:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --primary-light: #3b82f6;
    --secondary: #64748b;
    --secondary-hover: #475569;
    --success: #10b981;
    --error: #ef4444;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3b8;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --radius-sm: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.25rem;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-fast: all 0.15s ease;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
}

body.dark-mode {
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;
}

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

body {
    font-family: var(--font-family);
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 50%, #f0f9ff 100%);
    background-attachment: fixed;
    color: var(--gray-900);
    line-height: 1.6;
    transition: var(--transition);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

body.dark-mode {
    background: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
}

.theme-toggle {
    position: fixed;
    top: var(--spacing-lg);
    left: var(--spacing-lg);
    z-index: 1000;
    background: white;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-md);
    width: 3rem;
    height: 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-md);
}

.theme-toggle:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

body.dark-mode .theme-toggle {
    background: var(--gray-800) !important;
    border-color: var(--gray-700) !important;
}

#theme-icon {
    font-size: 1.5rem;
}

/* Footer Styles */
.footer {
    background: white;
    border-top: 2px solid var(--gray-200);
    margin-top: auto;
    padding: var(--spacing-xl) var(--spacing-lg);
    box-shadow: 0 -4px 6px -1px rgba(0, 0, 0, 0.05);
}

body.dark-mode .footer {
    background: var(--gray-800) !important;
    border-top-color: var(--gray-700) !important;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-2xl);
    position: relative;
}

.footer-section {
    text-align: center;
}

.footer-copyright {
    font-size: 0.875rem;
    color: var(--gray-600);
    margin-bottom: 0.25rem;
}

body.dark-mode .footer-copyright {
    color: var(--gray-400) !important;
}

.footer-powered {
    font-size: 0.875rem;
    color: var(--gray-600);
    margin: 0;
}

body.dark-mode .footer-powered {
    color: var(--gray-400) !important;
}

.footer-powered strong {
    color: var(--primary);
    font-weight: 700;
}

/* Footer Stats */
.footer-stats {
    position: absolute;
    right: 0;
    text-align: right;
}

.stats-header {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-xs);
}

.stats-title {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--gray-600);
}

body.dark-mode .stats-title {
    color: var(--gray-400) !important;
}

.toggle-stats-btn {
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.125rem;
    color: var(--gray-500);
    transition: var(--transition-fast);
    font-size: 0.75rem;
}

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

.stats-content {
    transition: var(--transition);
    overflow: hidden;
}

.stats-content.collapsed {
    max-height: 0;
    opacity: 0;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-xs);
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 0.125rem;
}

.stat-value {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--gray-900);
}

body.dark-mode .stat-value {
    color: var(--gray-100) !important;
}

.stat-label {
    font-size: 0.625rem;
    color: var(--gray-600);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

body.dark-mode .stat-label {
    color: var(--gray-500) !important;
}

.stats-cost {
    color: var(--success);
}

#usage-widget.stats-updated {
    animation: pulse 0.5s ease;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.02); }
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-lg) var(--spacing-lg);
    position: relative;
    flex: 1;
}

.header {
    text-align: center;
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md) 0;
}

.header-title {
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: var(--spacing-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    letter-spacing: -0.02em;
}

.icon {
    font-size: 2rem;
    background: none !important;
    -webkit-background-clip: initial !important;
    -webkit-text-fill-color: initial !important;
    background-clip: initial !important;
}

.title-text {
    background: linear-gradient(135deg, #1d4ed8 0%, #2563eb 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header-subtitle {
    font-size: 0.9375rem;
    color: var(--gray-600);
    font-weight: 500;
}

body.dark-mode .header-subtitle {
    color: var(--gray-300) !important;
}

.tab-nav {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
    background: white;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: 0.375rem;
    box-shadow: var(--shadow-sm);
}

body.dark-mode .tab-nav {
    background: var(--gray-800) !important;
    border-color: var(--gray-700) !important;
}

.tab-button {
    flex: 1;
    padding: var(--spacing-sm) var(--spacing-lg);
    background: transparent;
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--gray-600);
    cursor: pointer;
    transition: var(--transition);
}

body.dark-mode .tab-button {
    color: var(--gray-300) !important;
}

.tab-button:hover {
    color: var(--primary);
    background: var(--gray-50);
}

.tab-button.active {
    color: white;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-hover) 100%);
    box-shadow: var(--shadow-md);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.card {
    background: white;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.card:hover {
    box-shadow: var(--shadow-xl);
}

body.dark-mode .card {
    background: var(--gray-800) !important;
    border-color: var(--gray-700) !important;
}

