@import url('https://fonts.googleapis.com/css2?family=Inter:ital,opsz,wght@0,14..32,100..900;1,14..32,100..900&display=swap');

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Inter', sans-serif;
    color: #333;
    box-sizing: border-box;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: #151515;
}

.calculator {
    width: 326px;
    background: #212121;
    border-radius: 24px;
    box-shadow: 0 4px 15px #000000;
    padding: 20px;
}

#result {
    width: 100%;
    min-height: 30px;
    text-align: right;
    font-size: 18px;
    color: #666666;
    margin-bottom: 5px;
}

#display {
    width: 100%;
    height: 60px;
    font-size: 24px;
    text-align: right;
    margin-bottom: 10px;
    padding: 10px;
    background: #eee;
    border-radius: 10px;
    outline: none;
    border: solid 2px #4f4f4f;
    transition: border 0.2s;
}

#display:focus {
    border: solid 2px #8000ff;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 64px);
    gap: 10px;
}

.btn {
    padding: 20px;
    font-size: 20px;
    font-weight: 700;
    background: #f9f9f9;
    border: 1px solid #000000;
    border-radius: 20px;
    cursor: pointer;
    transition: background 0.2s;
}

.btn:active {
    transform: scale(0.95);
    box-shadow: 0px 0px 20px #8000ff;
    border: solid 1px #8000ff;
}

.btn:hover {
    background: #ddd;
}

.operator {
    background: #ffcc00;
}

.operator:active {
    transform: scale(0.95);
    box-shadow: 0px 0px 20px #ffd500;
    border: solid 1px #ffd500;
}

.operator:hover {
    background: #d1a000;
}

.equal {
    grid-column: span 3;
    background: #8000ff;
    color: white;
    font-weight: bold;
    border-radius: 10px;
}

.equal:active {
    transform: scale(0.95);
    box-shadow: 0px 0px 20px #a000ff;
    border: solid 1px #a000ff;
}

.equal:hover {
    background: #a000ff;
}

.delete {
    background: #ff4d4d;
    color: white;
    font-weight: bold;
    border-radius: 10px;
    display: flex;
    justify-content: center;
}
.delete:active {
    transform: scale(0.95);
    box-shadow: 0px 0px 20px #ff0000;
    border: solid 1px #ff0000;
}
.delete:hover {
    background: #e60000;
}