
  transform: skew(20deg);
  background: red;
}

// 六角星
#star-six {
  width: 0;
  height: 0;
  border-left: 50px solid transparent;
  border-right: 50px solid transparent;
  border-bottom: 100px solid red;
  position: relative;
}
#star-six:after {
  width: 0;
  height: 0;
  border-left: 50px solid transparent;
  border-right: 50px solid transparent;
  border-top: 100px solid red;
  position: absolute;
  content: "";
  top: 30px;
  left: -50px;
}

// 五角星
#star-five {
  margin: 50px 0;
  position: relative;
  display: block;
  color: red;
  width: 0px;
  height: 0px;
  border-right: 100px solid transparent;
  border-bottom: 70px solid red;
  border-left: 100px solid transparent;
  transform: rotate(35deg);
}
#star-five:before {
  border-bottom: 80px solid red;
  border-left: 30px solid transparent;
  border-right: 30px solid transparent;
  position: absolute;
  height: 0;
  width: 0;
  top: -45px;
  left: -65px;
  display: block;
  content: '';
  transform: rotate(-35deg);
}
#star-five:after {
  position: absolute;
  display: block;
  color: red;
  top: 3px;
  left: -105px;
  width: 0px;
  height: 0px;
  border-right: 100px solid transparent;
  border-bottom: 70px solid red;
  border-left: 100px solid transparent;
  transform: rotate(-70deg);
  content: '';
}

// 五边形
#pentagon {
  position: relative;
  width: 54px;
  box-sizing: content-box;
  border-width: 50px 18px 0;
  border-style: solid;
  border-color: red transparent;
}
#pentagon:before {
  content: "";
  position: absolute;
  height: 0;
  width: 0;
  top: -85px;
  left: -18px;
  border-width: 0 45px 35px;
  border-style: solid;
  border-color: transparent transparent red;
}

// 六边形
#hexagon {
  width: 100px;
  height: 55px;
  background: red;
  position: relative;
}
#hexagon:before {
  content: "";
  position: absolute;
  top: -25px;
  left: 0;
  width: 0;
  height: 0;
  border-left: 50px solid transparent;
  border-right: 50px solid transparent;
  border-bottom: 25px solid red;
}
#hexagon:after {
  content: "";
  position: absolute;
  bottom: -25px;
  left: 0;
  width: 0;
  height: 0;
  border-left: 50px solid transparent;
  border-right: 50px solid transparent;
  border-top: 25px solid red;
}

// 八边形
#octagon {
  width: 100px;
  height: 100px;
  background: red;
  position: relative;
}
#octagon:before {
  content: "";
  width: 100px;
  height: 0;
  position: absolute;
  top: 0;
  left: 0;
  border-bottom: 29px solid red;
  border-left: 29px solid #eee;
  border-right: 29px solid #eee;
}
#octagon:after {
  content: "";
  width: 100px;
  height: 0;
  position: absolute;
  bottom: 0;
  left: 0;
  border-top: 29px solid red;
  border-left: 29px solid #eee;
  border-right: 29px solid #eee;
}

// 爱心
#heart {
  position: relative;
  width: 100px;
  height: 90px;
}
#heart:before,
#heart:after {
  position: absolute;
  content: "";
  left: 50px;
  top: 0;
  width: 50px;
  height: 80px;
  background: red;
  border-radius: 50px 50px 0 0;
  transform: rotate(-45deg);
  transform-origin: 0 100%;
}
#heart:after {
  left: 0;
  transform: rotate(45deg);
  transform-origin: 100% 100%;
}

// 无穷大
#infinity {
  position: relative;
  width: 212px;
  height: 100px;
  box-sizing: content-box;
}
#infinity:before,
#infinity:after {
  content: "";
  box-sizing: content-box;
  position: absolute;
  top: 0;
  left: 0;
  width: 60px;
  height: 60px;
  border: 20px solid red;
  border-radius: 50px 50px 0 50px;
  transform: rotate(-45deg);
}
#infinity:after {
  left: auto;
  right: 0;
  border-radius: 50px 50px 50px 0;
  transform: rotate(45deg);
}

// 菱形
#diamond {
  width: 0;
  height: 0;
  border: 50px solid transparent;
  border-bottom-color: red;
  position: relative;
  top: -50px;
}
#diamond:after {
  content: '';
  position: absolute;
  left: -50px;
  top: 50px;
  width: 0;
  height: 0;
  border: 50px solid transparent;
  border-top-color: red;
}

// 钻石
#cut-diamond {
  border-style: solid;
  border-color: transparent transparent red transparent;
  border-width: 0 25px 25px 25px;
  height: 0;
  width: 50px;
  box-sizing: content-box;
  position: relative;
  margin: 20px 0 50px 0;
}
#cut-diamond:after {
  content: "";
  position: absolute;
  top: 25px;
  left: -25px;
  width: 0;
  height: 0;
  border-style: solid;
  border-color: red transparent transparent transparent;
  border-width: 70px 50px 0 50px;
}


