/* CSS Variables */
:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --secondary-color: #64748b;
    --secondary-hover: #475569;
    --background: #f8fafc;
    --surface: #ffffff;
    --surface-hover: #f1f5f9;
    --border: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.2s ease;
}

/* Reset */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

/* Base */
html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

/* App Container */
.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    max-width: 900px;
    margin: 0 auto;
    padding: 1.5rem;
}

/* Header */
.header {
    text-align: center;
    padding: 2rem 0;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

.logo-img {
    width: 48px;
    height: 48px;
    object-fit: contain;
}

.header h1 {
    font-size: 2rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), #8b5cf6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tagline {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* Sections */
section {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.section-header h2 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
}

/* Character/Word Count */
.char-count, .output-stats {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Textarea */
textarea {
    width: 100%;
    padding: 1rem;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 1rem;
    line-height: 1.6;
    resize: vertical;
    transition: border-color var(--transition), box-shadow var(--transition);
    background: var(--surface);
    color: var(--text-primary);
}

textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

textarea::placeholder {
    color: var(--text-muted);
}

/* Input Actions */
.input-actions {
    display: flex;
    gap: 0.75rem;
    margin-top: 1rem;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.25rem;
    border: none;
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
    text-decoration: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), #8b5cf6);
    color: white;
    width: 100%;
    padding: 1rem;
    font-size: 1.05rem;
    margin-top: 1rem;
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

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

.btn-secondary {
    background: var(--surface);
    color: var(--text-secondary);
    border: 1px solid var(--border);
}

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

/* Options */
.options-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.option-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.option-group label {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
}

select {
    padding: 0.75rem 1rem;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 0.95rem;
    background: var(--surface);
    color: var(--text-primary);
    cursor: pointer;
    transition: border-color var(--transition);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    padding-right: 2.5rem;
}

select:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* Tabs */
.output-tabs {
    display: flex;
    gap: 0.25rem;
    margin-bottom: 1rem;
    border-bottom: 2px solid var(--border);
    padding-bottom: 0;
}

.tab-btn {
    padding: 0.75rem 1.25rem;
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    margin-bottom: -2px;
    font-family: inherit;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-muted);
    cursor: pointer;
    transition: all var(--transition);
}

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

.tab-btn.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

/* Tab Content */
.tab-content {
    display: none;
}

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

/* Summary Output */
.summary-output {
    padding: 1rem;
    background: var(--background);
    border-radius: var(--radius-sm);
    min-height: 150px;
    line-height: 1.8;
}

.summary-output p {
    margin-bottom: 0.75rem;
}

.summary-output p:last-child {
    margin-bottom: 0;
}

.placeholder-text {
    color: var(--text-muted);
    font-style: italic;
}

/* Keywords */
.keywords-container {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    padding: 1rem;
    background: var(--background);
    border-radius: var(--radius-sm);
    min-height: 100px;
}

.keyword-tag {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0.5rem 1rem;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.1), rgba(139, 92, 246, 0.1));
    color: var(--primary-color);
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 500;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.keyword-count {
    font-size: 0.75rem;
    color: var(--text-muted);
    background: var(--surface);
    padding: 0.1rem 0.4rem;
    border-radius: 50px;
    margin-left: 0.25rem;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 1rem;
}

.stat-card {
    background: var(--background);
    padding: 1rem;
    border-radius: var(--radius-sm);
    text-align: center;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: 0.25rem;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

/* Output Actions */
.output-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border);
}

/* Footer */
.footer {
    text-align: center;
    padding: 2rem 0 1rem;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition);
}

.footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

/* Toast */
.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--text-primary);
    color: white;
    padding: 0.875rem 1.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    transition: all 0.3s ease;
    z-index: 1000;
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

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

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

/* Hidden class */
.hidden {
    display: none !important;
}

/* Responsive Design */
@media (max-width: 768px) {
    .app-container {
        padding: 1rem;
    }

    .header {
        padding: 1.5rem 0;
    }

    .header h1 {
        font-size: 1.75rem;
    }

    .tagline {
        font-size: 1rem;
    }

    section {
        padding: 1.25rem;
    }

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

    textarea {
        font-size: 16px; /* Prevents zoom on iOS */
    }

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

    .output-tabs {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }

    .tab-btn {
        padding: 0.6rem 1rem;
        white-space: nowrap;
    }

    .output-actions {
        flex-direction: column;
    }

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

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

@media (max-width: 480px) {
    .header h1 {
        font-size: 1.5rem;
    }

    .logo {
        flex-direction: column;
        gap: 0.5rem;
    }

    .input-actions {
        flex-direction: column;
    }

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

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

    .stat-value {
        font-size: 1.25rem;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --background: #0f172a;
        --surface: #1e293b;
        --surface-hover: #334155;
        --border: #334155;
        --text-primary: #f1f5f9;
        --text-secondary: #94a3b8;
        --text-muted: #64748b;
    }

    textarea, select {
        background: var(--surface);
    }

    .summary-output, .keywords-container, .stat-card {
        background: rgba(0, 0, 0, 0.2);
    }

    .keyword-tag {
        background: linear-gradient(135deg, rgba(99, 102, 241, 0.2), rgba(139, 92, 246, 0.2));
    }

    .keyword-count {
        background: var(--surface);
    }
}

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

.output-section {
    animation: fadeIn 0.3s ease;
}

/* Loading state */
.btn-primary.loading {
    pointer-events: none;
    opacity: 0.7;
}

.btn-primary.loading::after {
    content: '';
    display: inline-block;
    width: 16px;
    height: 16px;
    border: 2px solid white;
    border-top-color: transparent;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin-left: 0.5rem;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}