body {
    margin: 30px auto;
    padding: 0;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: #3c493f;
    font-family: 'Roboto Condensed', sans-serif;
}

/* top/input section */
#top {
    width: 400px;
    height: 250px;
    display: flex;
    flex-direction: column;
    align-items: center;
    color: #3c493f;
    font-weight: bold;
    background-image: linear-gradient(
        135deg,
        hsl(121deg 100% 24%) 0%,
        hsl(75deg 100% 35%) 68%,
        hsl(55deg 99% 51%) 100%
        );
    border-radius: 10px 10px 0 0;
}

h3 {
    font-weight: bolder;
    font-size: 31px;
    text-shadow: .5px .5px black;
}

input {
    width: 300px;
    height: 60px;
    padding-bottom: 25px;
    text-align: center;
    border: none;
    background: none;
    color: #fff;
    font-weight: bold;
    font-size: 60px;
}

/* buttons */
.btns {
    display: flex;
    flex-direction: row;
    justify-content: space-between;
}

.btn-convert,
.btn-reset {
    margin: 0 10px;
    padding: 10px 15px;
    background: #3c493f;
    color: #fff;
    font-weight: bold;
    font-size: 18px;
    border: none;
    border-radius: 5px;
}

/* bottom/conversion section */
#bottom {
    width: 400px;
    height: 350px;
    background: #fff;
    color: #3c493f;
    border-radius: 0 0 10px 10px;
}

.unit {
    font-weight: bolder;
    font-size: 20px; 
}