style.css

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@200&display=swap');

:root {
  --primary-color: #3d3d3d;
  --secondary-color: #636e72;
  --font: 'Poppins', sans-serif
}

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

.btn {
  padding: .6rem .8rem;
  text-transform: uppercase;
  font-family: var(--font);
  background: var(--primary-color);
  color: white;
  font-size: 16px;
  text-decoration: none;
  outline: none;
  border: 2px solid var(--primary-color);
  transition: .3s;
  cursor: pointer;
}

.btn:hover {
  background: transparent;
}

body {
  background: black;
  font-family: var(--font);
}

nav {
  position: fixed;
  width: 100vw;
  height: 60px;
  border-top: .5rem solid var(--primary-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  z-index: 999999;
}

.logo {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 55px;
  width: 15%;
  font-weight: 700;
  background: var(--primary-color);
}

.logo::before {
  content: "NJ";
  color: white;
}

.logo::after {
  content: "Fitness";
  color: black;
}

ul {
  display: flex;
  align-items: center;
  height: 60px;

}

ul a {
  text-decoration: none;
  color: white;
  margin: 0 2rem;
  text-transform: uppercase;
  font-family: var(--font);
  font-weight: 700;
  font-size: 16px;
}

ul li {
  list-style: none;
}

ul a:hover {
  color: var(--primary-color);
}

.banner {
  background: url(images/bg.jpg);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-attachment: fixed;
  height: 85vh;
}

.intro {
  position: absolute;
  top: 30%;
  left: 10%;
  color: white;
}

.intro h2,
p {
  display: block;
  width: 60%;
  align-items: center;
}

.intro h2 {
  text-transform: uppercase;
  letter-spacing: 2px;
  font-size: 30px;
}

.intro .btn {
  margin-top: 2rem;
}

.row {
  display: flex;
  justify-content: center;
}

.card {
  width: 33.3%;
  height: 250px;
  display: flex;
  justify-content: center;
  flex-direction: column;
  align-items: center;
}

.card h2 {
  text-transform: uppercase;
}