Simple yet ellegant CSS buttons

buttons.css

//from https://codepen.io/simonbusborg/pen/cyxad
// converted from scss to css

:root {
  --color-dark: #161616;
  --color-ocean: #416dea;
  --color-grass: #3dd28d;
  --color-snow: #fff;
  --color-salmon: #f32c52;
  --color-sun: #feee7d;
  --color-alge: #7999a9;
  --color-flower: #353866;
  --color-smoke: #e4e4e4;
  --font-face: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
}
html {
  box-sizing: border-box;
}
*, *:before, *:after {
  box-sizing: inherit;
}
body {
  display: flex;
  box-sizing: border-box;
  min-height: 100vh;
  background: whitesmoke;
  font-family: var(--font-face);
  font-size: 16px;
  font-weight: 700;
  line-height: 1;
  justify-content: center;
  align-items: center;
}
@media (min-width: 992px) {
  body {
    border-width: 30px;
  }
}
body.linked .button, body.linked h1 {
  opacity: 0.3;
  transition: opacity 300ms linear;
}
body.linked p {
  color: var(--color-smoke);
  transition: color 300ms linear;
}
h1 {
  text-align: center;
  transition: opacity 300ms linear;
  color: var(--color-dark);
  font-family: var(--font-face);
  font-size: 32px;
  font-weight: 700;
}
h1 span {
  font-weight: 400;
}
p {
  max-width: 460px;
  margin: 0 auto;
  transition: color 300ms linear;
  text-align: center;
  color: var(--color-dark);
  font-weight: 400;
  line-height: 1.5;
}
a, a:visited {
  text-decoration: none;
  color: var(--color-ocean);
  font-weight: 500;
}
a:hover, a:visited:hover {
  text-decoration: underline;
  color: var(--color-ocean);
}
.container {
  display: flex;
  flex-direction: column;
  width: 100%;
  padding: 20px;
}
.button-container {
  display: flex;
  margin: 60px auto;
  flex-wrap: wrap;
  justify-content: center;
}
.button {
  display: flex;
  overflow: hidden;
  margin: 10px;
  padding: 12px 12px;
  cursor: pointer;
  user-select: none;
  transition: all 150ms linear;
  text-align: center;
  white-space: nowrap;
  text-decoration: none !important;
  text-transform: none;
  text-transform: capitalize;
  color: #fff;
  border: 0 none;
  border-radius: 4px;
  font-size: 13px;
  font-weight: 500;
  line-height: 1.3;
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  justify-content: center;
  align-items: center;
  flex: 0 0 160px;
  box-shadow: 2px 5px 10px var(--color-smoke);
}
.button:hover {
  transition: all 150ms linear;
  opacity: 0.85;
}
.button:active {
  transition: all 150ms linear;
  opacity: 0.75;
}
.button:focus {
  outline: 1px dotted #959595;
  outline-offset: -4px;
}
.button.-regular {
  color: #202129;
  background-color: #f2f2f2;
}
.button.-regular:hover {
  color: #202129;
  background-color: #e1e2e2;
  opacity: 1;
}
.button.-regular:active {
  background-color: #d5d6d6;
  opacity: 1;
}
.button.-dark {
  color: var(--color-snow);
  background: var(--color-dark);
}
.button.-dark:focus {
  outline: 1px dotted white;
  outline-offset: -4px;
}
.button.-green {
  color: var(--color-snow);
  background: var(--color-grass);
}
.button.-blue {
  color: var(--color-snow);
  background: var(--color-ocean);
}
.button.-salmon {
  color: var(--color-snow);
  background: var(--color-salmon);
}
.button.-sun {
  color: #f15c5c;
  background: var(--color-sun);
}
.button.-alge {
  color: #e7ff20;
  background: var(--color-alge);
}
.button.-flower {
  color: #fe8cdf;
  background: var(--color-flower);
}

This is converted from SCSS to CSS by this converter. If you want more info on how to use them, refer to the original code here.