/* ─── Reset & Base ─── */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
  background: #ffffff;
  color: #1f2937;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ─── Nav ─── */
nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: rgba(255,255,255,0.94);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid #e5e7eb;
}
.nav-inner {
  max-width: 1100px; margin: 0 auto; padding: 0 24px;
  display: flex; align-items: center; justify-content: space-between; height: 64px;
}
.logo {
  font-size: 20px; font-weight: 700;
  color: #111827;
  letter-spacing: -0.3px;
}
.nav-links { display: flex; gap: 28px; }
.nav-links a {
  color: #6b7280; text-decoration: none; font-size: 14px; font-weight: 500;
  transition: color .2s;
}
.nav-links a:hover, .nav-links a.active { color: #2563eb; }
.nav-download {
  display: inline-flex; align-items: center;
  background: #2563eb; color: #fff;
  padding: 8px 22px; border-radius: 6px;
  font-size: 14px; font-weight: 600; text-decoration: none;
  transition: background .2s, box-shadow .2s;
}
.nav-download:hover { background: #1d4ed8; box-shadow: 0 2px 8px rgba(37,99,235,0.3); }

/* ─── Hero ─── */
.hero {
  background: linear-gradient(135deg, #f8fafc 0%, #eef2ff 50%, #f0f9ff 100%);
  min-height: 90vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
}
.hero-content {
  max-width: 700px;
  margin: 0 auto;
  padding: 120px 24px 80px;
}
.hero-content h1 {
  font-size: 52px;
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: 20px;
  color: #111827;
  letter-spacing: -1px;
}
.hero-content p {
  font-size: 18px;
  color: #6b7280;
  margin: 0 auto 36px;
  max-width: 520px;
  line-height: 1.7;
}
.hero-actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.btn-primary, .btn-secondary {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 14px 28px; border-radius: 8px; font-size: 15px; font-weight: 600;
  text-decoration: none; transition: all .2s;
}
.btn-primary {
  background: #2563eb; color: #fff;
  box-shadow: 0 1px 3px rgba(0,0,0,0.12);
}
.btn-primary:hover { background: #1d4ed8; box-shadow: 0 4px 12px rgba(37,99,235,0.35); transform: translateY(-1px); }
.btn-secondary {
  background: #fff; color: #374151; border: 1px solid #d1d5db;
}
.btn-secondary:hover { background: #f9fafb; border-color: #9ca3af; }

/* ─── Sections ─── */
section { padding: 100px 24px; }
.section-header { text-align: center; margin-bottom: 56px; }
.section-header h2 { font-size: 32px; font-weight: 700; margin-bottom: 12px; color: #111827; }
.section-header p { color: #6b7280; font-size: 16px; }

/* ─── Sticky Notes ─── */
.story-section { background: #f8fafc; }
.story-grid {
  max-width: 780px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}
.sticky-note {
  position: relative;
  padding: 32px 28px 28px;
  border-radius: 4px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.06);
  animation: stickyPop .5s ease both;
  transition: opacity .4s, transform .4s;
}
.sticky-note.hidden { opacity: 0; transform: scale(0.9); pointer-events: none; position: absolute; }
.sticky-note .pin {
  position: absolute;
  top: -6px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 22px;
  filter: drop-shadow(0 2px 3px rgba(0,0,0,0.15));
  z-index: 1;
}
.sticky-note .close-btn {
  position: absolute;
  top: 8px;
  right: 10px;
  width: 24px;
  height: 24px;
  border: none;
  background: none;
  cursor: pointer;
  color: rgba(0,0,0,0.2);
  font-size: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 4px;
  transition: all .2s;
}
.sticky-note .close-btn:hover { background: rgba(0,0,0,0.06); color: rgba(0,0,0,0.5); }
.sticky-note h3 {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 10px;
  letter-spacing: 0.3px;
}
.sticky-note p { font-size: 14px; line-height: 1.7; color: rgba(0,0,0,0.65); }
.sticky-note.yellow {
  background: #fef9e7;
  transform: rotate(-1deg);
  color: #8b6f00;
}
.sticky-note.green {
  background: #e8f5e9;
  transform: rotate(1.5deg);
  color: #2e7d32;
}
.sticky-note.blue {
  background: #e3f2fd;
  transform: rotate(-0.5deg);
  color: #1565c0;
}
.sticky-note.pink {
  background: #fce4ec;
  transform: rotate(2deg);
  color: #c62828;
}
.sticky-note:nth-child(1) { animation-delay: 0s; }
.sticky-note:nth-child(2) { animation-delay: .15s; }
.sticky-note:nth-child(3) { animation-delay: .3s; }
.sticky-note:nth-child(4) { animation-delay: .45s; }
.story-reopen {
  text-align: center;
  margin-top: 32px;
}
.story-reopen a {
  color: #9ca3af;
  font-size: 13px;
  text-decoration: none;
  cursor: pointer;
}
.story-reopen a:hover { color: #2563eb; }
@keyframes stickyPop {
  from { opacity: 0; transform: scale(0.92) translateY(16px); }
  to { opacity: 1; transform: scale(1) translateY(0) rotate(var(--rot, 0deg)); }
}

