:root {
    --bg-color: #f5f6fb;
    --card-bg: #ffffff;
    --card-border: #e8e9eb;
    --text-primary: #44475b;
    --text-secondary: #7c7e8c;
    --accent: #00d09c;
    --accent-hover: #00b386;
    --success: #00d09c;
    --danger: #eb5b3c;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding-top: 3rem;
}

/* Layout */
.container {
    width: 100%;
    max-width: 960px;
    padding: 0 1rem 2rem 1rem;
}

header {
    text-align: left;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

header p {
    color: var(--text-secondary);
    font-size: 1rem;
}

.calculator {
    display: grid;
    grid-template-columns: 3fr 2fr;
    gap: 1.5rem;
}

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

.left-column {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* Panels */
.glass-panel, .input-panel, .trades-panel, .output-panel {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: var(--shadow);
}

.glass-panel h2 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--card-border);
    color: var(--text-primary);
}

/* Form Styles */
.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.form-group {
    margin-bottom: 1.5rem;
    display: flex;
    flex-direction: column;
}

.form-group label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

input, select {
    background: #ffffff;
    border: 1px solid #dcdce0;
    border-radius: 8px;
    padding: 0.75rem 1rem;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1rem;
    transition: all 0.2s ease;
    outline: none;
}

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

input::placeholder {
    color: #c0c2cc;
}

.custom-select {
    position: relative;
}

.custom-select select {
    appearance: none;
    width: 100%;
    cursor: pointer;
}

.custom-select::after {
    content: "▼";
    font-size: 0.6rem;
    position: absolute;
    right: 1rem;
    top: 50%;
    transform: translateY(-50%);
    pointer-events: none;
    color: var(--text-secondary);
}

/* Button */
.btn-calculate {
    width: 100%;
    background: var(--accent);
    color: white;
    border: none;
    border-radius: 8px;
    padding: 1rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    margin-top: 0.5rem;
    transition: all 0.2s ease;
}

.btn-calculate:hover {
    background: var(--accent-hover);
}

.btn-calculate svg {
    display: none;
}

/* Results Styles */
.results {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.result-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.result-row .value, .result-row span:last-child {
    color: var(--text-primary);
    font-weight: 500;
}

.primary-row {
    font-size: 1.05rem;
}

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

.divider {
    height: 1px;
    background: var(--card-border);
    margin: 0.25rem 0;
}

.total-charges {
    font-size: 1.05rem;
    font-weight: 600;
}

.total-charges .value, .total-charges span:last-child {
    color: var(--text-primary);
    font-weight: 600;
}

.text-danger {
    color: var(--danger) !important;
}

.text-success {
    color: var(--success) !important;
}

.result-card {
    background: var(--bg-color);
    border: 1px solid var(--card-border);
    border-radius: 8px;
    padding: 1.25rem;
    text-align: center;
    margin-top: 1rem;
}

.pnl-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.pnl-value {
    font-size: 1.75rem;
    font-weight: 600;
}

/* Trades Panel Styles */
.trades-panel {
    max-height: 400px;
    display: flex;
    flex-direction: column;
}

.trades-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--card-border);
}

.trades-header h2 {
    margin-bottom: 0;
    padding-bottom: 0;
    border-bottom: none;
}

.btn-clear {
    background: transparent;
    color: var(--danger);
    border: none;
    padding: 0;
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
}

.btn-clear:hover {
    text-decoration: underline;
}

.trades-list {
    overflow-y: auto;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    padding-right: 0.5rem;
}

.trades-list::-webkit-scrollbar {
    width: 4px;
}

.trades-list::-webkit-scrollbar-thumb {
    background-color: var(--card-border);
    border-radius: 4px;
}

.empty-state {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    padding: 2rem 0;
}

.trade-item {
    background: #ffffff;
    border: 1px solid var(--card-border);
    border-radius: 8px;
    padding: 1rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.5rem;
    font-size: 0.85rem;
}

.trade-item-header {
    grid-column: span 2;
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.trade-detail {
    display: flex;
    justify-content: space-between;
    color: var(--text-secondary);
}

.trade-detail .val {
    color: var(--text-primary);
    font-weight: 500;
}

.trade-remove {
    background: none;
    border: none;
    color: var(--danger);
    cursor: pointer;
    font-size: 0.8rem;
    font-weight: 500;
}

.trade-remove:hover {
    text-decoration: underline;
}

/* ===== SEO Content Sections ===== */

/* Shared section styles */
.seo-info-section,
.seo-how-section,
.faq-section {
    margin-top: 3rem;
    padding: 2rem;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.seo-info-section h2,
.seo-how-section h2,
.faq-section h2 {
    font-size: 1.35rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.75rem;
}

.seo-info-section > p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

/* Charge Rate Cards Grid */
.charge-cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
    margin-top: 1.25rem;
}

@media (max-width: 768px) {
    .charge-cards {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .charge-cards {
        grid-template-columns: 1fr;
    }
}

.charge-card {
    background: var(--bg-color);
    border: 1px solid var(--card-border);
    border-radius: 10px;
    padding: 1.25rem;
}

.charge-card h3 {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--accent);
    margin-bottom: 0.6rem;
}

.charge-card p {
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.55;
}

.charge-card strong {
    color: var(--text-primary);
}

/* How-to List */
.how-to-list {
    margin-top: 1.25rem;
    padding-left: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.85rem;
    counter-reset: how-to;
}

.how-to-list li {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.how-to-list li strong {
    color: var(--text-primary);
}

/* FAQ Accordion */
.faq-section h2 {
    margin-bottom: 1.25rem;
}

.faq-item {
    border: 1px solid var(--card-border);
    border-radius: 8px;
    margin-bottom: 0.75rem;
    overflow: hidden;
    transition: box-shadow 0.2s ease;
}

.faq-item:hover {
    box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.faq-item summary {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.25rem;
    cursor: pointer;
    list-style: none;
    user-select: none;
    background: var(--bg-color);
    transition: background 0.15s ease;
}

.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item summary::after {
    content: "＋";
    font-size: 1.1rem;
    color: var(--accent);
    font-weight: 400;
    flex-shrink: 0;
    margin-left: 1rem;
    transition: transform 0.2s ease;
}

.faq-item[open] summary::after {
    content: "－";
}

.faq-item summary:hover {
    background: #edfaf5;
}

.faq-item summary h3 {
    font-size: 0.97rem;
    font-weight: 500;
    color: var(--text-primary);
    margin: 0;
}

.faq-item > p {
    padding: 1rem 1.25rem 1.25rem;
    font-size: 0.93rem;
    color: var(--text-secondary);
    line-height: 1.65;
    border-top: 1px solid var(--card-border);
}

.faq-item > p strong {
    color: var(--text-primary);
}

/* Site Footer */
.site-footer {
    margin-top: 3rem;
    padding: 1.5rem;
    text-align: center;
    border-top: 1px solid var(--card-border);
}

.site-footer p {
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 0.5rem;
}

.site-footer p strong {
    color: var(--text-primary);
}

.site-footer .disclaimer {
    font-size: 0.8rem;
    color: #aaaaaa;
}