<div class="calculator">
    <input type="text" placeholder="0" readonly>
    <div>
        <button class="operator">AC</button>
        <button class="operator">DEL</button>
        <button class="operator">%</button>
        <button class="operator">/</button>
    </div>
    <div>
        <button class="">7</button>
        <button class="">8</button>
        <button class="">9</button>
        <button class="operator">*</button>
    </div>
    <div>
        <button class="">4</button>
        <button class="">5</button>
        <button class="">6</button>
        <button class="operator">-</button>
    </div>
    <div>
        <button class="">1</button>
        <button class="">2</button>
        <button class="">3</button>
        <button class="operator">+</button>
    </div>
    <div>
        <button class="">00</button>
        <button class="">0</button>
        <button class="">.</button>
        <button class="equalBtn">=</button>
    </div>
</div>

@import url("https://fonts.googleapis.com/css2?family=Poppins:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;0,800;0,900;1,100;1,200;1,300;1,400;1,500;1,600;1,700;1,800;1,900&display=swap");

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

body {
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(45deg, #0a0a0a, #3a4452);
}

.calculator {
    padding: 20px;
    border-radius: 1rem;
    background: transparent;
    box-shadow: 0 0 15px #71737780;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}

input {
    width: 320px;
    border: none;
    padding: 24px;
    margin: 10px;
    background: transparent;
    font-size: 2.5rem;
    text-align: right;
    cursor: pointer;
    color: #ffffff;
    resize: none;
}

input::placeholder {
    color: #fff;
}

button {
    border: none;
    width: 60px;
    height: 60px;
    margin: 10px;
    border-radius: 50%;
    background: transparent;
    color: #ffffff;
    font-size: 1.25rem;
    box-shadow: 0 0 15px rgba(255, 255, 255, 0.1);
    cursor: pointer;
}

.operator {
    color: #6dee0a;
}

.equalBtn {
    background: #fb7c14;
}

let input = document.querySelector("input");
let buttons = document.querySelectorAll("button");
let string = "";
let arr = Array.from(buttons);
arr.forEach((button) => {
    button.addEventListener("click", (e) => {
        if (e.target.innerHTML == "=") {
            try {
                string = eval(string);
            } catch (error) {
                string = "Syntax Error";
            }
            input.value = string;
        } else if (e.target.innerHTML == "AC") {
            string = "";
            input.value = string;
        } else if (e.target.innerHTML == "DEL") {
            string = string.substring(0, string.length - 1);
            input.value = string;
        } else {
            string += e.target.innerHTML;
            input.value = string;
        }
    });
});