/* ===== CSS Variables & Design Tokens ===== */
:root {
    /* Colors - Dark Theme */
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #21262d;
    --bg-hover: #30363d;
    
    --border-primary: #30363d;
    --border-secondary: #21262d;
    
    --text-primary: #e6edf3;
    --text-secondary: #8b949e;
    --text-muted: #6e7681;
    
    --accent-primary: #58a6ff;
    --accent-secondary: #388bfd;
    --accent-glow: rgba(88, 166, 255, 0.15);
    
    --success: #3fb950;
    --warning: #d29922;
    --error: #f85149;
    
    /* Gradients */
    --gradient-header: linear-gradient(135deg, #161b22 0%, #0d1117 100%);
    --gradient-panel: linear-gradient(180deg, rgba(22, 27, 34, 0.8) 0%, rgba(13, 17, 23, 0.9) 100%);
    --gradient-glow: radial-gradient(ellipse at center, var(--accent-glow) 0%, transparent 70%);
    
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 30px var(--accent-glow);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 400ms ease;
}

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

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

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow: hidden;
}

/* ===== App Container ===== */
.app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    background: var(--gradient-header);
}

/* ===== Header ===== */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 4.5rem;
    padding: 0 var(--space-xl);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-primary);
    backdrop-filter: blur(12px);
    position: relative;
    z-index: 10;
}

.header::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--accent-primary), transparent);
    opacity: 0.3;
}

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

.logo svg {
    color: var(--accent-primary);
    filter: drop-shadow(0 0 8px var(--accent-glow));
}

.logo h1 {
    font-size: 1.25rem;
    font-weight: 600;
    background: linear-gradient(135deg, var(--text-primary), var(--accent-primary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.gist-info {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--text-secondary);
    padding: var(--space-sm) var(--space-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-primary);
}

.gist-info a {
    color: var(--accent-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.gist-info a:hover {
    color: var(--accent-secondary);
    text-decoration: underline;
}

/* ===== Gist Title Section ===== */
.gist-title-section {
    padding: var(--space-lg) var(--space-xl) 0;
    background: transparent;
}

.gist-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.4;
    max-width: 1200px;
}

/* ===== Main Content ===== */
.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: var(--space-lg);
    padding: var(--space-lg);
    flex: 1;
    overflow: hidden;
}

/* ===== Panels ===== */
.panel {
    display: flex;
    flex-direction: column;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-primary);
    overflow: hidden;
    transition: box-shadow var(--transition-normal), border-color var(--transition-normal);
    position: relative;
}

.panel:hover {
    border-color: var(--border-primary);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

.panel::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 100%;
    background: var(--gradient-glow);
    opacity: 0;
    transition: opacity var(--transition-slow);
    pointer-events: none;
}

.panel:hover::before {
    opacity: 1;
}

.panel.maximized {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1000;
    border-radius: 0;
    border: none;
    margin: 0;
}

.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-md) var(--space-lg);
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-primary);
    position: relative;
    z-index: 1;
}

.panel-title {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-weight: 500;
    font-size: 0.9rem;
}

.panel-title svg {
    color: var(--accent-primary);
}

.panel-controls {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.panel-status {
    font-size: 0.75rem;
    font-family: var(--font-mono);
    padding: var(--space-xs) var(--space-sm);
    border-radius: var(--radius-sm);
    background: var(--bg-primary);
}

.panel-status.success {
    display: none; /* hide success status */
    color: var(--success);
    border: 1px solid var(--success);
}

.panel-status.error {
    color: var(--error);
    border: 1px solid var(--error);
}

.panel-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: 1px solid transparent;
    color: var(--text-secondary);
    padding: var(--space-xs);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

.panel-content {
    flex: 1;
    overflow: auto;
    padding: var(--space-lg);
    position: relative;
    z-index: 1;
}

.preview-panel .panel-content {
    overflow: hidden;
}

/* ===== Markdown Styling ===== */
.markdown-body {
    color: var(--text-primary);
    font-size: 0.95rem;
    line-height: 1.7;
}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4,
.markdown-body h5,
.markdown-body h6 {
    margin-top: var(--space-xl);
    margin-bottom: var(--space-md);
    font-weight: 600;
    line-height: 1.3;
    color: var(--text-primary);
}

.markdown-body h1 {
    font-size: 1.75rem;
    padding-bottom: var(--space-sm);
    border-bottom: 1px solid var(--border-primary);
}

.markdown-body h2 {
    font-size: 1.4rem;
    padding-bottom: var(--space-xs);
    border-bottom: 1px solid var(--border-secondary);
}

.markdown-body h3 {
    font-size: 1.2rem;
}

.markdown-body h1:first-child,
.markdown-body h2:first-child,
.markdown-body h3:first-child {
    margin-top: 0;
}

.markdown-body p {
    margin-bottom: var(--space-md);
}

.markdown-body a {
    color: var(--accent-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.markdown-body a:hover {
    color: var(--accent-secondary);
    text-decoration: underline;
}

.markdown-body code {
    font-family: var(--font-mono);
    font-size: 0.875em;
    padding: 0.2em 0.4em;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    color: var(--accent-primary);
}

.markdown-body pre {
    margin: var(--space-md) 0;
    padding: var(--space-md);
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-primary);
    overflow-x: auto;
}

.markdown-body pre code {
    padding: 0;
    background: none;
    color: var(--text-primary);
}

.markdown-body ul,
.markdown-body ol {
    margin-bottom: var(--space-md);
    padding-left: var(--space-xl);
}

.markdown-body li {
    margin-bottom: var(--space-xs);
}

.markdown-body blockquote {
    margin: var(--space-md) 0;
    padding: var(--space-sm) var(--space-md);
    border-left: 4px solid var(--accent-primary);
    background: var(--bg-tertiary);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    color: var(--text-secondary);
}

