/* ==========================================================================
   Elegant Markdown Reader Design System
   ========================================================================== */

/* Design Tokens & Theme Setup */
:root {
  /* User-provided Color Rules Palette (Orange to Yellow) */
  --palette-0: #ff7b00;
  --palette-1: #ff8800;
  --palette-2: #ff9500;
  --palette-3: #ffa200;
  --palette-4: #ffaa00;
  --palette-5: #ffb700;
  --palette-6: #ffc300;
  --palette-7: #ffd000;
  --palette-8: #ffdd00;
  --palette-9: #ffea00;

  /* Fonts */
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-serif: 'Lora', Georgia, Cambria, serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Transitions */
  --transition-speed: 0.25s;
  --transition-bezier: cubic-bezier(0.4, 0, 0.2, 1);
  --transition: all var(--transition-speed) var(--transition-bezier);

  /* Shared Dimensions */
  --sidebar-width: 300px;
  --header-height: 56px;
  --content-max-width: 720px;
}

/* Light Theme Variables */
[data-theme="light"] {
  --bg-primary: #FAF9F6;      /* Off-white, soft reading background */
  --bg-secondary: #FFFFFF;    /* Pure white for panels & blocks */
  --bg-sidebar: #F2EFE9;      /* Warm gray sidebar */
  --text-primary: #1C1917;    /* Deep charcoal */
  --text-secondary: #57534E;  /* Warm stone gray */
  --text-muted: #878580;      /* Muted gray */
  
  --border-color: #E7E5E4;    /* Light stone border */
  --border-hover: #D6D3D1;    
  
  --accent-color: var(--palette-0);    /* Vibrant deep orange */
  --accent-hover: var(--palette-1);
  --accent-light: rgba(255, 123, 0, 0.08);

  --code-bg: #F5F5F4;
  --code-border: #E7E5E4;
  --code-color: #d95200;      /* Readable dark orange for inline code */

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.02);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.06), 0 4px 6px -2px rgba(0, 0, 0, 0.03);
}

/* Dark Theme Variables */
[data-theme="dark"] {
  --bg-primary: #141210;      /* Soft dark charcoal */
  --bg-secondary: #1F1B18;    /* Dark panel gray */
  --bg-sidebar: #191614;      /* Deep dark sidebar */
  --text-primary: #F5F5F4;    /* Light stone cream */
  --text-secondary: #A8A29E;  /* Muted cool stone */
  --text-muted: #78716C;      
  
  --border-color: #2E2A28;    /* Dark warm border */
  --border-hover: #443E3B;    
  
  --accent-color: var(--palette-6);    /* Warm golden yellow */
  --accent-hover: var(--palette-7);
  --accent-light: rgba(255, 195, 0, 0.1);

  --code-bg: #2E2A28;
  --code-border: #3E3835;
  --code-color: var(--palette-8);      /* Bright yellow-orange for inline code */

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
}

/* ==========================================================================
   Base resets and Layout structure
   ========================================================================== */

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

body {
  font-family: var(--font-sans);
  font-size: 16px;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  line-height: 1.5;
  overflow: hidden;
  transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
}

.app-container {
  display: flex;
  height: 100vh;
  width: 100vw;
  position: relative;
}

/* Scrollbars styling */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--border-hover);
}

/* ==========================================================================
   Sidebar Navigation & Panels
   ========================================================================== */

.sidebar {
  width: var(--sidebar-width);
  height: 100%;
  background-color: var(--bg-sidebar);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  transition: transform var(--transition-speed) var(--transition-bezier), background-color var(--transition-speed) ease, border-color var(--transition-speed) ease;
  z-index: 100;
  overflow-y: auto;
}

.sidebar-header {
  padding: 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--accent-color);
}

.brand h1 {
  font-size: 1.15rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-primary);
}

.icon {
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.logo {
  stroke-width: 2.5;
}

.panel {
  margin: 0 16px 16px 16px;
  padding: 16px;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  box-shadow: var(--shadow-sm);
}

.panel-title {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 6px;
}

/* File Upload Zone */
.file-section {
  padding: 0 16px 16px 16px;
}

.upload-zone {
  border: 2px dashed var(--border-color);
  border-radius: 8px;
  padding: 24px 16px;
  text-align: center;
  background-color: var(--bg-secondary);
  transition: var(--transition);
  cursor: pointer;
}

