/* AIForScience 下载站 · 学术论文主题
   纸白 / 墨黑 / 档案绿 / 高亮黄 — 无外部字体依赖,nginx 静态托管 */

:root {
  --paper: #f7f6f2;
  --ink: #20241f;
  --ink-soft: #4a4f47;
  --ink-faint: #8a8f87;
  --green: #2f5d4f;
  --green-deep: #24493e;
  --green-ink: #1c3a31;
  --hl: #e9c46a;
  --hl-soft: #f5e3ae;
  --line: #dcd9d0;
  --white: #fffdf8;
  --radius: 10px;
  --serif: Georgia, "Noto Serif SC", "Songti SC", "SimSun", serif;
  --sans: system-ui, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  --mono: "SF Mono", "Cascadia Mono", Consolas, "Courier New", monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 24px; }
a { color: var(--green); }
code {
  font-family: var(--mono);
  font-size: 0.86em;
  background: #ecebe4;
  padding: 0.1em 0.35em;
  border-radius: 4px;
}

.eyebrow {
  font-size: 0.78rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--green);
  font-weight: 700;
  margin: 0 0 12px;
}
.section-title {
  font-family: var(--serif);
  font-size: clamp(1.55rem, 3.2vw, 2.1rem);
  font-weight: 600;
  margin: 0 0 36px;
  line-height: 1.3;
}

/* ---------- Header ---------- */
.site-header {
  border-bottom: 1px solid var(--line);
  background: var(--paper);
  position: sticky;
  top: 0;
  z-index: 10;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.brand {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: 0.02em;
}
.brand-zh {
  font-size: 0.78rem;
  color: var(--ink-faint);
  font-family: var(--sans);
  margin-left: 8px;
  letter-spacing: 0.15em;
}
.site-nav a {
  color: var(--ink-soft);
  text-decoration: none;
  margin-left: 24px;
  font-size: 0.92rem;
}
.site-nav a:hover { color: var(--green); }

/* ---------- Hero ---------- */
.hero { padding: 72px 0 88px; }
.hero-grid {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 56px;
  align-items: center;
}
h1 {
  font-family: var(--serif);
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  font-weight: 700;
  line-height: 1.18;
  margin: 0 0 20px;
  letter-spacing: -0.01em;
}
.hero-sub {
  font-size: 1.05rem;
  color: var(--ink-soft);
  max-width: 46ch;
  margin: 0 0 32px;
}
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; }
.hero-note {
  margin: 18px 0 0;
  font-size: 0.86rem;
  color: var(--ink-faint);
}

.btn {
  display: inline-flex;
  flex-direction: column;
  align-items: flex-start;
  padding: 13px 22px;
  border-radius: var(--radius);
  text-decoration: none;
  font-weight: 600;
  transition: transform 0.12s ease, box-shadow 0.12s ease, background 0.12s ease;
}
.btn:focus-visible {
  outline: 2px solid var(--hl);
  outline-offset: 2px;
}
.btn-primary {
  background: var(--green);
  color: var(--white);
  box-shadow: 0 1px 2px rgba(32,36,31,0.25);
}
.btn-primary:hover {
  background: var(--green-deep);
  transform: translateY(-1px);
  box-shadow: 0 3px 8px rgba(32,36,31,0.3);
}
.btn-label { font-size: 1rem; line-height: 1.25; }
.btn-sub {
  font-size: 0.78rem;
  font-weight: 400;
  opacity: 0.85;
  margin-top: 2px;
}
.btn-ghost {
  background: transparent;
  color: var(--green);
  border: 1.5px solid var(--green);
  padding: 13px 24px;
  font-size: 0.95rem;
  justify-content: center;
}
.btn-ghost:hover { background: #eef1e9; }

/* ---------- 签名元素:论文纸页 ---------- */
.hero-paper { position: relative; perspective: 1200px; }
.paper-sheet {
  position: relative;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 4px;
  box-shadow: 0 14px 40px rgba(32,36,31,0.14), 0 2px 6px rgba(32,36,31,0.08);
  padding: 26px 26px 22px;
  transform: rotate(-1.2deg);
  animation: paper-in 0.7s ease both;
}
@keyframes paper-in {
  from { opacity: 0; transform: rotate(-1.2deg) translateY(16px); }
  to   { opacity: 1; transform: rotate(-1.2deg) translateY(0); }
}
.paper-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
}
.paper-title-text {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.06rem;
}
.paper-tag {
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 2px 6px;
  color: var(--ink-faint);
}
.paper-meta {
  display: flex;
  gap: 14px;
  font-size: 0.76rem;
  color: var(--ink-faint);
  margin-bottom: 16px;
  border-bottom: 1px solid var(--line);
  padding-bottom: 12px;
}
.paper-grain {
  height: 9px;
  background: #e9e7de;
  border-radius: 2px;
  margin: 0 0 10px;
}
.paper-grain-long { width: 96%; }
.paper-grain-med { width: 78%; }
.paper-grain-short { width: 52%; }
.paper-hl {
  margin: 16px 0 10px;
  padding: 2px 4px;
  background: linear-gradient(transparent 55%, var(--hl) 55%);
  font-size: 0.9rem;
  line-height: 1.7;
  border-radius: 2px;
}
.paper-hl-soft {
  background: linear-gradient(transparent 55%, var(--hl-soft) 55%);
}
.paper-cite {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--green-ink);
  background: var(--hl);
  border-radius: 4px;
  padding: 0 5px;
  margin-left: 6px;
  vertical-align: super;
  transition: background 0.15s ease;
}
.paper-cite-alt { background: var(--hl-soft); }
.paper-sheet:hover .paper-cite { background: var(--hl); }

