:root {
    --primary: #007bff;
    --secondary: #6c757d;
    --background: #f8f9fa;
    --card-bg: #ffffff;
    --text: #212529;
    --text-muted: #6c757d;
    --border: #dee2e6;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --primary-hover: #0056b3;
    --secondary-hover: #5a6268;
    --accent: #28a745;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--background);
    color: var(--text);
    line-height: 1.6;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

header h1 {
    font-size: 2.5rem;
    color: var(--primary);
}

header p {
    color: var(--text-muted);
    font-size: 1.1rem;
}

main {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.calculator-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}

@media (max-width: 768px) {
    .calculator-section {
        grid-template-columns: 1fr;
    }
}

.card {
    background: var(--card-bg);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 25px;
    border: 1px solid var(--border);
}

.card h2 {
    margin-bottom: 20px;
    font-size: 1.5rem;
    border-bottom: 2px solid var(--primary);
    padding-bottom: 10px;
    color: var(--primary);
}

.input-group {
    margin-bottom: 20px;
}

.input-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 8px;
}

.input-group input {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 1rem;
    transition: border-color 0.2s;
}

.input-group input:focus {
    border-color: var(--primary);
    outline: none;
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.1);
}

.range-info,
.average-rate-info {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 5px;
}

.button-group {
    display: flex;
    gap: 10px;
    margin-top: 25px;
}

.btn {
    flex: 1;
    padding: 12px;
    border: none;
    border-radius: 4px;
    font-weight: bold;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background 0.2s;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-hover);
}

.btn-secondary {
    background-color: var(--secondary);
    color: white;
}

.btn-secondary:hover {
    background-color: var(--secondary-hover);
}

.summary-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
    margin-bottom: 30px;
}

.summary-item {
    background: #f1f8ff;
    padding: 15px;
    border-radius: 6px;
    text-align: center;
    border: 1px solid #cce5ff;
}

.summary-item .label {
    display: block;
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
}

.summary-item .value {
    display: block;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
}

.chart-container {
    height: 300px;
    margin-top: 20px;
}

.export-actions {
    margin-top: 20px;
}

.export-actions .btn {
    width: 100%;
}

.info-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}

@media (max-width: 768px) {
    .info-section {
        grid-template-columns: 1fr;
    }
}

.rate-list {
    list-style: none;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

.rate-list li {
    padding: 8px;
    background: #f8f9fa;
    border: 1px dashed var(--border);
    border-radius: 4px;
    font-size: 0.9rem;
}

.info-box p {
    margin-bottom: 12px;
    font-size: 0.95rem;
}

.details-section {
    margin-top: 10px;
}

.market-rates-section {
    margin-top: 10px;
}

.market-rates-section .card {
    max-width: 540px;
}

@media (max-width: 768px) {
    .market-rates-section .card {
        max-width: 100%;
    }
}

table th,
table td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

table th {
    background-color: #f8f9fa;
    position: sticky;
    top: 0;
    z-index: 10;
}

table tbody tr:hover {
    background-color: #f1f1f1;
}

.info-subsection {
    margin-bottom: 20px;
    padding-bottom: 15px;
}

.info-subsection h3 {
    font-size: 1.1rem;
    color: var(--primary);
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.info-subsection p {
    margin-bottom: 10px;
    font-size: 0.95rem;
    line-height: 1.5;
}

.info-subsection ul {
    margin-bottom: 10px;
    padding-left: 20px;
}

.info-subsection li {
    margin-bottom: 6px;
    font-size: 0.95rem;
    line-height: 1.4;
}

footer {
    text-align: center;
    margin-top: 50px;
    padding-bottom: 20px;
    color: var(--text-muted);
    font-size: 0.9rem;
}