/* ─── Features (row style) ─── */
.features { max-width: 660px; margin: 0 auto; }
.feature-row {
  display: flex;
  gap: 20px;
  align-items: flex-start;
  padding: 24px 0;
  border-bottom: 1px solid #f3f4f6;
}
.feature-row:last-child { border-bottom: none; }
.feature-row-icon {
  width: 48px;
  height: 48px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  background: #eff6ff;
  color: #2563eb;
}
.feature-row-text h3 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 4px;
  color: #111827;
}
.feature-row-text p { font-size: 14px; color: #6b7280; line-height: 1.7; }
.features-link {
  text-align: center;
  margin-top: 32px;
}
.features-link a {
  color: #2563eb;
  text-decoration: none;
  font-size: 15px;
  font-weight: 500;
}
.features-link a:hover { text-decoration: underline; }

/* ─── Download ─── */
.download { max-width: 700px; margin: 0 auto; text-align: center; }
.download-cards { display: flex; gap: 24px; justify-content: center; margin-bottom: 24px; }
.download-card {
  background: #fff; border: 1px solid #e5e7eb;
  border-radius: 16px; padding: 36px 28px; flex: 1; max-width: 300px;
  transition: box-shadow .25s, transform .25s;
}
.download-card:hover { box-shadow: 0 8px 30px rgba(0,0,0,0.06); transform: translateY(-3px); }
.download-card.disabled { opacity: 0.5; }
.download-card.disabled:hover { box-shadow: none; transform: none; }
.download-icon { margin-bottom: 14px; color: #2563eb; }
.download-card h3 { font-size: 18px; font-weight: 600; margin-bottom: 6px; color: #111827; }
.download-meta { font-size: 13px; color: #9ca3af; margin-bottom: 2px; }
.download-btn { justify-content: center; margin-top: 20px; }
.btn-disabled {
  display: inline-block; margin-top: 20px; padding: 12px 24px;
  border-radius: 8px; font-size: 15px; font-weight: 600;
  background: #f3f4f6; color: #d1d5db; cursor: not-allowed;
}
.download-note { font-size: 13px; color: #9ca3af; line-height: 1.7; max-width: 500px; margin: 0 auto; }

/* ─── FAQ ─── */
.faq { max-width: 700px; margin: 0 auto; }
.faq-list { display: flex; flex-direction: column; gap: 8px; }
.faq-item {
  background: #fff; border: 1px solid #e5e7eb;
  border-radius: 10px; overflow: hidden; cursor: pointer;
  transition: border-color .2s;
}
.faq-item:hover { border-color: #d1d5db; }
.faq-question {
  display: flex; justify-content: space-between; align-items: center;
  padding: 18px 22px; font-size: 15px; font-weight: 500; color: #374151;
  user-select: none;
}
.faq-question svg { transition: transform .3s; flex-shrink: 0; color: #9ca3af; }
.faq-item.open .faq-question svg { transform: rotate(180deg); }
.faq-answer {
  max-height: 0; overflow: hidden; transition: max-height .3s, padding .3s;
  padding: 0 22px; font-size: 14px; color: #6b7280; line-height: 1.7;
}
.faq-item.open .faq-answer { max-height: 200px; padding: 0 22px 18px; }

/* ─── Footer ─── */
footer {
  background: #f8fafc; border-top: 1px solid #e5e7eb;
  padding: 56px 24px 24px;
}
.footer-inner {
  max-width: 1100px; margin: 0 auto;
  display: flex; gap: 80px;
}
.footer-col { }
.footer-col.brand { min-width: 160px; }
.footer-col.brand .logo { margin-bottom: 8px; }
.footer-col.brand p { font-size: 13px; color: #9ca3af; }
.footer-col h4 {
  font-size: 12px; font-weight: 600; color: #6b7280;
  margin-bottom: 14px; text-transform: uppercase; letter-spacing: 0.06em;
}
.footer-col a {
  display: block; color: #9ca3af; text-decoration: none;
  font-size: 14px; margin-bottom: 8px; transition: color .2s;
}
.footer-col a:hover { color: #2563eb; }
.footer-bottom { text-align: center; margin-top: 40px; padding-top: 20px; border-top: 1px solid #e5e7eb; }
.footer-bottom p { font-size: 13px; color: #d1d5db; }

/* ─── Sub-page shared ─── */
.sub-hero {
  background: linear-gradient(135deg, #f8fafc 0%, #eef2ff 100%);
  padding: 120px 24px 60px;
  text-align: center;
}
.sub-hero h1 { font-size: 36px; font-weight: 700; margin-bottom: 10px; color: #111827; }
.sub-hero p { font-size: 16px; color: #6b7280; max-width: 560px; margin: 0 auto; }
.sub-content { max-width: 800px; margin: 0 auto; padding: 60px 24px 80px; }

