/* ============================================================
   海拔高度实时查询工具 — 样式表
   设计规范：Feedzy Design System
   ============================================================ */

/* ---------- Design Tokens ---------- */
:root {
  /* Colors */
  --color-primary: #0062ff;
  --color-primary-light: #0090ff;
  --color-primary-hover: #004fcc;
  --color-primary-active: #003e99;
  --color-accent-blue: #3b82f6;
  --color-bg: #ffffff;
  --color-bg-alt: #fafafa;
  --color-bg-light: #f4f4f6;
  --color-surface-dark: #1a1e24;
  --color-text-primary: #0d0f12;
  --color-text-secondary: #8a919e;
  --color-text-tertiary: #5a606c;
  --color-text-muted: #a0a0a0;
  --color-text-inverse: #ffffff;
  --color-border-primary: #d1d6db;
  --color-border-light: #c0c0c4;

  /* Typography */
  --font-display: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', 'Helvetica', sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace;

  /* Radius */
  --radius-sm: 8px;
  --radius-md: 10px;
  --radius-lg: 12px;
  --radius-xl: 18px;
  --radius-full: 9999px;

  /* Elevation */
  --shadow-card: rgba(0, 0, 0, 0.02) 0px 4px 12px 0px;
  --shadow-card-hover: rgba(0, 0, 0, 0.05) 0px 8px 24px 0px;
  --shadow-dropdown: rgba(0, 0, 0, 0.2) 0px 2px 12px 0px;

  /* Motion */
  --dur-fast: 0.2s;
  --dur-base: 0.3s;
  --ease-out: cubic-bezier(0, 0, .2, 1);
  --ease-in-out: cubic-bezier(.4, 0, .2, 1);

  /* Layout */
  --max-width: 1200px;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-body);
  font-size: 16px;
  font-weight: 500;
  line-height: 1.5;
  color: var(--color-text-primary);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
img { max-width: 100%; display: block; }
ul, ol { list-style: none; }
a { color: inherit; text-decoration: none; }
button { font-family: inherit; }

/* ---------- Typography ---------- */
h1, h2, h3, h4 { font-family: var(--font-display); font-weight: 500; line-height: 1.2; color: var(--color-text-primary); }
h1 { font-size: 44px; }
h2 { font-size: 38px; }
h3 { font-size: 22px; }
h4 { font-size: 18px; }
p { color: var(--color-text-tertiary); }
.mono { font-family: var(--font-mono); }

/* ---------- Layout Helpers ---------- */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; }
.section { padding: 64px 0; }
.section-alt { background-color: var(--color-bg-alt); }
.section-head { max-width: 760px; margin: 0 auto 40px; text-align: center; }
.section-head h2 { margin-bottom: 16px; }
.section-head p { font-size: 17px; color: var(--color-text-tertiary); }
.eyebrow {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-primary);
  margin-bottom: 12px;
}

/* ---------- Dotted Grid Background ---------- */
.dotted-grid {
  background-image: radial-gradient(var(--color-border-primary) 1px, transparent 1px);
  background-size: 22px 22px;
}

/* ============================================================
   Navigation
   ============================================================ */
.nav-bar {
  position: sticky;
  top: 0;
  z-index: 20;
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border-primary);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 72px;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}
.brand { display: flex; align-items: center; gap: 10px; font-family: var(--font-display); font-weight: 600; font-size: 18px; }
.brand-mark {
  width: 34px; height: 34px; border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  display: grid; place-items: center; color: #fff;
}
.brand-mark svg { width: 20px; height: 20px; }
.nav-links { display: flex; align-items: center; gap: 4px; }
.nav-link {
  color: var(--color-text-primary);
  font-size: 15px; font-weight: 500;
  padding: 8px 12px; border-radius: var(--radius-sm);
  transition: color var(--dur-fast) var(--ease-in-out), background-color var(--dur-fast) var(--ease-in-out);
}
.nav-link:hover { color: var(--color-primary); background-color: var(--color-bg-light); }
.nav-toggle { display: none; background: none; border: none; cursor: pointer; padding: 8px; }
.nav-toggle svg { width: 24px; height: 24px; }

