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

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

.calculator {
    background: linear-gradient(145deg, #ffffff, #f5f5f5);
    border-radius: 30px;
    padding: 25px;
    width: 380px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3),
                0 0 0 1px rgba(255, 255, 255, 0.1) inset;
}

.calculator-header {
    text-align: center;
    font-size: 18px;
    font-weight: 600;
    color: #333;
    margin-bottom: 20px;
    letter-spacing: 1px;
}

.display {
    width: 100%;
    height: 90px;
    background: linear-gradient(145deg, #f0f0f0, #e8e8e8);
    color: #333;
    font-size: 2.5em;
    text-align: right;
    padding: 20px;
    margin-bottom: 20px;
    border-radius: 20px;
    border: 1px solid rgba(102, 126, 234, 0.1);
    box-shadow: inset 0 4px 10px rgba(0, 0, 0, 0.1),
                0 0 0 1px rgba(255, 255, 255, 0.5) inset;
    overflow-x: auto;
    font-weight: 500;
    word-wrap: break-word;
    word-break: break-all;
}

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

.btn {
    padding: 20px;
    border: none;
    border-radius: 15px;
    font-size: 1.3em;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    background: linear-gradient(145deg, #f5f5f5, #e8e8e8);
    color: #333;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.5);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
}

.btn:active {
    transform: translateY(0px);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.btn-clear {
    background: linear-gradient(145deg, #ff6b6b, #ee5a6f);
    color: white;
    box-shadow: 0 4px 15px rgba(255, 107, 107, 0.3);
}

.btn-clear:hover {
    box-shadow: 0 6px 20px rgba(255, 107, 107, 0.4);
}

.btn-operator {
    background: linear-gradient(145deg, #667eea, #764ba2);
    color: white;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.btn-operator:hover {
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
}

.btn-divide {
    background: linear-gradient(145deg, #667eea, #764ba2);
    color: white;
}

.btn-multiply {
    background: linear-gradient(145deg, #667eea, #764ba2);
    color: white;
}

.btn-minus {
    background: linear-gradient(145deg, #667eea, #764ba2);
    color: white;
}

.btn-plus {
    background: linear-gradient(145deg, #667eea, #764ba2);
    color: white;
}

.btn-equals {
    background: linear-gradient(145deg, #4facfe, #00f2fe);
    color: white;
    grid-column: span 1;
    box-shadow: 0 4px 15px rgba(79, 172, 254, 0.3);
}

.btn-equals:hover {
    box-shadow: 0 6px 20px rgba(79, 172, 254, 0.4);
}

.btn-zero {
    grid-column: span 2;
}