body {
    background-color: #f0f0f0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-family: Arial, sans-serif;
}

.calc-body {
    background: #1e1e1e;
    padding: 25px;
    border-radius: 25px;
    box-shadow: 15px 15px 30px rgba(0,0,0,0.4);
    width: 320px;
}

/* Screen */
.screen-container {
    background: #9fa979; 
    padding: 15px;
    border-radius: 12px;
    box-shadow: inset 5px 5px 15px rgba(0,0,0,0.5);
    margin-bottom: 25px;
    border: 2px solid #2a2a2a;
}

#display {
    width: 100%;
    background: transparent;
    border: none;
    text-align: right;
    font-family: 'Courier New', Courier, monospace;
    font-size: 2.2rem;
    font-weight: bold;
    color: #1a1a1a;
    outline: none;
}

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

.key {
    background: linear-gradient(145deg, #3a3a3a, #1a1a1a);
    color: white;
    border: none;
    padding: 18px 0;
    border-radius: 12px;
    font-size: 1.2rem;
    font-weight: bold;
    cursor: pointer;
    box-shadow: 4px 4px 8px #000, 
                inset 1px 1px 2px rgba(255,255,255,0.1);
    transition: all 0.1s;
}

.key:active {
    box-shadow: inset 3px 3px 6px #000;
    transform: translateY(2px);
}

/* Colors */
.red { background: linear-gradient(145deg, #ff4d4d, #9e0000); }
.blue { background: linear-gradient(145deg, #3b9fff, #0056a3); }

/* Bottom Layout */
.bottom-group {
    grid-column: span 4;
    display: flex;
    gap: 12px;
}

.num-pad {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    flex: 3;
}

.equal {
    flex: 1;
    height: auto;
    border-radius: 12px;
}