.section-title {
    font-size: 1.375rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: var(--spacing-xs);
    letter-spacing: -0.01em;
}

body.dark-mode .section-title {
    color: var(--gray-50) !important;
}

.section-description {
    font-size: 0.9375rem;
    color: var(--gray-600);
    margin-bottom: var(--spacing-md);
    line-height: 1.5;
}

body.dark-mode .section-description {
    color: var(--gray-400) !important;
}

.input-group {
    margin-bottom: var(--spacing-md);
}

.input-label {
    display: block;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: var(--spacing-xs);
}

body.dark-mode .input-label {
    color: var(--gray-300) !important;
}

.text-input {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.9375rem;
    border: 2px solid var(--gray-300);
    border-radius: var(--radius-lg);
    background: white;
    color: var(--gray-900);
    transition: var(--transition);
}

.text-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.1);
}

body.dark-mode .text-input {
    background: var(--gray-700) !important;
    border-color: var(--gray-600) !important;
    color: var(--gray-100) !important;
}

.btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 0.9375rem;
    font-weight: 600;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:hover::before {
    width: 300px;
    height: 300px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-hover) 100%);
    color: white;
    box-shadow: 0 4px 14px rgba(37, 99, 235, 0.3);
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

.btn-primary:active:not(:disabled) {
    transform: translateY(0);
}

.btn-secondary {
    background: var(--gray-100);
    color: var(--gray-700);
    border: 2px solid var(--gray-300);
}

.btn-secondary:hover:not(:disabled) {
    background: var(--gray-200);
    border-color: var(--gray-400);
}

.btn-large {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1rem;
    width: 100%;
    font-weight: 700;
}

.btn-small {
    padding: 0.375rem var(--spacing-sm);
    font-size: 0.8125rem;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.btn-refresh {
    background: var(--gray-100);
    color: var(--gray-700);
    padding: 0.5rem;
    min-width: 2.25rem;
    border: 1px solid var(--gray-300);
}

.btn-refresh:hover:not(:disabled) {
    background: var(--gray-200);
    transform: rotate(180deg);
}

body.dark-mode .btn-refresh {
    background: var(--gray-700);
    color: var(--gray-300);
    border-color: var(--gray-600);
}

.spinner {
    width: 1.125rem;
    height: 1.125rem;
    border: 2.5px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.spinner.hidden {
    display: none;
}

@keyframes spin {
    to { transform: translate(-50%, -50%) rotate(360deg); }
}

.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.topics-grid.hidden {
    display: none;
}

.topic-card {
    background: white;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    transition: var(--transition);
}

.topic-card:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

body.dark-mode .topic-card {
    background: var(--gray-800) !important;
    border-color: var(--gray-700) !important;
}

.topic-number {
    display: inline-block;
    width: 1.75rem;
    height: 1.75rem;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-hover) 100%);
    color: white;
    border-radius: 50%;
    font-size: 0.8125rem;
    font-weight: 700;
    text-align: center;
    line-height: 1.75rem;
    margin-bottom: var(--spacing-xs);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.topic-name {
    font-size: 1.0625rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: var(--spacing-xs);
    letter-spacing: -0.01em;
}

body.dark-mode .topic-name {
    color: var(--gray-50) !important;
}

.topic-tier {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--success);
    margin-bottom: var(--spacing-xs);
}

.topic-description {
    font-size: 0.875rem;
    color: var(--gray-600);
    margin-bottom: var(--spacing-md);
    line-height: 1.5;
}

body.dark-mode .topic-description {
    color: var(--gray-400) !important;
}

.results-section {
    transition: var(--transition);
}

.results-section.hidden {
    display: none;
}

.results-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-sm);
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    padding-bottom: 0.25rem;
    border-bottom: 2px solid var(--gray-200);
}

.result-actions {
    display: flex;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
}

.result-block {
    margin-bottom: var(--spacing-sm);
    padding-bottom: 0.25rem;
    border-bottom: 1px solid var(--gray-200);
}

.result-block:last-child {
    border-bottom: none;
}

.result-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.25rem;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.result-title {
    font-size: 1.0625rem;
    font-weight: 700;
    color: var(--gray-900);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    letter-spacing: -0.01em;
}

body.dark-mode .result-title {
    color: var(--gray-50) !important;
}

.count {
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--primary);
    background: rgba(37, 99, 235, 0.1);
    padding: 0.125rem 0.5rem;
    border-radius: var(--radius-sm);
}

