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

:root {
  --blue: #2563eb;
  --blue-light: #eff6ff;
  --green: #10b981;
  --orange: #f59e0b;
  --red: #ef4444;
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.05);
  --shadow: 0 1px 3px rgba(0,0,0,.1), 0 1px 2px rgba(0,0,0,.06);
  --shadow-md: 0 4px 6px rgba(0,0,0,.07), 0 2px 4px rgba(0,0,0,.06);
  --shadow-lg: 0 10px 15px rgba(0,0,0,.1), 0 4px 6px rgba(0,0,0,.05);
  --radius: 12px;
  --radius-sm: 8px;
  --max-w: 1200px;
}

html { font-size: 16px; -webkit-font-smoothing: antialiased; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--gray-50);
  color: var(--gray-800);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ===== Header ===== */
#header {
  background: #fff;
  border-bottom: 1px solid var(--gray-200);
  position: sticky;
  top: 0;
  z-index: 100;
}
.header-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  gap: 20px;
}
.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--gray-900);
  white-space: nowrap;
}
.logo:hover { text-decoration: none; }

.search-wrap {
  flex: 1;
  max-width: 480px;
  position: relative;
}
#searchInput {
  width: 100%;
  padding: 10px 16px;
  border: 1px solid var(--gray-300);
  border-radius: 999px;
  font-size: .9375rem;
  outline: none;
  transition: border-color .2s, box-shadow .2s;
  background: var(--gray-50);
}
#searchInput:focus {
  border-color: var(--blue);
  box-shadow: 0 0 0 3px rgba(37,99,235,.15);
  background: #fff;
}
.search-hint {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  background: var(--gray-100);
  border: 1px solid var(--gray-300);
  border-radius: 4px;
  padding: 1px 6px;
  font-size: .75rem;
  color: var(--gray-500);
  pointer-events: none;
}

/* ===== Main ===== */
#app {
  flex: 1;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 24px;
  width: 100%;
}

/* ===== Loading ===== */
.loading {
  text-align: center;
  padding: 80px 0;
  color: var(--gray-400);
  font-size: 1.1rem;
}

/* ===== Home Page ===== */
.hero {
  text-align: center;
  padding: 48px 0 32px;
}
.hero h1 {
  font-size: 2rem;
  font-weight: 800;
  color: var(--gray-900);
  margin-bottom: 8px;
}
.hero p {
  font-size: 1.1rem;
  color: var(--gray-500);
}

.stats-bar {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-bottom: 40px;
}
.stat-item {
  text-align: center;
}
.stat-num {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--blue);
}
.stat-label {
  font-size: .8125rem;
  color: var(--gray-500);
}

.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
}

.category-card {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 20px 24px;
  cursor: pointer;
  transition: transform .15s, box-shadow .15s, border-color .15s;
  display: flex;
  align-items: center;
  gap: 16px;
}
.category-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--blue);
  text-decoration: none;
}

.category-icon {
  font-size: 2rem;
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--blue-light);
  border-radius: var(--radius-sm);
}
.category-info h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--gray-900);
  margin-bottom: 2px;
}
.category-info span {
  font-size: .8125rem;
  color: var(--gray-500);
}

/* ===== Category Page ===== */
.category-header {
  margin-bottom: 24px;
}
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  color: var(--gray-500);
  font-size: .875rem;
  margin-bottom: 12px;
}
.back-link:hover { color: var(--blue); text-decoration: none; }

.category-title {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 8px;
}
.category-title .icon { font-size: 1.75rem; }
.category-title h1 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--gray-900);
}

.subcat-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 20px;
}
.subcat-tab {
  padding: 6px 14px;
  border-radius: 999px;
  font-size: .8125rem;
  border: 1px solid var(--gray-200);
  background: #fff;
  color: var(--gray-600);
  cursor: pointer;
  transition: all .15s;
}
.subcat-tab:hover {
  border-color: var(--blue);
  color: var(--blue);
}
.subcat-tab.active {
  background: var(--blue);
  color: #fff;
  border-color: var(--blue);
}

.sort-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
  font-size: .8125rem;
  color: var(--gray-500);
}
.sort-bar select {
  padding: 4px 8px;
  border: 1px solid var(--gray-200);
  border-radius: 6px;
  font-size: .8125rem;
  background: #fff;
  color: var(--gray-700);
}

