style.css

*{
    margin: 0;
    padding: 0;
    font-family:'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    box-sizing: border-box;
}

.container{
    width: 100%;
    min-height: 100vh;
    background: linear-gradient(500deg, #124066, #ffffff);
    color: #fff;
    padding: 10px;
}
.calculator{
    width: 100%;
    max-width: 600px;
    margin-left: 10%;
    margin-top: 10%;
}
.calculator h1{
    font-size: 60px;
}
.calculator h1 span{
    color: yellow;
}
.input-box{
    margin: 40px 0;
    padding: 35px;
    border-radius: 10px;
    background: rgba(255,255,255,0.3);
    display: flex;
    align-items: center;
}
.input-box input{
    position: relative;
    flex: 1;
    margin-right: 20px;
    padding: 14px 20px;
    border: 0;
    outline: 0;
    font-size: 18px;
    border-radius: 5px;
    cursor: pointer;
}
.input-box button{
    background: #ffff76;
    color: #333;
    position: relative;
    padding: 15px 30px;
    border: 0;
    outline: 0;
    font-size: 18px;
    font-weight: 600;
    border-radius: 5px;
    cursor: pointer;
}
.input-box button:hover{
    background: rgb(9, 134, 9);
    color: white;
}
.input-box input::-webkit-calender-picker-indicator{
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    width: auto;
    position: absolute;
    background-position: calc(100% - 10px);
    background-size: 30px;
    cursor: pointer;
}

#result{
    font-size: 20px;
    font-weight: 600;
}
#result span{
    color: rgb(255, 251, 0);
}
.video{
    border-radius: 200px;
    margin-top: -485px;
    margin-left: 825px;
}
footer{
    color: rgb(0, 0, 0);
    font-weight: 600;
}