.result-content {
    background-color: transparent;
    padding: 0.125rem 0;
    font-size: 0.9375rem;
    line-height: 1.4;
    color: var(--gray-800);
}

.checkbox-item {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-sm);
    padding: 0.25rem var(--spacing-md);
    margin: 0;
    transition: var(--transition-fast);
    border-radius: var(--radius-md);
    border: 1px solid transparent;
}

.checkbox-item:hover {
    background-color: rgba(37, 99, 235, 0.05);
    border-color: var(--primary-light);
}

.item-checkbox {
    margin-top: 0.125rem;
    cursor: pointer;
    width: 1.125rem;
    height: 1.125rem;
    flex-shrink: 0;
    accent-color: var(--primary);
}

.item-label {
    color: var(--gray-900);
    flex: 1;
    font-size: 0.9375rem;
    line-height: 1.5;
}

body.dark-mode .item-label {
    color: var(--gray-100) !important;
}

.item-checkbox:checked ~ .item-label {
    color: var(--primary);
    font-weight: 500;
}

/* Keyword-specific styles with metrics */
.keyword-item {
    flex-direction: row;
    align-items: flex-start;
}

.keyword-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.375rem;
}

.keyword-text {
    color: var(--gray-900);
    font-size: 0.9375rem;
    font-weight: 500;
    line-height: 1.4;
}

body.dark-mode .keyword-text {
    color: var(--gray-100) !important;
}

.keyword-item .item-checkbox:checked ~ .keyword-content .keyword-text {
    color: var(--primary);
    font-weight: 600;
}

.keyword-metrics {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.metric {
    font-size: 0.75rem;
    padding: 0.125rem 0.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    letter-spacing: 0.01em;
}

.metric-volume {
    background: rgba(59, 130, 246, 0.1);
    color: #2563eb;
}

body.dark-mode .metric-volume {
    background: rgba(59, 130, 246, 0.2);
    color: #60a5fa;
}

.metric-cpc {
    background: rgba(16, 185, 129, 0.1);
    color: #059669;
}

body.dark-mode .metric-cpc {
    background: rgba(16, 185, 129, 0.2);
    color: #34d399;
}

.metric-competition {
    background: rgba(107, 114, 128, 0.1);
    color: #4b5563;
}

body.dark-mode .metric-competition {
    background: rgba(107, 114, 128, 0.2);
    color: #9ca3af;
}

.metric-low {
    background: rgba(16, 185, 129, 0.1);
    color: #059669;
}

body.dark-mode .metric-low {
    background: rgba(16, 185, 129, 0.2);
    color: #34d399;
}

.metric-medium {
    background: rgba(245, 158, 11, 0.1);
    color: #d97706;
}

body.dark-mode .metric-medium {
    background: rgba(245, 158, 11, 0.2);
    color: #fbbf24;
}

.metric-high {
    background: rgba(239, 68, 68, 0.1);
    color: #dc2626;
}

body.dark-mode .metric-high {
    background: rgba(239, 68, 68, 0.2);
    color: #f87171;
}

.toast {
    position: fixed;
    bottom: var(--spacing-xl);
    left: 50%;
    transform: translateX(-50%);
    background: var(--gray-900);
    color: white;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
    z-index: 1001;
    transition: var(--transition);
    font-weight: 600;
    font-size: 0.875rem;
}

.toast.hidden {
    opacity: 0;
    pointer-events: none;
    transform: translate(-50%, 20px);
}

.toast.success {
    background: var(--success);
}

.toast.error {
    background: var(--error);
}

.hidden {
    display: none !important;
}

@media (max-width: 768px) {
    .container {
        padding: var(--spacing-lg) var(--spacing-md);
    }

    .header-title {
        font-size: 2rem;
    }

    .header-subtitle {
        font-size: 1.0625rem;
    }

    .card {
        padding: var(--spacing-lg);
    }

    .results-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .result-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .result-actions {
        width: 100%;
    }

    .result-actions .btn {
        flex: 1;
    }

    .topics-grid {
        grid-template-columns: 1fr;
    }

    .footer-content {
        flex-direction: column;
        text-align: center;
    }

    .footer-section {
        width: 100%;
    }

    .footer-stats {
        position: relative;
        right: auto;
        text-align: center;
        margin-top: var(--spacing-lg);
    }

    .stats-header {
        justify-content: center;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .stat-item {
        align-items: center;
    }
}