/* ==========================================================================
   Project Based Learning Tracker - Core Design System & Styles
   ========================================================================== */

/* --- 1. CSS Custom Properties / Design Tokens --- */
:root {
  /* Color Palette - Modern High-Contrast Neutral & Accent Tokens (HSL) */
  --hue-primary: 224; /* Deep Indigo / Sapphire */
  --hue-success: 142; /* Emerald Green */
  --hue-warning: 38;  /* Amber / Gold */
  --hue-danger: 0;    /* Crimson Red */
  --hue-info: 199;    /* Cyan / Sky */

  /* Light Mode (Default) */
  --color-bg-app: hsl(220, 20%, 97%);
  --color-bg-card: hsl(0, 0%, 100%);
  --color-bg-card-hover: hsl(220, 25%, 99%);
  --color-bg-subtle: hsl(220, 18%, 94%);
  --color-border: hsl(220, 15%, 88%);
  --color-border-subtle: hsl(220, 15%, 92%);

  --color-text-main: hsl(220, 30%, 12%);
  --color-text-muted: hsl(220, 12%, 46%);
  --color-text-light: hsl(220, 10%, 65%);

  --color-primary: hsl(var(--hue-primary), 76%, 54%);
  --color-primary-hover: hsl(var(--hue-primary), 76%, 46%);
  --color-primary-subtle: hsl(var(--hue-primary), 85%, 96%);

  /* Difficulty Semantic Colors */
  --color-beginner: hsl(var(--hue-success), 70%, 42%);
  --color-beginner-bg: hsl(var(--hue-success), 75%, 95%);
  --color-intermediate: hsl(var(--hue-warning), 92%, 42%);
  --color-intermediate-bg: hsl(var(--hue-warning), 95%, 95%);
  --color-advanced: hsl(var(--hue-danger), 76%, 52%);
  --color-advanced-bg: hsl(var(--hue-danger), 85%, 96%);

  /* Must-Do Flagship Colors */
  --color-mustdo-gold: hsl(38, 92%, 50%);
  --color-mustdo-bg: hsl(42, 95%, 94%);
  --color-mustdo-border: hsl(38, 85%, 72%);
  --color-mustdo-text: hsl(30, 90%, 28%);

  /* Status Semantic Colors */
  --status-not-started: hsl(220, 10%, 60%);
  --status-in-progress: hsl(210, 85%, 52%);
  --status-completed: hsl(142, 70%, 42%);
  --status-bookmarked: hsl(38, 95%, 50%);

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Menlo, Monaco, Consolas, monospace;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.08), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -2px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

  /* Radius & Transitions */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-full: 9999px;
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
}

/* Dark Theme Overrides */
[data-theme="dark"] {
  --color-bg-app: hsl(222, 24%, 10%);
  --color-bg-card: hsl(222, 22%, 14%);
  --color-bg-card-hover: hsl(222, 22%, 17%);
  --color-bg-subtle: hsl(222, 20%, 18%);
  --color-border: hsl(222, 16%, 22%);
  --color-border-subtle: hsl(222, 16%, 18%);

  --color-text-main: hsl(220, 20%, 94%);
  --color-text-muted: hsl(220, 12%, 65%);
  --color-text-light: hsl(220, 10%, 45%);

  --color-primary: hsl(var(--hue-primary), 85%, 64%);
  --color-primary-hover: hsl(var(--hue-primary), 85%, 72%);
  --color-primary-subtle: hsl(var(--hue-primary), 40%, 18%);

  --color-beginner: hsl(var(--hue-success), 65%, 55%);
  --color-beginner-bg: hsl(var(--hue-success), 40%, 16%);
  --color-intermediate: hsl(var(--hue-warning), 85%, 60%);
  --color-intermediate-bg: hsl(var(--hue-warning), 40%, 16%);
  --color-advanced: hsl(var(--hue-danger), 80%, 65%);
  --color-advanced-bg: hsl(var(--hue-danger), 40%, 16%);

