* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(135deg, #667eea, #764ba2);
    font-family: Arial, sans-serif;
}

.calculator {
    width: 320px;
    padding: 22px;
    border-radius: 20px;
    background: #ffffff;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
}

h1 {
    text-align: center;
    color: #26356b;
}

#display {
    width: 100%;
    height: 65px;
    margin-bottom: 15px;
    padding: 12px;
    font-size: 28px;
    text-align: right;
    border: 2px solid #ddd;
    border-radius: 10px;
    background: #f5f7ff;
    color: #222;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 9px;
}

button {
    height: 55px;
    border: none;
    border-radius: 10px;
    background: #edf0f7;
    font-size: 20px;
    cursor: pointer;
}

button:hover {
    filter: brightness(0.93);
}

.operator {
    background: #dce5ff;
    color: #244ac4;
}

.clear {
    background: #ffdede;
    color: #b42318;
}

.equal {
    grid-column: span 2;
    background: #3157d5;
    color: white;
}
.history {
    margin-top: 22px;
    padding-top: 15px;
    border-top: 2px solid #ddd;
}

.history h2 {
    font-size: 18px;
    color: #26356b;
}

#clear-history {
    width: 100%;
    height: 38px;
    font-size: 14px;
    background: #ffdede;
    color: #b42318;
}

#history-list {
    padding-left: 20px;
}

#history-list li {
    padding: 8px;
    margin: 5px 0;
    background: #f0f3ff;
    border-radius: 6px;
    overflow-wrap: anywhere;
}