/* ═══════════════════════════════════════════════
   45d.cn · 短网址 — 站点样式
   纸面排版：暖白纸底 + 墨色 + 朱砂/松绿点缀
   ═══════════════════════════════════════════════ */

/* ═══════════ 基础 ═══════════ */
* { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --ink: #1c1b18;
  --ink-soft: #55524a;
  --ink-faint: #8a867c;
  --paper: #faf8f4;
  --paper-deep: #f2eee6;
  --line: #e2ddd1;
  --line-dark: #c9c2b2;
  --cinnabar: #b5451d;      /* 朱砂 */
  --cinnabar-deep: #933614;
  --pine: #33523f;          /* 松绿 */
  --serif: "Noto Serif SC", "Songti SC", "SimSun", Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --mono: "SF Mono", "Cascadia Code", Consolas, "Courier New", monospace;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

/* 纸张肌理（极淡，避免“AI 平板感”） */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  opacity: .35;
  background-image: radial-gradient(rgba(28,27,24,.045) 1px, transparent 1px);
  background-size: 22px 22px;
}

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 28px; position: relative; z-index: 1; }

a { color: var(--cinnabar); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

/* ═══════════ 顶栏 ═══════════ */
.masthead {
  border-bottom: 1px solid var(--line);
  background: rgba(250,248,244,.92);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 900;
}

.masthead-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 0;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 12px;
  color: var(--ink);
  text-decoration: none;
}
.brand:hover { text-decoration: none; }

.brand .mark {
  font-family: var(--serif);
  font-size: 26px;
  font-weight: 700;
  letter-spacing: -0.5px;
}
.brand .mark em { font-style: normal; color: var(--cinnabar); }

.brand .tag {
  font-size: 12px;
  color: var(--ink-faint);
  border-left: 1px solid var(--line-dark);
  padding-left: 12px;
  letter-spacing: 2px;
}

.site-nav { display: flex; gap: 30px; }
.site-nav a {
  color: var(--ink-soft);
  font-size: 14px;
  letter-spacing: 1px;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
  transition: color .15s, border-color .15s;
}
.site-nav a:hover { color: var(--ink); text-decoration: none; border-bottom-color: var(--cinnabar); }

#menuBtn {
  display: none;
  background: none;
  border: 1px solid var(--line-dark);
  border-radius: 4px;
  width: 40px; height: 40px;
  cursor: pointer;
  color: var(--ink);
}
#menuBtn svg { display: block; margin: auto; }

#mobileNav {
  display: none;
  border-top: 1px solid var(--line);
  padding: 10px 0 16px;
}
#mobileNav.open { display: block; }
#mobileNav a {
  display: block;
  padding: 12px 4px;
  color: var(--ink-soft);
  font-size: 15px;
  border-bottom: 1px dashed var(--line);
}
#mobileNav a:last-child { border-bottom: none; }

/* ═══════════ 题头 ═══════════ */
.lead-section { padding: 72px 0 56px; }

.kicker {
  font-size: 12px;
  letter-spacing: 4px;
  color: var(--cinnabar);
  margin-bottom: 18px;
  display: flex;
  align-items: center;
  gap: 12px;
}
.kicker::after { content: ''; height: 1px; width: 72px; background: var(--line-dark); }

h1 {
  font-family: var(--serif);
  font-size: clamp(30px, 5vw, 46px);
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: -0.5px;
  max-width: 640px;
  margin-bottom: 22px;
}

.lead-desc {
  font-size: 17px;
  color: var(--ink-soft);
  max-width: 620px;
  margin-bottom: 28px;
}

.lead-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 0;
  border-top: 1px solid var(--line-dark);
  border-bottom: 1px solid var(--line-dark);
}
.lead-stats > div {
  padding: 14px 32px 14px 0;
  margin-right: 32px;
  border-right: 1px solid var(--line);
}
.lead-stats > div:last-child { border-right: none; margin-right: 0; padding-right: 0; }
.stat-n {
  font-family: var(--serif);
  font-size: 26px;
  font-weight: 700;
  color: var(--ink);
  font-variant-numeric: tabular-nums;
  line-height: 1.2;
}
.stat-n small { font-size: 13px; font-weight: 400; color: var(--ink-faint); margin-left: 2px; }
.stat-l { font-size: 12px; color: var(--ink-faint); letter-spacing: 1px; }

/* ═══════════ 工具区 ═══════════ */
.tool-section {
  display: grid;
  grid-template-columns: 7fr 5fr;
  gap: 0;
  border: 1px solid var(--line-dark);
  background: #fffdf9;
  margin-bottom: 88px;
  box-shadow: 0 1px 0 var(--line-dark), 6px 6px 0 rgba(28,27,24,.04);
}

.tool-pane { padding: 40px 40px 44px; }
.tool-pane + .tool-pane { border-left: 1px solid var(--line-dark); background: var(--paper-deep); }