  --color-mustdo-gold: hsl(42, 95%, 60%);
  --color-mustdo-bg: hsl(38, 45%, 18%);
  --color-mustdo-border: hsl(42, 70%, 38%);
  --color-mustdo-text: hsl(42, 95%, 75%);

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.6);
}

/* --- 2. Base & Reset --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg-app);
  color: var(--color-text-main);
  line-height: 1.5;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

a {
  color: inherit;
  text-decoration: none;
}

button, input, select, textarea {
  font-family: inherit;
  font-size: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
}

/* --- 3. Layout Container --- */
.container {
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

.app-layout {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* --- 4. Top Header --- */
.site-header {
  background-color: var(--color-bg-card);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 40;
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(8px);
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.25rem;
  gap: 1rem;
}

.brand-section {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.brand-logo {
  width: 2.5rem;
  height: 2.5rem;
  background: linear-gradient(135deg, var(--color-primary), hsl(265, 80%, 55%));
  color: #fff;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1.25rem;
  box-shadow: 0 2px 8px rgba(59, 130, 246, 0.35);
}

.brand-title h1 {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--color-text-main);
  line-height: 1.2;
}

.brand-subtitle {
  font-size: 0.78rem;
  color: var(--color-text-muted);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  flex-wrap: wrap;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.55rem 0.95rem;
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn-primary {
  background-color: var(--color-primary);
  color: #fff;
}
.btn-primary:hover {
  background-color: var(--color-primary-hover);
  transform: translateY(-1px);
}

.btn-secondary {
  background-color: var(--color-bg-subtle);
  color: var(--color-text-main);
  border: 1px solid var(--color-border);
}
.btn-secondary:hover {
  background-color: var(--color-border);
}

.btn-special {
  background: linear-gradient(135deg, hsl(260, 85%, 62%), hsl(224, 76%, 54%));
  color: #fff;
  box-shadow: 0 2px 8px rgba(124, 58, 237, 0.3);
}
.btn-special:hover {
  filter: brightness(1.1);
  transform: translateY(-1px);
}

.btn-mustdo-toggle {
  background-color: var(--color-mustdo-bg);
  color: var(--color-mustdo-text);
  border: 1px solid var(--color-mustdo-border);
  font-weight: 700;
}
.btn-mustdo-toggle:hover, .btn-mustdo-toggle.active {
  background-color: var(--color-mustdo-gold);
  color: #111;
  border-color: var(--color-mustdo-gold);
  box-shadow: 0 2px 10px rgba(245, 158, 11, 0.35);
}

.btn-icon {
  width: 2.25rem;
  height: 2.25rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  background-color: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  transition: all var(--transition-fast);
}
.btn-icon:hover {
  color: var(--color-text-main);
  background-color: var(--color-border);
}

/* --- 5. Analytics & KPI Overview Section --- */
.analytics-section {
  padding: 1.5rem 0 0.75rem;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1rem;
}

.stat-card {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.2rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}
.stat-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.overall-progress-card {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 1.25rem;
}

.ring-wrapper {
  position: relative;
  width: 80px;
  height: 80px;
  flex-shrink: 0;
}

.progress-svg {
  transform: rotate(-90deg);
}

.progress-svg-bg {
  fill: none;
  stroke: var(--color-bg-subtle);
  stroke-width: 8;
}

.progress-svg-fill {
  fill: none;
  stroke: var(--color-primary);
  stroke-width: 8;
  stroke-linecap: round;
  stroke-dasharray: 226.19;
  stroke-dashoffset: 226.19;
  transition: stroke-dashoffset 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.ring-text {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--color-text-main);
  font-family: var(--font-mono);
}

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

.stat-label {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
}

.stat-value {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--color-text-main);
  line-height: 1.2;
}

.stat-subtext {
  font-size: 0.78rem;
  color: var(--color-text-muted);
  margin-top: 0.25rem;
}

/* Difficulty Breakdown Bars inside Stat Card */
.difficulty-breakdown {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-top: 0.5rem;
}

.diff-bar-item {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.diff-bar-header {
  display: flex;
  justify-content: space-between;
  font-size: 0.74rem;
  font-weight: 600;
  color: var(--color-text-muted);
}

