:root {
    --bg-color: #f2f2f7;
    --card-bg: #ffffff;
    --text-color: #1c1c1e;
    --accent-color: #007aff;
    --border-color: #c6c6c8;
    --success-color: #34c759;
    --error-color: #ff3b30;
    --muted-text: #8e8e93;
}

/* System Dark Mode Support */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #1c1c1e;
        --card-bg: #2c2c2e;
        --text-color: #ffffff;
        --accent-color: #0a84ff;
        --border-color: #38383a;
    }
}

* {
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 20px;
    padding-top: max(20px, env(safe-area-inset-top));
}

.container {
    max-width: 500px;
    margin: 0 auto;
}

h1 {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 20px;
    text-align: center;
}

.card {
    background-color: var(--card-bg);
    border-radius: 12px;
    padding: 16px;
    margin-bottom: 16px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

.card-title {
    font-size: 14px;
    font-weight: 600;
    text-transform: uppercase;
    color: var(--muted-text);
    margin-bottom: 12px;
}

.input-group {
    margin-bottom: 12px;
}

.input-group:last-child {
    margin-bottom: 0;
}

label {
    display: block;
    font-size: 14px;
    margin-bottom: 4px;
}

input, select {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--bg-color);
    color: var(--text-color);
    font-size: 16px; 
    outline: none;
    transition: border-color 0.2s ease;
    -webkit-appearance: none; 
}

/* Treatment for Non-Editable Inputs */
.readonly-field {
    background-color: rgba(142, 142, 147, 0.12) !important;
    color: var(--muted-text) !important;
    border: 1px dashed var(--border-color) !important;
    font-style: italic;
    cursor: not-allowed;
}

/* Treatment for Non-Editable Output Calculations */
.uneditable-result {
    color: var(--muted-text);
    font-size: 14px;
}

.uneditable-result .value {
    color: var(--text-color);
    font-family: Menlo, Monaco, Consolas, monospace; /* Clear diagnostic data visualization font */
}

select {
    background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'><path fill='%238e8e93' d='M0,0 L5,5 L10,0 Z'/></svg>");
    background-repeat: no-repeat;
    background-position: right 12px center;
    background-size: 10px 6px;
    padding-right: 30px;
}

input:focus, select:focus {
    border-color: var(--accent-color);
}

.btn {
    width: 100%;
    background-color: var(--accent-color);
    color: white;
    border: none;
    border-radius: 8px;
    padding: 14px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    margin-top: 8px;
    transition: opacity 0.1s ease;
}

.btn:active {
    opacity: 0.8;
}

.results {
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid var(--border-color);
}

.result-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
    font-size: 15px;
}

.result-row .value {
    font-weight: 600;
}

.divider {
    border: 0;
    border-top: 1px solid var(--border-color);
    margin: 10px 0;
}

.highlight {
    font-weight: bold;
    color: var(--accent-color);
    font-size: 16px;
}

small {
    display: block;
    line-height: 1.4;
}