/* ============================================================
   Aviation Instructor's Handbook - 航空教员手册
   九元航空 型别教员培训 · 教学法网站
   ============================================================ */

/* ---------- CSS Variables ---------- */
:root {
  --navy: #0A1628;
  --navy-mid: #122240;
  --navy-light: #1B2D4F;
  --blue: #2E6DB4;
  --blue-bright: #4A9FE5;
  --cyan: #5BC0EB;
  --gold: #D4A843;
  --gold-light: #F0D68A;
  --green: #3CB371;
  --red: #E74C3C;
  --purple: #9B59B6;
  --orange: #F39C12;
  --text: #E8EDF5;
  --text-dim: #8899AA;
  --text-bright: #FFFFFF;
  --card-bg: rgba(18, 34, 64, 0.7);
  --card-border: rgba(74, 159, 229, 0.15);
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 24px rgba(0,0,0,0.3);
  --max-w: 1200px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", "PingFang SC", "Hiragino Sans GB", sans-serif;
  --nav-h: 60px;
}

/* ---------- Reset ---------- */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background: var(--navy);
  color: var(--text);
  line-height: 1.8;
  min-height: 100vh;
  overflow-x: hidden;
}
a { color: var(--cyan); text-decoration: none; transition: color .2s; }
a:hover { color: var(--gold); }
img { max-width: 100%; }
ul, ol { padding-left: 1.5em; }

/* ---------- Background Atmosphere ---------- */
body::before {
  content: '';
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background:
    radial-gradient(ellipse 80% 60% at 20% 10%, rgba(46,109,180,0.08) 0%, transparent 60%),
    radial-gradient(ellipse 60% 50% at 80% 80%, rgba(91,192,235,0.05) 0%, transparent 60%);
  pointer-events: none;
  z-index: 0;
}

/* ---------- Navigation ---------- */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(10, 22, 40, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(74, 159, 229, 0.12);
  height: var(--nav-h);
}
.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: flex;
  align-items: center;
  height: 100%;
  padding: 0 1.5rem;
  gap: 0.3rem;
  overflow-x: auto;
  scrollbar-width: none;
}
.nav-inner::-webkit-scrollbar { display: none; }
.nav-brand {
  color: var(--blue-bright);
  font-weight: 700;
  font-size: 0.95rem;
  white-space: nowrap;
  margin-right: 1rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.nav-brand svg { width: 20px; height: 20px; }
.nav-link {
  color: var(--text-dim);
  font-size: 0.8rem;
  padding: 0.4rem 0.7rem;
  border-radius: 6px;
  white-space: nowrap;
  transition: all .2s;
  border: 1px solid transparent;
}
.nav-link:hover, .nav-link.active {
  color: var(--text-bright);
  background: rgba(74, 159, 229, 0.1);
  border-color: rgba(74, 159, 229, 0.2);
}
.nav-link.active { color: var(--gold); border-color: rgba(212,168,67,0.3); }

/* ---------- Main Content ---------- */
.main {
  position: relative;
  z-index: 1;
  padding-top: var(--nav-h);
}

/* ---------- Hero Section ---------- */
.hero {
  min-height: calc(100vh - var(--nav-h));
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 4rem 2rem 3rem;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -50%; left: -50%;
  width: 200%; height: 200%;
  background: conic-gradient(from 0deg at 50% 50%, transparent 0deg, rgba(46,109,180,0.03) 60deg, transparent 120deg, rgba(91,192,235,0.03) 180deg, transparent 240deg, rgba(212,168,67,0.02) 300deg, transparent 360deg);
  animation: heroRotate 60s linear infinite;
}
@keyframes heroRotate { to { transform: rotate(360deg); } }
.hero-content { position: relative; z-index: 1; }
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(74, 159, 229, 0.1);
  border: 1px solid rgba(74, 159, 229, 0.2);
  padding: 0.4rem 1.2rem;
  border-radius: 50px;
  font-size: 0.8rem;
  color: var(--cyan);
  margin-bottom: 1.5rem;
}
.hero h1 {
  font-size: 3.2rem;
  font-weight: 800;
  color: var(--text-bright);
  letter-spacing: 4px;
  margin-bottom: 0.8rem;
  line-height: 1.2;
}
.hero .subtitle {
  font-size: 1.2rem;
  color: var(--text-dim);
  font-weight: 300;
  margin-bottom: 2rem;
  letter-spacing: 1px;
}
.hero-meta {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
}
.hero-meta span {
  background: rgba(74, 159, 229, 0.08);
  border: 1px solid rgba(74, 159, 229, 0.15);
  padding: 0.45rem 1rem;
  border-radius: 50px;
  font-size: 0.82rem;
  color: var(--blue-bright);
}

