/* 計算機 */
 .calculator {
    background-color: #2c3e50; /* Dark blue-grey theme */
    padding: 20px;
    border-radius: 15px;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.3);
    width: 100%; /* Make it responsive */
    max-width: 52%; /* Max width for larger screens */
    box-sizing: border-box;
    margin: auto;
}

.screen-container {
    background-color: #1d2b3a; /* Darker screen background */
    padding: 10px;
    border-radius: 8px;
    margin-bottom: 20px;
    box-shadow: inset 0 2px 5px rgba(0,0,0,0.2);
}

.formula-screen {
    width: 100%;
    min-height: 25px; /* Min height */
    color: #bdc3c7; /* Lighter grey for formula */
    text-align: right;
    font-size: 0.9em;
    margin-bottom: 5px;
    box-sizing: border-box;
    overflow-x: auto;
    white-space: nowrap;
    line-height: 1.5;
    padding-right: 5px;
}

.calculator-screen { /* Main display */
    width: 100%;
    height: 60px;
    background-color: transparent; /* Transparent to use container bg */
    color: #ecf0f1; /* Light text for main display */
    text-align: right;
    padding: 0 5px;
    font-size: 2.2em; /* Slightly reduced for more digits */
    border: none;
    box-sizing: border-box;
    overflow: hidden;
    white-space: nowrap;
    line-height: 60px;
}

.calculator-keys {
    display: grid;
    /* Adjust to 5 columns for more functions */
    grid-template-columns: repeat(5, 1fr);
    gap: 10px;
}

.calculator-keys button {
    background-color: #34495e; /* Button color */
    color: #ecf0f1; /* Button text color */
    border: none;
    padding: 15px 5px; /* Adjusted padding */
    font-size: 1.1em; /* Adjusted font size */
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s;
    box-shadow: 0 3px 5px rgba(0,0,0,0.15);
}

.calculator-keys button:hover {
    background-color: #4a6278; /* Lighter on hover */
}

.calculator-keys button:active {
    background-color: #283747; /* Darker on active */
    transform: translateY(1px);
    box-shadow: 0 1px 2px rgba(0,0,0,0.2);
}

.operator {
    background-color: #e67e22; /* Orange for operators */
    color: white;
}
.operator:hover { background-color: #d35400; }

.function, .scientific { /* Style for function keys */
    background-color: #1abc9c; /* Teal for functions */
    color: white;
}
.function:hover, .scientific:hover { background-color: #16a085; }

.clear, .delete {
    background-color: #e74c3c; /* Red for clear/delete */
    color: white;
}
.clear:hover, .delete:hover { background-color: #c0392b; }

.equal-sign {
    background-color: #2ecc71; /* Green for equals */
    color: white;
    grid-column: span 2; /* Make equals button wider */
}
.equal-sign:hover { background-color: #27ae60; }

.span-two { /* Utility class for buttons spanning two columns */
    grid-column: span 2;
}

/* --- Styles for Programs --- */
.program-ui {
    padding: 15px;
    background-color: #ecf0f1; /* Light grey background */
    color: #2c3e50; /* Dark text */
    border-radius: 8px;
    margin-top: 10px;
    text-align: left;
}
.program-ui h4 {
    margin-top: 0;
    border-bottom: 1px solid #bdc3c7;
    padding-bottom: 10px;
    margin-bottom: 15px;
}
.program-ui .equation-row {
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    flex-wrap: wrap; /* Allow wrapping on small screens */
    gap: 5px;
}
.program-ui input[type="number"] {
    width: 60px;
    padding: 8px;
    border: 1px solid #bdc3c7;
    border-radius: 4px;
    font-size: 1em;
    text-align: center;
    background-color: white;
    color: #2c3e50;        }
.program-ui input[type="number"]::-webkit-outer-spin-button,
.program-ui input[type="number"]::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}
.program-ui .program-exe {
    background-color: #2ecc71; /* Green */
    color: white;
    border: none;
    padding: 10px 20px;
    font-size: 1em;
    border-radius: 5px;
    cursor: pointer;
    margin-top: 10px;
    transition: background-color 0.2s;
}
.program-ui .program-exe:hover {
    background-color: #27ae60;
}
.program-results {
    margin-top: 15px;
    font-weight: bold;
    font-size: 1.1em;
    background-color: #dff9fb;
    padding: 10px;
    border-radius: 4px;
    border-left: 5px solid #2ecc71;
    color: #333;
}