/* ==========================================================================
   Angular 17-20 Senior Developer Knowledge Base - Modern Design System
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Fira+Code:wght@400;500;600&family=Inter:wght@300;400;500;600;700;800&display=swap');

:root {
  --bg-dark: #0b0f19;
  --bg-card: #131b2e;
  --bg-card-hover: #1c2742;
  --bg-sidebar: #0f172a;
  --accent-red: #dd0031;
  --accent-gradient: linear-gradient(135deg, #c3002f 0%, #dd0031 50%, #f44336 100%);
  --accent-cyan: #38bdf8;
  --accent-purple: #a855f7;
  --text-main: #f1f5f9;
  --text-muted: #94a3b8;
  --border-color: #1e293b;
  --border-glow: rgba(221, 0, 49, 0.3);
  --easy-color: #10b981;
  --medium-color: #f59e0b;
  --hard-color: #ef4444;
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'Fira Code', monospace;
  --sidebar-width: 340px;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  height: 100vh;
  display: flex;
}

/* App Container Layout */
#app {
  display: flex;
  width: 100vw;
  height: 100vh;
  overflow: hidden;
}

/* Sidebar Styling */
.sidebar {
  width: var(--sidebar-width);
  background-color: var(--bg-sidebar);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  height: 100%;
  flex-shrink: 0;
  transition: transform 0.3s ease;
  z-index: 100;
}

.sidebar-header {
  padding: 24px 20px 16px;
  border-bottom: 1px solid var(--border-color);
  background: linear-gradient(180deg, rgba(221, 0, 49, 0.08) 0%, transparent 100%);
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.brand-logo {
  width: 36px;
  height: 36px;
  background: var(--accent-gradient);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 20px;
  color: #fff;
  box-shadow: 0 0 15px rgba(221, 0, 49, 0.4);
}

.brand-text h1 {
  font-size: 1.1rem;
  font-weight: 700;
  background: linear-gradient(90deg, #ffffff, #cbd5e1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.brand-text span {
  font-size: 0.75rem;
  color: var(--accent-cyan);
  font-weight: 600;
  letter-spacing: 0.5px;
}

.search-box {
  position: relative;
  margin-bottom: 12px;
}

.search-box input {
  width: 100%;
  padding: 10px 14px 10px 38px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: #fff;
  font-size: 0.875rem;
  outline: none;
  transition: all 0.2s;
}

.search-box input:focus {
  border-color: var(--accent-red);
  box-shadow: 0 0 10px rgba(221, 0, 49, 0.2);
}

.search-icon {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Difficulty Filters */
.filter-pills {
  display: flex;
  gap: 6px;
}

.pill {
  flex: 1;
  padding: 6px 8px;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-muted);
  cursor: pointer;
  text-align: center;
  transition: all 0.2s;
}

.pill.active {
  background: var(--bg-card-hover);
  color: #fff;
  border-color: var(--accent-cyan);
}

/* Sidebar Nav Tree */
.sidebar-nav {
  flex: 1;
  overflow-y: auto;
  padding: 16px 12px;
}

.module-group {
  margin-bottom: 16px;
}

.module-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 8px 8px 4px;
  letter-spacing: 0.5px;
}

.question-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 12px;
  margin-bottom: 4px;
  border-radius: 8px;
  font-size: 0.85rem;
  color: #cbd5e1;
  cursor: pointer;
  transition: all 0.2s;
  border: 1px solid transparent;
}

.question-item:hover {
  background-color: var(--bg-card);
  color: #fff;
}

.question-item.active {
  background-color: var(--bg-card-hover);
  color: #fff;
  border-color: var(--accent-red);
  box-shadow: inset 3px 0 0 var(--accent-red);
}

.badge-diff {
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
}

.badge-diff.easy { background: rgba(16, 185, 129, 0.15); color: var(--easy-color); }
.badge-diff.medium { background: rgba(245, 158, 11, 0.15); color: var(--medium-color); }
.badge-diff.hard { background: rgba(239, 68, 68, 0.15); color: var(--hard-color); }

/* Main Content Workspace */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-dark);
}

.top-bar {
  padding: 16px 32px;
  border-bottom: 1px solid var(--border-color);
  background-color: rgba(15, 23, 42, 0.8);
  backdrop-filter: blur(10px);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.top-bar-title h2 {
  font-size: 1.25rem;
  font-weight: 700;
}

.top-actions {
  display: flex;
  gap: 12px;
}

.btn-action {
  padding: 8px 16px;
  border-radius: 8px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: all 0.2s;
}

.btn-action:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-cyan);
}

/* Article Viewer */
.content-viewer {
  flex: 1;
  overflow-y: auto;
  padding: 32px 48px;
}

.question-header {
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border-color);
}

.question-tags {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}

.tag-module {
  background: rgba(56, 189, 248, 0.15);
  color: var(--accent-cyan);
  padding: 4px 10px;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 700;
}

.question-title {
  font-size: 2rem;
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 16px;
  background: linear-gradient(90deg, #ffffff, #e2e8f0);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Markdown Styling inside Viewer */
.markdown-body {
  font-size: 1rem;
  color: #cbd5e1;
}

.markdown-body h2 {
  font-size: 1.4rem;
  font-weight: 700;
  margin: 32px 0 16px;
  color: #fff;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 8px;
}

.markdown-body h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin: 24px 0 12px;
  color: var(--accent-cyan);
}

.markdown-body p {
  margin-bottom: 16px;
}

.markdown-body ul, .markdown-body ol {
  margin: 0 0 16px 24px;
}

.markdown-body li {
  margin-bottom: 6px;
}

.markdown-body blockquote {
  border-left: 4px solid var(--accent-red);
  background: rgba(221, 0, 49, 0.05);
  padding: 16px 20px;
  border-radius: 0 8px 8px 0;
  margin-bottom: 20px;
}

/* Code Blocks */
.code-wrapper {
  position: relative;
  margin: 20px 0;
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid var(--border-color);
  background-color: #090d16;
}

.code-wrapper pre {
  padding: 20px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.5;
}

.copy-btn {
  position: absolute;
  top: 10px;
  right: 10px;
  padding: 6px 12px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-muted);
  font-size: 0.75rem;
  cursor: pointer;
  transition: all 0.2s;
}

.copy-btn:hover {
  color: #fff;
  background: var(--bg-card-hover);
}

/* Mermaid Diagrams */
.mermaid-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 24px;
  margin: 24px 0;
  display: flex;
  justify-content: center;
}

/* Custom Scrollbars */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg-dark);
}
::-webkit-scrollbar-thumb {
  background: #1e293b;
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: #334155;
}

/* Mobile Responsiveness */
@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    transform: translateX(-100%);
  }
  .sidebar.open {
    transform: translateX(0);
  }
  .content-viewer {
    padding: 20px;
  }
}