/* ===== Tool Navigation ===== */
.tool-nav {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 12px 0;
    position: sticky;
    top: 60px;
    z-index: 40;
    backdrop-filter: blur(12px);
    background: rgba(255, 255, 255, 0.85);
}

.tool-nav .container {
    display: flex;
    align-items: center;
    gap: 20px;
}

.tool-nav-back {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 6px;
    transition: var(--transition);
}

.tool-nav-back:hover {
    color: var(--primary);
}

.tool-nav-title {
    font-weight: 600;
    color: var(--text);
    font-size: 0.9rem;
}

/* ===== Calculator ===== */
.calculator-wrapper {
    padding: 24px 0 60px;
}

.calc-header {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 28px;
}

.calc-icon {
    width: 56px;
    height: 56px;
    background: var(--primary-light);
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    border: 1px solid var(--border);
    color: var(--primary);
}

.calc-icon svg {
    width: 28px;
    height: 28px;
}

.calc-header h1 {
    font-size: 1.6rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.calc-header p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* ===== Mode Tabs ===== */
.mode-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
    background: var(--surface);
    padding: 4px;
    border-radius: 12px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
}

.mode-tab {
    flex: 1;
    padding: 10px 16px;
    border: none;
    background: transparent;
    border-radius: 8px;
    font-family: inherit;
    font-weight: 600;
    font-size: 0.85rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}

.mode-tab:hover {
    color: var(--text);
    background: var(--bg);
}

.mode-tab.active {
    background: var(--primary);
    color: white;
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25);
}

.calc-grid {
    display: grid;
    grid-template-columns: 340px 1fr;
    gap: 32px;
    align-items: start;
}

@media (max-width: 1024px) {
    .calc-grid {
        grid-template-columns: 1fr;
    }
}

/* ===== Form ===== */
.calc-form {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow);
    position: sticky;
    top: 140px;
}

@media (max-width: 1024px) {
    .calc-form {
        position: static;
    }
}

.mode-content {
    display: none;
}

.mode-content.active {
    display: block;
}

.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    font-weight: 600;
    font-size: 0.85rem;
    margin-bottom: 5px;
    color: var(--text);
}

.input-wrapper {
    position: relative;
}

.input-wrapper input {
    width: 100%;
    padding: 10px 48px 10px 14px;
    font-size: 0.95rem;
    font-family: inherit;
    border: 1.5px solid var(--border);
    border-radius: 10px;
    background: var(--bg);
    transition: var(--transition);
    outline: none;
    color: var(--text);
}

.input-wrapper input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.08);
}

.input-wrapper input::placeholder {
    color: var(--text-muted);
}

.input-currency {
    position: absolute;
    right: 14px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    font-weight: 500;
    font-size: 0.8rem;
}

/* Direction buttons */
.direction-buttons {
    display: flex;
    gap: 8px;
}

.direction-btn {
    flex: 1;
    padding: 8px 12px;
    border: 1.5px solid var(--border);
    border-radius: 8px;
    background: var(--bg);
    font-family: inherit;
    font-weight: 600;
    font-size: 0.85rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}

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

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

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

.calc-btn {
    width: 100%;
    padding: 12px;
    font-size: 0.95rem;
    font-weight: 700;
    font-family: inherit;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: 0 4px 16px rgba(37, 99, 235, 0.25);
    margin-top: 4px;
}

.calc-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 28px rgba(37, 99, 235, 0.35);
}

/* ===== Results ===== */
.calc-results {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.result-display {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px 24px;
    box-shadow: var(--shadow);
    text-align: center;
}

.result-main {
    margin-bottom: 6px;
}

.result-label {
    display: block;
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.result-value {
    display: block;
    font-size: 2.4rem;
    font-weight: 800;
    color: var(--text);
    letter-spacing: -0.03em;
}