.upload-zone:hover, .upload-zone.dragover {
  border-color: var(--accent-color);
  background-color: var(--accent-light);
}

.upload-zone svg {
  color: var(--text-muted);
  margin-bottom: 8px;
  transition: var(--transition);
}

.upload-zone:hover svg {
  color: var(--accent-color);
  transform: translateY(-2px);
}

.upload-zone p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.hidden-input {
  display: none;
}

/* Shared Buttons & Controls */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px 16px;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 500;
  border-radius: 6px;
  cursor: pointer;
  transition: var(--transition);
  border: 1px solid transparent;
  text-decoration: none;
}

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

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

.btn-outline {
  background-color: transparent;
  border-color: var(--border-color);
  color: var(--text-primary);
}

.btn-outline:hover {
  background-color: var(--code-bg);
  border-color: var(--border-hover);
}

.btn-block {
  display: flex;
  width: 100%;
}

.btn-group {
  display: inline-flex;
  border-radius: 6px;
}

.btn-group .btn {
  border-radius: 0;
}

.btn-group .btn:first-child {
  border-top-left-radius: 6px;
  border-bottom-left-radius: 6px;
}

.btn-group .btn:last-child {
  border-top-right-radius: 6px;
  border-bottom-right-radius: 6px;
}

.btn-group .btn + .btn {
  border-left: none;
}

.icon-btn {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 6px;
  border-radius: 6px;
  transition: var(--transition);
}

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

/* Document stats grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}

.stat-item {
  display: flex;
  flex-direction: column;
  min-width: 0; /* Fix: allow grid cells to shrink below content width */
}

.stat-label {
  font-size: 0.7rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.stat-val {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 100%;
}

/* Long filenames get a softer wrap treatment */
#stat-filename {
  white-space: normal;
  word-break: break-all;
  line-height: 1.4;
}

/* Table of Contents */
.toc-container {
  max-height: 250px;
  overflow-y: auto;
}

.toc-list {
  list-style: none;
}

.toc-item {
  margin-bottom: 6px;
}

.toc-link {
  display: block;
  font-size: 0.8rem;
  color: var(--text-secondary);
  text-decoration: none;
  line-height: 1.3;
  padding: 4px 6px;
  border-radius: 4px;
  border-left: 2px solid transparent;
  transition: var(--transition);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.toc-link:hover {
  color: var(--accent-color);
  background-color: var(--accent-light);
}

.toc-link.active {
  color: var(--accent-color);
  font-weight: 500;
  border-left-color: var(--accent-color);
  background-color: var(--accent-light);
}

.toc-link.h1-link { padding-left: 6px; }
.toc-link.h2-link { padding-left: 16px; }
.toc-link.h3-link { padding-left: 26px; }

.toc-placeholder {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-style: italic;
  padding: 4px;
}

/* Customization select panel */
.control-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.control-row:last-child {
  margin-bottom: 0;
}

.select-control {
  font-family: var(--font-sans);
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 0.8rem;
  outline: none;
  cursor: pointer;
  transition: var(--transition);
}

.select-control:focus {
  border-color: var(--accent-color);
}

/* Sidebar Footer & Theme Toggle */
.sidebar-footer {
  margin-top: auto;
  padding: 16px;
  border-top: 1px solid var(--border-color);
}

.theme-toggle-btn {
  display: flex;
  justify-content: center;
  align-items: center;
}

.theme-icon {
  display: flex;
  align-items: center;
  gap: 8px;
}

[data-theme="light"] .dark-icon { display: none; }
[data-theme="dark"] .light-icon { display: none; }

/* ==========================================================================
   Main Reading Workspace
   ========================================================================== */

.main-content {
  flex-grow: 1;
  height: 100%;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  position: relative;
}

/* Top Header Bar */
.top-nav {
  height: var(--header-height);
  padding: 0 24px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  background-color: var(--bg-secondary);
  z-index: 50;
  box-shadow: var(--shadow-sm);
  flex-shrink: 0;
}

.top-nav-left {
  display: flex;
  align-items: center;
  gap: 16px;
}

.mobile-filename {
  font-weight: 500;
  font-size: 0.9rem;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 250px;
}

.theme-icon-sun, .theme-icon-moon {
  transition: var(--transition);
}

[data-theme="light"] .theme-icon-sun { display: none; }
[data-theme="dark"] .theme-icon-moon { display: none; }