.diff-bar-track {
  height: 6px;
  background-color: var(--color-bg-subtle);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.diff-bar-fill {
  height: 100%;
  border-radius: var(--radius-full);
  transition: width 0.6s ease;
}

.diff-bar-fill.beginner { background-color: var(--color-beginner); }
.diff-bar-fill.intermediate { background-color: var(--color-intermediate); }
.diff-bar-fill.advanced { background-color: var(--color-advanced); }

/* --- 6. Controls & Filter Toolbar --- */
.controls-section {
  padding: 0.75rem 0 1rem;
}

.controls-card {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1rem 1.25rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.search-and-views {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.search-box {
  position: relative;
  flex: 1;
  min-width: 260px;
}

.search-box input {
  width: 100%;
  padding: 0.6rem 1rem 0.6rem 2.4rem;
  background-color: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-main);
  font-size: 0.88rem;
  transition: border-color var(--transition-fast), background-color var(--transition-fast);
}

.search-box input:focus {
  outline: none;
  border-color: var(--color-primary);
  background-color: var(--color-bg-card);
  box-shadow: 0 0 0 3px var(--color-primary-subtle);
}

.search-icon {
  position: absolute;
  left: 0.8rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--color-text-light);
  font-size: 0.95rem;
  pointer-events: none;
}

.view-toggles {
  display: flex;
  align-items: center;
  background-color: var(--color-bg-subtle);
  padding: 0.2rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  gap: 0.2rem;
}

.view-btn {
  padding: 0.4rem 0.75rem;
  font-size: 0.82rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.view-btn.active {
  background-color: var(--color-bg-card);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

/* Multi-criteria filter row */
.filters-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.filter-group {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.filter-label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--color-text-muted);
}

.filter-select {
  padding: 0.45rem 1.8rem 0.45rem 0.75rem;
  font-size: 0.82rem;
  font-weight: 500;
  background-color: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-main);
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%23888' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.6rem center;
  cursor: pointer;
}

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

/* Quick Tech Track Pills Bar */
.tech-tracks-pills-bar {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  overflow-x: auto;
  padding: 0.25rem 0 0.5rem;
  scrollbar-width: thin;
  -webkit-overflow-scrolling: touch;
}

.tech-track-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.75rem;
  font-size: 0.76rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  background-color: var(--color-bg-subtle);
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  white-space: nowrap;
  transition: all var(--transition-fast);
  cursor: pointer;
}

.tech-track-pill:hover {
  background-color: var(--color-border-subtle);
  color: var(--color-text-main);
  border-color: var(--color-primary-subtle);
}

.tech-track-pill.active {
  background-color: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
  box-shadow: 0 2px 6px rgba(59, 130, 246, 0.3);
}

.badge-track {
  background-color: var(--color-primary-subtle);
  color: var(--color-primary);
  font-size: 0.68rem;
  font-weight: 700;
  border: 1px solid rgba(59, 130, 246, 0.2);
}

/* --- Portfolio Showcase Mode Styling --- */
.showcase-banner-card {
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.08) 0%, rgba(139, 92, 246, 0.08) 100%);
  border: 1px solid var(--color-primary-subtle);
  border-radius: var(--radius-lg);
  padding: 1.25rem 1.5rem;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.showcase-hero-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--color-text-main);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.25rem;
}

.showcase-hero-subtitle {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.showcase-mode-switcher {
  display: inline-flex;
  background-color: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  padding: 0.25rem;
  gap: 0.25rem;
}

.showcase-mode-btn {
  border: 0;
  background: transparent;
  padding: 0.4rem 0.9rem;
  font-size: 0.8rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  color: var(--color-text-muted);
  cursor: pointer;
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.showcase-mode-btn:hover {
  color: var(--color-text-main);
}

.showcase-mode-btn.active {
  background-color: var(--color-primary);
  color: #fff;
  box-shadow: 0 2px 6px rgba(59, 130, 246, 0.3);
}

