<header class="pen-header">
  <h1>Hover effects</h1>
</header>

<div class="pen-container">
    <div>
      <span>01</span>
      <button type="button" class="btn btn--1"><span class="btn__text">Button</span></button>
    </div>
    <div>
      <span>02</span>
      <button type="button" class="btn btn--2"><span class="btn__text">Button</span></button>
    </div>
    <div>
      <span>03</span>
      <button type="button" class="btn btn--3"><span class="btn__text">Button</span></button>
    </div>
    <div>
      <span>04</span>
      <button type="button" class="btn btn--4"><span class="btn__text">Button</span></button>
    </div>
    <div>
      <span>05</span>
      <button type="button" class="btn btn--5"><span class="btn__text">Button</span></button>
    </div>
    <div>
      <span>06</span>
      <button type="button" class="btn btn--6"><span class="btn__text">Button</span></button>
    </div>
</div>

<footer class="pen-footer">
  <p>Template design: <a href="https://www.behance.net/barrud" target="_blank">Barrud</a> &verbar; Code: <a href="https://crocoder.pl" target="_blank">CroCoder</a></p>
</footer>

$font-main: 'Poppins', sans-serif;
$font-code: 'Source Code Pro', monospace;
$color-light-dark: #ebebeb;
$color-dark: #232426;
$color-red: #e4562a;
$btn-width: 180px;
$btn-height: 45px;
$time: 0.3s;

html{ box-sizing: border-box; }
*, *:before, *:after{ box-sizing: inherit; }
html, body{ width: 100%; }

body{
  font-family: $font-main;
  color: $color-dark;
  padding: 5%;
}

h1{
  position: relative;
  text-align: center;
  font-size: 36px;
  line-height: 1;
  &::before{
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    bottom: -12px;
    z-index: -1;
    color: $color-light-dark;
    content: "Button";
    font-size: 3em;
  }
}

.pen-container{
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
  align-items: center;
  width: 300px;
  max-width: 450px;
  margin: 0 auto;
  padding: 5%;
  background-color: $color-light-dark;
  & > div{
    width: $btn-width;
    padding: 40px 0;
    & >span{
       display: block;
       margin-bottom: 2em;
       font-size: 14px;
       font-family: $font-code;
    }
  }
}

/**
 * Base
 */
.btn{
  position: relative;
  border: 0;
  padding: 0;
  width: $btn-width;
  height: $btn-height;
  cursor: pointer;
  &__text{
    font-size: 14px;
    text-transform: uppercase;
    font-weight: 700;
    color: #fff;
  }
}

/**
 * Button 01
 */
.btn--1{
  background: $color-dark;

  .btn__text{
    position: relative;
    z-index: 1;
  }

  &::before, &::after{
    position: absolute;
    top: 0;
    display: block;
    height: 100%;
    width: 0;
    background-color: $color-red;
    content: "";
  }

  &::before{
    left: 0;
  }

  &::after{
    right: 0;
    transition: width $time;
  }
  
  &:hover::before{
    width: 100%;
    transition: width $time;
  }

  &:hover::after{
    background-color: transparent;
    width: 100%;
  }
}

/**
 * Button 02
 */
.btn--2{
  background: $color-dark;
  overflow: hidden;

  .btn__text{
    position: absolute;
    top: 0;
    left: 0;
    display: inline-block;
    width: 100%;
    height: 100%;
    line-height: $btn-height;
    transition: top $time;
  }

  &::after{
    position: absolute;
    top: 100%;
    left: 0;
    display: block;
    width: 100%;
    height: 100%;
    line-height: $btn-height;
    background-color: $color-red;
    content: "Click!";
    transition: top $time;
    font-size: 14px;
    font-weight: 700;
    color: #fff;
    text-transform: uppercase;
  }

  &:hover::after{ top: 0; }
  &:hover > .btn__text{ top: -100%; }
}

/**
 * Button 03
 */
.btn--3{
  background: transparent;

  .btn__text{
    position: relative;
    z-index: 1;
    color: $color-dark;
    transition: color $time;
  }

  &::after{
    position: absolute;
    top: calc(100% - 2px);
    left: 0;
    display: block;
    height: 2px;
    width: 100%;
    content: "";
    background-color: $color-red;
    transition: all $time;
  }

  &:hover::after{
    top: 0;
    height: 100%;
  }
  
  &:hover .btn__text{
    color: #fff;
  }
}

/**
 * Button 04
 */
.btn--4{
  background-color: $color-dark;

  .btn__text{
    position: relative;
    z-index: 1;
  }

  &::after{
    position: absolute;
    top: 0;
    left: 0;
    display: block;
    width: 100%;
    height: 100%;
    content: "";
  }

  &::after{
    background-color: $color-dark;
    transition: all $time;
  }

  &:hover::after{
    background-color: $color-red;
    transform: scale(1.1);
  }
}

/**
 * Button 05
 */
.btn--5{
  background-color: $color-dark;

  .btn__text{
    position: relative;
    z-index: 1;
  }

  &::after{
    position: absolute;
    top: 0;
    left: 0;
    display: block;
    width: 100%;
    height: 100%;
    content: "";
    transition: all $time;
  }

  &::after{
    background-color: $color-red;
    transform: scale(0.5);
    opacity: 0;
  }

  &:hover::after{
    opacity: 1;
    transform: scale(1);
  }
}

/**
 * Button 06
 */
.btn--6{
  background-color: transparent;
  .btn__text{
    position: relative;
    z-index: 1;
    color: $color-dark;
  }
  
  &::before, &::after{
    position: absolute;
    bottom: 0;
    display: block;
    height: 50%;
    width: 0;
    background-color: $color-red;
    content: "";
  }

  &::before{
    left: 0;
  }

  &::after{
    right: 0;
    transition: width $time;
  }
  
  &:hover::before{
    width: 100%;
    transition: width $time;
  }

  &:hover::after{
    background-color: transparent;
    width: 100%;
  }
}

.pen-footer{
  margin-top: 50px;
  font-size: 14px;
  text-align: center;
}

@media all and (min-width: 768px){
  .pen-container{
    flex-direction: row;
    justify-content: space-between;
    width: 100%;
    max-width: 740px;
  }
}