.pane-label {
  font-size: 12px;
  letter-spacing: 3px;
  color: var(--ink-faint);
  margin-bottom: 6px;
}
.pane-title {
  font-family: var(--serif);
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 26px;
}
.pane-title .no {
  font-size: 14px;
  color: var(--cinnabar);
  vertical-align: super;
  margin-right: 6px;
  font-family: var(--serif);
}

.field { margin-bottom: 22px; }
.field label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--ink-soft);
  margin-bottom: 8px;
  letter-spacing: 1px;
}

.field input {
  width: 100%;
  padding: 13px 15px;
  font-size: 15px;
  font-family: var(--sans);
  color: var(--ink);
  background: #fffdf9;
  border: 1px solid var(--line-dark);
  border-radius: 2px;
  transition: border-color .15s, box-shadow .15s;
}
.tool-pane + .tool-pane .field input { background: #fff; }
.field input:focus {
  outline: none;
  border-color: var(--cinnabar);
  box-shadow: 2px 2px 0 rgba(181,69,29,.12);
}
.field input::placeholder { color: var(--ink-faint); }

/* 后缀组合输入框 */
.suffix-box {
  display: flex;
  border: 1px solid var(--line-dark);
  border-radius: 2px;
  overflow: hidden;
  background: #fffdf9;
  transition: border-color .15s, box-shadow .15s;
}
.suffix-box:focus-within {
  border-color: var(--cinnabar);
  box-shadow: 2px 2px 0 rgba(181,69,29,.12);
}
.suffix-box .prefix {
  display: flex;
  align-items: center;
  padding: 0 14px;
  font-family: var(--mono);
  font-size: 14px;
  color: var(--ink-soft);
  background: var(--paper-deep);
  border-right: 1px solid var(--line-dark);
  white-space: nowrap;
}
.suffix-box input {
  flex: 1;
  border: none;
  border-radius: 0;
  box-shadow: none;
  background: transparent;
  font-family: var(--mono);
}
.suffix-box input:focus { box-shadow: none; }

.hint { font-size: 12px; color: var(--ink-faint); margin-top: 7px; }

/* 按钮 */
.btn {
  width: 100%;
  padding: 15px 20px;
  font-size: 15px;
  font-weight: 600;
  font-family: var(--sans);
  letter-spacing: 4px;
  text-indent: 4px;
  cursor: pointer;
  border-radius: 2px;
  transition: transform .1s, background .15s, box-shadow .15s;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
}
.btn-cinnabar {
  background: var(--cinnabar);
  color: #fdf9f3;
  border: 1px solid var(--cinnabar-deep);
  box-shadow: 3px 3px 0 rgba(147,54,20,.25);
}
.btn-cinnabar:hover { background: var(--cinnabar-deep); }
.btn-cinnabar:active { transform: translate(2px,2px); box-shadow: 1px 1px 0 rgba(147,54,20,.25); }
.btn-cinnabar:disabled { opacity: .55; cursor: not-allowed; transform: none; }
.btn-outline {
  background: transparent;
  color: var(--pine);
  border: 1px solid var(--pine);
}
.btn-outline:hover { background: rgba(51,82,63,.07); }
.btn-outline:active { transform: translate(1px,1px); }

.btn svg { flex-shrink: 0; }

/* 生成结果 */
#resultBox {
  display: none;
  margin-top: 24px;
  padding: 22px;
  background: #f3f7f2;
  border: 1px solid #b8cbb4;
  border-left: 4px solid var(--pine);
}
#resultBox.show { display: block; animation: rise .25s ease; }
@keyframes rise { from { opacity: 0; transform: translateY(-6px); } to { opacity: 1; transform: none; } }

.result-head {
  font-size: 13px;
  color: var(--pine);
  font-weight: 600;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}
.result-head code {
  font-family: var(--mono);
  font-size: 13px;
  background: #fff;
  border: 1px solid var(--line-dark);
  padding: 2px 8px;
  color: var(--ink);
}
.mini-btn {
  font-size: 12px;
  padding: 4px 12px;
  background: var(--pine);
  color: #fff;
  border: none;
  border-radius: 2px;
  cursor: pointer;
}
.mini-btn:hover { background: #27402f; }

#shortUrlOut {
  font-family: var(--mono);
  font-size: 17px;
  font-weight: 600;
  color: var(--ink);
  background: #fff;
  border: 1px solid var(--line-dark);
  padding: 13px 15px;
  word-break: break-all;
  margin-bottom: 14px;
}

.result-note { font-size: 12px; color: var(--ink-faint); margin-top: 10px; }

/* ═══════════ 章节通用 ═══════════ */
.section { padding: 0 0 80px; }

.sec-head { margin-bottom: 40px; }
.sec-head .kicker { margin-bottom: 14px; }
.sec-head h2 {
  font-family: var(--serif);
  font-size: clamp(24px, 3.4vw, 32px);
  font-weight: 700;
  letter-spacing: -0.3px;
}
.sec-head p { color: var(--ink-soft); margin-top: 10px; max-width: 620px; }

