*{
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    overflow-x: hidden; 
    /* background: url(bg.png) no-repeat center center fixed; 
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover; */
}

body{
    width: 100%;
    overflow-x: hidden;
}

.container {
    width: 100%;
    padding : 5% 36%;
}

.calculator {
    width: 100%;
    padding: 10px 2%;
    -webkit-box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    background: rgba(255, 255, 255, 0.9) none;
    border-radius: 5px;
}

.input-wrapper {
    padding: 15px;
}

.input {
    width: 100%;
    padding: 10px 10px;
    font-size: 28px;
    border: 1px solid #C5C5C5;
    color: black;
    text-align: center;
}

.input:hover {
    border: 1px solid #bbb;
    -webkit-box-shadow: inset 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    box-shadow: inset 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
}

.number-wrapper {
    padding: 0px 15px;
    width: 100%; 
    display: flex;
}

.invisible {
    opacity: 0;
    cursor: unset !important;
}

.button {
    padding: 0px 15px;
    width: 100%; 
    display: inline;
}

.number-first, .number-second, .number-third, .number-fourth {
    font-weight: lighter;
}

.number-first {
    width: 25%;
    border: 1px solid #C5C5C5;
    padding: 3% 5%;
    font-size: 28px;
    text-align: center;
    margin: 5px 0px;
    background-color: #f5f5f5;
    transition: border-color .2s ease-in-out, background-color .2s, box-shadow .2s;
    cursor: pointer;
}

.number-first:hover {
    background-color: #ddd;
    -webkit-box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    border-color: #aaa;
}

.number-fourth {
    width: 25%;
    border: 1px solid #C5C5C5;
    padding: 3% 5%;
    font-size: 28px;
    text-align: center;
    margin: 5px 0px;
    background-color: #f5f5f5;
    transition: border-color .2s ease-in-out, background-color .2s, box-shadow .2s;
    cursor: pointer;
}

.number-fourth:hover {
    background-color: #ddd;
    -webkit-box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    border-color: #aaa;
}

.number-second {
    width: 25%;
    border: 1px solid #C5C5C5;
    padding: 3% 5%;
    font-size: 28px;
    text-align: center;
    margin: 5px 0px 5px 20px;
    background-color: #f5f5f5;
    transition: border-color .2s ease-in-out, background-color .2s, box-shadow .2s;
    cursor: pointer;
}

.number-second:hover {
    background-color: #ddd;
    -webkit-box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    border-color: #aaa;
}

.number-third {
    width: 25%;
    border: 1px solid #C5C5C5;
    padding: 3% 5%;
    font-size: 28px;
    text-align: center;
    margin: 5px 20px;
    background-color: #f5f5f5;
    transition: border-color .2s ease-in-out, background-color .2s, box-shadow .2s;
    cursor: pointer;
}

.number-third:hover {
    background-color: #ddd;
    -webkit-box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
    border-color: #aaa;
}

.button {
    display: inline-block;
    text-align: center;
    padding: 15px 0px;
}

.button-login, .button-clear  {
    padding: 8px 25px;
    font-size: 20px;  
    color: white;
    border: none;
    border-radius: 5px;
}

.button-login {
    background: forestgreen;
}

.button-clear {
    background: red;
}

@media screen and (max-width: 600px) {
    .container {
        padding : 20% 5%;
        overflow-x: hidden;
    }
}