styles.css

/* Page styling */
h1 {
  font-family: "Lucida Console";
  color: rgb(255, 78, 47);
  background-color: rgb(126, 54, 35);
  padding-left: 0.5em;
}

body {
  background-color: rgb(83, 40, 0);
}

/* Input hint */
.form-hint {
  text-align: center;
  display: flex;
  justify-content: center;
}
.form-hint p {
  text-align: center;
  display: flex;
  justify-content: center;

  font-family: "Courier New";
  color: rgb(121, 80, 20);
  font-weight: bold;
  background-color: rgb(235, 200, 106);
  padding-right: 0.5em;
  padding-left: 0.5em;
  padding-bottom: 0.1em;
  margin-top: 0.6em;
}
/* User input field*/
input {
  text-align: center;
  border-radius: 0;
  border-style: solid;
  border-color: rgb(245, 116, 66);
  padding-top: 0.3em;
  padding-bottom: 0.2em;
  padding-left: 2em;
  padding-right: 2em;
  display: flex;
  justify-content: center;
  background-color: rgb(247, 233, 222);
}
input:focus {
  outline: none;
}
/* Submit button */
.submit-button {
  padding: 0.5em 3em;
  background-color: rgb(75, 219, 87);
  border: none;
  border-radius: 0.4em;
  color: rgb(20, 97, 26);
  font-family: "Lucida Console";
  font-size: 1.2em;
}
.submit-button:hover {
  transition: all 0.2s ease-in;
  background-color: rgb(126, 233, 137);
}
.submit-button:focus {
  transition: all 0.1s ease-in;
  background-color: rgb(158, 247, 167);
}
.submit-div {
  margin-top: 5em;
  text-align: center;
}
/* Wrapper for input field */
.form {
  margin-top: 1em;
  display: flex;
  justify-content: center;
}

/* Form field validation styles */
input.valid {
  border-color: rgb(64, 185, 80);
  border-width: 0.2em;
}
input.invalid {
  border-color: rgb(245, 116, 66);
}

/*

how 2 apply style whenever valid? probably inserting class with js but regex time not js time
.form input.valid + .form-hint p {
  color: rgb(108, 245, 66);
}
input.invalid + .form-hint p {
  color: rgb(245, 116, 66);
}
*/