@charset "UTF-8";
/**
 * Skin: Bare — 中性骨架皮肤（裸皮肤）
 *
 * 用于新克隆站的默认皮肤。
 * 不含任何站型偏向（无数学蓝、无着色彩虹等）。
 * 只提供最基本的视觉可用性：按钮可点、卡片可区分、文字可读。
 *
 * 所有颜色通过 CSS 变量引用 tokens.css，不硬编码。
 * Design Expert (Phase 6) 会用站型专属皮肤替换此文件。
 *
 * @layer skin
 */

/* ========================================
   Base Overrides
   ======================================== */

html {
  scroll-behavior: smooth;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* Selection */
::selection {
  background: var(--site-primary-light, #dbeafe);
  color: var(--site-primary-dark, #1e40af);
}

::-moz-selection {
  background: var(--site-primary-light, #dbeafe);
  color: var(--site-primary-dark, #1e40af);
}

/* Focus */
*:focus-visible {
  outline: 3px solid var(--site-primary, #3b82f6);
  outline-offset: 2px;
  border-radius: 4px;
}

/* ========================================
   Typography — Minimal
   ======================================== */

.page-header h1 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--site-text, #1f2937);
  line-height: 1.3;
}

/* ========================================
   Page Header — Clean, no gradient
   ======================================== */

.page-header {
  background: var(--site-primary-light, #f0f4ff);
  border-bottom: 3px solid var(--site-primary, #3b82f6);
  border-radius: var(--detail-border-radius, 12px) var(--detail-border-radius, 12px) 0 0;
}

/* ========================================
   Variant Chips
   ======================================== */

.variant-chip {
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.25rem 0.6rem;
  border-radius: 999px;
  color: var(--site-primary, #3b82f6);
  background: var(--site-primary-light, #eff6ff);
  border: 1px solid var(--site-primary-border, #bfdbfe);
}

/* ========================================
   Breadcrumb — Simple
   ======================================== */

.breadcrumb {
  background: #f9fafb;
  border: 1px solid var(--site-border, #e5e7eb);
  border-radius: 8px;
}

.breadcrumb ol {
  font-size: 0.875rem;
  color: #4b5563;
}

.breadcrumb a {
  color: var(--site-primary, #3b82f6);
  text-decoration: none;
}

.breadcrumb a:hover {
  color: var(--site-primary-hover, #2563eb);
  text-decoration: underline;
}

.breadcrumb li:not(:last-child)::after {
  content: '›';
  color: #9ca3af;
  font-weight: 600;
}

.breadcrumb li:last-child {
  color: var(--site-text, #1f2937);
  font-weight: 600;
}

/* ========================================
   Set Switcher — Clean box
   ======================================== */

.set-switcher {
  background: white;
  border: 1px solid var(--site-border, #e5e7eb);
  border-radius: var(--detail-border-radius, 12px);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.set-switcher-label {
  font-size: 1rem;
  font-weight: 600;
  color: var(--site-text, #1f2937);
}

.set-btn {
  background: white;
  border: 2px solid var(--site-border, #e5e7eb);
  border-radius: 8px;
  color: var(--site-text, #1f2937);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: border-color 150ms ease, background 150ms ease;
}

.set-btn:hover {
  border-color: var(--site-primary, #3b82f6);
  background: var(--site-primary-light, #eff6ff);
}

.set-btn.active {
  background: var(--site-primary, #3b82f6);
  color: white;
  border-color: var(--site-primary-dark, #1e40af);
}

/* ========================================
   Buttons — Solid, no gradient
   ======================================== */

.btn {
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  border: 2px solid transparent;
  border-radius: var(--radius-button, 8px);
  background: white;
  color: var(--site-text, #1f2937);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  transition: background 150ms ease, box-shadow 150ms ease;
}

.btn:hover {
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.btn-primary {
  background: var(--site-primary, #3b82f6);
  color: white;
  border-color: var(--site-primary-dark, #1e40af);
}

.btn-primary:hover {
  background: var(--site-primary-hover, #2563eb);
}

.btn-success,
.btn-answers {
  background: var(--site-accent, #10b981);
  color: white;
  border-color: var(--site-accent-dark, #047857);
}

.btn-success:hover,
.btn-answers:hover {
  background: var(--site-accent-hover, #059669);
}

.btn-check {
  background: #f59e0b;
  color: white;
  border-color: #d97706;
}

.btn-check:hover {
  background: #d97706;
}

.btn:focus-visible {
  outline: 3px solid var(--site-primary, #3b82f6);
  outline-offset: 3px;
}

/* ========================================
   Body Content / Worksheet
   ======================================== */

.body-content {
  background: white;
  border-radius: 0 0 var(--detail-border-radius, 12px) var(--detail-border-radius, 12px);
  border: 1px solid var(--site-border, #e5e7eb);
  border-top: none;
}

