/* ════════════════════════════════════════════════════════════════════
   COMPONENTS.CSS – Buttons, Cards, Viewer, Summary Content
   ════════════════════════════════════════════════════════════════════ */

/* ─── BUTTONS ────────────────────────────────────────────────────── */
.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 26px;
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  font-weight: 700;
  border: 1.5px solid transparent;
  cursor: pointer;
  transition: transform var(--transition-bounce), box-shadow var(--transition),
              background var(--transition), border-color var(--transition), color var(--transition);
  text-decoration: none;
  overflow: hidden;
  letter-spacing: 0.01em;
}

.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255,255,255,0.15);
  opacity: 0;
  transition: opacity var(--transition);
  border-radius: inherit;
}

.btn:hover::after { opacity: 1; }
.btn:active { transform: scale(0.97); }
.btn:hover { text-decoration: none; transform: translateY(-2px); }

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  color: #fff;
  border-color: var(--color-primary);
  box-shadow: 0 4px 16px var(--color-primary-glow);
}

.btn-primary:hover {
  box-shadow: 0 8px 28px var(--color-primary-glow);
}

.btn-secondary {
  background: var(--color-surface);
  color: var(--color-primary);
  border-color: var(--color-border);
}

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

.btn-success {
  background: linear-gradient(135deg, var(--color-success), #10b981);
  color: #fff;
  border-color: var(--color-success);
  box-shadow: 0 4px 16px rgba(5, 150, 105, 0.3);
}

.btn-success:hover {
  box-shadow: 0 8px 28px rgba(5, 150, 105, 0.4);
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* ─── LESSON CARD ────────────────────────────────────────────────── */
.lesson-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: 28px;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-bounce), box-shadow var(--transition),
              border-color var(--transition), background var(--transition);
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  animation: fadeInScale 0.5s ease both;
  position: relative;
  overflow: hidden;
}

/* Subtle gradient accent line on top */
.lesson-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent), var(--color-teal));
  transform: scaleX(0);
  transform-origin: right;
  transition: transform var(--transition-slow);
}

.lesson-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-lg);
  transform: translateY(-6px);
}

.lesson-card:hover::before {
  transform: scaleX(1);
}

.lesson-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 16px;
}

.lesson-order {
  font-size: 0.72rem;
  font-weight: 800;
  color: var(--color-primary);
  background: var(--color-primary-soft);
  padding: 4px 12px;
  border-radius: 100px;
  font-family: var(--font-latin);
  border: 1px solid rgba(79, 70, 229, 0.2);
  transition: background var(--transition), color var(--transition);
}

.lesson-card:hover .lesson-order {
  background: var(--color-primary);
  color: #fff;
}

.lesson-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--color-primary-soft), var(--color-teal-soft));
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  transition: transform var(--transition-bounce);
}

.lesson-card:hover .lesson-icon {
  transform: rotate(10deg) scale(1.1);
}

.lesson-card h3 {
  font-size: 1.08rem;
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.45;
  margin-bottom: 6px;
  transition: color var(--transition);
}

.lesson-card:hover h3 { color: var(--color-primary); }

.lesson-en {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  font-family: var(--font-latin);
  margin-bottom: 12px;
}

.lesson-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  flex: 1;
  margin-bottom: 20px;
  line-height: 1.7;
}

.lesson-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 20px;
}

.tag {
  font-size: 0.7rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 100px;
  background: var(--color-surface-muted);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border-light);
  transition: background var(--transition), color var(--transition), border-color var(--transition);
}

.lesson-card:hover .tag {
  background: var(--color-primary-soft);
  color: var(--color-primary);
  border-color: rgba(79, 70, 229, 0.2);
}

.lesson-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 16px;
  border-top: 1px solid var(--color-border-light);
}

.lesson-card-footer .btn {
  padding: 9px 18px;
  font-size: 0.82rem;
}

.lesson-meta-text {
  font-size: 0.78rem;
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
  gap: 4px;
}

/* ─── LESSON VIEWER ──────────────────────────────────────────────── */
.viewer-shell {
  min-height: calc(100vh - var(--header-height));
  animation: fadeIn 0.3s ease;
}

.viewer-toolbar {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: 16px 24px;
  position: sticky;
  top: var(--header-height);
  z-index: 90;
  backdrop-filter: blur(8px);
  transition: background var(--transition-slow), border-color var(--transition);
}

[data-theme="dark"] .viewer-toolbar {
  background: rgba(19, 25, 41, 0.9);
}

.viewer-toolbar-inner {
  max-width: var(--content-width);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
}