/* ─── Comparison table ─── */
.compare-section { max-width: 800px; margin: 0 auto; padding: 60px 24px 80px; }
.compare-table {
  width: 100%;
  border-collapse: collapse;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 1px 4px rgba(0,0,0,0.06);
}
.compare-table th {
  background: #f8fafc;
  padding: 16px 20px;
  font-size: 14px;
  font-weight: 600;
  text-align: left;
  color: #374151;
  border-bottom: 1px solid #e5e7eb;
}
.compare-table th:first-child { width: 30%; }
.compare-table td {
  padding: 14px 20px;
  font-size: 14px;
  color: #6b7280;
  border-bottom: 1px solid #f3f4f6;
}
.compare-table tr:last-child td { border-bottom: none; }
.compare-table .check { color: #059669; font-weight: 600; }
.compare-table .cross { color: #dc2626; }
.compare-table .highlight { font-weight: 600; color: #111827; }

/* ─── Changelog ─── */
.changelog-list { max-width: 600px; margin: 0 auto; }
.changelog-item {
  padding: 24px 0;
  border-bottom: 1px solid #f3f4f6;
}
.changelog-item:last-child { border-bottom: none; }
.changelog-version {
  display: inline-block;
  font-size: 16px;
  font-weight: 700;
  color: #2563eb;
  margin-bottom: 4px;
}
.changelog-date {
  font-size: 12px;
  color: #9ca3af;
  margin-left: 10px;
  font-weight: 400;
}
.changelog-item ul {
  margin-top: 8px;
  padding-left: 20px;
}
.changelog-item li {
  font-size: 14px;
  color: #6b7280;
  margin-bottom: 4px;
  line-height: 1.6;
}

/* ─── About page ─── */
.about-author {
  display: flex;
  gap: 32px;
  align-items: flex-start;
  margin-bottom: 48px;
}
.about-author-avatar {
  width: 100px;
  height: 100px;
  border-radius: 16px;
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 40px;
  color: #fff;
  flex-shrink: 0;
}
.about-author-text h2 { font-size: 24px; font-weight: 700; margin-bottom: 6px; }
.about-author-text p { font-size: 15px; color: #6b7280; line-height: 1.7; }
.about-timeline { margin-top: 40px; }
.about-timeline h3 { font-size: 18px; font-weight: 600; margin-bottom: 20px; }
.timeline-item {
  display: flex;
  gap: 20px;
  padding-bottom: 28px;
  position: relative;
  padding-left: 28px;
  border-left: 2px solid #e5e7eb;
}
.timeline-item:last-child { border-left-color: transparent; }
.timeline-dot {
  position: absolute;
  left: -6px;
  top: 4px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #2563eb;
}
.timeline-item time {
  font-size: 13px;
  color: #9ca3af;
  white-space: nowrap;
  min-width: 80px;
  padding-top: 1px;
}
.timeline-item p { font-size: 14px; color: #6b7280; line-height: 1.6; }

/* ─── Help page ─── */
.help-section { margin-bottom: 36px; }
.help-section h2 { font-size: 20px; font-weight: 600; margin-bottom: 16px; color: #111827; }
.help-card {
  background: #fff;
  border: 1px solid #e5e7eb;
  border-radius: 12px;
  padding: 20px 24px;
  margin-bottom: 12px;
}
.help-card h3 { font-size: 15px; font-weight: 600; margin-bottom: 6px; color: #374151; }
.help-card p, .help-card li { font-size: 14px; color: #6b7280; line-height: 1.7; }
.help-card ol, .help-card ul { padding-left: 20px; margin-top: 6px; }
.help-card li { margin-bottom: 4px; }

/* ─── Page header ─── */
.page-header {
  background: linear-gradient(135deg, #f8fafc 0%, #eef2ff 100%);
  padding: 120px 24px 60px;
  text-align: center;
}
.page-header h1 { font-size: 36px; font-weight: 700; margin-bottom: 10px; color: #111827; }
.page-header p { font-size: 16px; color: #6b7280; max-width: 560px; margin: 0 auto; }

/* ─── Responsive ─── */
@media (max-width: 768px) {
  .story-grid { grid-template-columns: 1fr; }
  .about-author { flex-direction: column; align-items: center; text-align: center; }
  .about-timeline { padding-left: 0; }
}
@media (max-width: 600px) {
  .nav-links { display: none; }
  .hero-content h1 { font-size: 36px; }
  .download-cards { flex-direction: column; align-items: center; }
  section { padding: 64px 16px; }
  .feature-row { gap: 16px; }
  .feature-row-icon { width: 40px; height: 40px; }
  .feature-row-icon svg { width: 22px; height: 22px; }
  .footer-inner { gap: 32px; flex-direction: column; }
  .page-header { padding: 100px 16px 40px; }
  .page-header h1 { font-size: 28px; }
  .sub-content { padding: 40px 16px 60px; }
  .compare-section { padding: 40px 16px 60px; }
  .compare-table th, .compare-table td { padding: 10px 12px; font-size: 12px; }
  .about-author-avatar { width: 72px; height: 72px; font-size: 28px; }
}