/* Reader Container */
.reader-container {
  flex-grow: 1;
  overflow-y: auto;
  padding: 48px 24px;
  scroll-behavior: smooth;
}

/* ==========================================================================
   Core Typography & Markdown Styling
   ========================================================================== */

.markdown-body {
  max-width: var(--content-max-width);
  margin: 0 auto;
  transition: var(--transition);
  font-size: var(--doc-font-size, 1.05rem);
}

.font-serif {
  font-family: var(--font-serif);
}

.font-sans {
  font-family: var(--font-sans);
}

/* Markdown elements formatting */
.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4,
.markdown-body h5,
.markdown-body h6 {
  font-family: var(--font-sans);
  color: var(--text-primary);
  font-weight: 700;
  line-height: 1.25;
  margin-top: 1.8em;
  margin-bottom: 0.6em;
  letter-spacing: -0.015em;
}

.markdown-body h1 {
  font-size: 2.15em;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.3em;
  margin-top: 0.5em; /* first element space adjustment */
}

.markdown-body h2 {
  font-size: 1.55em;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.3em;
}

.markdown-body h3 { font-size: 1.25em; }
.markdown-body h4 { font-size: 1.1em; }
.markdown-body h5 { font-size: 0.95em; }
.markdown-body h6 { font-size: 0.85em; color: var(--text-secondary); }

.markdown-body p {
  margin-top: 0;
  margin-bottom: 1.4em;
  line-height: 1.75;
  color: var(--text-primary);
}

/* Stylized lists */
.markdown-body ul,
.markdown-body ol {
  margin-top: 0;
  margin-bottom: 1.4em;
  padding-left: 2em;
}

.markdown-body li {
  margin-bottom: 0.5em;
  line-height: 1.65;
}

.markdown-body li > p {
  margin-top: 0.5em;
  margin-bottom: 0;
}

.markdown-body ul ul,
.markdown-body ul ol,
.markdown-body ol ul,
.markdown-body ol ol {
  margin-top: 0.3em;
  margin-bottom: 0;
}

/* Task lists (styled natively) */
.markdown-body .task-list-item {
  list-style-type: none;
  padding-left: 0;
}

.markdown-body input[type="checkbox"] {
  margin: 0 0.4em 0.25em -1.4em;
  vertical-align: middle;
  accent-color: var(--accent-color);
  width: 14px;
  height: 14px;
}

/* Beautiful blockquotes */
.markdown-body blockquote {
  margin: 0 0 1.6em 0;
  padding: 12px 24px;
  border-left: 4px solid var(--accent-color);
  background-color: var(--bg-secondary);
  border-radius: 0 8px 8px 0;
  color: var(--text-secondary);
  font-style: italic;
  box-shadow: var(--shadow-sm);
}

.markdown-body blockquote p:last-child {
  margin-bottom: 0;
}

/* Links */
.markdown-body a {
  color: var(--accent-color);
  text-decoration: none;
  border-bottom: 1px dotted var(--accent-color);
  transition: var(--transition);
}

.markdown-body a:hover {
  color: var(--accent-hover);
  border-bottom-style: solid;
}

/* Code structures & highlight.js integration */
.markdown-body code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background-color: var(--code-bg);
  color: var(--code-color);
  padding: 3px 6px;
  border-radius: 4px;
  border: 1px solid var(--code-border);
  transition: var(--transition);
}

/* Code Block Wrapper containing copy-button */
.code-block-wrapper {
  position: relative;
  margin-bottom: 1.6em;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

/* Header bar for preformatted blocks */
.code-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 16px;
  background-color: var(--bg-sidebar);
  border-bottom: 1px solid var(--border-color);
  font-family: var(--font-sans);
  font-size: 0.75rem;
  color: var(--text-secondary);
  font-weight: 500;
  user-select: none;
}

.code-header-lang {
  text-transform: uppercase;
}

.copy-btn {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 4px 8px;
  border-radius: 4px;
  cursor: pointer;
  transition: var(--transition);
  font-size: 0.7rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 4px;
}

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

.copy-btn.copied {
  background-color: var(--accent-color);
  color: var(--bg-secondary);
  border-color: var(--accent-color);
}

/* Reset inner pre rules */
.markdown-body pre {
  margin: 0;
  padding: 16px;
  overflow-x: auto;
  background-color: var(--bg-secondary);
}

