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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.calculator {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 20px;
    padding: 25px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    width: 350px;
    backdrop-filter: blur(10px);
}

.display {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    font-size: 2.5rem;
    padding: 25px;
    border-radius: 15px;
    text-align: right;
    margin-bottom: 20px;
    min-height: 80px;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    word-wrap: break-word;
    word-break: break-all;
    box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.2);
    transition: all 0.3s ease;
}

.display.updated {
    animation: pulse 0.3s ease;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.02); }
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
}

.btn {
    padding: 20px;
    font-size: 1.5rem;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.4s ease;
    font-weight: 600;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.5);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:active::before {
    width: 300px;
    height: 300px;
}

.btn:active {
    transform: scale(0.95);
}

.number {
    background: linear-gradient(135deg, #eaeaed 0%, #e2e8e8 100%);
    color: rgb(15, 15, 15);
}

.number:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(9, 13, 23, 0.708);
}

.operator {
    background: linear-gradient(135deg, #04bbdfef 0%, #5296d1 100%);
    color: white;
}

.operator:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgb(14, 14, 14);
}

.equals {
    background: linear-gradient(135deg, #e177c3 0%, #ba07f0 100%);
    color: white;
    grid-row: span 2 ;
}

.equals:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(218, 91, 216, 0.829);
}

.clear {
    background: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
    color: white;
    grid-column: span 2;
}

.clear:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(231, 160, 9, 0.861);
}

.delete {
    background: linear-gradient(135deg, #ff6b6b 0%, #ee5a6f 100%);
    color: white;
}

.delete:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(230, 26, 26, 0.854);
}

.zero {
    grid-column: span 2 ;
}

@media (max-width: 400px) {
    .calculator {
        width: 95%;
        padding: 15px;
    }
    
    .display {
        font-size: 2rem;
        padding: 20px;
    }
    
    .btn {
        padding: 15px;
        font-size: 1.2rem;
    }
}