/* ============================================
   Atelier Zero — 玩转AI
   Warm paper editorial system
   ============================================ */

/* ─── Reset & Tokens ─── */

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

:root {
  --paper:      #efe7d2;
  --paper-lt:   #f7f1de;
  --paper-dk:   #ddd2b6;
  --ink:        #2c2420;
  --ink-muted:  #8a7a6a;
  --ink-faint:  #bfae98;
  --coral:      #c45b3e;
  --coral-lt:   #e07a5f;

  --font-serif: 'Noto Serif SC', 'Songti SC', Georgia, serif;
  --font-sans:  'Noto Sans SC', -apple-system, 'PingFang SC', sans-serif;

  --space-xl: 8rem;
  --space-lg: 5rem;
  --space-md: 3rem;
  --space-sm: 1.5rem;
  --space-xs: 0.75rem;

  --content-w: 1080px;
  --content-narrow: 720px;
}

body {
  font-family: var(--font-sans);
  background: var(--paper);
  color: var(--ink);
  line-height: 1.7;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }

::selection { background: var(--paper-dk); color: var(--ink); }

/* ─── Type ─── */

h1, h2, h3, h4 {
  font-family: var(--font-serif);
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: 0.01em;
}

.serif { font-family: var(--font-serif); }
.italic-em { font-style: italic; }


/* ─── Container ─── */

.container { max-width: var(--content-w); margin: 0 auto; padding: 0 2rem; }
.container--narrow { max-width: var(--content-narrow); margin: 0 auto; padding: 0 2rem; }

/* ─── Nav ─── */

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.5rem 2rem;
  max-width: var(--content-w);
  margin: 0 auto;
  position: relative;
  z-index: 10;
}

.nav-logo {
  font-family: var(--font-serif);
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.nav-links {
  display: flex;
  gap: 2rem;
  font-size: 0.875rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.nav-links a {
  position: relative;
  color: var(--ink-muted);
  transition: color 0.2s;
}
.nav-links a:hover,
.nav-links a.active { color: var(--ink); }
.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 1px;
  background: var(--coral);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 24px;
  height: 1.5px;
  background: var(--ink);
  transition: 0.3s;
}

/* ─── Hero (index page) ─── */

.hero {
  padding: var(--space-lg) 0 var(--space-xl);
  position: relative;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 40%;
  bottom: 0;
  background: var(--paper-lt);
  z-index: 0;
}

.hero-inner {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
  align-items: start;
}

.hero-eyebrow {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: var(--space-sm);
  grid-column: 1 / -1;
}

.hero-headline {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: 0.02em;
  grid-column: 1 / 2;
}

.hero-decor {
  position: relative;
  grid-column: 2 / 3;
  grid-row: 2 / 4;
  align-self: start;
  justify-self: end;
  width: 100%;
  max-width: 320px;
  aspect-ratio: 4 / 5;
  background: var(--paper-dk);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-serif);
  font-size: clamp(4rem, 10vw, 8rem);
  font-weight: 700;
  font-style: italic;
  color: var(--paper-lt);
  line-height: 1;
}

.hero-body {
  font-size: 1rem;
  color: var(--ink-muted);
  line-height: 1.8;
  max-width: 36em;
  grid-column: 1 / 2;
}

.hero-actions {
  display: flex;
  gap: var(--space-md);
  grid-column: 1 / 2;
}

.hero-actions a {
  font-family: var(--font-serif);
  font-size: 1rem;
  font-style: italic;
  color: var(--ink);
  border-bottom: 1px solid var(--coral);
  padding-bottom: 2px;
  transition: color 0.2s;
}
.hero-actions a:hover { color: var(--coral); }

/* ─── Section heading ─── */

.section-heading {
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  font-weight: 600;
  margin-bottom: var(--space-md);
  letter-spacing: 0.02em;
}

/* ─── Features (index page) ─── */

.features {
  padding: var(--space-lg) 0;
}

.features-intro {
  font-size: 1rem;
  color: var(--ink-muted);
  max-width: 32em;
  margin-bottom: var(--space-md);
}