.markdown-body pre code {
  background-color: transparent !important;
  color: inherit;
  padding: 0;
  border: none;
  font-size: 0.9em;
  line-height: 1.5;
  white-space: pre;
  display: block;
}

/* Horizontal Rules */
.markdown-body hr {
  height: 2px;
  padding: 0;
  margin: 2.5em 0;
  background-color: var(--border-color);
  border: 0;
}

/* Gorgeous spacing for tables */
.markdown-body table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1.6em;
  box-shadow: var(--shadow-sm);
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid var(--border-color);
}

.markdown-body th,
.markdown-body td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border-color);
  text-align: left;
}

.markdown-body th {
  background-color: var(--bg-sidebar);
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--text-primary);
}

.markdown-body tr:last-child td {
  border-bottom: none;
}

.markdown-body tr:nth-child(even) td {
  background-color: rgba(0, 0, 0, 0.015);
}
[data-theme="dark"] .markdown-body tr:nth-child(even) td {
  background-color: rgba(255, 255, 255, 0.01);
}

/* Images */
.markdown-body img {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  margin: 1.6em 0;
  box-shadow: var(--shadow-md);
  display: block;
  margin-left: auto;
  margin-right: auto;
}

/* Inline Elements details */
.markdown-body kbd {
  background-color: var(--bg-sidebar);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  box-shadow: 0 1px 0 rgba(0,0,0,0.2);
  color: var(--text-primary);
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75em;
  line-height: 1.4;
  padding: 2px 5px;
  white-space: nowrap;
}

/* ==========================================================================
   Loading, Blank and Overlay states
   ========================================================================= */

.loading-state, .empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 80px 24px;
  text-align: center;
  color: var(--text-muted);
}

.empty-state svg {
  margin-bottom: 16px;
  color: var(--border-hover);
}

.empty-state h3 {
  color: var(--text-primary);
  margin-bottom: 8px;
}

.empty-state p {
  max-width: 400px;
  font-size: 0.9rem;
  line-height: 1.5;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--border-color);
  border-top-color: var(--accent-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin-bottom: 16px;
}

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

/* Global Drop Overlay */
.drop-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: rgba(255, 123, 0, 0.95); /* Deep orange translucent */
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #FFFFFF;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}

[data-theme="dark"] .drop-overlay {
  background-color: rgba(20, 20, 20, 0.96);
}

.drop-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.drop-overlay-content {
  text-align: center;
  transform: scale(0.95);
  transition: transform 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
}

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

.drop-overlay h2 {
  font-size: 2rem;
  margin-top: 16px;
  margin-bottom: 8px;
  font-weight: 600;
}

.drop-overlay p {
  font-size: 1.1rem;
  opacity: 0.8;
}

/* ==========================================================================
   Responsive Breakpoints & Print Config
   ========================================================================= */

/* Hide items based on screens */
.mobile-only {
  display: none !important;
}

@media (max-width: 900px) {
  /* Toggle Sidebar state on Mobile */
  .sidebar {
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    transform: translateX(-100%);
    box-shadow: var(--shadow-lg);
  }

  .sidebar.active {
    transform: translateX(0);
  }

  .sidebar-header {
    border-bottom: 1px solid var(--border-color);
  }

  .mobile-only {
    display: inline-flex !important;
  }

  .top-nav {
    display: flex;
  }

  .reader-container {
    padding: 24px 16px;
  }
}

@media (min-width: 901px) {
  /* Top menu button hidden on desktop */
  #menu-toggle-btn {
    display: none;
  }
  
  .top-nav {
    /* Hide top nav entirely on desktops to maximize clean UI */
    display: none;
  }
  
  .reader-container {
    padding: 60px 40px;
    height: 100vh;
  }
}

/* Print Layout */
@media print {
  .sidebar, .top-nav, .drop-overlay {
    display: none !important;
  }
  
  .app-container {
    display: block;
    height: auto;
  }

  .main-content {
    display: block;
    overflow: visible;
    height: auto;
  }

  .reader-container {
    padding: 0;
    overflow: visible;
    height: auto;
  }

  body {
    background-color: #ffffff !important;
    color: #000000 !important;
    overflow: visible;
  }

  .markdown-body {
    max-width: 100%;
  }

  .code-block-wrapper {
    page-break-inside: avoid;
    border: 1px solid #000000;
  }
  
  .copy-btn {
    display: none !important;
  }
}