.showcase-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
  position: relative;
}

.showcase-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary-subtle);
}

.showcase-card-header {
  margin-bottom: 0.75rem;
}

.showcase-card-tabs {
  display: flex;
  border-bottom: 1px solid var(--color-border-subtle);
  gap: 0.35rem;
  margin: 0.75rem 0;
}

.showcase-tab-btn {
  background: transparent;
  border: 0;
  padding: 0.4rem 0.75rem;
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--color-text-muted);
  border-bottom: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}

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

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

.showcase-tab-content {
  background-color: var(--color-bg-subtle);
  border: 1px solid var(--color-border-subtle);
  border-radius: var(--radius-md);
  padding: 0.85rem;
  min-height: 180px;
  max-height: 320px;
  overflow-y: auto;
  font-size: 0.82rem;
  margin-bottom: 1rem;
}

.showcase-code-wrapper {
  position: relative;
}

.showcase-code-pre {
  margin: 0;
  padding: 0.5rem;
  background: #0f172a;
  color: #f8fafc;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  line-height: 1.45;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-all;
}

.showcase-copy-btn {
  position: absolute;
  top: 0.4rem;
  right: 0.4rem;
  background: rgba(255, 255, 255, 0.15);
  border: 0;
  color: #fff;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  font-size: 0.68rem;
  cursor: pointer;
}

.showcase-copy-btn:hover {
  background: rgba(255, 255, 255, 0.3);
}

.showcase-diagram-render {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 150px;
  overflow-x: auto;
}

.showcase-diagram-render svg {
  max-width: 100%;
  height: auto;
}

.showcase-notes-render {
  line-height: 1.5;
  color: var(--color-text-main);
  white-space: pre-wrap;
}

/* --- Dedicated Project Page Deep-Dive Layout --- */
.project-detail-page {
  max-width: 980px;
  margin: 0 auto;
  padding: 1rem 0 3rem;
  animation: fadeIn 0.2s ease-out;
}

.detail-nav-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.detail-back-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.45rem 0.9rem;
  font-size: 0.82rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  color: var(--color-text-main);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.detail-back-btn:hover {
  background-color: var(--color-bg-subtle);
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateX(-2px);
}

.detail-hero-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  margin-bottom: 1.75rem;
  box-shadow: var(--shadow-sm);
}

.detail-hero-title {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--color-text-main);
  line-height: 1.3;
  margin-bottom: 0.75rem;
}

.detail-hero-desc {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.6;
  margin-bottom: 1.25rem;
}

.detail-meta-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--color-border-subtle);
}

.detail-section-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin-bottom: 1.75rem;
  box-shadow: var(--shadow-sm);
}

.detail-section-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--color-text-main);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--color-border-subtle);
}

.detail-diagram-container {
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border-subtle);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow-x: auto;
}

.detail-diagram-container svg {
  max-width: 100%;
  height: auto;
}

.detail-notes-container,
.showcase-notes-render {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--color-text-main);
}

.detail-notes-container h1,
.showcase-notes-render h1 {
  font-size: 1.4rem;
  font-weight: 800;
  margin: 1.25rem 0 0.6rem;
  color: var(--color-text-main);
}

.detail-notes-container h2,
.showcase-notes-render h2 {
  font-size: 1.2rem;
  font-weight: 700;
  margin: 1.1rem 0 0.5rem;
  color: var(--color-text-main);
}

.detail-notes-container h3,
.showcase-notes-render h3 {
  font-size: 1.05rem;
  font-weight: 700;
  margin: 1rem 0 0.4rem;
  color: var(--color-primary);
}

.detail-notes-container p,
.showcase-notes-render p {
  margin-bottom: 0.85rem;
}

.detail-notes-container ul,
.showcase-notes-render ul,
.detail-notes-container ol,
.showcase-notes-render ol {
  margin: 0.5rem 0 1rem 1.4rem;
  padding-left: 0.5rem;
}

.detail-notes-container li,
.showcase-notes-render li {
  margin-bottom: 0.4rem;
  line-height: 1.6;
}

