main.css

:root {
  --pink: #ff1493;
  --blue: #1493ff;
  --gray: #212121;
  --white: #fff;

  --c1: var(--pink);
  --c2: var(--blue);
  --c3: var(--gray);
  --c4: var(--white);

  --base-font-size: 2rem;
  --base-line-height: 1.3;

  --font-size-title: 7.2rem;
  --font-size-subtitle: 2.4rem;

  --source-sans-pro: "Source Sans Pro", sans-serif;
  --source-code-pro: "Source Code Pro", monospace;

  --socialbar-icon-size: 6.4rem;
  --socialbar-font-size: 3.6rem;
}

@media screen and (min-width: 576px) {
  :root {
    --font-size-title: 9.6rem;

    --socialbar-icon-size: 7.2rem;
    --socialbar-font-size: 4.2rem;
  }
}

/* keyframes */

@keyframes fade-in-down {
  from {
    transform: translateY(-50%);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

@keyframes fade-in {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes fade-in-up {
  from {
    transform: translateY(50%);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

/* box-sizing */

*,
::after,
::before {
  box-sizing: border-box;
}

/* selection */

*::selection {
  background-color: rgba(255, 20, 147, 0.5);
}

img::selection {
  background: none;
}

/* basic elements */

html,
body {
  position: relative;
  width: 100%;
  overflow: hidden;
}

html {
  height: 100%;
  overflow-y: auto;
  font-size: 62.5%;
  color: var(--c4);
  background-color: var(--c3);
}

body {
  font-family: var(--source-sans-pro);
  font-size: var(--base-font-size);
  line-height: var(--base-line-height);
  min-height: 100%;
  text-rendering: geometricPrecision;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a:focus {
  outline: none;
}

/* tabbar */

.tabbar {
  position: fixed;
  left: 0;
  bottom: 0;
  z-index: 1;
  display: flex;
  width: 100%;
}

.tab {
  flex-grow: 1;
  background: none;
  border: none;
  color: var(--c4);
}

.tab:focus {
  outline: none;
}

/* page */

.page,
.page__inner {
  width: 100%;
}

.page {
  display: flex;
  align-items: center;
  min-height: 100vh;
}

.page__inner {
  padding-top: 2.5rem;
  padding-bottom: 2.5rem;
}

@media screen and (min-width: 768px) {
  .page__inner {
    padding-top: 5rem;
    padding-bottom: 5rem;
  }
}

/* app */

.title,
.subtitle {
  text-align: center;
}

.title {
  margin-top: 0;
  font-size: var(--font-size-title);
  line-height: 1;
  color: var(--c1);
  animation-name: fade-in-down;
  animation-duration: 0.8s;
  animation-delay: 0.4s;
  animation-timing-function: ease-out;
  animation-fill-mode: both;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  padding-left: 0;
  list-style: none;
  font-size: var(--font-size-subtitle);
  font-family: var(--source-code-pro);
  animation-name: fade-in;
  animation-duration: 0.8s;
  animation-delay: 1.2s;
  animation-timing-function: ease-out;
  animation-fill-mode: both;
}

.tag {
  margin-right: 0.25em;
  margin-left: 0.25em;
}

.tag::before {
  content: "#";
  color: var(--c1);
}

/* socialbar */

.socialbar {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  list-style: none;
  padding-left: 0;
  margin-bottom: 0;
  font-size: var(--socialbar-font-size);
  line-height: 1;
  animation-name: fade-in-up;
  animation-duration: 0.8s;
  animation-delay: 0.8s;
  animation-timing-function: ease-out;
  animation-fill-mode: both;
}

.socialbar__item {
  margin-right: 0.4rem;
  margin-left: 0.4rem;
}

.socialbar__link {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
  width: var(--socialbar-icon-size);
  height: var(--socialbar-icon-size);
  color: var(--c4);
  transition: all 0.3s ease;
  border: 0.2rem solid var(--c4);
  border-radius: 50%;
  will-change: transform, color, border;
  backface-visibility: hidden;
  transform-origin: center center;
  transform: scale(0.9);
  backface-visibility: hidden;
  will-change: transform;
}

.socialbar__link::before {
  position: absolute;
  top: calc(100% + 0.6rem);
  z-index: 1;
  display: block;
  padding: 0.4rem 0.6rem;
  font-family: var(--source-code-pro);
  content: attr(data-channel-name);
  font-size: 1.8rem;
  visibility: hidden;
  opacity: 0;
  color: var(--c3);
  background-color: var(--c4);
  transition:
    all 0.3s ease,
    visibility 0s 0.3s ease;
}

.socialbar__link,
.socialbar__link:active,
.socialbar__link:focus,
.socialbar__link:hover {
  text-decoration: none;
}

.socialbar__link:focus,
.socialbar__link:hover {
  z-index: 1;
  color: var(--c1);
  border-color: var(--c1);
  transform: scale(1);
}

.socialbar__link:focus::before,
.socialbar__link:hover::before {
  background-color: var(--c1);
  opacity: 1;
  visibility: visible;
  transition-delay: 0s;
}