.features-list {
  display: flex;
  flex-direction: column;
  max-width: var(--content-narrow);
}

.feature-item {
  display: grid;
  grid-template-columns: 3rem 1fr;
  gap: var(--space-sm);
  padding: var(--space-sm) 0;
  border-bottom: 1px solid var(--paper-dk);
  align-items: baseline;
}
.feature-item:first-child { padding-top: 0; }
.feature-item:last-child { border-bottom: none; }

.feature-num {
  font-family: var(--font-serif);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--coral);
  font-variant-numeric: tabular-nums;
}

.feature-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.feature-desc {
  font-size: 0.9375rem;
  color: var(--ink-muted);
  line-height: 1.6;
}

/* ─── Latest posts (index page) ─── */

.latest-posts {
  padding: var(--space-lg) 0;
}

.posts-empty {
  font-family: var(--font-serif);
  font-style: italic;
  color: var(--ink-muted);
  font-size: 1rem;
}

.view-all {
  display: inline-block;
  margin-top: var(--space-md);
  font-family: var(--font-serif);
  font-size: 1rem;
  font-style: italic;
  color: var(--ink);
  border-bottom: 1px solid var(--coral);
  padding-bottom: 2px;
  transition: color 0.2s;
}
.view-all:hover { color: var(--coral); }

/* ─── Page header ─── */

.page-header {
  padding: var(--space-lg) 0 var(--space-md);
}

.page-header-eyebrow {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: var(--space-xs);
}

.page-header h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: 0.02em;
}

.page-header-desc {
  font-size: 1rem;
  color: var(--ink-muted);
  margin-top: var(--space-sm);
  max-width: 28em;
}

.page-header-headline {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  letter-spacing: 0.02em;
  margin-bottom: 1rem;
}

/* ─── Blog page ─── */

.blog-tags {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: var(--space-md);
}

.tag-btn {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  color: var(--ink-muted);
  background: none;
  border: 1px solid var(--paper-dk);
  padding: 0.375rem 1rem;
  cursor: pointer;
  transition: all 0.2s;
}

.tag-btn:hover {
  border-color: var(--ink);
  color: var(--ink);
}

.tag-btn.active {
  border-color: var(--coral);
  color: var(--coral);
}

.posts-list { max-width: var(--content-narrow); }

.post-item {
  display: grid;
  grid-template-columns: 5.5rem 1fr;
  gap: var(--space-sm);
  padding: var(--space-sm) 0 var(--space-sm) 0.75rem;
  border-bottom: 1px solid var(--paper-dk);
  align-items: baseline;
  transition: background 0.2s;
  margin-left: -0.75rem;
}
.post-item:last-child { border-bottom: none; }
.post-item:hover { background: var(--paper-lt); }

.post-date {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  color: var(--ink-muted);
  font-variant-numeric: tabular-nums;
}

.post-title {
  font-family: var(--font-serif);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--ink);
  transition: color 0.2s;
}
.post-item:hover .post-title { color: var(--coral); }

.post-tag {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.6875rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-left: 0.75rem;
}

.loading-text {
  font-family: var(--font-serif);
  font-style: italic;
  color: var(--ink-muted);
  font-size: 1rem;
  padding: var(--space-md) 0;
}

/* ─── Post detail ─── */

.post-detail {
  max-width: var(--content-narrow);
  margin: 0 auto;
  padding: var(--space-lg) 2rem var(--space-xl);
}

.back-link {
  display: inline-block;
  font-family: var(--font-serif);
  font-size: 0.9375rem;
  font-style: italic;
  color: var(--ink-muted);
  margin-bottom: var(--space-md);
  transition: color 0.2s;
}
.back-link:hover { color: var(--coral); }

.post-detail .post-title {
  font-family: var(--font-serif);
  font-size: clamp(1.75rem, 3.5vw, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: 0.02em;
  margin-bottom: var(--space-sm);
}

