/**
 * GoTryTech Premium Component Library CSS
 * 
 * Feeling: Frontend Masters × Linear × Vercel Docs
 * Part of Phase 2 UI Redesign. Contains all reusable UI components (C-01 to C-30)
 * styled strictly using CSS custom properties from variables.css.
 */

/* ==========================================================================
   1. GRID & LAYOUT SYSTEM
   ========================================================================== */
.gtt-grid {
  display: grid;
  gap: var(--space-5);
}
@media (min-width: 768px) {
  .gtt-grid {
    gap: var(--space-6);
  }
}

/* Col Mappings */
.gtt-grid--2 { grid-template-columns: 1fr; }
.gtt-grid--3 { grid-template-columns: 1fr; }
.gtt-grid--4 { grid-template-columns: 1fr; }
.gtt-grid--auto { grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }

@media (min-width: 640px) {
  .gtt-grid--2 { grid-template-columns: repeat(2, 1fr); }
  .gtt-grid--4 { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 768px) {
  .gtt-grid--3 { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 1024px) {
  .gtt-grid--3 { grid-template-columns: repeat(3, 1fr); }
  .gtt-grid--4 { grid-template-columns: repeat(4, 1fr); }
}

/* Special Featured Layout (1 large + 2 small) */
.gtt-grid--featured {
  grid-template-columns: 1fr;
}
@media (min-width: 1024px) {
  .gtt-grid--featured {
    grid-template-columns: 2fr 1fr 1fr;
  }
  .gtt-grid--featured > :first-child {
    grid-row: span 2;
  }
}

/* Page Article + Sidebar Layout */
.gtt-layout--article {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-10);
  align-items: start;
}
@media (min-width: 1024px) {
  .gtt-layout--article {
    grid-template-columns: 1fr var(--sidebar-width);
  }
}

/* ==========================================================================
   2. C-01: GLASS CARD BASE
   ========================================================================== */
.gtt-card {
  position: relative;
  background: var(--bg-glass);
  backdrop-filter: var(--glass-blur-md);
  -webkit-backdrop-filter: var(--glass-blur-md);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-card);
  box-shadow: var(--glass-shadow);
  overflow: hidden;
  transition: var(--transition-card);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.gtt-card:hover {
  border-color: var(--border-accent);
  box-shadow: var(--shadow-card-hover);
  transform: translateY(-4px);
}

.gtt-card__image {
  position: relative;
  aspect-ratio: 16/9;
  overflow: hidden;
  flex-shrink: 0;
  background: var(--bg-canvas);
}

.gtt-card__image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--duration-slow) var(--ease-out);
}

.gtt-card:hover .gtt-card__image img {
  transform: scale(1.04);
}

.gtt-card__body {
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  flex: 1;
  gap: var(--space-3);
}
@media (min-width: 768px) {
  .gtt-card__body {
    padding: var(--space-6);
  }
}

.gtt-card__footer {
  padding: 0 var(--space-5) var(--space-5);
  margin-top: auto;
}
@media (min-width: 768px) {
  .gtt-card__footer {
    padding: 0 var(--space-6) var(--space-6);
  }
}

/* ==========================================================================
   3. C-07: DIFFICULTY BADGE SYSTEM
   ========================================================================== */
.gtt-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1-5);
  padding: var(--space-1) var(--space-3);
  font-size: var(--text-2xs);
  font-weight: var(--weight-bold);
  line-height: var(--leading-none);
  border-radius: var(--radius-badge);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wider);
  transition: var(--transition-color);
  width: fit-content;
}

/* Difficulty Variant Colors */
.gtt-badge--beginner {
  background-color: var(--cyan-muted);
  color: var(--cyan-500);
  border: 1px solid var(--cyan-border);
}

.gtt-badge--intermediate {
  background-color: var(--amber-muted);
  color: var(--amber-500);
  border: 1px solid rgba(245, 158, 11, 0.25);
}

.gtt-badge--advanced {
  background-color: var(--red-muted);
  color: var(--red-500);
  border: 1px solid rgba(239, 68, 68, 0.25);
}

.gtt-badge--expert {
  background-color: var(--purple-muted);
  color: var(--purple-500);
  border: 1px solid var(--purple-border);
}

