index.css

:root {
  --font-color: #ffffff;
  --background-color: #323b44;
}

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

body {
  background-color: var(--background-color);
  color: var(--font-color);
}

.container {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container > form {
  width: 80%;
  text-align: center;
}

.container > form > input {
  display: block;
  width: 100%;
  padding: 0.375rem 0.75rem;
  font-size: 3rem;
  text-align: center;
  line-height: 1.5;
  color: white;
  background-color: initial;
  background-clip: padding-box;
  border: none;
  border-bottom: 2px solid #ffa300;
  -webkit-transition: border-color 0.15s ease-in-out,
    box-shadow 0.15s ease-in-out;
  transition: border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out;
}

.container > form > label {
  font-size: 24px;
}

.row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  margin-bottom: 20px;
}