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font-family: var(--font-body); font-size: 15px; font-weight: 600;
  padding: 10px 20px; border-radius: var(--radius-sm);
  border: 1px solid transparent; cursor: pointer; white-space: nowrap;
  transition: background-color var(--dur-fast) var(--ease-in-out),
              border-color var(--dur-fast) var(--ease-in-out),
              box-shadow var(--dur-fast) var(--ease-in-out),
              color var(--dur-fast) var(--ease-in-out);
}
.btn svg { width: 18px; height: 18px; }
.btn-primary { background-color: var(--color-primary); color: var(--color-text-inverse); }
.btn-primary:hover { background-color: var(--color-primary-hover); box-shadow: 0 4px 12px rgba(0,98,255,0.2); }
.btn-primary:active { background-color: var(--color-primary-active); box-shadow: none; }
.btn-primary:disabled { background-color: var(--color-bg-light); color: var(--color-text-secondary); cursor: not-allowed; box-shadow: none; }
.btn-secondary { background-color: var(--color-bg); color: var(--color-text-primary); border-color: var(--color-border-primary); }
.btn-secondary:hover { background-color: var(--color-bg-light); border-color: var(--color-primary); box-shadow: 0 2px 8px rgba(0,0,0,0.05); }
.btn-ghost { background: transparent; color: var(--color-text-primary); padding: 8px 12px; }
.btn-ghost:hover { color: var(--color-primary); }
.btn-block { width: 100%; }
.btn-lg { padding: 13px 26px; font-size: 16px; }

/* ============================================================
   Hero
   ============================================================ */
.hero { position: relative; padding: 56px 0 72px; overflow: hidden; }
.hero-grid {
  display: grid; grid-template-columns: 1fr 1.05fr; gap: 48px; align-items: center;
}
.hero-copy h1 { margin-bottom: 20px; letter-spacing: -0.01em; }
.hero-copy h1 .hl { color: var(--color-primary); }
.hero-copy .lead { font-size: 18px; color: var(--color-text-tertiary);max-width: 520px; }
.hero-stats { display: flex; gap: 32px; margin-top: 32px; flex-wrap: wrap; }
.hero-stat .num { font-family: var(--font-display); font-size: 28px; font-weight: 600; color: var(--color-text-primary); }
.hero-stat .lbl { font-size: 13px; color: var(--color-text-secondary); }

/* ---------- Tool Card ---------- */
.tool-card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border-primary);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-card-hover);
  padding: 28px;
}
.tool-tabs { display: flex; gap: 4px; background: var(--color-bg-light); padding: 4px; border-radius: var(--radius-md); margin-bottom: 24px; }
.tool-tab {
  flex: 1; text-align: center; font-size: 14px; font-weight: 600;
  padding: 10px 8px; border-radius: var(--radius-sm); border: none; background: transparent;
  color: var(--color-text-tertiary); cursor: pointer;
  transition: all var(--dur-fast) var(--ease-in-out);
}
.tool-tab.active { background: var(--color-bg); color: var(--color-primary); box-shadow: var(--shadow-card); }
.tool-panel { display: none; }
.tool-panel.active { display: block; animation: fade-in var(--dur-base) var(--ease-out); }
.field { margin-bottom: 16px; }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.form-label { display: block; font-size: 14px; font-weight: 500; color: var(--color-text-primary); margin-bottom: 8px; }
.input-text {
  width: 100%; background-color: var(--color-bg); color: var(--color-text-primary);
  font-family: var(--font-body); font-size: 16px; font-weight: 500;
  padding: 12px 16px; border: 1px solid var(--color-border-primary); border-radius: var(--radius-sm);
  transition: border-color var(--dur-fast) var(--ease-in-out), box-shadow var(--dur-fast) var(--ease-in-out);
}
.input-text::placeholder { color: var(--color-text-secondary); }
.input-text:focus { border-color: var(--color-primary); outline: none; box-shadow: 0 0 0 2px rgba(0,98,255,0.2); }
.field-hint { font-size: 12px; color: var(--color-text-secondary); margin-top: 6px; }

/* ---------- Search autocomplete ---------- */
.search-wrap { position: relative; }
.search-results {
  position: absolute; top: calc(100% + 6px); left: 0; right: 0; z-index: 10;
  background: var(--color-bg); border: 1px solid var(--color-border-primary);
  border-radius: var(--radius-sm); box-shadow: var(--shadow-dropdown);
  max-height: 260px; overflow-y: auto; display: none;
}
.search-results.show { display: block; }
.search-item { padding: 10px 16px; cursor: pointer; display: flex; justify-content: space-between; gap: 12px; transition: background-color var(--dur-fast) var(--ease-in-out); }
.search-item:hover, .search-item.active { background: var(--color-bg-light); }
.search-item .place { font-size: 15px; color: var(--color-text-primary); }
.search-item .region { font-size: 12px; color: var(--color-text-secondary); }