.post-detail .post-info {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  color: var(--ink-muted);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--paper-dk);
  margin-bottom: var(--space-md);
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.post-detail .post-info .post-tag-inline {
  font-weight: 500;
  color: var(--coral);
}

.post-detail .post-info .post-tag-inline::before {
  content: '# ';
}

.post-detail .post-content {
  font-size: 1rem;
  line-height: 2;
  color: var(--ink);
}

.post-detail .post-content h2 {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 600;
  margin: 3rem 0 1rem;
  letter-spacing: 0.01em;
}

.post-detail .post-content h3 {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 600;
  margin: 2rem 0 0.75rem;
}

.post-detail .post-content p {
  margin-bottom: 1.25rem;
}

.post-detail .post-content pre {
  background: var(--paper-dk);
  color: var(--ink);
  padding: 1.5rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.8125rem;
  line-height: 1.7;
}

.post-detail .post-content :not(pre) > code {
  background: var(--paper-lt);
  color: var(--ink);
  padding: 0.125rem 0.5rem;
  font-size: 0.875rem;
}

.post-detail .post-content blockquote {
  border-left: 2px solid var(--coral);
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  color: var(--ink-muted);
  font-family: var(--font-serif);
  font-style: italic;
}

.post-detail .post-content a {
  color: var(--coral);
  text-decoration: underline;
  text-underline-offset: 2px;
  transition: color 0.2s;
}
.post-detail .post-content a:hover { color: var(--coral-lt); }

.post-detail .post-content ul,
.post-detail .post-content ol {
  margin: 1rem 0 1.25rem 1.5rem;
}

.post-detail .post-content li {
  margin-bottom: 0.5rem;
}

.post-detail .post-content hr {
  border: none;
  border-top: 1px solid var(--paper-dk);
  margin: 2rem 0;
}

/* ─── Tools page ─── */

.tools-list { max-width: var(--content-narrow); }

.tool-item {
  display: grid;
  grid-template-columns: 3rem 1fr;
  gap: var(--space-sm);
  padding: var(--space-sm) 0;
  border-bottom: 1px solid var(--paper-dk);
  align-items: baseline;
}
.tool-item:first-child { padding-top: 0; }
.tool-item:last-child { border-bottom: none; }

.tool-num {
  font-family: var(--font-serif);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--coral);
  font-variant-numeric: tabular-nums;
}

.tool-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.tool-status {
  font-family: var(--font-sans);
  font-size: 0.6875rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  color: var(--ink-muted);
}

.tool-desc {
  font-size: 0.9375rem;
  color: var(--ink-muted);
  line-height: 1.6;
  margin: 0.25rem 0 var(--space-xs);
}

.tool-link {
  display: inline-block;
  font-family: var(--font-serif);
  font-size: 0.9375rem;
  font-style: italic;
  color: var(--ink);
  border-bottom: 1px solid var(--coral);
  padding-bottom: 1px;
  transition: color 0.2s;
}
.tool-link:hover { color: var(--coral); }

/* ─── About page ─── */

.collage-plate {
  position: relative;
  background: var(--paper-dk);
  padding: var(--space-lg) 0;
  margin: 0;
  overflow: hidden;
}

.collage-plate::before {
  content: attr(data-glyph);
  position: absolute;
  right: -2rem;
  bottom: -2rem;
  font-family: var(--font-serif);
  font-size: clamp(12rem, 25vw, 20rem);
  font-weight: 700;
  font-style: italic;
  color: rgba(44,36,32,0.04);
  line-height: 1;
  pointer-events: none;
  user-select: none;
}

.collage-plate .container--narrow {
  position: relative;
  z-index: 1;
}

.collage-quote {
  font-family: var(--font-serif);
  font-size: clamp(1.375rem, 2.5vw, 1.75rem);
  font-style: italic;
  line-height: 1.5;
  color: var(--ink);
  max-width: 28em;
}

.collage-attribution {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  letter-spacing: 0.05em;
  color: var(--ink-muted);
  margin-top: var(--space-xs);
}