.detail-notes-container code,
.showcase-notes-render code {
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.86em;
  color: var(--color-primary);
}

.detail-notes-container strong,
.showcase-notes-render strong {
  font-weight: 700;
  color: var(--color-text-main);
}

.detail-notes-container blockquote,
.showcase-notes-render blockquote {
  border-left: 3px solid var(--color-primary);
  background: var(--color-bg-subtle);
  padding: 0.5rem 1rem;
  margin: 0.75rem 0;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--color-text-muted);
}

.detail-code-container {
  position: relative;
}

.detail-code-pre {
  margin: 0;
  padding: 1.25rem;
  background: #090d16;
  color: #f1f5f9;
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: 0.84rem;
  line-height: 1.55;
  overflow-x: auto;
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.detail-code-copy-btn {
  position: absolute;
  top: 0.75rem;
  right: 0.75rem;
  background: rgba(255, 255, 255, 0.15);
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: #fff;
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.detail-code-copy-btn:hover {
  background: rgba(255, 255, 255, 0.3);
}

.results-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  padding-top: 0.25rem;
  border-top: 1px solid var(--color-border-subtle);
}

.reset-filters-btn {
  color: var(--color-primary);
  font-weight: 600;
  cursor: pointer;
}
.reset-filters-btn:hover {
  text-decoration: underline;
}

/* --- 7. Project Cards Grid --- */
.projects-container {
  padding: 0.5rem 0 3rem;
  flex: 1;
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.15rem;
}

.project-card {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
  position: relative;
  cursor: pointer;
}

.project-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.project-card.completed {
  border-left: 4px solid var(--status-completed);
}
.project-card.in_progress {
  border-left: 4px solid var(--status-in-progress);
}
.project-card.bookmarked {
  border-left: 4px solid var(--status-bookmarked);
}
.project-card.must-do-highlight {
  border-top: 2px solid var(--color-mustdo-gold);
}

.card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 0.65rem;
}

.badges-row {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  flex-wrap: wrap;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.2rem 0.55rem;
  font-size: 0.72rem;
  font-weight: 600;
  border-radius: var(--radius-full);
}

.badge-lang {
  background-color: var(--color-bg-subtle);
  color: var(--color-text-main);
  border: 1px solid var(--color-border);
}

.badge-must-do {
  background-color: var(--color-mustdo-bg);
  color: var(--color-mustdo-text);
  border: 1px solid var(--color-mustdo-border);
  font-weight: 700;
}

.badge-diff-beginner {
  background-color: var(--color-beginner-bg);
  color: var(--color-beginner);
}
.badge-diff-intermediate {
  background-color: var(--color-intermediate-bg);
  color: var(--color-intermediate);
}
.badge-diff-advanced {
  background-color: var(--color-advanced-bg);
  color: var(--color-advanced);
}

.bookmark-btn {
  color: var(--color-text-light);
  font-size: 1.15rem;
  transition: color var(--transition-fast);
  line-height: 1;
}
.bookmark-btn.active, .bookmark-btn:hover {
  color: var(--color-mustdo-gold);
}

.card-title {
  font-size: 1.02rem;
  font-weight: 700;
  color: var(--color-text-main);
  line-height: 1.35;
  margin-bottom: 0.45rem;
}

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

.card-desc {
  font-size: 0.83rem;
  color: var(--color-text-muted);
  line-height: 1.45;
  margin-bottom: 0.85rem;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-tags {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  flex-wrap: wrap;
  margin-bottom: 1rem;
}

.tag-pill {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--color-text-muted);
  background-color: var(--color-bg-subtle);
  padding: 0.15rem 0.4rem;
  border-radius: var(--radius-sm);
}

.card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--color-border-subtle);
}

.status-dropdown-wrapper {
  position: relative;
}

.status-select {
  padding: 0.35rem 1.4rem 0.35rem 0.65rem;
  font-size: 0.78rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background-color: var(--color-bg-subtle);
  color: var(--color-text-main);
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='0 0 24 24' fill='none' stroke='%23888' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.4rem center;
  cursor: pointer;
}

