/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: #f9fafb;
    color: #111827;
    line-height: 1.6;
    min-height: 100vh;
}

/* Screen Reader Only */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Container */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 2rem 1rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header Styles */
.header {
    text-align: center;
    margin-bottom: 3rem;
}

.title {
    font-size: 2.5rem;
    font-weight: 700;
    color: #1d4ed8;
    margin-bottom: 0.5rem;
    letter-spacing: -0.025em;
}

.tagline {
    font-size: 1.125rem;
    color: #6b7280;
    font-weight: 400;
    max-width: 600px;
    margin: 0 auto;
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 2.5rem;
}

/* Input Section */
.input-section {
    background: #ffffff;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    border: 1px solid #e5e7eb;
}

.textarea-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.text-input {
    width: 100%;
    min-height: 200px;
    padding: 1rem;
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    font-family: inherit;
    font-size: 1rem;
    line-height: 1.5;
    resize: vertical;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
    background-color: #ffffff;
}

.text-input:focus {
    outline: none;
    border-color: #1d4ed8;
    box-shadow: 0 0 0 3px rgba(29, 78, 216, 0.1);
}

.text-input::placeholder {
    color: #9ca3af;
}

/* Button Styles */
.button-group {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
}

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-family: inherit;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.btn-primary {
    background-color: #1d4ed8;
    color: #ffffff;
}

.btn-primary:hover {
    background-color: #1e40af;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(29, 78, 216, 0.3);
}

.btn-secondary {
    background-color: #f3f4f6;
    color: #374151;
    border: 1px solid #d1d5db;
}

.btn-secondary:hover {
    background-color: #e5e7eb;
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.btn:active {
    transform: translateY(0);
}

/* Section Titles */
.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: #111827;
    margin-bottom: 1.5rem;
    text-align: center;
}

/* Statistics Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 1rem;
}

.stat-card {
    background: #ffffff;
    border: 1px solid #e5e7eb;
    border-radius: 12px;
    padding: 1.5rem;
    text-align: center;
    transition: all 0.2s ease;
    box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px 0 rgba(0, 0, 0, 0.15), 0 2px 4px 0 rgba(0, 0, 0, 0.1);
    border-color: #d1d5db;
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: #111827;
    margin-bottom: 0.5rem;
    line-height: 1;
}

.stat-label {
    font-size: 0.875rem;
    color: #6b7280;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Keyword Section */
.keyword-section {
    background: #ffffff;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    border: 1px solid #e5e7eb;
}

.keyword-container {
    display: flex;
    flex-direction: column;
}

.keyword-tabs {
    display: flex;
    border-bottom: 2px solid #e5e7eb;
    margin-bottom: 1.5rem;
}

.tab-btn {
    padding: 0.75rem 1.5rem;
    border: none;
    background: none;
    font-family: inherit;
    font-size: 0.875rem;
    font-weight: 500;
    color: #6b7280;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    transition: all 0.2s ease;
}

.tab-btn:hover {
    color: #1d4ed8;
    background-color: #f8fafc;
}

.tab-btn.active {
    color: #1d4ed8;
    border-bottom-color: #1d4ed8;
}

.keyword-content {
    position: relative;
}

.keyword-table {
    display: none;
}

.keyword-table.active {
    display: block;
}

.density-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875rem;
}

.density-table th {
    background-color: #f9fafb;
    padding: 0.75rem;
    text-align: left;
    font-weight: 600;
    color: #374151;
    border-bottom: 2px solid #e5e7eb;
}

.density-table td {
    padding: 0.75rem;
    border-bottom: 1px solid #e5e7eb;
    color: #111827;
}

.density-table tr:hover {
    background-color: #f9fafb;
}

.no-data {
    text-align: center;
    color: #6b7280;
    font-style: italic;
}

/* Footer */
.footer {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid #e5e7eb;
    text-align: center;
    color: #6b7280;
    font-size: 0.875rem;
}

.footer a {
    color: #1d4ed8;
    text-decoration: none;
    font-weight: 500;
}

.footer a:hover {
    text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    .title {
        font-size: 2rem;
    }
    
    .tagline {
        font-size: 1rem;
    }
    
    .input-section,
    .keyword-section {
        padding: 1.5rem;
    }
    
    .button-group {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
    }
    
    .stats-grid {
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
        gap: 1rem;
    }
    
    .stat-card {
        padding: 1rem;
    }
    
    .stat-value {
        font-size: 1.5rem;
    }
    
    .keyword-tabs {
        flex-wrap: wrap;
    }
    
    .tab-btn {
        flex: 1;
        min-width: 80px;
    }
    
    .density-table {
        font-size: 0.8rem;
    }
    
    .density-table th,
    .density-table td {
        padding: 0.5rem;
    }
}

@media (max-width: 480px) {
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .title {
        font-size: 1.75rem;
    }
    
    .section-title {
        font-size: 1.25rem;
    }
}

/* Focus Styles for Accessibility */
.btn:focus,
.tab-btn:focus,
.text-input:focus {
    outline: 2px solid #1d4ed8;
    outline-offset: 2px;
}

/* Animation for smooth transitions */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.stat-card,
.keyword-section,
.input-section {
    animation: fadeIn 0.3s ease-out;
}

/* Loading state for tables */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

/* Custom scrollbar for textarea */
.text-input::-webkit-scrollbar {
    width: 8px;
}

.text-input::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 4px;
}

.text-input::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 4px;
}

.text-input::-webkit-scrollbar-thumb:hover {
    background: #a1a1a1;
}