/* ========== Topics Page (DevPress style) ========== */
.page-topics {
  background: var(--bg-page);
}

.topics-main {
  background: var(--bg-page);
}

/* Hero Banner */
.topics-hero {
  background: linear-gradient(135deg, #1a2332 0%, #2d3a4f 50%, #1e3a5f 100%);
  color: #fff;
  padding: 32px 24px;
}

.topics-hero-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
}

.topics-hero-title {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 8px;
}

.topics-hero-desc {
  font-size: var(--font-md);
  color: rgba(255, 255, 255, 0.75);
  line-height: 1.6;
}

.topics-hero-stats {
  display: flex;
  gap: 32px;
}

.hero-stat {
  text-align: center;
}

.hero-stat strong {
  display: block;
  font-size: var(--font-xl);
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 4px;
}

.hero-stat span {
  font-size: var(--font-sm);
  color: rgba(255, 255, 255, 0.6);
}

/* Toolbar */
.topics-toolbar {
  background: var(--bg-white);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  position: sticky;
  top: var(--header-height);
  z-index: 40;
}

.topics-tabs {
  display: flex;
  gap: 0;
  border-bottom: 1px solid var(--border);
}

.topics-tab {
  padding: 16px 24px;
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  font-size: var(--font-base);
  font-family: inherit;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
  margin-bottom: -1px;
}

.topics-tab:hover {
  color: var(--primary);
}

.topics-tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  font-weight: 500;
}

.topics-filter {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  padding: 14px 0;
}

.filter-label {
  font-size: var(--font-md);
  color: var(--text-primary);
  font-weight: 500;
}

.filter-divider {
  color: var(--border);
  margin: 0 4px;
}

.filter-btn {
  padding: 4px 12px;
  background: none;
  border: 1px solid transparent;
  border-radius: 14px;
  font-size: var(--font-md);
  font-family: inherit;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
}

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

.filter-btn.active {
  color: var(--primary);
  background: var(--primary-light);
  border-color: rgba(255, 94, 59, 0.3);
}

.filter-reset {
  margin-left: auto;
  padding: 4px 12px;
  background: none;
  border: none;
  font-size: var(--font-md);
  font-family: inherit;
  color: var(--text-muted);
  cursor: pointer;
}

.filter-reset:hover {
  color: var(--primary);
}

/* Content Grid */
.topics-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 20px;
}

.topic-card {
  background: var(--bg-white);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06);
  transition: box-shadow var(--transition), transform var(--transition);
  display: flex;
  flex-direction: column;
}

.topic-card:hover {
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
  transform: translateY(-2px);
}

.topic-card.hidden {
  display: none;
}

.topic-body {
  padding: 16px;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.topic-header {
  display: flex;
  gap: 12px;
  margin-bottom: 12px;
}

.topic-logo {
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  border-radius: 8px;
  background: var(--primary-light);
  color: var(--primary);
  font-size: var(--font-sm);
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(255, 94, 59, 0.2);
}

.topic-info {
  flex: 1;
  min-width: 0;
}

.topic-name {
  font-size: var(--font-lg);
  font-weight: 600;
  margin-bottom: 6px;
  line-height: 1.4;
}

.topic-badge {
  display: inline-block;
  padding: 1px 6px;
  background: var(--primary-light);
  color: var(--primary);
  font-size: var(--font-xs);
  border-radius: 3px;
  font-weight: 500;
  vertical-align: middle;
  margin-left: 6px;
}

.topic-desc {
  font-size: var(--font-md);
  color: var(--text-secondary);
  line-height: 1.6;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.topic-meta {
  font-size: var(--font-sm);
  color: var(--text-muted);
  margin-bottom: 14px;
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.topic-join-btn {
  margin-top: auto;
  width: 100%;
  padding: 8px 0;
  background: none;
  border: 1px solid var(--primary);
  color: var(--primary);
  border-radius: 4px;
  font-size: var(--font-md);
  font-family: inherit;
  cursor: pointer;
  transition: all var(--transition);
}

.topic-join-btn:hover {
  background: var(--primary);
  color: #fff;
}

.topic-join-btn.joined {
  background: var(--bg-page);
  border-color: var(--border);
  color: var(--text-muted);
  cursor: default;
}

.topics-empty {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-muted);
  font-size: var(--font-base);
}

.topics-empty.hidden {
  display: none;
}

/* Modal */
.topic-modal {
  position: fixed;
  inset: 0;
  z-index: 500;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s, visibility 0.2s;
}

.topic-modal.open {
  opacity: 1;
  visibility: visible;
}

.topic-modal-mask {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
}

.topic-modal-box {
  position: relative;
  background: var(--bg-white);
  border-radius: 8px;
  padding: 32px 40px;
  width: 90%;
  max-width: 420px;
  text-align: center;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.15);
}

.topic-modal-close {
  position: absolute;
  top: 12px;
  right: 16px;
  background: none;
  border: none;
  font-size: 24px;
  color: var(--text-muted);
  cursor: pointer;
  line-height: 1;
}

.topic-modal-close:hover {
  color: var(--text-primary);
}

.topic-modal-icon {
  margin-bottom: 16px;
}

.topic-modal-title {
  font-size: var(--font-lg);
  font-weight: 600;
  margin-bottom: 8px;
}

.topic-modal-desc {
  font-size: var(--font-md);
  color: var(--text-secondary);
  margin-bottom: 24px;
  line-height: 1.6;
}

.topic-modal-actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.btn-modal-primary {
  display: block;
  padding: 10px 20px;
  background: var(--primary);
  color: #fff;
  border-radius: 4px;
  font-size: var(--font-base);
  transition: background var(--transition);
}

.btn-modal-primary:hover {
  background: var(--primary-hover);
  color: #fff;
}

.btn-modal-secondary {
  padding: 8px 20px;
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: var(--font-md);
  font-family: inherit;
  cursor: pointer;
}

.btn-modal-secondary:hover {
  color: var(--text-secondary);
}

/* Back to top */
.back-to-top {
  position: fixed;
  right: 24px;
  bottom: 32px;
  width: 48px;
  height: 48px;
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: 50%;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0;
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 10px;
  font-family: inherit;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition);
  z-index: 100;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  color: var(--primary);
  border-color: var(--primary);
}

/* Responsive */
@media (max-width: 768px) {
  .topics-hero {
    padding: 24px 16px;
  }

  .topics-hero-title {
    font-size: 22px;
  }

  .topics-hero-stats {
    gap: 20px;
    width: 100%;
    justify-content: space-around;
  }

  .topics-toolbar {
    padding: 0 12px;
  }

  .topics-tab {
    padding: 14px 16px;
    font-size: var(--font-md);
  }

  .topics-content {
    padding: 16px 12px;
  }

  .topics-grid {
    grid-template-columns: 1fr;
  }

  .filter-reset {
    margin-left: 0;
    width: 100%;
    text-align: right;
  }
}