.status-select.completed {
  background-color: var(--color-beginner-bg);
  color: var(--color-beginner);
  border-color: var(--color-beginner);
}
.status-select.in_progress {
  background-color: var(--color-primary-subtle);
  color: var(--color-primary);
  border-color: var(--color-primary);
}
.status-select.bookmarked {
  background-color: var(--color-mustdo-bg);
  color: var(--color-mustdo-text);
  border-color: var(--color-mustdo-border);
}

.card-action-btn {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--color-text-muted);
  padding: 0.35rem 0.65rem;
  border-radius: var(--radius-sm);
  background-color: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  transition: all var(--transition-fast);
}
.card-action-btn:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
}

/* --- 8. Table View Layout --- */
.projects-table-wrapper {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow-x: auto;
  box-shadow: var(--shadow-sm);
}

.projects-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.84rem;
}

.projects-table th {
  background-color: var(--color-bg-subtle);
  color: var(--color-text-muted);
  font-weight: 600;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--color-border);
}

.projects-table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--color-border-subtle);
  vertical-align: middle;
}

.projects-table tr:last-child td {
  border-bottom: none;
}

.projects-table tr:hover td {
  background-color: var(--color-bg-card-hover);
}

/* --- 9. Modals (Details, Custom Add, Data Backup, Learn Studio) --- */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.65);
  backdrop-filter: blur(4px);
  z-index: 100;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.modal-backdrop.open {
  display: flex;
}

.modal-card {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 600px;
  max-height: 90vh;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-xl);
  animation: modalFadeIn 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.modal-card-lg {
  max-width: 840px;
}

/* Modal Tabs Navigation */
.modal-tabs-header {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.5rem 1.5rem 0;
  border-bottom: 1px solid var(--color-border);
  background-color: var(--color-bg-subtle);
  overflow-x: auto;
}

.modal-tab-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.65rem 1rem;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--color-text-muted);
  border-bottom: 2px solid transparent;
  transition: all var(--transition-fast);
  white-space: nowrap;
  cursor: pointer;
}

.modal-tab-btn:hover {
  color: var(--color-text-main);
  background-color: var(--color-bg-card);
}

.modal-tab-btn.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
  background-color: var(--color-bg-card);
  border-top-left-radius: var(--radius-md);
  border-top-right-radius: var(--radius-md);
}

.modal-tab-pane {
  display: none;
}

.modal-tab-pane.active {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

/* Code Snippet Editor & Diagram Styling */
.code-editor-textarea {
  background-color: hsl(220, 20%, 10%);
  color: hsl(210, 30%, 94%);
  border: 1px solid hsl(220, 15%, 22%);
  border-radius: var(--radius-md);
  padding: 0.85rem;
  tab-size: 2;
  white-space: pre;
  overflow-x: auto;
}

[data-theme="dark"] .code-editor-textarea {
  background-color: hsl(222, 24%, 9%);
}

.diagram-preview-wrapper {
  background-color: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.diagram-preview-header {
  padding: 0.5rem 0.85rem;
  border-bottom: 1px solid var(--color-border-subtle);
  background-color: var(--color-bg-card);
}

.diagram-preview-canvas {
  padding: 1.25rem;
  min-height: 180px;
  max-height: 420px;
  overflow: auto;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg-canvas);
}

.diagram-preview-canvas svg {
  max-width: 100%;
  height: auto;
}

@keyframes modalFadeIn {
  from { opacity: 0; transform: scale(0.96) translateY(8px); }
  to { opacity: 1; transform: scale(1) translateY(0); }
}

.modal-header {
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--color-text-main);
}

.modal-close-btn {
  font-size: 1.5rem;
  color: var(--color-text-muted);
  line-height: 1;
}
.modal-close-btn:hover {
  color: var(--color-text-main);
}

.modal-body {
  padding: 1.25rem 1.5rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.modal-footer {
  padding: 1rem 1.5rem;
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 0.75rem;
}

/* Forms in Modal */
.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.form-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-muted);
}