/* ---------- Chapter Page Hero ---------- */
.ch-hero {
  padding: 5rem 2rem 3rem;
  text-align: center;
  background: linear-gradient(180deg, rgba(46,109,180,0.08) 0%, transparent 100%);
  border-bottom: 1px solid rgba(74, 159, 229, 0.08);
}
.ch-hero .ch-num {
  display: inline-block;
  background: linear-gradient(135deg, var(--blue), var(--cyan));
  color: #fff;
  padding: 0.25rem 1rem;
  border-radius: 50px;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 1px;
  margin-bottom: 0.8rem;
}
.ch-hero h1 {
  font-size: 2.4rem;
  font-weight: 700;
  color: var(--text-bright);
  margin-bottom: 0.5rem;
}
.ch-hero .ch-sub {
  font-size: 0.95rem;
  color: var(--text-dim);
  max-width: 600px;
  margin: 0 auto;
}
.divider {
  width: 50px; height: 3px;
  background: linear-gradient(90deg, var(--blue), var(--cyan));
  margin: 1rem auto;
  border-radius: 2px;
}

/* ---------- Section Container ---------- */
.section {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 3rem 2rem;
}
.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-bright);
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.section-title .icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px; height: 36px;
  border-radius: 10px;
  font-size: 1rem;
  flex-shrink: 0;
}

/* ---------- Cards Grid ---------- */
.cards {
  display: grid;
  gap: 1.2rem;
  margin-bottom: 2rem;
}
.c2 { grid-template-columns: repeat(2, 1fr); }
.c3 { grid-template-columns: repeat(3, 1fr); }
.c4 { grid-template-columns: repeat(4, 1fr); }

/* ---------- Card ---------- */
.card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: transform .2s, border-color .2s;
}
.card:hover {
  transform: translateY(-2px);
  border-color: rgba(74, 159, 229, 0.3);
}
.card-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px; height: 42px;
  border-radius: 10px;
  font-size: 1.2rem;
  margin-bottom: 0.8rem;
}
.card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-bright);
  margin-bottom: 0.5rem;
}
.card p, .card li {
  font-size: 0.88rem;
  color: var(--text-dim);
  line-height: 1.7;
}
.card ul { list-style: none; padding: 0; }
.card ul li {
  padding: 0.15rem 0 0.15rem 1.2rem;
  position: relative;
}
.card ul li::before {
  content: '\25CF';
  position: absolute;
  left: 0;
  color: var(--blue-bright);
  font-size: 0.5rem;
  top: 0.5rem;
}

/* ---------- Content Block ---------- */
.block {
  border-radius: var(--radius);
  padding: 2rem;
  margin-bottom: 1.5rem;
  border-left: 4px solid var(--blue);
}
.block-blue { background: rgba(46,109,180,0.06); border-color: var(--blue); }
.block-cyan { background: rgba(91,192,235,0.06); border-color: var(--cyan); }
.block-gold { background: rgba(212,168,67,0.06); border-color: var(--gold); }
.block-green { background: rgba(60,179,113,0.06); border-color: var(--green); }
.block-red { background: rgba(231,76,60,0.06); border-color: var(--red); }
.block-purple { background: rgba(155,89,182,0.06); border-color: var(--purple); }
.block-orange { background: rgba(243,156,18,0.06); border-color: var(--orange); }
.block h3 {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-bright);
  margin-bottom: 0.8rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.block p, .block li {
  font-size: 0.9rem;
  color: var(--text);
  line-height: 1.8;
}

/* ---------- Table ---------- */
.tbl-wrap {
  overflow-x: auto;
  border-radius: var(--radius);
  border: 1px solid var(--card-border);
  margin: 1rem 0;
}
table {
  width: 100%;
  border-collapse: collapse;
  background: var(--card-bg);
}
th {
  background: rgba(46,109,180,0.2);
  padding: 0.75rem 1rem;
  text-align: left;
  font-weight: 600;
  font-size: 0.82rem;
  color: var(--cyan);
  border-bottom: 1px solid var(--card-border);
  white-space: nowrap;
}
td {
  padding: 0.65rem 1rem;
  border-bottom: 1px solid rgba(74, 159, 229, 0.06);
  font-size: 0.85rem;
  color: var(--text);
}
tr:hover td { background: rgba(74, 159, 229, 0.04); }

/* ---------- Flow / Steps ---------- */
.flow {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  justify-content: center;
  margin: 1.5rem 0;
}
.flow-step {
  background: rgba(46,109,180,0.12);
  border: 1px solid rgba(74, 159, 229, 0.25);
  border-radius: var(--radius-sm);
  padding: 0.7rem 1.2rem;
  text-align: center;
  min-width: 100px;
}
.flow-step strong {
  display: block;
  font-size: 0.85rem;
  color: var(--cyan);
}
.flow-step small {
  font-size: 0.75rem;
  color: var(--text-dim);
}
.flow-arrow {
  color: var(--blue-bright);
  font-size: 1.1rem;
}

/* ---------- Pyramid ---------- */
.pyramid {
  max-width: 520px;
  margin: 1.5rem auto;
}
.pyr-level {
  padding: 0.8rem 1.5rem;
  text-align: center;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 4px;
  border-radius: 6px;
  color: #fff;
  transition: transform .2s;
}
.pyr-level:hover { transform: scale(1.02); }
.pyr-1 { background: var(--red); width: 50%; margin-left: auto; margin-right: auto; }
.pyr-2 { background: var(--orange); width: 65%; margin-left: auto; margin-right: auto; }
.pyr-3 { background: var(--blue); width: 80%; margin-left: auto; margin-right: auto; }
.pyr-4 { background: var(--green); width: 95%; margin-left: auto; margin-right: auto; }
.pyr-5 { background: var(--purple); width: 100%; }

