@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: #6b7280;
}

.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: #d1d5db;
  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: #6b7280;
  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: #6b7280;
}

.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);
}

/* ========================================
   SEO Components — Visual Treatment
   ======================================== */

.seo-components {
  border-top: 1px solid var(--site-border, #e5e7eb);
  padding-top: 1rem;
}

.seo-block {
  background: var(--site-bg-alt, #f9fafb);
  border-color: var(--site-border, #e5e7eb);
  border-top-color: var(--site-primary, #3b82f6);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
  transition: box-shadow 150ms ease, border-color 150ms ease;
}

.seo-block:hover {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
  border-color: var(--site-primary-border, #bfdbfe);
}

/* ── SEO Card — header-band accent ── */
.seo-card {
  background: var(--site-background, #ffffff);
  border-color: var(--site-border, #e5e7eb);
  border-top: none;
}

.seo-card::before {
  background: var(--site-primary, #3b82f6);
}

.seo-card:hover {
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--site-primary, #3b82f6) 15%, transparent);
}

/* Card band color per SEO type */
.seo-card.features::before  { background: var(--site-primary, #3b82f6); }
.seo-card.benefits::before  { background: var(--site-accent, #10b981); }
.seo-card.faq::before       { background: var(--site-primary-dark, #1d4ed8); }
.seo-card.tips::before      { background: #f59e0b; }
.seo-card.steps::before     { background: var(--site-accent-hover, #059669); }
.seo-card.tutorial::before  { background: var(--site-accent, #10b981); }
.seo-card.examples::before  { background: #06b6d4; }
.seo-card.use-cases::before { background: #ec4899; }
.seo-card.common-mistakes::before { background: #ef4444; }
.seo-card.practice::before  { background: #f97316; }
.seo-card.requirements::before { background: #6366f1; }
.seo-card.resources::before { background: #14b8a6; }
.seo-card.next-steps::before { background: var(--site-primary, #3b82f6); }
.seo-card.summary::before   { background: #64748b; }
.seo-card.related::before   { background: #a855f7; }

.seo-block h2,
.seo-block h3 {
  font-weight: 700;
  color: var(--site-text, #1f2937);
}

.seo-block h2::before,
.seo-block h3::before {
  background: var(--site-primary-light, #eff6ff);
  color: var(--site-primary, #3b82f6);
}

/* Per-type accent colors for visual variety */
.seo-block.faq {
  border-top-color: var(--site-primary, #3b82f6);
}

.seo-block.faq h2::before,
.seo-block.faq h3::before {
  content: '?';
}

.seo-block.tips {
  border-top-color: #f59e0b;
}

.seo-block.tips h2::before,
.seo-block.tips h3::before {
  content: '!';
  background: #fef3c7;
  color: #d97706;
}

.seo-block.tutorial,
.seo-block.steps {
  border-top-color: var(--site-accent, #10b981);
}

.seo-block.tutorial h2::before,
.seo-block.tutorial h3::before,
.seo-block.steps h2::before,
.seo-block.steps h3::before {
  content: '\2192';
  background: #d1fae5;
  color: #059669;
}

.seo-block.features {
  border-top-color: #8b5cf6;
}

.seo-block.features h2::before,
.seo-block.features h3::before {
  content: '\2713';
  background: #ede9fe;
  color: #7c3aed;
}

.seo-block.benefits {
  border-top-color: var(--site-accent, #10b981);
}

.seo-block.benefits h2::before,
.seo-block.benefits h3::before {
  content: '\2605';
  background: #d1fae5;
  color: #059669;
}

.seo-block.examples {
  border-top-color: #06b6d4;
}

.seo-block.examples h2::before,
.seo-block.examples h3::before {
  content: '\25B6';
  background: #cffafe;
  color: #0891b2;
  font-size: 0.625rem;
}

.seo-block.use-cases {
  border-top-color: #ec4899;
}

.seo-block.use-cases h2::before,
.seo-block.use-cases h3::before {
  content: '\25CB';
  background: #fce7f3;
  color: #db2777;
}

.seo-block.common-mistakes {
  border-top-color: #ef4444;
}

.seo-block.common-mistakes h2::before,
.seo-block.common-mistakes h3::before {
  content: '\2716';
  background: #fee2e2;
  color: #dc2626;
}

