@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@500&display=swap');

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

body {
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(45deg, #0a0a0a, #2e3744);
}

/* Calculator Container: Adds the container look with borders and shadow */
.calculator {
    border: 1px solid #717377;
    padding: 20px;
    border-radius: 16px;
    background: transparent;
    box-shadow: 0px 3px 15px rgba(255, 255, 255, 0.1);
}

/* Display (Input) Styling: Styles the screen area to be right-aligned and legible */
input {
    width: 320px;
    border: none;
    padding: 24px;
    margin: 10px;
    background: transparent;
    box-shadow: 0px 3px 15px rgba(84, 84, 84, 0.1);
    font-size: 40px;
    text-align: right;
    cursor: pointer;
    color: #ffffff;
    outline: none;
}

input::placeholder {
    color: #ffffff;
}

/* Button Design: Creates the circular buttons with 3D shadow effects */
button {
    width: 60px;
    height: 60px;
    margin: 10px;
    border: none;
    border-radius: 50%;
    background: transparent;
    color: #ffffff;
    font-size: 20px;
    box-shadow: -8px -8px 15px rgba(255, 255, 255, 0.1);
    cursor: pointer;
    transition: transform 0.1s ease, box-shadow 0.1s ease, filter 0.1s ease;
}

button:hover {
    filter: brightness(1.15);
}

button:active,
button.active {
    transform: scale(0.93);
    box-shadow: inset -4px -4px 8px rgba(255, 255, 255, 0.1), inset 4px 4px 8px rgba(0, 0, 0, 0.5);
}

/* Specific Button Colors: Distinguishes operators and the equals button */
.equal-btn {
    background-color: #fb7c14;
    color: #ffffff;
}

.operator {
    color: #6dee0a;
}