/* ============================================================
   Result Card
   ============================================================ */
.result-card {
  background-color: var(--color-surface-dark);
  color: var(--color-text-inverse);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin-top: 20px;
  display: none;
}
.result-card.show { display: block; animation: fade-in var(--dur-base) var(--ease-out); }
.result-top { display: flex; align-items: baseline; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.result-place { font-size: 14px; color: #b8bec9; }
.result-place strong { color: #fff; font-size: 16px; font-weight: 600; }
.result-value { font-family: var(--font-display); font-weight: 600; line-height: 1; margin: 10px 0 4px; }
.result-value .big { font-size: 64px; }
.result-value .unit { font-size: 22px; color: var(--color-primary-light); margin-left: 6px; }
.result-coords { font-family: var(--font-mono); font-size: 13px; color: #9aa2ad; }
.result-badge {
  display: inline-flex; align-items: center; gap: 6px;
  background: rgba(0,98,255,0.18); color: #7db4ff; border: 1px solid rgba(0,98,255,0.4);
  font-size: 12px; font-weight: 600; padding: 5px 12px; border-radius: var(--radius-full);
}
.result-metrics { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin-top: 24px; }
.metric { background: rgba(255,255,255,0.05); border: 1px solid rgba(255,255,255,0.08); border-radius: var(--radius-md); padding: 14px; }
.metric .m-val { font-family: var(--font-display); font-size: 22px; font-weight: 600; color: #fff; }
.metric .m-lbl { font-size: 12px; color: #9aa2ad; margin-top: 2px; }
.result-note { font-size: 12px; color: #7c8390; margin-top: 16px; }

/* Loading / error states */
.state-msg { display: none; margin-top: 16px; padding: 12px 16px; border-radius: var(--radius-sm); font-size: 14px; }
.state-msg.show { display: block; }
.state-loading { background: var(--color-bg-light); color: var(--color-text-tertiary); }
.state-error { background: #fef2f2; color: #b91c1c; border: 1px solid #fecaca; }
.spinner {
  display: inline-block; width: 14px; height: 14px; margin-right: 8px; vertical-align: -2px;
  border: 2px solid var(--color-border-primary); border-top-color: var(--color-primary);
  border-radius: 50%; animation: spin 0.7s linear infinite;
}

/* ============================================================
   Cards Grid (features / use cases)
   ============================================================ */
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }
.card {
  background-color: var(--color-bg-alt);
  border: 1px solid var(--color-border-primary);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  padding: 24px;
  transition: box-shadow var(--dur-fast) var(--ease-out), transform var(--dur-fast) var(--ease-out);
}
.card:hover { box-shadow: var(--shadow-card-hover); transform: translateY(-2px); }
.card-icon {
  width: 44px; height: 44px; border-radius: var(--radius-md);
  background: rgba(0,98,255,0.1); color: var(--color-primary);
  display: grid; place-items: center; margin-bottom: 16px;
}
.card-icon svg { width: 22px; height: 22px; }
.card h3 { font-size: 19px; margin-bottom: 8px; }
.card h4 { font-size: 17px; margin-bottom: 8px; }
.card p { font-size: 15px; color: var(--color-text-tertiary); }

/* ============================================================
   Content prose
   ============================================================ */
.prose { max-width: 820px; margin: 0 auto; }
.prose h3 { font-size: 24px; margin: 32px 0 12px; }
.prose h4 { font-size: 18px; margin: 24px 0 10px; }
.prose p { font-size: 16px; color: var(--color-text-tertiary); margin-bottom: 16px; }
.prose ul.bullets { margin: 0 0 16px; padding-left: 4px; }
.prose ul.bullets li { position: relative; padding-left: 26px; margin-bottom: 10px; color: var(--color-text-tertiary); }
.prose ul.bullets li::before {
  content: ""; position: absolute; left: 4px; top: 9px; width: 8px; height: 8px;
  border-radius: 50%; background: var(--color-primary);
}
.prose strong { color: var(--color-text-primary); font-weight: 600; }
.callout {
  background: var(--color-bg-light); border-left: 3px solid var(--color-primary);
  border-radius: var(--radius-sm); padding: 16px 20px; margin: 20px 0; font-size: 15px; color: var(--color-text-tertiary);
}
.callout strong { color: var(--color-text-primary); }