/* ---------- Numbered List ---------- */
.num-list {
  counter-reset: item;
  list-style: none;
  padding: 0;
}
.num-list li {
  counter-increment: item;
  padding: 0.5rem 0 0.5rem 2.5rem;
  position: relative;
  font-size: 0.9rem;
  color: var(--text);
}
.num-list li::before {
  content: counter(item);
  position: absolute;
  left: 0; top: 0.5rem;
  width: 1.6rem; height: 1.6rem;
  background: var(--blue);
  color: #fff;
  border-radius: 50%;
  text-align: center;
  line-height: 1.6rem;
  font-size: 0.75rem;
  font-weight: 700;
}

/* ---------- Compare Grid ---------- */
.compare {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
}
.compare .card { border-top: 3px solid var(--blue); }

/* ---------- Highlight Box ---------- */
.highlight {
  background: linear-gradient(135deg, rgba(212,168,67,0.1), rgba(212,168,67,0.03));
  border: 1px solid rgba(212,168,67,0.2);
  border-radius: var(--radius);
  padding: 1.2rem 1.5rem;
  margin: 1rem 0;
  font-size: 0.9rem;
  color: var(--gold-light);
}
.highlight strong { color: var(--gold); }

/* ---------- Tip Box ---------- */
.tip {
  background: rgba(60,179,113,0.06);
  border: 1px solid rgba(60,179,113,0.2);
  border-radius: var(--radius);
  padding: 1.2rem 1.5rem;
  margin: 1rem 0;
  font-size: 0.88rem;
  color: var(--text);
}
.tip::before {
  content: '\2714 \6280\5DE7';
  font-weight: 700;
  color: var(--green);
  display: block;
  margin-bottom: 0.3rem;
}

/* ---------- Warning Box ---------- */
.warn {
  background: rgba(231,76,60,0.06);
  border: 1px solid rgba(231,76,60,0.2);
  border-radius: var(--radius);
  padding: 1.2rem 1.5rem;
  margin: 1rem 0;
  font-size: 0.88rem;
  color: var(--text);
}
.warn::before {
  content: '\26A0 \6CE8\610F';
  font-weight: 700;
  color: var(--red);
  display: block;
  margin-bottom: 0.3rem;
}

/* ---------- Quote ---------- */
.quote {
  border-left: 3px solid var(--gold);
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  background: rgba(212,168,67,0.04);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-style: italic;
  color: var(--text-dim);
  font-size: 0.95rem;
}

/* ---------- Tag ---------- */
.tag {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  font-size: 0.72rem;
  font-weight: 600;
  margin: 0.15rem;
}
.tag-blue { background: rgba(46,109,180,0.2); color: var(--blue-bright); }
.tag-cyan { background: rgba(91,192,235,0.2); color: var(--cyan); }
.tag-gold { background: rgba(212,168,67,0.2); color: var(--gold); }
.tag-green { background: rgba(60,179,113,0.2); color: var(--green); }
.tag-red { background: rgba(231,76,60,0.2); color: var(--red); }
.tag-purple { background: rgba(155,89,182,0.2); color: var(--purple); }

/* ---------- Chapter Nav (bottom) ---------- */
.ch-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 2rem;
  max-width: var(--max-w);
  margin: 0 auto;
  border-top: 1px solid rgba(74, 159, 229, 0.08);
}
.ch-nav a {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  border: 1px solid var(--card-border);
  border-radius: var(--radius-sm);
  color: var(--text-dim);
  font-size: 0.85rem;
  transition: all .2s;
}
.ch-nav a:hover {
  border-color: var(--blue);
  color: var(--text-bright);
  background: rgba(46,109,180,0.08);
}

/* ---------- Footer ---------- */
.footer {
  background: rgba(6, 12, 24, 0.8);
  border-top: 1px solid rgba(74, 159, 229, 0.08);
  padding: 3rem 2rem;
  text-align: center;
  margin-top: 2rem;
}
.footer h3 { font-size: 1.2rem; margin-bottom: 1rem; color: var(--text-bright); }
.footer p { font-size: 0.82rem; color: var(--text-dim); margin: 0.3rem 0; }

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .c2, .c3, .c4, .compare { grid-template-columns: 1fr; }
  .hero h1 { font-size: 2.2rem; letter-spacing: 2px; }
  .ch-hero h1 { font-size: 1.8rem; }
  .pyr-1,.pyr-2,.pyr-3,.pyr-4,.pyr-5 { width: 100%; }
  .nav-link { font-size: 0.72rem; padding: 0.3rem 0.5rem; }
}
@media (max-width: 600px) {
  .hero h1 { font-size: 1.8rem; }
  .section { padding: 2rem 1rem; }
  .block { padding: 1.2rem; }
  .card { padding: 1.2rem; }
}