*{
    margin: 0;
    padding: 0;
    font-family: 'Poppins', sans-serif;
    box-sizing: border-box;
}

.container{
    width: 100%;
    min-height: 100vh;
    background: linear-gradient(135deg, #4203a9, #90bafc);
    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: #ffff76;

}
 
.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{
    flex: 1;
    margin-right: 20px;
    padding: 14px 20px;
    border: 0;
    outline: 0;
    font-size: 18px;
    border-radius: 5px;
    position: relative;
}

.input-box button{
    background: #ffff76;
    border: 0;
    outline: 0;
    padding: 15px 30px;
    border-radius: 5px;
    font-weight: 500;
    color: #333;
    cursor: pointer;
}

.input-box input::-webkit-calendar-picker-indicator{
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    width: auto;
    height: auto;
    position: absolute;
    background-position: calc(100% - 10px);
    background-size: 30px;
    cursor: pointer;
}

#result{
    font-size: 20px;
}

#result span {
    color: #ffff76;
}

/*  Responsive design for mobile */
@media (max-width: 768px) {
    .calculator {
        margin: 20px auto;   /* center it */
        text-align: center;
    }

    .calculator h1 {
        font-size: 40px;    /* smaller heading */
        line-height: 1.3;
    }

    .input-box {
        flex-direction: column;  /* stack input + button */
        padding: 20px;
        gap: 15px; /* spacing between input and button */
    }

    .input-box input {
        margin-right: 0;
        width: 100%;
        font-size: 16px;
    }

    .input-box button {
        width: 100%;
        font-size: 16px;
        padding: 12px;
    }

    #result {
        font-size: 18px;
    }
}

/*  Extra small screens */
@media (max-width: 480px) {
    .calculator h1 {
        font-size: 32px;
    }

    .input-box {
        padding: 15px;
    }

    .input-box input,
    .input-box button {
        font-size: 14px;
    }
}