:root {
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --text-color: #212529;
    --primary-color: #007bff;
    --border-color: #dee2e6;
    --highlight-bg: #e9ecef;
    --info-bg: #eef7ff;
    --info-border: #b8d9f3;
    --info-text: #314a61;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 20px;
    box-sizing: border-box;
}

main, footer {
    max-width: 900px;
    margin: 0 auto;
}

header {
    max-width: 900px;
    margin: 0 auto 40px auto;
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 20px;
}

.header-content {
    flex: 1;
    min-width: 300px;
}

h1 {
    color: var(--primary-color);
    margin: 0;
    font-size: 2.2em;
}

.intro {
    font-size: 1.1em;
    color: #495057;
    margin-top: 10px;
}

.language-selector {
    margin-left: 20px;
    margin-top: 10px;
}

.language-selector label {
    font-weight: bold;
    margin-right: 5px;
}

.language-selector select {
    padding: 5px 8px;
    border-radius: 4px;
    border: 1px solid var(--border-color);
    background-color: var(--card-bg);
}

section {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 25px;
    margin-bottom: 30px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

h2 {
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 10px;
    margin-top: 0;
    font-size: 1.8em;
}

.description {
    margin-bottom: 25px;
    color: #6c757d;
    font-size: 1.05em;
}

.calculator {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
}

.inputs label {
    display: block;
    font-weight: bold;
    margin-top: 15px;
    margin-bottom: 5px;
}

input[type="number"], select, textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 1em;
    box-sizing: border-box;
}

textarea {
    resize: vertical;
    min-height: 80px;
}

.radio-group {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-top: 10px;
}

.radio-group input {
    margin-right: -10px;
}

.param-input-group {
    display: flex;
    align-items: center;
}

.param-input-group input[type="number"] {
    flex-grow: 1;
    border-top-right-radius: 0;
    border-bottom-right-radius: 0;
    position: relative;
    z-index: 1;
}

.param-presets {
    display: flex;
}

.preset-btn {
    padding: 10px 12px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-color);
    cursor: pointer;
    font-size: 0.9em;
    color: var(--primary-color);
    font-weight: bold;
    margin-left: -1px; 
    transition: background-color 0.2s, border-color 0.2s;
    z-index: 0;
}

.preset-btn:hover {
    background-color: #e2e6ea;
    z-index: 2; 
}

.preset-btn:first-child {
    border-top-left-radius: 4px;
    border-bottom-left-radius: 4px;
}

.preset-btn:last-child {
    border-top-right-radius: 4px;
    border-bottom-right-radius: 4px;
}


.outputs {
    background-color: var(--bg-color);
    padding: 20px;
    border-radius: 6px;
    border: 1px dashed var(--border-color);
}

.outputs h3 {
    margin-top: 0;
}

.highlight {
    font-weight: bold;
    color: var(--primary-color);
    background-color: var(--highlight-bg);
    padding: 3px 6px;
    border-radius: 4px;
    font-family: "Courier New", Courier, monospace;
}

.highlight-total {
    font-size: 1.2em;
    font-weight: bold;
    color: #dc3545;
    background-color: #f8d7da;
    padding: 5px 8px;
    border-radius: 4px;
    font-family: "Courier New", Courier, monospace;
}

.highlight-info {
    background-color: #d1ecf1;
    border-left: 5px solid #0c5460;
    padding: 15px;
    color: #0c5460;
    border-radius: 4px;
}

.explanation-detail {
    margin-top: 20px;
    padding: 15px;
    background-color: var(--info-bg);
    border: 1px solid var(--info-border);
    color: var(--info-text);
    border-radius: 4px;
    font-size: 0.95em;
}

.explanation-detail strong {
    display: block;
    margin-bottom: 5px;
    color: #2a4053;
}

.explanation-detail p {
    margin: 0;
}

small {
    display: block;
    margin-top: 5px;
    color: #6c757d;
}

.hidden {
    display: none;
}

footer {
    text-align: center;
    margin-top: 40px;
    padding-bottom: 20px;
    color: #6c757d;
    font-size: 0.9em;
}

@media (max-width: 768px) {
    h1 {
        font-size: 1.8em;
    }
    .header {
        flex-direction: column;
        align-items: flex-start;
    }
    .language-selector {
        margin-left: 0;
        margin-top: 15px;
        align-self: flex-start;
    }
    .calculator {
        grid-template-columns: 1fr;
    }
    .param-input-group {
        flex-direction: column;
        align-items: stretch;
    }
    .param-input-group input[type="number"] {
        border-radius: 4px;
        margin-bottom: 8px;
    }
    .param-presets {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 8px;
    }
    .preset-btn {
        margin-left: 0;
        border-radius: 4px !important;
    }
}