body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f3f4f6;
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 20px;
    box-sizing: border-box;
}
.calculator {
    background-color: #ffffff;
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 500px;
    text-align: center;
}
.display {
    width: 100%;
    height: 50px;
    font-size: 18px;
    margin-bottom: 20px;
    padding: 10px;
    box-sizing: border-box;
    border: 1px solid #ccc;
    border-radius: 5px;
}
.keyboard {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    margin-bottom: 20px;
}
.btn-key {
    background-color: #e5e7eb;
    border: none;
    padding: 15px 10px;
    font-size: 16px;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.2s;
    color: #374151;
    font-weight: bold;
}
.btn-key:hover {
    background-color: #d1d5db;
}
.btn-advanced {
    background-color: #bfdbfe;
    color: #1e3a8a;
}
.btn-advanced:hover {
    background-color: #93c5fd;
}
.btn-action {
    background-color: #fca5a5;
    color: #7f1d1d;
}
.btn-action:hover {
    background-color: #f87171;
}
.btn-submit {
    background-color: #10b981;
    color: white;
    border: none;
    padding: 15px 30px;
    font-size: 18px;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.2s;
    width: 100%;
}
.btn-submit:hover {
    background-color: #059669;
}


.result-title {
    display: block;
    font-size: 12px;
    font-weight: bold;
    color: #10b981;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 10px;
}

.result {
    margin-top: 25px;
    padding: 20px;
    background-color: #f8fafc;
    border-left: 5px solid #10b981;
    border-radius: 4px 8px 8px 4px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    text-align: left;
    color: #334155;
    font-size: 16px;
    line-height: 1.6;
    overflow-x: auto;
    max-width: 100%;
}