// 鸡蛋
#egg {
  display: block;
  width: 126px;
  height: 180px;
  background-color: red;
  border-radius: 50% 50% 50% 50% / 60% 60% 40% 40%;
}

// 吃豆人
#pacman {
  width: 0px;
  height: 0px;
  border-right: 60px solid transparent;
  border-top: 60px solid red;
  border-left: 60px solid red;
  border-bottom: 60px solid red;
  border-top-left-radius: 60px;
  border-top-right-radius: 60px;
  border-bottom-left-radius: 60px;
  border-bottom-right-radius: 60px;
}

// 对话框
#talkbubble {
  width: 120px;
  height: 80px;
  background: red;
  position: relative;
  -moz-border-radius: 10px;
  -webkit-border-radius: 10px;
  border-radius: 10px;
}
#talkbubble:before {
  content: "";
  position: absolute;
  right: 100%;
  top: 26px;
  width: 0;
  height: 0;
  border-top: 13px solid transparent;
  border-right: 26px solid red;
  border-bottom: 13px solid transparent;
}

// 太极
#yin-yang {
  width: 96px;
  box-sizing: content-box;
  height: 48px;
  background: #eee;
  border-color: red;
  border-style: solid;
  border-width: 2px 2px 50px 2px;
  border-radius: 100%;
  position: relative;
}
#yin-yang:before {
  content: "";
  position: absolute;
  top: 50%;
  left: 0;
  background: #eee;
  border: 18px solid red;
  border-radius: 100%;
  width: 12px;
  height: 12px;
  box-sizing: content-box;
}
#yin-yang:after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  background: red;
  border: 18px solid #eee;
  border-radius: 100%;
  width: 12px;
  height: 12px;
  box-sizing: content-box;
}  

// 勋章
#badge-ribbon {
  position: relative;
  background: red;
  height: 100px;
  width: 100px;
  border-radius: 50px;
}
#badge-ribbon:before,
#badge-ribbon:after {
  content: '';
  position: absolute;
  border-bottom: 70px solid red;
  border-left: 40px solid transparent;
  border-right: 40px solid transparent;
  top: 70px;
  left: -10px;
  transform: rotate(-140deg);
}
#badge-ribbon:after {
  left: auto;
  right: -10px;
  transform: rotate(140deg);
}

// 放大镜
#magnifying-glass {
  font-size: 10em;
  display: inline-block;
  width: 0.4em;
  box-sizing: content-box;
  height: 0.4em
  border: 0.1em solid red;
  position: relative;
  border-radius: 0.35em;
}
#magnifying-glass:before {
  content: "";
  display: inline-block;
  position: absolute;
  right: -0.25em;
  bottom: -0.1em;
  border-width: 0;
  background: red;
  width: 0.35em;
  height: 0.08em;
  transform: rotate(45deg);
}

// facebook图标
#facebook-icon {
  background: red;
  text-indent: -999em;
  width: 100px;
  height: 110px;
  box-sizing: content-box;
  border-radius: 5px;
  position: relative;
  overflow: hidden;
  border: 15px solid red;
  border-bottom: 0;
}
#facebook-icon:before {
  content: "/20";
  position: absolute;
  background: red;
  width: 40px;
  height: 90px;
  bottom: -30px;
  right: -37px;
  border: 20px solid #eee;
  border-radius: 25px;
  box-sizing: content-box;
}
#facebook-icon:after {
  content: "/20";
  position: absolute;
  width: 55px;
  top: 50px;
  height: 20px;
  background: #eee;
  right: 5px;
  box-sizing: content-box;
}

// 月亮
#moon {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  box-shadow: 15px 15px 0 0 red;
}

// 指示器

#pointer {
  width: 200px;
  height: 40px;
  position: relative;
  background: red;
}
#pointer:after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 0;
  border-left: 20px solid white;
  border-top: 20px solid transparent;
  border-bottom: 20px solid transparent;
}
#pointer:before {
  content: "";
  position: absolute;
  right: -20px;
  bottom: 0;
  width: 0;
  height: 0;
  border-left: 20px solid red;
  border-top: 20px solid transparent;
  border-bottom: 20px solid transparent;
}

// 锁
#lock {
  font-size: 8px;
  position: relative;
  width: 18em;
  height: 13em;
  border-radius: 2em;
  top: 10em;
  box-sizing: border-box;
  border: 3.5em solid red;
  border-right-width: 7.5em;
  border-left-width: 7.5em;
  margin: 0 0 6rem 0;
}
#lock:before {
  content: "";
  box-sizing: border-box;
  position: absolute;
  border: 2.5em solid red;
  width: 14em;
  height: 12em;
  left: 50%;
  margin-left: -7em;
  top: -12em;
  border-top-left-radius: 7em;
  border-top-right-radius: 7em;
}
#lock:after {
  content: "";
  box-sizing: border-box;
  position: absolute;
  border: 1em solid red;
  width: 5em;
  height: 8em;
  border-radius: 2.5em;
  left: 50%;
  top: -1em;
  margin-left: -2.5em;
}