.form-input, .form-select, .form-textarea {
  padding: 0.55rem 0.75rem;
  background-color: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-main);
  font-size: 0.85rem;
}
.form-input:focus, .form-select:focus, .form-textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  background-color: var(--color-bg-card);
}

.form-textarea {
  min-height: 100px;
  resize: vertical;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

/* --- 10. "Learn How It's Built" Architectural Studio Modal --- */
.learn-modal-card {
  max-width: 960px;
  height: 85vh;
}

.learn-layout {
  display: flex;
  flex: 1;
  overflow: hidden;
}

.learn-sidebar {
  width: 260px;
  background-color: var(--color-bg-subtle);
  border-right: 1px solid var(--color-border);
  padding: 0.75rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  flex-shrink: 0;
}

.learn-nav-item {
  text-align: left;
  padding: 0.65rem 0.85rem;
  font-size: 0.84rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.learn-nav-item:hover {
  background-color: var(--color-border-subtle);
  color: var(--color-text-main);
}

.learn-nav-item.active {
  background-color: var(--color-primary);
  color: #fff;
}

.learn-content-pane {
  flex: 1;
  padding: 1.5rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.learn-hero-header h2 {
  font-size: 1.35rem;
  font-weight: 800;
  margin-bottom: 0.25rem;
}

.learn-hero-subtitle {
  font-size: 0.88rem;
  color: var(--color-text-muted);
}

.learn-overview-box {
  background-color: var(--color-bg-subtle);
  border-left: 4px solid var(--color-primary);
  padding: 0.85rem 1rem;
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font-size: 0.88rem;
  line-height: 1.5;
}

.learn-concept-card {
  background-color: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1rem;
}

.concept-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--color-text-main);
  margin-bottom: 0.4rem;
}

.concept-desc {
  font-size: 0.84rem;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
}

.code-block {
  background-color: hsl(222, 25%, 10%);
  color: hsl(220, 20%, 92%);
  padding: 0.85rem;
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  line-height: 1.5;
  overflow-x: auto;
  border: 1px solid hsl(222, 16%, 22%);
}

.pro-tip-box {
  background-color: var(--color-mustdo-bg);
  border: 1px solid var(--color-mustdo-border);
  color: var(--color-mustdo-text);
  padding: 0.85rem 1rem;
  border-radius: var(--radius-md);
  font-size: 0.82rem;
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
}

/* --- 11. Empty State --- */
.empty-state {
  text-align: center;
  padding: 4rem 1rem;
  background-color: var(--color-bg-card);
  border: 1px dashed var(--color-border);
  border-radius: var(--radius-lg);
}

.empty-icon {
  font-size: 2.5rem;
  margin-bottom: 0.5rem;
  color: var(--color-text-light);
}

.empty-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text-main);
  margin-bottom: 0.25rem;
}

.empty-subtext {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 1rem;
}

/* --- 12. Toast Notifications --- */
.toast-container {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 200;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  pointer-events: none;
}

.toast {
  background-color: var(--color-bg-card);
  color: var(--color-text-main);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-lg);
  padding: 0.75rem 1.15rem;
  border-radius: var(--radius-md);
  font-size: 0.84rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  animation: toastSlideUp 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  pointer-events: auto;
}

@keyframes toastSlideUp {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

/* --- 13. Site Footer --- */
.site-footer {
  background-color: var(--color-bg-card);
  border-top: 1px solid var(--color-border);
  padding: 1.5rem 0;
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

.footer-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* --- 14. Responsive Breakpoints --- */
@media (max-width: 768px) {
  .header-content {
    height: auto;
    padding: 0.85rem 0;
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .learn-layout {
    flex-direction: column;
  }

  .learn-sidebar {
    width: 100%;
    border-right: none;
    border-bottom: 1px solid var(--color-border);
    max-height: 140px;
  }

  .filters-row {
    flex-direction: column;
    align-items: stretch;
  }

  .filter-group {
    justify-content: space-between;
  }

  .filter-select {
    flex: 1;
  }
}