/* ==================== CSS Variables ==================== */
:root {
    /* Colors - Study Ink Theme */
    --bg-primary: #faf8f5;
    --bg-secondary: #f5f3ef;
    --bg-tertiary: #ffffff;
    --bg-card: #ffffff;
    
    --accent-primary: #2d5a4a;
    --accent-secondary: #3d7a64;
    --accent-tertiary: #b8860b;
    --accent-highlight: #c75643;
    
    --text-primary: #2c2c2c;
    --text-secondary: #6b6b6b;
    --text-muted: #9a9a9a;
    
    --border-color: #e8e5e0;
    --border-active: var(--accent-primary);
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    
    /* Spacing */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-2xl: 48px;
    
    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
}

body {
    font-family: 'Noto Serif SC', 'Lora', Georgia, serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100dvh;
    line-height: 1.6;
}

/* ==================== App Container ==================== */
.app-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--space-lg);
    min-height: 100dvh;
    display: flex;
    flex-direction: column;
}

/* ==================== Header ==================== */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: var(--space-lg);
    border-bottom: 1px solid var(--border-color);
    margin-bottom: var(--space-xl);
}

.header-brand {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.logo {
    width: 48px;
    height: 48px;
    background: var(--accent-primary);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
}

.logo svg {
    width: 28px;
    height: 28px;
    color: white;
}

.brand-text h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: 0.05em;
}

.brand-text span {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.header-actions {
    display: flex;
    gap: var(--space-sm);
}

.btn-icon {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition-fast);
}

.btn-icon svg {
    width: 20px;
    height: 20px;
}

.btn-icon:hover {
    background: var(--bg-secondary);
    color: var(--accent-primary);
    border-color: var(--accent-primary);
}

/* ==================== Type Selector ==================== */
.section-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: var(--space-md);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.type-selector {
    margin-bottom: var(--space-xl);
}

.type-grid {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: var(--space-md);
}

.type-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--space-lg) var(--space-md);
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: var(--transition-normal);
    text-align: center;
}

.type-card:hover {
    border-color: var(--accent-secondary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.type-card.active {
    border-color: var(--accent-primary);
    background: linear-gradient(to bottom, rgba(45, 90, 74, 0.05), transparent);
    box-shadow: var(--shadow-md);
}

.type-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-sm);
    transition: var(--transition-fast);
}

.type-card.active .type-icon {
    background: var(--accent-primary);
}

.type-icon svg {
    width: 24px;
    height: 24px;
    color: var(--accent-primary);
    transition: var(--transition-fast);
}

.type-card.active .type-icon svg {
    color: white;
}

.type-name {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--space-xs);
}

.type-desc {
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* ==================== Writing Panels ==================== */
.writing-panels {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-xl);
    flex: 1;
}

.panel {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-md) var(--space-lg);
    border-bottom: 1px solid var(--border-color);
    background: var(--bg-secondary);
}

.panel-header h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.panel-actions {
    display: flex;
    gap: var(--space-sm);
}

.btn-action {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-xs) var(--space-md);
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 0.8125rem;
    cursor: pointer;
    transition: var(--transition-fast);
}

.btn-action svg {
    width: 14px;
    height: 14px;
}

.btn-action:hover:not(:disabled) {
    background: var(--bg-tertiary);
    color: var(--accent-primary);
    border-color: var(--accent-primary);
}

.btn-action:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.panel-body {
    padding: var(--space-lg);
    flex: 1;
    overflow-y: auto;
}

/* ==================== Parameters ==================== */
.params-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-md);
    margin-bottom: var(--space-lg);
}

.param-group {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
}

.param-group label {
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.param-group select,
.param-group input {
    padding: var(--space-sm) var(--space-md);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 0.875rem;
    color: var(--text-primary);
    outline: none;
    transition: var(--transition-fast);
}

.param-group select:focus,
.param-group input:focus {
    border-color: var(--accent-primary);
    background: var(--bg-tertiary);
}

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

/* ==================== Topic Input ==================== */
.topic-input {
    margin-bottom: var(--space-lg);
}

.topic-input label {
    display: block;
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: var(--space-sm);
}

.topic-input textarea {
    width: 100%;
    min-height: 180px;
    padding: var(--space-md);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-family: inherit;
    font-size: 0.9375rem;
    line-height: 1.7;
    color: var(--text-primary);
    resize: vertical;
    outline: none;
    transition: var(--transition-fast);
}

.topic-input textarea:focus {
    border-color: var(--accent-primary);
    background: var(--bg-tertiary);
}

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

/* ==================== Generate Button ==================== */
.btn-generate {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-xl);
    background: var(--accent-primary);
    border: none;
    border-radius: var(--radius-md);
    color: white;
    font-family: inherit;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-fast);
    box-shadow: var(--shadow-md);
}

.btn-generate svg {
    width: 20px;
    height: 20px;
}

.btn-generate:hover:not(:disabled) {
    background: var(--accent-secondary);
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

