*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
html,body {
    width: 100%;
    height: 100%;
    font-size: 10px;
}
.wrapper {
    margin: 0 auto;
    max-width: 500px;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
}
.text-display {
    width: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 5rem;
    flex-grow: 1;
}
.btns {
    width: 100%;
    display: flex;
    justify-content: center;
    flex-grow: 0;
}
.btn {
    width: 100%;
    height: 60px;
    border: 1px solid #aaa;
}
.btn:active {
    background-color: #999;
}
.input-display {
    width: 100%;
    display: flex;
    justify-content: center;
    flex-grow: 0;
}
.input-display input {
    width: 100%;
    height: 50px;
}