/* 三步流程 */
.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0;
  border-top: 1px solid var(--line-dark);
}
.step {
  padding: 30px 32px 34px 0;
  border-right: 1px solid var(--line);
}
.step:last-child { border-right: none; padding-right: 0; }
.step + .step { padding-left: 32px; }
.step-n {
  font-family: var(--serif);
  font-size: 40px;
  font-weight: 700;
  color: var(--paper-deep);
  -webkit-text-stroke: 1px var(--line-dark);
  line-height: 1;
  margin-bottom: 14px;
}
.step h3 { font-size: 17px; font-weight: 700; margin-bottom: 8px; }
.step p { font-size: 14px; color: var(--ink-soft); line-height: 1.8; }

/* 特性：竖排细目，避免“卡片墙” */
.specs {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0 56px;
}
.spec {
  display: flex;
  gap: 18px;
  padding: 26px 0;
  border-bottom: 1px solid var(--line);
}
.spec:nth-last-child(-n+2) { border-bottom: none; }
.spec-ico {
  width: 42px; height: 42px;
  flex-shrink: 0;
  border: 1px solid var(--line-dark);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--cinnabar);
  background: #fffdf9;
}
.spec h3 { font-family: var(--serif); font-size: 17px; font-weight: 700; margin-bottom: 6px; }
.spec p { font-size: 14px; color: var(--ink-soft); }

/* FAQ */
.faq { border-top: 1px solid var(--line-dark); }
.faq details { border-bottom: 1px solid var(--line); }
.faq summary {
  list-style: none;
  cursor: pointer;
  padding: 22px 36px 22px 0;
  position: relative;
  font-size: 16px;
  font-weight: 600;
  font-family: var(--serif);
  transition: color .15s;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary:hover { color: var(--cinnabar); }
.faq summary::after {
  content: '+';
  position: absolute;
  right: 6px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--serif);
  font-size: 22px;
  color: var(--ink-faint);
  transition: transform .2s;
}
.faq details[open] summary::after { content: '−'; }
.faq details[open] summary { color: var(--cinnabar); }
.faq .answer {
  padding: 0 40px 26px 0;
  font-size: 15px;
  color: var(--ink-soft);
  max-width: 720px;
}

/* 使用须知 */
.notice {
  border: 1px solid var(--line-dark);
  background: #fffdf9;
  padding: 34px 38px;
  box-shadow: 6px 6px 0 rgba(28,27,24,.04);
}
.notice h3 {
  font-family: var(--serif);
  font-size: 18px;
  margin-bottom: 18px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.notice h3::before { content: '※'; color: var(--cinnabar); font-size: 15px; }
.notice ul { list-style: none; }
.notice li {
  position: relative;
  padding-left: 22px;
  font-size: 14.5px;
  color: var(--ink-soft);
  margin-bottom: 12px;
  line-height: 1.8;
}
.notice li:last-child { margin-bottom: 0; }
.notice li::before {
  content: '';
  position: absolute;
  left: 2px;
  top: 12px;
  width: 7px; height: 1px;
  background: var(--cinnabar);
}

/* ═══════════ 页脚 ═══════════ */
.colophon {
  border-top: 1px solid var(--line-dark);
  padding: 44px 0 56px;
  background: var(--paper-deep);
}
.colophon-inner {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 20px;
  align-items: flex-start;
}
.colophon .sig {
  font-family: var(--serif);
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 8px;
}
.colophon .sig em { font-style: normal; color: var(--cinnabar); }
.colophon p { font-size: 13px; color: var(--ink-faint); }
.colophon .links { display: flex; gap: 26px; font-size: 13px; padding-top: 4px; }

/* ═══════════ 轻提示 ═══════════ */
.toast {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 9999;
  padding: 13px 20px;
  font-size: 14px;
  background: var(--ink);
  color: #f5f1e8;
  border-radius: 2px;
  box-shadow: 0 6px 20px rgba(28,27,24,.3);
  animation: rise .2s ease;
  max-width: 320px;
}
.toast.ok { background: var(--pine); }
.toast.err { background: #8c2f1b; }

/* 锚点跳转时避开吸顶导航条的遮挡 */
section[id], header[id] { scroll-margin-top: 84px; }

/* ═══════════ 响应式 ═══════════ */
@media (max-width: 900px) {
  .tool-section { grid-template-columns: 1fr; }
  .tool-pane + .tool-pane { border-left: none; border-top: 1px solid var(--line-dark); }
  .steps { grid-template-columns: 1fr; }
  .step { border-right: none; border-bottom: 1px solid var(--line); padding: 24px 0; }
  .step + .step { padding-left: 0; }
  .specs { grid-template-columns: 1fr; }
}

@media (max-width: 720px) {
  .site-nav { display: none; }
  #menuBtn { display: block; }
  .brand .tag { display: none; }
  .wrap { padding: 0 20px; }
  .lead-section { padding: 48px 0 40px; }
  .tool-pane { padding: 28px 22px 32px; }
  .lead-stats > div { padding-right: 20px; margin-right: 20px; }
  .notice { padding: 26px 22px; }
  .toast { left: 20px; right: 20px; max-width: none; }
}