style.css

@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;700&display=swap');

/* Box sizing rules */
*,
*::before,
*::after {
  box-sizing: border-box;
}

/* Remove default margin */
* {
  margin: 0;
  padding: 0;
  font: inherit;
}

html,
body {
  height: 100%;
  font-family: 'Roboto', arial;
  display: flex;
  flex-direction: column;
  justify-content: center;
  background-color: #282828;
}

p {
    text-align: center;
    color: #fff;
}

.input {
    display: grid;
    justify-content: center;
    margin-top: 10px;
}

.container {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 50px;
    margin: 50px;
}

.clock {
    height: 50px;
    width: 150px;
    color: #1d1e22;
    border-radius: 5px;
    cursor: pointer;
    background-color: #fff;
}

.clock h2 {
    font-size: 24px;
    font-weight: 700;;
    display: flex;
    justify-content: center;
    align-items: center;
}

.button {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100px;
    padding: 5px;
    cursor: pointer;
    border-radius: 5px;
    border: none;
}

.button:disabled {
    cursor: default;
    background-color: #b3b3b3;
}

.black {
    /* background-color: #181818; if inactive */
    background-color: #000; 
}

.black h2 {
    color: #fff;
    /* color: #404040; if inactive */
}