.problems-grid {
  border-top: 2px solid var(--site-border, #e5e7eb);
}

.problem {
  border-bottom: 1px solid #f3f4f6;
  font-size: 1.125rem;
  color: var(--site-text, #1f2937);
}

/* ========================================
   Intro Section
   ======================================== */

.intro {
  background: var(--site-primary-light, #f0f4ff);
  border: 1px solid var(--site-primary-border, #bfdbfe);
  border-radius: var(--detail-border-radius, 12px);
}

.intro h3 {
  font-weight: 600;
  color: var(--site-text, #1f2937);
}

.intro p {
  color: #4b5563;
  line-height: 1.6;
}

/* ========================================
   Page Navigation
   ======================================== */

.page-nav {
  background: white;
  border: 1px solid var(--site-border, #e5e7eb);
  border-radius: var(--detail-border-radius, 12px);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.page-nav a {
  color: var(--site-primary, #3b82f6);
  text-decoration: none;
  font-weight: 500;
}

.page-nav a:hover {
  text-decoration: underline;
}

/* ========================================
   Homepage / Category Pages
   ======================================== */

.hero {
  background: var(--site-primary-light, #eff6ff);
  border-bottom: 2px solid var(--site-primary-border, #bfdbfe);
}

.hero h1 {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--site-text, #1f2937);
}

.hero .subtitle {
  font-size: 1.2rem;
  color: #4b5563;
}

.category-card {
  background: white;
  border: 1px solid var(--site-border, #e5e7eb);
  border-radius: var(--detail-border-radius, 12px);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
  transition: box-shadow 150ms ease;
}

.category-card:hover {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.category-card h3 {
  font-weight: 600;
  color: var(--site-text, #1f2937);
}

/* ========================================
   Print Styles — Minimal
   ======================================== */

/* Removed: all print rules are now consolidated in platform layer:
   - print-base.css (dedicated print route)
   - main.css @media print (browser Ctrl+P path)
   - print-profile-*.css (site-type-specific density) */

/* ==========================================================
   SKIN ENHANCEMENTS: Sidebar-Nav — Docs/App Feel
   ==========================================================
   Sidebar has subtle dark tint, active state with left
   border. Compact cards, hierarchical visual structure.
   ========================================================== */

/* ── Sidebar Categories: Tinted Background ── */
.categories-section {
  background: var(--site-surface, #f8fafc);
  border-radius: 12px;
  padding: 1.25rem 1rem;
  border: 1px solid var(--site-border, #e5e7eb);
}

.category-card {
  box-shadow: none;
  background: transparent;
  border: none;
  border-left: 3px solid transparent;
  border-radius: 0 8px 8px 0;
}

.category-card:hover {
  background: white;
  border-left-color: var(--site-primary, #3b82f6);
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}

/* ── Sidebar List Items ── */
.category-list li a {
  background: transparent;
}

.category-list li a:hover {
  background: white;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}

/* ── Hero: Understated ── */
.hero {
  border-bottom-width: 1px;
}

/* ── SEO Horizontal Cards ── */
.seo-card {
  border-radius: 12px;
  border: 1.5px solid var(--site-border, #e5e7eb);
}

/* Scrollbar styling for sidebar overflow */
.categories-section::-webkit-scrollbar,
.subcategories::-webkit-scrollbar {
  width: 4px;
}

.categories-section::-webkit-scrollbar-track,
.subcategories::-webkit-scrollbar-track {
  background: transparent;
}

.categories-section::-webkit-scrollbar-thumb,
.subcategories::-webkit-scrollbar-thumb {
  background: var(--site-border, #e5e7eb);
  border-radius: 4px;
}

/* ── List page sidebar: Tinted ── */
.subcategories {
  background: var(--site-surface, #f8fafc);
  border-radius: 12px;
  padding: 1.25rem 0.75rem;
  border: 1px solid var(--site-border, #e5e7eb);
}

/* ── Horizontal SEO scroll: Hide scrollbar on desktop ── */
.seo-components--primary::-webkit-scrollbar {
  height: 4px;
}

.seo-components--primary::-webkit-scrollbar-track {
  background: transparent;
}

.seo-components--primary::-webkit-scrollbar-thumb {
  background: var(--site-border, #e5e7eb);
  border-radius: 4px;
}

/* On tablet collapse, pills style */
@media (max-width: 1024px) {
  .categories-section {
    background: transparent;
    border: none;
    padding: 0;
  }

  .category-card {
    background: white;
    border: 1.5px solid var(--site-border, #e5e7eb);
    border-radius: 999px;
    border-left: 1.5px solid var(--site-border, #e5e7eb);
  }

  .category-card:hover {
    border-color: var(--site-primary, #3b82f6);
    border-left-color: var(--site-primary, #3b82f6);
  }

  .subcategories {
    background: transparent;
    border: none;
    padding: 0;
  }
}