/* ===== Project Cards ===== */
.project-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.project-card {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 16px 20px;
  transition: border-color .15s, box-shadow .15s;
}
.project-card:hover {
  border-color: var(--blue);
  box-shadow: var(--shadow-sm);
}
.project-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 6px;
}
.project-name {
  font-weight: 600;
  color: var(--gray-900);
  font-size: .9375rem;
}
.project-name a { color: inherit; }
.project-name a:hover { color: var(--blue); text-decoration: none; }

.project-stars {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: .8125rem;
  font-weight: 600;
  color: var(--orange);
  flex-shrink: 0;
}
.project-desc {
  font-size: .875rem;
  color: var(--gray-600);
  margin-bottom: 8px;
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.project-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: .75rem;
  color: var(--gray-400);
  flex-wrap: wrap;
}
.lang-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  display: inline-block;
  margin-right: 4px;
  vertical-align: middle;
}
.subcat-tag {
  background: var(--blue-light);
  color: var(--blue);
  padding: 2px 8px;
  border-radius: 4px;
  font-size: .75rem;
}
.project-link {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  color: var(--gray-400);
  transition: color .15s;
}
.project-link:hover { color: var(--blue); text-decoration: none; }

/* ===== Search Results ===== */
.search-info {
  margin-bottom: 16px;
  font-size: .875rem;
  color: var(--gray-500);
}
.search-info strong {
  color: var(--gray-800);
}

/* ===== Empty State ===== */
.empty-state {
  text-align: center;
  padding: 64px 0;
  color: var(--gray-400);
}
.empty-state .icon { font-size: 3rem; margin-bottom: 12px; }
.empty-state p { font-size: .9375rem; }

/* ===== Footer ===== */
footer {
  text-align: center;
  padding: 24px;
  font-size: .8125rem;
  color: var(--gray-400);
  border-top: 1px solid var(--gray-200);
  margin-top: auto;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .header-inner { padding: 10px 16px; }
  .search-hint { display: none; }
  #app { padding: 16px; }
  .hero h1 { font-size: 1.5rem; }
  .hero { padding: 32px 0 20px; }
  .category-grid { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .category-card { padding: 14px 16px; gap: 12px; }
  .category-icon { font-size: 1.5rem; width: 40px; height: 40px; }
  .stats-bar { gap: 20px; }
}
@media (max-width: 480px) {
  .category-grid { grid-template-columns: 1fr; }
  .category-title h1 { font-size: 1.25rem; }
}

/* ===== Filter Bar (Difficulty) ===== */
.filter-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
  font-size: .8125rem;
  color: var(--gray-500);
}
.diff-filter {
  padding: 4px 12px;
  border-radius: 999px;
  font-size: .75rem;
  border: 1px solid var(--gray-200);
  background: #fff;
  color: var(--gray-600);
  cursor: pointer;
  transition: all .15s;
}
.diff-filter:hover {
  border-color: var(--blue);
  color: var(--blue);
}
.diff-filter.active {
  background: var(--blue);
  color: #fff;
  border-color: var(--blue);
}

/* ===== Tags ===== */
.diff-tag, .special-tag {
  display: inline-block;
  padding: 1px 7px;
  border-radius: 4px;
  font-size: .6875rem;
  font-weight: 500;
  margin-left: 6px;
  vertical-align: middle;
}
.diff-tag.tag-easy {
  background: #ecfdf5;
  color: #059669;
}
.diff-tag.tag-medium {
  background: #fffbeb;
  color: #d97706;
}
.diff-tag.tag-hard {
  background: #fef2f2;
  color: #dc2626;
}
.special-tag.tag-edge {
  background: #fef3c7;
  color: #92400e;
}
.special-tag.tag-commercial {
  background: #f0fdf4;
  color: #166534;
}

/* ===== Locked Card ===== */
.project-card.locked {
  position: relative;
  overflow: hidden;
}
.lock-overlay {
  position: absolute;
  inset: 0;
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: rgba(255,255,255,.7);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-radius: var(--radius);
}
.unlock-btn {
  padding: 8px 24px;
  border-radius: 999px;
  background: var(--blue);
  color: #fff;
  border: none;
  font-size: .875rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform .15s, box-shadow .15s;
}
.unlock-btn:hover {
  transform: scale(1.05);
  box-shadow: var(--shadow-md);
}
.lock-hint {
  margin-top: 8px;
  font-size: .75rem;
  color: var(--gray-500);
}
.blurred {
  filter: blur(4px);
  user-select: none;
  pointer-events: none;
}
.blurred-name {
  filter: blur(4px);
  user-select: none;
}