/* Overlay Badge for thumbnails */
.gtt-card__image-badge {
  position: absolute;
  top: var(--space-3);
  right: var(--space-3);
  z-index: var(--z-10);
  box-shadow: var(--shadow-sm);
  backdrop-filter: var(--glass-blur-sm);
  -webkit-backdrop-filter: var(--glass-blur-sm);
}

/* ==========================================================================
   4. C-08: TECHNOLOGY TAG SYSTEM
   ========================================================================== */
.gtt-tags-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.gtt-tag {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-2-5);
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  line-height: var(--leading-none);
  border-radius: var(--radius-tag);
  background-color: var(--border-faint);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  transition: var(--transition-all);
}

.gtt-tag:hover {
  background-color: var(--border-subtle);
  border-color: var(--border-strong);
  color: var(--text-primary);
  transform: translateY(-1px);
}

/* Active/Featured tag variant */
.gtt-tag--featured {
  background-color: var(--green-muted);
  border-color: var(--green-border);
  color: var(--green-500);
}
.gtt-tag--featured:hover {
  border-color: var(--green-400);
  color: var(--green-400);
  box-shadow: var(--shadow-glow-sm);
}

/* ==========================================================================
   5. C-09: BUTTON SYSTEM
   ========================================================================== */
.gtt-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font-family: var(--font-sans);
  font-weight: var(--weight-semibold);
  text-decoration: none;
  border: 1px solid transparent;
  border-radius: var(--radius-button);
  cursor: pointer;
  white-space: nowrap;
  user-select: none;
  transition: var(--transition-all);
}

/* Variants */
.gtt-btn--primary {
  background-color: var(--green-500);
  color: var(--text-inverse);
  box-shadow: var(--shadow-sm);
}
.gtt-btn--primary:hover {
  background-color: var(--green-400);
  box-shadow: var(--shadow-glow-sm);
}
.gtt-btn--primary:active {
  background-color: var(--green-300);
}

.gtt-btn--outline {
  background-color: transparent;
  border-color: var(--border-medium);
  color: var(--text-primary);
}
.gtt-btn--outline:hover {
  background-color: var(--border-faint);
  border-color: var(--border-strong);
}
.gtt-btn--outline:active {
  background-color: var(--border-subtle);
}

.gtt-btn--ghost {
  background-color: transparent;
  color: var(--text-secondary);
}
.gtt-btn--ghost:hover {
  background-color: var(--border-faint);
  color: var(--text-primary);
}
.gtt-btn--ghost:active {
  background-color: var(--border-subtle);
}

.gtt-btn--danger {
  background-color: var(--red-muted);
  border-color: rgba(239, 68, 68, 0.3);
  color: var(--red-500);
}
.gtt-btn--danger:hover {
  background-color: rgba(239, 68, 68, 0.2);
  border-color: var(--red-500);
}

.gtt-btn--glass {
  background-color: var(--bg-glass-light);
  backdrop-filter: var(--glass-blur-sm);
  -webkit-backdrop-filter: var(--glass-blur-sm);
  border-color: var(--glass-border);
  color: var(--text-primary);
  box-shadow: var(--glass-shadow);
}
.gtt-btn--glass:hover {
  background-color: var(--bg-glass);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
}

/* Sizes */
.gtt-btn--sm {
  padding: var(--space-1-5) var(--space-3);
  font-size: var(--text-xs);
}
.gtt-btn--md {
  padding: var(--space-2-5) var(--space-5);
  font-size: var(--text-sm);
}
.gtt-btn--lg {
  padding: var(--space-3-5) var(--space-7);
  font-size: var(--text-base);
}
.gtt-btn--xl {
  padding: var(--space-4) var(--space-8);
  font-size: var(--text-lg);
  border-radius: var(--radius-lg);
}

.gtt-btn--full {
  width: 100%;
}

/* ==========================================================================
   6. C-10: SECTION HEADER
   ========================================================================== */
.gtt-section-header {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-6);
  margin-bottom: var(--space-10);
  border-bottom: 1px solid var(--border-faint);
  padding-bottom: var(--space-6);
}