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

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

.btn-generate .icon-loading {
    display: none;
    animation: spin 1s linear infinite;
}

.btn-generate.loading .icon-generate {
    display: none;
}

.btn-generate.loading .icon-loading {
    display: block;
}

/* ==================== Preview Panel ==================== */
.preview-content {
    min-height: 300px;
    margin-bottom: var(--space-md);
}

.preview-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 300px;
    color: var(--text-muted);
    text-align: center;
}

.preview-placeholder svg {
    width: 64px;
    height: 64px;
    margin-bottom: var(--space-md);
    opacity: 0.5;
}

.preview-placeholder p {
    font-size: 0.9375rem;
}

.preview-content .output-text {
    font-size: 0.9375rem;
    line-height: 1.8;
    color: var(--text-primary);
}

.preview-content .output-text h1,
.preview-content .output-text h2,
.preview-content .output-text h3 {
    margin-top: var(--space-lg);
    margin-bottom: var(--space-md);
    color: var(--text-primary);
}

.preview-content .output-text h1 { font-size: 1.5rem; }
.preview-content .output-text h2 { font-size: 1.25rem; }
.preview-content .output-text h3 { font-size: 1.125rem; }

.preview-content .output-text p {
    margin-bottom: var(--space-md);
}

.preview-content .output-text ul,
.preview-content .output-text ol {
    margin-bottom: var(--space-md);
    padding-left: var(--space-lg);
}

.preview-content .output-text li {
    margin-bottom: var(--space-xs);
}

.preview-content .output-text blockquote {
    border-left: 3px solid var(--accent-primary);
    padding-left: var(--space-md);
    margin: var(--space-md) 0;
    color: var(--text-secondary);
    font-style: italic;
}

.preview-content .output-text code {
    font-family: 'Courier New', monospace;
    font-size: 0.875em;
    background: var(--bg-secondary);
    padding: 2px 6px;
    border-radius: var(--radius-sm);
}

.preview-content .output-text pre {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: var(--space-md);
    margin: var(--space-md) 0;
    overflow-x: auto;
}

.preview-content .output-text pre code {
    background: transparent;
    padding: 0;
}

.preview-stats {
    display: flex;
    gap: var(--space-lg);
    padding-top: var(--space-md);
    border-top: 1px solid var(--border-color);
}

.stat {
    font-size: 0.8125rem;
    color: var(--text-secondary);
}

.stat strong {
    color: var(--accent-primary);
    font-weight: 600;
}

/* ==================== Modal ==================== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-normal);
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--bg-tertiary);
    border-radius: var(--radius-xl);
    width: 90%;
    max-width: 480px;
    box-shadow: var(--shadow-lg);
    transform: scale(0.95);
    transition: var(--transition-normal);
}

.modal-overlay.active .modal {
    transform: scale(1);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-lg);
    border-bottom: 1px solid var(--border-color);
}

.modal-header h2 {
    font-size: 1.125rem;
    font-weight: 600;
}

.close-btn {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: var(--transition-fast);
}

.close-btn svg {
    width: 20px;
    height: 20px;
}

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

.modal-body {
    padding: var(--space-lg);
}

.setting-group {
    margin-bottom: var(--space-lg);
}

.setting-group:last-child {
    margin-bottom: 0;
}

.setting-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: var(--space-sm);
}

.setting-group input,
.setting-group select {
    width: 100%;
    padding: var(--space-sm) var(--space-md);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 0.9375rem;
    color: var(--text-primary);
    outline: none;
    transition: var(--transition-fast);
}

.setting-group input:focus,
.setting-group select:focus {
    border-color: var(--accent-primary);
}

.modal-footer {
    padding: var(--space-lg);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
}

.btn-primary {
    padding: var(--space-sm) var(--space-xl);
    background: var(--accent-primary);
    border: none;
    border-radius: var(--radius-md);
    color: white;
    font-family: inherit;
    font-size: 0.9375rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition-fast);
}

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

/* ==================== Toast ==================== */
.toast {
    position: fixed;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--text-primary);
    color: white;
    padding: var(--space-sm) var(--space-xl);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    z-index: 1001;
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translate(-50%, 20px);
    }
    to {
        opacity: 1;
        transform: translate(-50%, 0);
    }
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* ==================== Responsive ==================== */
@media (max-width: 1200px) {
    .type-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 900px) {
    .writing-panels {
        grid-template-columns: 1fr;
    }
    
    .type-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 600px) {
    .app-container {
        padding: var(--space-md);
    }
    
    .type-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-sm);
    }
    
    .type-card {
        padding: var(--space-md);
    }
    
    .type-icon {
        width: 40px;
        height: 40px;
    }
    
    .type-icon svg {
        width: 20px;
        height: 20px;
    }
    
    .params-grid {
        grid-template-columns: 1fr;
    }
    
    .panel-body {
        padding: var(--space-md);
    }
}

/* ==================== Accessibility ==================== */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
    }
}

:focus-visible {
    outline: 2px solid var(--accent-primary);
    outline-offset: 2px;
}