/* 对话气泡 */
.paper-bubble {
  position: absolute;
  left: -18px;
  bottom: -26px;
  width: 74%;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 10px 10px 10px 2px;
  box-shadow: 0 8px 24px rgba(32,36,31,0.16);
  padding: 12px 16px;
  font-size: 0.82rem;
  animation: bubble-in 0.6s ease 0.25s both;
}
@keyframes bubble-in {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}
.bubble-q {
  margin: 0 0 6px;
  color: var(--ink-faint);
  font-size: 0.78rem;
}
.bubble-a { margin: 0; color: var(--ink-soft); line-height: 1.55; }
.bubble-ref {
  font-family: var(--mono);
  color: var(--green-ink);
  background: var(--hl);
  border-radius: 3px;
  padding: 0 4px;
  font-size: 0.75em;
}
.paper-stamp {
  position: absolute;
  right: -14px;
  top: 18px;
  border: 2px solid var(--green);
  color: var(--green);
  border-radius: 4px;
  padding: 4px 10px;
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  transform: rotate(6deg);
  opacity: 0.85;
}

/* ---------- 特性 ---------- */
.features { padding: 16px 0 80px; }
.feature-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 20px;
}
.feature-card {
  border: 1px solid var(--line);
  background: var(--white);
  border-radius: var(--radius);
  padding: 24px 22px;
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.feature-card:hover {
  border-color: var(--green);
  transform: translateY(-2px);
}
.feature-mark {
  font-family: var(--serif);
  font-size: 1.5rem;
  color: var(--green);
  display: inline-block;
  margin-bottom: 12px;
}
.feature-card h3 {
  font-family: var(--serif);
  font-size: 1.12rem;
  margin: 0 0 8px;
}
.feature-card p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--ink-soft);
}

/* ---------- 工作流 ---------- */
.how { padding: 0 0 88px; }
.steps {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line);
}
.step {
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 20px;
  align-items: baseline;
  padding: 22px 0;
  border-bottom: 1px solid var(--line);
}
.step-num {
  font-family: var(--mono);
  font-size: 1.05rem;
  color: var(--green);
  font-weight: 700;
}
.step h3 { font-family: var(--serif); margin: 0 0 4px; font-size: 1.12rem; }
.step p { margin: 0; color: var(--ink-soft); font-size: 0.92rem; }

/* ---------- 下载区 ---------- */
.download { padding: 0 0 96px; }
.version-chip {
  font-family: var(--mono);
  background: var(--green);
  color: var(--white);
  border-radius: 999px;
  padding: 3px 12px;
  font-size: 0.95rem;
  vertical-align: middle;
  margin-left: 6px;
}
.download-card {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px 28px 24px;
}
.download-main {
  display: flex;
  align-items: center;
  gap: 18px;
  flex-wrap: wrap;
}
.dl-icon {
  font-family: var(--serif);
  font-size: 2rem;
  color: var(--green);
  border: 1.5px solid var(--green);
  border-radius: 50%;
  width: 52px;
  height: 52px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: none;
}
.dl-info { flex: 1 1 300px; }
.dl-info h3 {
  margin: 0 0 6px;
  font-family: var(--mono);
  font-size: 1.02rem;
  word-break: break-all;
}
.dl-meta { margin: 2px 0; color: var(--ink-faint); font-size: 0.86rem; }
.btn-dl {
  flex-direction: row;
  align-items: center;
  padding: 14px 34px;
  font-size: 1.05rem;
}

.dl-details { margin-top: 22px; border-top: 1px solid var(--line); padding-top: 14px; }
.dl-details summary {
  cursor: pointer;
  color: var(--green);
  font-weight: 600;
  font-size: 0.9rem;
  user-select: none;
}
.dl-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 14px;
  font-size: 0.84rem;
}
.dl-table th, .dl-table td {
  text-align: left;
  padding: 8px 10px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
.dl-table th {
  color: var(--ink-faint);
  font-weight: 600;
}
.dl-table td code {
  font-size: 0.76rem;
  word-break: break-all;
  background: none;
  padding: 0;
}
.dl-table td a { text-decoration: none; }
.dl-table td a:hover { text-decoration: underline; }
.dl-hint { font-size: 0.8rem; color: var(--ink-faint); margin: 10px 0 0; }

.dl-faq { margin-top: 22px; border-top: 1px solid var(--line); padding-top: 14px; }
.dl-faq h3 { font-family: var(--serif); font-size: 1rem; margin: 0 0 10px; }
.dl-faq ul { margin: 0; padding-left: 18px; color: var(--ink-soft); font-size: 0.9rem; }
.dl-faq li { margin-bottom: 8px; }
.dl-faq b { color: var(--ink); }

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 26px 0;
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  font-size: 0.85rem;
  color: var(--ink-faint);
}

/* ---------- 响应式 & 可访问性 ---------- */
@media (max-width: 860px) {
  .hero-grid { grid-template-columns: 1fr; gap: 64px; }
  .hero { padding: 48px 0 56px; }
  .hero-paper { max-width: 460px; margin: 0 auto; }
  .paper-bubble { left: 8px; bottom: -20px; width: 82%; }
}
@media (max-width: 520px) {
  .site-nav { display: none; }
  .step { grid-template-columns: 52px 1fr; gap: 14px; }
  .download-card { padding: 20px 16px; }
  .paper-stamp { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .paper-sheet, .paper-bubble { animation: none; }
  .btn, .feature-card { transition: none; }
}