.gtt-section-header__text {
  flex: 1;
  min-width: 280px;
}

.gtt-section-label {
  display: block;
  font-size: var(--text-xs);
  font-weight: var(--weight-bold);
  color: var(--green-500);
  letter-spacing: var(--tracking-widest);
  text-transform: uppercase;
  margin-bottom: var(--space-2);
}

.gtt-section-title {
  font-size: var(--text-display-sm);
  font-weight: var(--weight-extrabold);
  color: var(--text-primary);
  letter-spacing: var(--tracking-snug);
  line-height: var(--leading-none);
  margin: 0;
}

.gtt-section-subtitle {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  max-width: var(--container-prose);
  line-height: var(--leading-relaxed);
  margin-top: var(--space-3);
  margin-bottom: 0;
}

/* ==========================================================================
   7. C-17: CALLOUT BOX
   ========================================================================== */
.gtt-callout {
  position: relative;
  padding: var(--space-5) var(--space-6);
  margin: var(--space-6) 0;
  background-color: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-left-width: 4px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.gtt-callout--info {
  border-left-color: var(--cyan-500);
}
.gtt-callout--warning {
  border-left-color: var(--amber-500);
}
.gtt-callout--danger {
  border-left-color: var(--red-500);
}

.gtt-callout__title {
  font-size: var(--text-base);
  font-weight: var(--weight-bold);
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}
.gtt-callout__content {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: var(--leading-relaxed);
}

/* ==========================================================================
   8. C-18: ACCORDION
   ========================================================================== */
.gtt-accordion {
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  background-color: var(--bg-base);
  overflow: hidden;
}

.gtt-accordion__item {
  border-bottom: 1px solid var(--border-subtle);
}
.gtt-accordion__item:last-child {
  border-bottom: none;
}

.gtt-accordion__trigger {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--space-5);
  background: transparent;
  border: none;
  font-size: var(--text-base);
  font-weight: var(--weight-bold);
  color: var(--text-primary);
  text-align: left;
  cursor: pointer;
  transition: background-color var(--duration-fast) var(--ease-out);
}
.gtt-accordion__trigger:hover {
  background-color: var(--border-faint);
}

.gtt-accordion__trigger-icon {
  width: 20px;
  height: 20px;
  fill: none;
  stroke: var(--text-secondary);
  stroke-width: 2;
  transition: transform var(--duration-normal) var(--ease-bounce);
}

/* Trigger rotation on active state */
.gtt-accordion__item--active .gtt-accordion__trigger-icon {
  transform: rotate(180deg);
}

.gtt-accordion__content {
  padding: 0 var(--space-5) var(--space-5);
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: var(--leading-relaxed);
  display: none; /* Controlled by JS UI toggle */
}
.gtt-accordion__item--active .gtt-accordion__content {
  display: block;
}

/* ==========================================================================
   9. C-19: PROGRESS BAR
   ========================================================================== */
.gtt-progress-bar {
  background-color: var(--border-medium);
  border-radius: var(--radius-full);
  overflow: hidden;
  height: 8px;
  width: 100%;
}

.gtt-progress-bar__fill {
  background-color: var(--green-500);
  height: 100%;
  width: 0%; /* Dynamic inline-style width */
  transition: width var(--duration-slow) var(--ease-in-out);
  border-radius: var(--radius-full);
}

/* Progress Colors Mappings */
.gtt-progress-bar__fill--cyan { background-color: var(--cyan-500); }
.gtt-progress-bar__fill--purple { background-color: var(--purple-500); }
.gtt-progress-bar__fill--warning { background-color: var(--amber-500); }
.gtt-progress-bar__fill--danger { background-color: var(--red-500); }

.gtt-progress-bar--sm { height: 4px; }
.gtt-progress-bar--lg { height: 12px; }

/* ==========================================================================
   10. C-20: TABLE OF CONTENTS (ARTICLE SIDEBAR)
   ========================================================================== */
.gtt-toc {
  position: sticky;
  top: calc(var(--header-height-desktop) + var(--space-6));
  padding: var(--space-5);
  background-color: var(--bg-glass);
  backdrop-filter: var(--glass-blur-md);
  -webkit-backdrop-filter: var(--glass-blur-md);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-panel);
  box-shadow: var(--glass-shadow);
  max-height: calc(100vh - var(--header-height-desktop) - var(--space-12));
  overflow-y: auto;
}

