:root {
  --font-family: "Segoe UI", Arial, sans-serif;
  --line-height: 1.6;
  --background-color: #35424a;
  --header-color: #ffffff;
}

* {
  box-sizing: border-box;
}

body {
  font-family: var(--font-family);
  line-height: var(--line-height);
  margin: 0;
  padding: 0;
  background-color: var(--background-color);
  scroll-behavior: smooth;
}

header {
  background: var(--background-color);
  color: var(--header-color);
  padding: 10px 0;
  text-align: center;
  position: sticky;
  top: 0;
}

nav a {
  color: var(--header-color);
  text-decoration: none;
  padding: 10px 15px;
}

section {
  width: 50%;
  margin: 20px auto;
  padding: 20px;
  background: var(--header-color);
  border-radius: 8px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

main {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background-color: #f4f4f4;
  min-height: 100dvh;
  overflow: auto;
}

.sign-in {
  text-align: right;
}

.sign-in-link {
  color: #0078d4;
  text-decoration: none;
}

.signup-form {
  display: flex;
  flex-direction: column;
}

.signup-heading {
  line-height: 1;
}

.signup-form .form-group {
  margin-bottom: 20px;
}

.signup-form label {
  display: block;
  margin-bottom: 5px;
  color: #333;
}

.signup-form input,
.signup-form select {
  width: 100%;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 4px;
}

.signup-form input[type="checkbox"] {
  width: auto;
  margin-right: 10px;
}

.submit-button {
  width: 100%;
  padding: 10px;
  background-color: rgb(106, 111, 245);
  color: #fff;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  margin-top: 20px;
}

.submit-button:hover {
  background-color: rgb(106, 111, 245, 0.8);
}

footer {
  text-align: center;
  padding: 10px 0;
  background: var(--background-color);
  color: var(--header-color);
  position: sticky;
  bottom: 0;
}

footer a {
  color: var(--header-color);
  text-decoration: none;
}

@media (max-width: 767px) {
  section {
    width: 90%;
  }
  .sign-in {
    text-align: center;
  }
}

@media (min-width: 768px) {
  .signup-form {
    flex-direction: row;
    flex-wrap: wrap;
  }
  .signup-form .form-group {
    width: 48%;
    margin-right: 4%;
  }
  .signup-form .form-group:nth-child(2n) {
    margin-right: 0;
  }

  .signup-form .form-group.referral {
    width: 100%;
    margin-right: 0;
  }

  .signup-form .form-group.password {
    width: 48%;
    margin-right: 0;
  }

  .signup-form .form-group.password:nth-child(2n) {
    margin-right: 4%;
  }
}