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

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

.calculator {
    background: #1a1a2e;
    border-radius: 20px;
    padding: 25px;
    width: 320px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.display {
    background: #16213e;
    color: #fff;
    font-size: 2.5rem;
    font-weight: 300;
    text-align: right;
    padding: 20px;
    margin-bottom: 20px;
    border-radius: 12px;
    min-height: 80px;
    word-wrap: break-word;
    overflow: hidden;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

.btn {
    padding: 18px;
    font-size: 1.3rem;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.15s ease;
    background: #0f3460;
    color: #fff;
}

.btn:hover {
    transform: translateY(-2px);
    filter: brightness(1.2);
}

.btn:active {
    transform: translateY(0);
    filter: brightness(0.9);
}

.operator {
    background: #e94560;
    color: #fff;
}

.clear {
    background: #533483;
}

.equal {
    background: #0f3460;
    grid-column: 4;
    grid-row: 2 / 6;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #e94560, #533483);
}