.seo-block.practice {
  border-top-color: #f97316;
}

.seo-block.practice h2::before,
.seo-block.practice h3::before {
  content: '\270E';
  background: #ffedd5;
  color: #ea580c;
}

.seo-block.requirements {
  border-top-color: #6366f1;
}

.seo-block.requirements h2::before,
.seo-block.requirements h3::before {
  content: '\2261';
  background: #e0e7ff;
  color: #4f46e5;
}

.seo-block.resources {
  border-top-color: #14b8a6;
}

.seo-block.resources h2::before,
.seo-block.resources h3::before {
  content: '\2197';
  background: #ccfbf1;
  color: #0d9488;
}

.seo-block.next-steps {
  border-top-color: var(--site-primary, #3b82f6);
}

.seo-block.next-steps h2::before,
.seo-block.next-steps h3::before {
  content: '\21E8';
  background: var(--site-primary-light, #eff6ff);
  color: var(--site-primary, #3b82f6);
}

.seo-block.summary {
  border-top-color: #64748b;
}

.seo-block.summary h2::before,
.seo-block.summary h3::before {
  content: '\2630';
  background: #f1f5f9;
  color: #475569;
}

.seo-block.related {
  border-top-color: #a855f7;
}

.seo-block.related h2::before,
.seo-block.related h3::before {
  content: '\2194';
  background: #f3e8ff;
  color: #9333ea;
}

.seo-block p {
  color: var(--site-text-secondary, #4b5563);
  font-size: 0.9375rem;
}

.seo-block li {
  color: var(--site-text-secondary, #4b5563);
  font-size: 0.9375rem;
}

/* Homepage body content section */
.homepage > .content {
  background: white;
  border-color: var(--site-border, #e5e7eb);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

.homepage > .content h2 {
  color: var(--site-text, #1f2937);
  border-bottom-color: var(--site-border, #e5e7eb);
  font-weight: 700;
}

.homepage > .content p {
  color: var(--site-text-secondary, #4b5563);
}

.homepage > .content li {
  color: var(--site-text-secondary, #4b5563);
}

/* ========================================
   Print Styles — Consolidated at platform layer
   All print rules now live in:
   - print-base.css (dedicated print route)
/* 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) */

/* 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: Grid-Cards — Product Polish
   ==========================================================
   Uniform shadows, hover border color + lift, centered
   icons with scale animation. E-commerce catalog feel.
   ========================================================== */

/* ── Cards: Uniform Shadow + Border Hover ── */
.category-card {
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
  border: 2px solid var(--site-border, #e5e7eb);
  transition: all var(--dur-normal, 250ms) cubic-bezier(0.4, 0, 0.2, 1);
}

.category-card:hover {
  border-color: var(--site-primary, #3b82f6);
  box-shadow: 0 8px 24px rgba(0,0,0,0.1);
  transform: translateY(-4px);
}

/* ── Icon: Scale on Hover ── */
.category-icon {
  transition: transform var(--dur-normal, 250ms) ease;
}

.category-card:hover .category-icon {
  transform: scale(1.15);
}

/* ── Grid List Items: Card Border Hover ── */
.category-list li a {
  box-shadow: 0 1px 4px rgba(0,0,0,0.05);
}

.category-list li a:hover {
  border-color: var(--site-primary, #3b82f6);
  box-shadow: var(--shadow-md, 0 4px 6px -1px rgba(0,0,0,0.1));
}

/* ── Worksheet Buttons: Filled on Hover ── */
.worksheet-list li a {
  box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}

.worksheet-list li a:hover {
  background: var(--site-primary, #3b82f6);
  color: white;
  border-color: var(--site-primary, #3b82f6);
  box-shadow: 0 4px 12px rgba(0,0,0,0.12);
}

/* ── SEO Cards: Large, Prominent ── */
.seo-card {
  border: 2px solid var(--site-border, #e5e7eb);
  border-radius: 14px;
}

.seo-card:hover {
  border-color: var(--site-primary-border, #bfdbfe);
  box-shadow: 0 6px 20px rgba(0,0,0,0.08);
}

/* ── Hero: Subtle Pattern Overlay ── */
.hero::after {
  content: '';
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle at 1px 1px, rgba(255,255,255,0.1) 1px, transparent 0);
  background-size: 24px 24px;
  pointer-events: none;
  z-index: 0;
}

.hero h1,
.hero .subtitle {
  position: relative;
  z-index: 1;
}