/* ===== Language Colors ===== */
.lang-js { background: #f1e05a; }
.lang-ts { background: #3178c6; }
.lang-py { background: #3572A5; }
.lang-go { background: #00ADD8; }
.lang-rust { background: #dea584; }
.lang-java { background: #b07219; }
.lang-c { background: #555555; }
.lang-cpp { background: #f34b7d; }
.lang-ruby { background: #701516; }
.lang-php { background: #4F5D95; }
.lang-swift { background: #F05138; }
.lang-kotlin { background: #A97BFF; }
.lang-dart { background: #00B4AB; }
.lang-shell { background: #89e051; }
.lang-vue { background: #41b883; }
.lang-html { background: #e34c26; }
.lang-css { background: #563d7c; }
.lang-scala { background: #c22d40; }
.lang-lua { background: #000080; }
.lang-r { background: #198CE7; }
.lang-jupyter { background: #DA5B0B; }
.lang-default { background: var(--gray-400); }

/* ===== Tag Editor Modal ===== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  pointer-events: none;
  transition: opacity .2s;
}
.modal-overlay.active {
  opacity: 1;
  pointer-events: auto;
}
.modal-content {
  background: #fff;
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  width: 90%;
  max-width: 420px;
  transform: translateY(20px);
  transition: transform .2s;
}
.modal-overlay.active .modal-content {
  transform: translateY(0);
}
.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--gray-200);
}
.modal-header h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--gray-900);
}
.modal-close {
  background: none;
  border: none;
  font-size: 1.25rem;
  color: var(--gray-500);
  cursor: pointer;
  padding: 4px;
  line-height: 1;
}
.modal-close:hover { color: var(--gray-900); }
.modal-body {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.form-group label {
  font-size: .8125rem;
  font-weight: 500;
  color: var(--gray-600);
}
.form-group span {
  font-size: .9375rem;
  color: var(--gray-900);
  font-weight: 500;
}
.form-group select {
  padding: 8px 12px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-sm);
  font-size: .875rem;
  background: #fff;
  color: var(--gray-700);
  outline: none;
  transition: border-color .2s;
}
.form-group select:focus {
  border-color: var(--blue);
  box-shadow: 0 0 0 3px rgba(37,99,235,.15);
}
.modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: 8px;
  padding: 16px 20px;
  border-top: 1px solid var(--gray-200);
}
.btn-cancel {
  padding: 8px 16px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-sm);
  background: #fff;
  color: var(--gray-600);
  font-size: .875rem;
  cursor: pointer;
  transition: all .15s;
}
.btn-cancel:hover {
  border-color: var(--gray-400);
  color: var(--gray-900);
}
.btn-save {
  padding: 8px 16px;
  border: none;
  border-radius: var(--radius-sm);
  background: var(--blue);
  color: #fff;
  font-size: .875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all .15s;
}
.btn-save:hover {
  background: #1d4ed8;
  box-shadow: var(--shadow-sm);
}
.modal-repo-name {
  font-size: .9375rem;
  color: var(--gray-900);
  font-weight: 500;
  word-break: break-all;
}

/* ===== Tag Edit Button ===== */
.tag-edit-btn {
  background: none;
  border: 1px solid var(--gray-200);
  border-radius: 4px;
  padding: 2px 6px;
  font-size: .75rem;
  cursor: pointer;
  margin-left: 8px;
  transition: all .15s;
}
.tag-edit-btn:hover {
  border-color: var(--blue);
  background: var(--blue-light);
}

/* ===== Favorites ===== */
.favorites-banner {
  display: block;
  margin: 0 auto 24px;
  padding: 12px 24px;
  background: linear-gradient(135deg, #fef2f2, #fff5f5);
  border: 1px solid #fecaca;
  border-radius: var(--radius);
  color: #b91c1c;
  font-weight: 600;
  text-align: center;
  text-decoration: none;
  transition: all .15s;
}
.favorites-banner:hover {
  background: linear-gradient(135deg, #fee2e2, #fef2f2);
  border-color: #fca5a5;
}

.project-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.fav-btn {
  background: none;
  border: none;
  font-size: 1rem;
  cursor: pointer;
  padding: 2px;
  opacity: .5;
  transition: all .15s;
}
.fav-btn:hover {
  opacity: 1;
  transform: scale(1.1);
}
.fav-btn.favorited {
  opacity: 1;
}

/* ===== Footer ===== */
.footer-copy {
  color: var(--gray-400);
  font-size: .85rem;
}