.gtt-toc__title {
  font-size: var(--text-xs);
  font-weight: var(--weight-bold);
  color: var(--text-primary);
  text-transform: uppercase;
  letter-spacing: var(--tracking-widest);
  margin-bottom: var(--space-4);
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: var(--space-2);
}

.gtt-toc__list {
  display: flex;
  flex-direction: column;
  gap: var(--space-2-5);
}

.gtt-toc__link {
  display: flex;
  align-items: flex-start;
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: var(--leading-snug);
  transition: var(--transition-color);
  font-weight: var(--weight-medium);
}
.gtt-toc__link:hover {
  color: var(--green-500);
}

/* Active Item highlighted state */
.gtt-toc__item--active .gtt-toc__link {
  color: var(--green-500);
  font-weight: var(--weight-bold);
}
.gtt-toc__item--active {
  position: relative;
}
/* Left line indicator */
.gtt-toc__item--active::before {
  content: "";
  position: absolute;
  left: calc(var(--space-5) * -1);
  top: 50%;
  transform: translateY(-50%);
  width: 4px;
  height: 16px;
  background-color: var(--green-500);
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-glow-sm);
}

/* Nested lists */
.gtt-toc__list--nested {
  margin-top: var(--space-2);
  padding-left: var(--space-4);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.gtt-toc__list--nested .gtt-toc__link {
  font-size: var(--text-xs);
  color: var(--text-tertiary);
}

/* ==========================================================================
   11. C-25: AD ZONE PLACEHOLDER
   ========================================================================== */
.gtt-ad-zone {
  display: flex;
  justify-content: center;
  align-items: center;
  margin: var(--space-8) 0;
  min-height: 90px;
  overflow: hidden;
  position: relative;
  background: repeating-linear-gradient(
    45deg,
    rgba(255, 255, 255, 0.015),
    rgba(255, 255, 255, 0.015) 10px,
    transparent 10px,
    transparent 20px
  );
  border: 1px dashed var(--border-subtle);
  border-radius: var(--radius-md);
}

.gtt-ad-zone::after {
  content: "ADVERTISEMENT";
  position: absolute;
  font-size: var(--text-2xs);
  color: var(--text-muted);
  font-weight: var(--weight-semibold);
  letter-spacing: var(--tracking-wider);
  top: 2px;
  right: var(--space-2);
}

.gtt-ad-zone--sidebar {
  margin: var(--space-6) 0;
  min-height: 250px;
}

.gtt-ad-zone--header {
  margin: 0;
  min-height: 90px;
  border: none;
}

/* ==========================================================================
   12. C-27: PAGINATION
   ========================================================================== */
.gtt-pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  margin-top: var(--space-12);
}

.gtt-page-numbers {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 40px;
  height: 40px;
  padding: 0 var(--space-2);
  font-size: var(--text-sm);
  font-weight: var(--weight-bold);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  background-color: var(--bg-glass-light);
  cursor: pointer;
  transition: var(--transition-all);
}

.gtt-page-numbers:hover {
  background-color: var(--border-faint);
  border-color: var(--border-strong);
  color: var(--text-primary);
  transform: translateY(-1px);
}

.gtt-page-numbers.current {
  background-color: var(--green-500);
  border-color: var(--green-500);
  color: var(--text-inverse);
  box-shadow: var(--shadow-glow-sm);
}

.gtt-page-numbers.dots {
  background-color: transparent;
  border-color: transparent;
  cursor: default;
}

/* ==========================================================================
   13. C-30: STATS STRIP
   ========================================================================== */
.gtt-stats-strip {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-3);
  margin: var(--space-6) 0;
}
@media (min-width: 768px) {
  .gtt-stats-strip {
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-4);
  }
}

.gtt-stat-card {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  padding: var(--space-4);
  background-color: var(--bg-glass);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-xs);
  transition: var(--transition-all);
}
.gtt-stat-card:hover {
  border-color: var(--border-medium);
  transform: translateY(-2px);
}

.gtt-stat-card__label {
  font-size: var(--text-2xs);
  font-weight: var(--weight-bold);
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wider);
}

.gtt-stat-card__value {
  font-size: var(--text-base);
  font-weight: var(--weight-bold);
  color: var(--text-primary);
}