style.css

* {
  margin: 0;
  padding: 0;
  box-sizing: inherit;
}

html {
  font-size: 62.5%;
  box-sizing: border-box;
}

body {
  position: relative;
  font-family: Verdana, Geneva, Tahoma, sans-serif;
  color: #333;
  line-height: 1.5;
  height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  background: linear-gradient(
    45deg,
    #f17c58,
    #e94584,
    #24aadb,
    #27dbb1,
    #ffdc18,
    #ff3706
  );
  background-size: 600% 100%;
  animation: gradient 16s linear infinite;
  animation-direction: alternate;
}

@keyframes gradient {
  0% {
    background-position: 0%;
  }
  100% {
    background-position: 100%;
  }
}

header {
  position: absolute;
  display: inline-block;
  margin-top: 5rem;
  padding: 0.8rem 1.4rem 2rem;
  border-radius: 5px;
  font-size: 1rem;
  font-weight: 700;
  text-align: center;
  color: #fff;
}

.header-txt:hover {
  color: #000;
  border-bottom: 2px solid #000;
  cursor: pointer;
}

.html,
.css,
.js {
  font-size: 2.2rem;
  font-weight: 600;
  margin: 20rem 1.5rem;
  padding: 1.25rem 5rem;
  color: #444;
  background-color: #fff;
  border: none;
  border-radius: 2.5rem;
  cursor: pointer;
}

.close-html-modal,
.close-css-modal,
.close-js-modal {
  position: absolute;
  top: 1.2rem;
  right: 2rem;
  font-size: 3.5rem;
  color: #333;
  background: none;
  border: none;
  cursor: pointer;
}

h1 {
  font-size: 2.5rem;
  margin-bottom: 2rem;
}

p {
  font-size: 1.5rem;
}

/* Classes to make Modal work */
.hidden {
  display: none;
}

.html-modal,
.css-modal,
.js-modal {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  padding: 6rem;
  width: 70%;
  background-color: #fff;
  border-radius: 5px;
  box-shadow: 0 3rem 5rem rgba(0, 0, 0, 0.3);
  z-index: 10;
}

.overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(3px);
  z-index: 5;
}