header{
    height: 200px;
    background-color: grey;
}
#menu{
    height: 800px;
    width: 20%;
    background-color: #eeeeee;
    float: left;
}
#content{
    height: 800px;
    width: 80%;
    background-color: rgb(150, 147, 110);
    float: left;
}
#content > div {padding-left: 15px;}
footer{
    height: 100px;
    clear: both;
    background-color: lightgreen;
}


.button-89 {
  --b: 3px;   /* border thickness */
  --s: .45em; /* size of the corner */
  --color: #373B44;
  
  padding: calc(.5em + var(--s)) calc(.9em + var(--s));
  color: var(--color);
  --_p: var(--s);
  background:
    conic-gradient(from 90deg at var(--b) var(--b),#0000 90deg,var(--color) 0)
    var(--_p) var(--_p)/calc(100% - var(--b) - 2*var(--_p)) calc(100% - var(--b) - 2*var(--_p));
  transition: .3s linear, color 0s, background-color 0s;
  outline: var(--b) solid #0000;
  outline-offset: .6em;
  font-size: 16px;

  border: 0;

  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
  border-radius: 4px;
  margin: 20px;
}

/* CSS */
.button-90 {
  color: #fff;
  padding: 15px 25px;
  border-radius: 100px;
  background-color: #4C43CD;
  background-image: radial-gradient(93% 87% at 87% 89%, rgba(0, 0, 0, 0.23) 0%, transparent 86.18%), radial-gradient(66% 87% at 26% 20%, rgba(255, 255, 255, 0.41) 0%, rgba(255, 255, 255, 0) 69.79%, rgba(255, 255, 255, 0) 100%);
  box-shadow: 2px 19px 31px rgba(0, 0, 0, 0.2);
  font-weight: bold;
  font-size: 16px;
width: 80%;
margin-bottom: 20px;
margin-left: 20px;
  border: 0;

  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;

  cursor: pointer;
}
/* CSS */
.button-85 {
  padding: 0.6em 2em;
  border: none;
  outline: none;
  color: rgb(255, 255, 255);
  background: #111;
  cursor: pointer;
  position: relative;
  z-index: 0;
  border-radius: 10px;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
}

.button-85:before {
  content: "";
  background: linear-gradient(
    45deg,
    #ff0000,
    #ff7300,
    #fffb00,
    #48ff00,
    #00ffd5,
    #002bff,
    #7a00ff,
    #ff00c8,
    #ff0000
  );
  position: absolute;
  top: -2px;
  left: -2px;
  background-size: 400%;
  z-index: -1;
  filter: blur(5px);
  -webkit-filter: blur(5px);
  width: calc(100% + 4px);
  height: calc(100% + 4px);
  animation: glowing-button-85 20s linear infinite;
  transition: opacity 0.3s ease-in-out;
  border-radius: 10px;
}

@keyframes glowing-button-85 {
  0% {
    background-position: 0 0;
  }
  50% {
    background-position: 400% 0;
  }
  100% {
    background-position: 0 0;
  }
}

.button-85:after {
  z-index: -1;
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  background: #222;
  left: 0;
  top: 0;
  border-radius: 10px;
}

/* CSS */
.button-91 {
  color: #fff;
  padding: 15px 25px;
  background-color: #38D2D2;
  background-image: radial-gradient(93% 87% at 87% 89%, rgba(0, 0, 0, 0.23) 0%, transparent 86.18%), radial-gradient(66% 66% at 26% 20%, rgba(255, 255, 255, 0.55) 0%, rgba(255, 255, 255, 0) 69.79%, rgba(255, 255, 255, 0) 100%);
  box-shadow: inset -3px -3px 9px rgba(255, 255, 255, 0.25), inset 0px 3px 9px rgba(255, 255, 255, 0.3), inset 0px 1px 1px rgba(255, 255, 255, 0.6), inset 0px -8px 36px rgba(0, 0, 0, 0.3), inset 0px 1px 5px rgba(255, 255, 255, 0.6), 2px 19px 31px rgba(0, 0, 0, 0.2);
  border-radius: 14px;
  font-weight: bold;
  font-size: 16px;

  border: 0;

  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;

  cursor: pointer;
}
div{
  font-family: cursive;
}