.markdown-body img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    margin: var(--space-md) 0;
}

.markdown-body table {
    width: 100%;
    margin: var(--space-md) 0;
    border-collapse: collapse;
}

.markdown-body th,
.markdown-body td {
    padding: var(--space-sm) var(--space-md);
    border: 1px solid var(--border-primary);
    text-align: left;
}

.markdown-body th {
    background: var(--bg-tertiary);
    font-weight: 600;
}

.markdown-body tr:nth-child(even) {
    background: var(--bg-tertiary);
}

/* ===== Iframe Container ===== */
.iframe-container {
    padding: 0;
    position: relative;
}

#preview-iframe {
    width: 100%;
    height: 100%;
    border: none;
    background: #fff;
}

#iframe-loading {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: var(--bg-secondary);
}

#iframe-loading.hidden {
    display: none;
}

/* ===== Loading Placeholder ===== */
.loading-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--space-md);
    padding: var(--space-2xl);
    color: var(--text-secondary);
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-primary);
    border-top-color: var(--accent-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* ===== Error Modal ===== */
.error-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    display: none;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(8px);
    z-index: 100;
}

.error-modal.visible {
    display: flex;
}

.error-content {
    text-align: center;
    padding: var(--space-2xl);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-primary);
    box-shadow: var(--shadow-lg);
    max-width: 400px;
}

.error-icon {
    margin-bottom: var(--space-lg);
}

.error-icon svg {
    color: var(--warning);
}

.error-content h2 {
    margin-bottom: var(--space-md);
    font-size: 1.5rem;
}

.error-content p {
    color: var(--text-secondary);
    margin-bottom: var(--space-lg);
}

.error-content code {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    padding: 0.2em 0.4em;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    color: var(--accent-primary);
}

.usage-example {
    padding: var(--space-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    text-align: left;
}

.usage-example p {
    margin-bottom: var(--space-sm);
    color: var(--text-primary);
}

.usage-example code {
    display: block;
    padding: var(--space-sm);
    background: var(--bg-primary);
    border-radius: var(--radius-sm);
}

/* ===== Error States ===== */
.error-message {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--space-md);
    padding: var(--space-2xl);
    color: var(--error);
    text-align: center;
}

.error-message svg {
    opacity: 0.5;
}

.error-message p {
    color: var(--text-secondary);
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--border-primary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--bg-hover);
}

/* ===== Source Code Panel ===== */
.source-container {
    padding: 0;
    background: var(--bg-primary);
}

.source-code {
    margin: 0;
    padding: var(--space-lg);
    background: var(--bg-primary);
    border-radius: 0;
    border: none;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    line-height: 1.6;
    overflow: auto;
    height: 100%;
    tab-size: 4;
}

.source-code code {
    /*font-family: var(--font-mono);*/
    background: transparent;
    padding: 0;
    color: var(--text-primary);
}

/* Override Prism theme to match our dark theme */
.source-code .token.comment,
.source-code .token.prolog,
.source-code .token.doctype,
.source-code .token.cdata {
    color: var(--text-muted);
}

.source-code .token.punctuation {
    color: var(--text-secondary);
}

.source-code .token.tag,
.source-code .token.namespace {
    color: #f85149;
}

.source-code .token.attr-name {
    color: #d2a8ff;
}

.source-code .token.attr-value,
.source-code .token.string {
    color: #a5d6ff;
}

/* ===== Responsive ===== */
@media (max-width: 1400px) {
    .main-content {
        grid-template-columns: 1fr 1fr;
        grid-template-rows: 1fr 1fr;
    }
    
    .source-panel {
        grid-column: span 2;
    }
}

@media (max-width: 1024px) {
    .main-content {
        grid-template-columns: 1fr;
        grid-template-rows: auto;
    }
    
    .source-panel {
        grid-column: span 1;
    }
    
    .panel {
        min-height: 300px;
    }
}

@media (max-width: 768px) {
    .header {
        flex-direction: column;
        gap: var(--space-md);
        padding: var(--space-md);
    }
    
    .main-content {
        padding: var(--space-md);
        gap: var(--space-md);
        overflow-y: auto;
    }
    
    .gist-info {
        font-size: 0.75rem;
    }
    
    .panel {
        min-height: 250px;
    }
}

/* ===== Badges ===== */
.gist-card-badges {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-xs);
    margin-top: var(--space-sm);
}

.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.15rem 0.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-family: var(--font-mono);
    text-decoration: none;
    transition: all var(--transition-fast);
    border: 1px solid transparent;
}

.badge:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

/* Library Badges */
.badge-lib {
    background: rgba(88, 166, 255, 0.1);
    color: var(--accent-primary);
    border-color: rgba(88, 166, 255, 0.2);
}

.badge-lib:hover {
    background: rgba(88, 166, 255, 0.2);
}

/* Difficulty Badges */
.badge-diff {
    background: var(--bg-tertiary);
    border-color: var(--border-primary);
}

.diff-0 { /* Beginner */
    color: var(--success);
    border-color: rgba(63, 185, 80, 0.3);
    background: rgba(63, 185, 80, 0.1);
}

.diff-1 { /* Intermediate */
    color: var(--warning);
    border-color: rgba(210, 153, 34, 0.3);
    background: rgba(210, 153, 34, 0.1);
}

.diff-2 { /* Advanced */
    color: var(--error);
    border-color: rgba(248, 81, 73, 0.3);
    background: rgba(248, 81, 73, 0.1);
}

/* Clear Filter Button */
.clear-filters-btn {
    display: inline-block;
    padding: var(--space-xs) var(--space-md);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    text-decoration: none;
    transition: all var(--transition-fast);
}

.clear-filters-btn:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
    border-color: var(--accent-primary);
}