.result-formula {
    font-size: 0.85rem;
    color: var(--text-secondary);
    background: var(--bg);
    padding: 8px 14px;
    border-radius: 8px;
    font-family: 'Courier New', monospace;
    word-break: break-all;
}

/* Results Grid */
.results-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

@media (max-width: 640px) {
    .results-grid {
        grid-template-columns: 1fr;
    }
}

.result-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 14px 18px;
    box-shadow: var(--shadow);
}

.result-card.highlight {
    background: var(--primary);
    border-color: var(--primary);
}

.result-card.highlight .result-label {
    color: rgba(255, 255, 255, 0.8);
}

.result-card.highlight .result-value {
    color: white;
}

.result-card .result-label {
    display: block;
    font-size: 0.65rem;
    font-weight: 500;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 2px;
}

.result-card .result-value {
    display: block;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text);
}

/* ===== Visualization ===== */
.visualization-container {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 18px 20px;
    box-shadow: var(--shadow);
}

.visualization-bar {
    position: relative;
    height: 32px;
    background: var(--bg);
    border-radius: 8px;
    overflow: hidden;
}

.bar-fill {
    height: 100%;
    background: var(--primary);
    border-radius: 8px;
    transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding-right: 10px;
}

.bar-label {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-weight: 700;
    font-size: 0.85rem;
    color: var(--text);
    pointer-events: none;
    white-space: nowrap;
}

/* ===== Quick Examples ===== */
.quick-examples {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 20px;
    box-shadow: var(--shadow);
}

.quick-examples h4 {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 10px;
}

.example-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.example-btn {
    padding: 5px 14px;
    border: 1px solid var(--border);
    border-radius: 16px;
    background: var(--bg);
    font-family: inherit;
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
}

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

/* ===== SEO Content ===== */
.seo-content {
    margin-top: 50px;
    padding-top: 40px;
    border-top: 1px solid var(--border);
}

.seo-inner {
    max-width: 760px;
}

.seo-content h2 {
    font-size: 1.4rem;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--text);
    letter-spacing: -0.02em;
}

.seo-content h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-top: 24px;
    margin-bottom: 10px;
    color: var(--text);
}

.seo-content h4 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-top: 16px;
    margin-bottom: 6px;
    color: var(--text);
}

.seo-content p {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 14px;
}

.seo-content ul {
    list-style: none;
    padding: 0;
    margin-bottom: 16px;
}

.seo-content ul li {
    font-size: 0.92rem;
    color: var(--text-secondary);
    line-height: 1.7;
    padding: 4px 0 4px 24px;
    position: relative;
}

.seo-content ul li::before {
    content: '—';
    position: absolute;
    left: 0;
    color: var(--primary);
    font-weight: 600;
}

.seo-content strong {
    color: var(--text);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .calc-header {
        flex-direction: column;
        text-align: center;
    }

    .calc-header h1 {
        font-size: 1.4rem;
    }

    .mode-tabs {
        flex-direction: column;
    }

    .mode-tab {
        padding: 8px 12px;
        font-size: 0.8rem;
    }
}

@media (max-width: 640px) {
    .calculator-wrapper {
        padding: 16px 0 40px;
    }

    .calc-form {
        padding: 16px;
    }

    .result-value {
        font-size: 1.8rem;
    }

    .result-display {
        padding: 16px;
    }

    .visualization-container {
        padding: 14px 16px;
    }

    .seo-content {
        margin-top: 30px;
        padding-top: 24px;
    }

    .seo-content h2 {
        font-size: 1.2rem;
    }

    .seo-content h3 {
        font-size: 1rem;
    }

    .seo-content p,
    .seo-content ul li {
        font-size: 0.88rem;
    }
}

@media (max-width: 480px) {
    .result-value {
        font-size: 1.5rem;
    }

    .result-card .result-value {
        font-size: 0.95rem;
    }

    .example-btn {
        font-size: 0.75rem;
        padding: 4px 10px;
    }
}