btn-css3.css

// 四角で囲う
.rectangle{
  color:#fff;
  background: rgb(255, 80, 49);
  position: relative;
  padding: 20px 30px;
  display: inline-block;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.rectangle::before{
  opacity: 0;
  position: absolute;
  content: '';
  display: block;
  border:1px solid  #ffffff;
  width: calc(100% - 10px);
  height: calc(100% - 10px);
  left: 5px;
  top: 5px;
  transition: .3s;
}
.rectangle:hover::before{
  opacity: 1;
}
.rectangle:active::before{
  border-style: dashed;
}
.rectangle:active::before{
  border-style: double;
  border-width: 4px;
}
// ブロックっぽいやつ
.block{
  font-size: 20px;
  letter-spacing: .3em;
  position: relative;
  display: inline-block;
  padding: 15px 20px;
  text-decoration: none;
  background: #00BCD4;/*背景色*/
  color: #00BCD4;/*=背景色*/
  box-shadow: inset 0 2px 0 rgba(255,255,255,0.2),0 2px 0 #118e9e;
  border-radius: 4px;
  font-weight: bold;
  text-shadow: -1px -1px rgba(255, 255, 255, 0.589), 1px 1px rgba(0, 0, 0, 0.38);
  transition: .3s;
}
.block:active {
  transform: translate(0,2px);
  box-shadow: none;
  text-shadow: -1px -1px rgba(255, 255, 255, 0.3), 1px 1px rgba(0, 0, 0, 0.3);
}

// 立体的なボタン
._3d{
  width: 200px;
  text-align: center;
  position: relative;
  display: block;
}
._3d span {
  padding: 15px 20px;
  display: block;
  position: absolute;
  width: 200px;
  border: 2px solid #333;
  text-align: center;
  transition: .3s;
}
._3d span:nth-child(1) { 
  background-color: #333;
  color: #fff;
  transform: rotateY(90deg);
  transform-origin: 50% 50% -50px;
}
._3d span:nth-child(2) {
  background-color: #fff;
  color: #333;
  transform: rotateY(0deg);
  transform-origin: 50% 50% -50px;
}
._3d:hover span:nth-child(1) {
  transform: rotateY(0deg);
  z-index: 1;
}
._3d:hover span:nth-child(2) {
  background-color: #333;
  transform: rotateY(-90deg);
}
._3d:active span:nth-child(1){
  background: rgb(255, 102, 42);
  border-color: rgb(255, 102, 42);
}

// 背景がアニメーションするボタン
.stripe{
  font-weight: bold;
  letter-spacing: .2em;
  display: inline-block;
  z-index: 1;
  padding: 16px 20px;
  width: 200px;
  overflow: hidden;
  text-align: center;
  background: rgb(245, 98, 0);
  color: #ffffff;
  position: relative;
}
.stripe::before{
  z-index: -1;
  content: '';
  width: calc(200% + 40px);
  position: absolute;
  left: calc(-100% - 40px);
  height: 100%;
  display: block;
  top: 0;
  background: linear-gradient(135deg, rgba(242,144,46,1) 55%,rgb(245, 98, 0) 55%);
  transition: .3s;
}
.stripe:hover::after{
  z-index: 1;
  content: '';
  width: 50px;
  height: 50px;
  position: absolute;
  display: block;
  bottom: 0;
  right: 0;
  background: linear-gradient(135deg, rgba(242,144,46,0) 50%,rgb(245, 98, 0) 50%);
}
.stripe:hover::before{
  left: 0;
}