.about-content {
  max-width: var(--content-narrow);
  margin: 0 auto;
  padding: var(--space-lg) 2rem;
}

.about-content h1 {
  font-size: clamp(1.75rem, 3.5vw, 2.5rem);
  font-weight: 700;
  margin-bottom: var(--space-sm);
}

.about-content .about-text {
  font-size: 1rem;
  line-height: 2;
  color: var(--ink-muted);
}

.about-content .about-text p {
  margin-bottom: 1.25rem;
}

/* ─── Collage plate divider ─── */

.section-divider {
  border: none;
  height: 1px;
  background: var(--paper-dk);
  max-width: var(--content-w);
  margin: 0 auto;
  padding: 0;
}

/* ─── Footer ─── */

.footer {
  border-top: 1px solid var(--paper-dk);
  padding: var(--space-md) 0;
  margin-top: var(--space-lg);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.8125rem;
  color: var(--ink-muted);
}

.footer-links {
  display: flex;
  gap: var(--space-sm);
}

.footer-links a { transition: color 0.2s; }
.footer-links a:hover { color: var(--ink); }

/* ─── Scroll reveal ─── */

.reveal {
  opacity: 0;
  transform: translateY(1rem);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ─── Back to top ─── */

.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 2.5rem;
  height: 2.5rem;
  background: var(--paper);
  border: 1px solid var(--paper-dk);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-sans);
  font-size: 1rem;
  color: var(--ink-muted);
  z-index: 50;
  opacity: 0;
  transform: translateY(0.75rem);
  pointer-events: none;
  transition: all 0.3s;
}
.back-to-top.visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}
.back-to-top:hover {
  background: var(--coral);
  border-color: var(--coral);
  color: var(--paper);
}

/* ─── Skeleton loading ─── */

@keyframes skeleton-pulse {
  0%   { opacity: 0.5; }
  50%  { opacity: 1; }
  100% { opacity: 0.5; }
}

.skeleton { background: var(--paper-dk); animation: skeleton-pulse 1.5s ease-in-out infinite; }

.skeleton-card {
  padding: var(--space-sm) 0;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  border-bottom: 1px solid var(--paper-dk);
}

.skeleton-tag { width: 50px; height: 14px; }
.skeleton-title { width: 75%; height: 20px; }
.skeleton-text { width: 100%; height: 14px; }
.skeleton-text.short { width: 55%; }
.skeleton-meta { width: 120px; height: 12px; margin-top: 8px; }

/* ─── Responsive ─── */

@media (max-width: 768px) {
  .nav { padding: 1rem; }
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--paper-lt);
    flex-direction: column;
    padding: 1rem;
    gap: 1rem;
    border-bottom: 1px solid var(--paper-dk);
  }
  .nav-links.open { display: flex; }
  .nav-toggle { display: flex; }

      .page-header { padding: var(--space-md) 0; }

      .hero { padding: var(--space-md) 0; }
      .hero::before { right: 0; bottom: 50%; }
      .hero-inner { grid-template-columns: 1fr; }
      .hero-headline { grid-column: 1; }
      .hero-body { grid-column: 1; }
      .hero-actions { grid-column: 1; }
      .hero-decor {
        grid-column: 1;
        grid-row: auto;
        justify-self: start;
        max-width: 200px;
        aspect-ratio: 3/4;
        margin-top: var(--space-sm);
      }

      .feature-item { grid-template-columns: 2rem 1fr; }
      .post-item { grid-template-columns: 4rem 1fr; }

      .tool-item { grid-template-columns: 2rem 1fr; }

  .post-detail { padding: var(--space-md) 1rem var(--space-lg); }
  .about-content { padding: var(--space-md) 1rem; }

  .container { padding: 0 1rem; }
  .container--narrow { padding: 0 1rem; }

  .footer-inner { flex-direction: column; gap: var(--space-xs); text-align: center; }

  .back-to-top { bottom: 1rem; right: 1rem; width: 2.25rem; height: 2.25rem; }
}