html {
    font-size: 10px;
    background: blue;
}
  
body,html {
    margin: 0;
    padding: 0;
    font-family: sans-serif;
    text-align: center;
}

.display__time-left {
    font-weight: 100;
    font-size: 20rem;
    margin: 0;
    color: white;
    text-shadow: 4px 4px 0 black;
}
  
.timer {
    display: flex;
    min-height: 100vh;
    flex-direction: column;
}

.timer__controls {
    display: flex;
}

.timer__controls > * {
    flex: 1;
}

.timer__controls form {
    flex: 1;
    display: flex;
}

.timer__controls input {
    flex: 1;
    border: 0;
    padding: 2rem;
}

.timer__button {
    background: none;
    border: 0;
    cursor: pointer;
    color: white;
    font-size: 2rem;
    text-transform: uppercase;
    background: black;
    border-bottom: 3px solid black;
    border-right: 1px solid black;
    padding: 1rem;
    font-family: 'Inconsolata', monospace;
}

.timer__button:hover,
.timer__button:focus {
    background: black;
    outline: 0;
}

.display {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.display__end-time {
    font-size: 4rem;
    color: white;
}