/* ============================================================
   Tables
   ============================================================ */
.table-wrap { overflow-x: auto; border: 1px solid var(--color-border-primary); border-radius: var(--radius-lg); box-shadow: var(--shadow-card); }
table.data { width: 100%; border-collapse: collapse; font-size: 15px; background: var(--color-bg); min-width: 520px; }
table.data thead th {
  background: var(--color-bg-light); color: var(--color-text-primary);
  font-weight: 600; text-align: left; padding: 14px 18px; white-space: nowrap;
  border-bottom: 1px solid var(--color-border-primary);
}
table.data tbody td { padding: 13px 18px; border-bottom: 1px solid var(--color-bg-light); color: var(--color-text-tertiary); }
table.data tbody tr:last-child td { border-bottom: none; }
table.data tbody tr:hover { background: var(--color-bg-alt); }
table.data td.place { color: var(--color-text-primary); font-weight: 600; }
table.data td.num { font-family: var(--font-mono); color: var(--color-text-primary); }
.tag { display: inline-block; font-size: 12px; font-weight: 600; padding: 3px 9px; border-radius: var(--radius-full); }
.tag-low { background: #e8f7ee; color: #15803d; }
.tag-mid { background: #fff7e6; color: #b45309; }
.tag-high { background: #fdeaea; color: #b91c1c; }

/* ============================================================
   FAQ Accordion
   ============================================================ */
.faq-list { max-width: 820px; margin: 0 auto; }
.faq-item { border: 1px solid var(--color-border-primary); border-radius: var(--radius-lg); background: var(--color-bg); margin-bottom: 12px; overflow: hidden; transition: box-shadow var(--dur-fast) var(--ease-out); }
.faq-item:hover { box-shadow: var(--shadow-card); }
.faq-q {
  width: 100%; text-align: left; background: none; border: none; cursor: pointer;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 20px 24px; font-size: 17px; font-weight: 600; color: var(--color-text-primary);
  font-family: var(--font-display);
}
.faq-q .chev { flex-shrink: 0; width: 20px; height: 20px; color: var(--color-text-secondary); transition: transform var(--dur-fast) var(--ease-in-out); }
.faq-item.open .faq-q .chev { transform: rotate(180deg); color: var(--color-primary); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height var(--dur-base) var(--ease-in-out); }
.faq-a-inner { padding: 0 24px 20px; font-size: 15px; color: var(--color-text-tertiary); }

/* ============================================================
   CTA banner
   ============================================================ */
.cta-band { background-color: var(--color-surface-dark); border-radius: var(--radius-xl); padding: 48px; text-align: center; color: var(--color-text-inverse); }
.cta-band h2 { color: #fff; margin-bottom: 12px; }
.cta-band p { color: #b8bec9; max-width: 560px; margin: 0 auto 24px; font-size: 16px; }

/* ============================================================
   Footer
   ============================================================ */
.footer { background: var(--color-bg-alt); border-top: 1px solid var(--color-border-primary); padding: 56px 0 32px; }
.footer-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.footer h4 { font-family: var(--font-body); font-size: 14px; font-weight: 600; color: var(--color-text-primary); margin-bottom: 16px; }
.footer .brand { margin-bottom: 14px; }
.footer p { font-size: 14px; color: var(--color-text-tertiary); max-width: 300px; }
.footer ul li { margin-bottom: 10px; }
.footer ul li a { font-size: 14px; color: var(--color-text-tertiary); transition: color var(--dur-fast) var(--ease-in-out); }
.footer ul li a:hover { color: var(--color-primary); }
.footer-bottom { border-top: 1px solid var(--color-border-primary); padding-top: 24px; display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; font-size: 13px; color: var(--color-text-secondary); }

/* ============================================================
   Animations
   ============================================================ */
@keyframes fade-in { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }
@keyframes spin { to { transform: rotate(360deg); } }
.reveal { opacity: 0; transform: translateY(20px); transition: opacity var(--dur-long, .5s) var(--ease-out), transform var(--dur-long, .5s) var(--ease-out); }
.reveal.in { opacity: 1; transform: translateY(0); }

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 960px) {
  .hero-grid { grid-template-columns: 1fr; gap: 36px; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .grid-3 { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 768px) {
  h1 { font-size: 24px; }
  h2 { font-size: 23px; }
  .nav-links { display: none; }
  .hero-stats { display: none; }
  .hero-copy .lead { font-size: 14px; }
  .hero { padding: 16px 0 72px; }
  .tool-card { padding: 0; border: none;box-shadow: none;}
  .nav-toggle { display: block; }
  .nav-links.open {
    display: flex; flex-direction: column; align-items: stretch; gap: 2px;
    position: fixed; top: 72px; left: 0; right: 0; width: 100vw;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border-primary); padding: 12px 16px;
    box-shadow: var(--shadow-dropdown); z-index: 19;
  }
  .nav-links.open .nav-link { display: block; width: 100%; padding: 16px; font-size: 17px; line-height: 1.5; }
  .section { padding: 48px 0; }
  .container { padding: 0 16px; }
  .result-metrics { grid-template-columns: 1fr 1fr; }
  .result-value .big { font-size: 52px; }
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .cta-band { padding: 32px 24px; }
}
@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
  .field-row { grid-template-columns: 1fr; }
}