.viewer-breadcrumb {
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

.viewer-breadcrumb span {
  color: var(--color-primary);
  font-weight: 600;
}

.viewer-title {
  flex: 1;
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  min-width: 180px;
}

/* ─── TABS ───────────────────────────────────────────────────────── */
.viewer-tabs {
  display: flex;
  gap: 4px;
  background: var(--color-surface-muted);
  padding: 4px;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}

.tab-btn {
  padding: 8px 20px;
  border: none;
  background: transparent;
  color: var(--color-text-secondary);
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition), color var(--transition), box-shadow var(--transition);
}

.tab-btn.active {
  background: var(--color-surface);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

.tab-btn:not(.active):hover {
  color: var(--color-primary);
  background: var(--color-surface-hover);
}

.viewer-content {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 44px 24px 88px;
}

.tab-panel { display: none; }

.tab-panel.active {
  display: block;
  animation: fadeIn 0.3s ease both;
}

/* ─── OBJECTIVES BOX ─────────────────────────────────────────────── */
.objectives-box {
  background: var(--color-primary-soft);
  border: 1px solid rgba(79, 70, 229, 0.2);
  border-right: 4px solid var(--color-primary);
  border-radius: var(--radius-lg);
  padding: 24px 28px;
  margin-bottom: 40px;
  transition: background var(--transition-slow), border-color var(--transition);
}

.objectives-box h2,
.objectives-label {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.objectives-list {
  padding-right: 20px;
}

.objectives-list li {
  color: var(--color-text-secondary);
  margin-bottom: 8px;
  position: relative;
}

/* ─── SUMMARY BODY ───────────────────────────────────────────────── */
.summary-body h2 {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--color-text);
  margin: 40px 0 16px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: 10px;
}

.summary-body h2::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 22px;
  background: linear-gradient(180deg, var(--color-primary), var(--color-accent));
  border-radius: 4px;
  flex-shrink: 0;
}

.summary-body h1 { display: none; }
.summary-body h2:first-child { margin-top: 0; }

.summary-body h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-primary);
  margin: 28px 0 12px;
}

.summary-body p {
  color: var(--color-text-secondary);
  margin-bottom: 16px;
  line-height: 1.8;
}

.summary-body ul,
.summary-body ol {
  padding-right: 24px;
  margin-bottom: 18px;
}

.summary-body li {
  color: var(--color-text-secondary);
  margin-bottom: 8px;
  line-height: 1.7;
}

.summary-body strong { color: var(--color-text); }

.summary-body code {
  background: var(--color-surface-muted);
  color: var(--color-primary);
  padding: 2px 8px;
  border-radius: 6px;
  font-family: var(--font-mono);
  font-size: 0.84em;
  direction: ltr;
  display: inline-block;
  border: 1px solid var(--color-border);
}

.summary-body pre {
  background: #0d1117;
  color: #e6edf3;
  border-radius: var(--radius-lg);
  padding: 24px;
  margin: 20px 0;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.7;
  direction: ltr;
  text-align: left;
  border: 1px solid #30363d;
  box-shadow: var(--shadow-md);
}

.summary-body pre code {
  background: none;
  color: inherit;
  padding: 0;
  border: none;
}

.summary-body .math,
.summary-body .math-block {
  direction: ltr;
  text-align: left;
}

.summary-body .math-block {
  background: var(--color-surface-muted);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 18px;
  margin: 18px 0;
  overflow-x: auto;
}

/* ─── TABLE ──────────────────────────────────────────────────────── */
.table-wrap {
  overflow-x: auto;
  margin: 24px 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.summary-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}

.summary-table th {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  color: #fff;
  padding: 13px 18px;
  font-weight: 700;
  text-align: right;
  white-space: nowrap;
}

.summary-table td {
  padding: 12px 18px;
  border-top: 1px solid var(--color-border-light);
  color: var(--color-text-secondary);
  vertical-align: top;
  transition: background var(--transition);
}

.summary-table tr:hover td { background: var(--color-surface-hover); }

.summary-table tr:nth-child(even) td {
  background: var(--color-surface-muted);
}

/* ─── EXERCISES ──────────────────────────────────────────────────── */
.exercises-section {
  margin-top: 52px;
  padding-top: 36px;
  border-top: 2px solid var(--color-border);
}

.exercises-section h2 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 24px;
}

.exercise-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-bottom: 16px;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.exercise-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

.exercise-card h3 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 14px;
}

.exercise-card p,
.exercise-card li {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}