@charset "utf-8";
/* CSS Document */
/* ═══════════════════════════════════════
   RESET & BASE
═══════════════════════════════════════ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'Segoe UI', Arial, sans-serif;
  background-color: #F8F3E7;
  color: #2F3437;
  font-size: 16px;
}

a { text-decoration: none; color: inherit; }

/* ═══════════════════════════════════════
   BREADCRUMB
═══════════════════════════════════════ */
.breadcrumb {
  background-color: #e8e2d6; padding: 10px 24px;
  font-size: 0.85rem; color: #555; border-bottom: 1px solid #d5cfc5;
}
.breadcrumb a { color: #1D3557; font-weight: 600; }
.breadcrumb a:hover { text-decoration: underline; }
.bc-sep { margin: 0 6px; color: #aaa; }
.bc-current { color: #2F3437; font-weight: 600; }

/* ═══════════════════════════════════════
   PAGE WRAPPER
═══════════════════════════════════════ */
.page-wrapper { max-width: 960px; margin: 0 auto; padding: 24px 20px 40px; }

/* ═══════════════════════════════════════
   PAGE TITLE BLOCK
═══════════════════════════════════════ */
.page-title-block {
  background: linear-gradient(135deg, #1D3557 0%, #2a4d73 100%);
  color: #F8F3E7; border-radius: 8px; padding: 36px 32px; margin-bottom: 28px;
}
.page-title-label {
  font-size: 0.8rem; font-weight: 700; letter-spacing: 0.12em;
  text-transform: uppercase; color: #F5B041; margin-bottom: 8px;
}
.page-title-main { font-size: 2rem; font-weight: 700; line-height: 1.2; margin-bottom: 12px; }
.page-title-sub  { font-size: 1rem; opacity: 0.85; line-height: 1.6; max-width: 680px; }

/* ═══════════════════════════════════════
   QUICK NAV
═══════════════════════════════════════ */
.quick-nav-label {
  font-size: 0.75rem; font-weight: 700; letter-spacing: 0.1em;
  text-transform: uppercase; color: #888; margin-bottom: 0.75rem;
}
.quick-nav-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
  gap: 0.6rem; margin-bottom: 2.5rem;
}
.qnav-card {
  background: #ffffff; border: 1px solid #e0dbd2; border-radius: 8px;
  padding: 0.75rem 0.5rem; text-align: center; color: #1D3557;
  font-size: 0.78rem; font-weight: 600; cursor: pointer;
  transition: box-shadow 0.2s, border-color 0.2s, transform 0.15s;
  text-decoration: none; display: flex; flex-direction: column;
  align-items: center; gap: 0.35rem;
}
.qnav-card:hover {
  border-color: #2a4d73; box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  transform: translateY(-2px);
}
.qnav-card.active {
  border-color: #2a4d73; box-shadow: 0 4px 16px rgba(0,0,0,0.12);
  transform: translateY(-2px); background-color: #1D3557; color: #fff;
}
.qnav-card.active .qnav-icon { filter: brightness(1.3); }
.qnav-icon { font-size: 1.7rem; line-height: 1; }

/* ═══════════════════════════════════════
   ARTICLE / SECTION
═══════════════════════════════════════ */
.section-art-txt {
  margin: 0 0 28px 0; padding: 28px 28px 24px;
  background-color: #ffffff; border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.07);
}
.section-art-title {
  font-size: 1.2rem; font-weight: 700; color: #1D3557;
  border-left: 4px solid #E63946; padding-left: 12px;
  margin-bottom: 20px; line-height: 1.3;
}
.section-art-txt > p { font-size: 1rem; color: #2F3437; line-height: 1.6; margin-bottom: 16px; }
.sub-heading {
  font-size: 1rem; font-weight: 700; color: #1D3557;
  margin: 24px 0 10px; padding-bottom: 4px;
  border-bottom: 1px solid #e0dbd2;
}

/* ═══════════════════════════════════════
   DEFINITION CARDS
═══════════════════════════════════════ */
.definition-cards {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px; margin-top: 8px; margin-bottom: 24px;
}
.def-card { border-radius: 8px; padding: 20px 18px; border-top: 5px solid transparent; }
.def-card--blue   { background: #EBF2FA; border-top-color: #1D3557; }
.def-card--red    { background: #FEF0F0; border-top-color: #E63946; }
.def-card--gold   { background: #FEF9EC; border-top-color: #F5B041; }
.def-card--green  { background: #F0F7F4; border-top-color: #2E7D52; }
.def-card--slate  { background: #ECEFF1; border-top-color: #455A64; }
.def-card--purple { background: #F3EFF8; border-top-color: #6A0DAD; }
.def-card-icon { font-size: 1.8rem; margin-bottom: 8px; }
.def-card h4 { font-size: 1rem; font-weight: 700; margin-bottom: 8px; color: #1D3557; }
.def-card p  { font-size: 0.9rem; line-height: 1.55; color: #3a3f42; }

/* ═══════════════════════════════════════
   REGULATION BLOCKS
═══════════════════════════════════════ */
.reg-block { border: 1px solid #e0dbd2; border-radius: 8px; overflow: hidden; margin-bottom: 20px; }
.reg-block-header { display: flex; align-items: center; gap: 12px; padding: 14px 18px; }
.reg-hdr--blue   { background-color: #1D3557; color: #F8F3E7; }
.reg-hdr--red    { background-color: #E63946; color: #F8F3E7; }
.reg-hdr--green  { background-color: #2E7D52; color: #F8F3E7; }
.reg-hdr--slate  { background-color: #455A64; color: #F8F3E7; }
.reg-hdr--gold   { background-color: #D4890A; color: #fff; }
.reg-icon { font-size: 1.3rem; flex-shrink: 0; }
.reg-block-header h4 { font-size: 1rem; font-weight: 700; flex: 1; line-height: 1.3; }
.reg-block-body { padding: 18px 20px; background-color: #fdfcfa; }
.reg-block-body p { font-size: 0.95rem; line-height: 1.6; color: #2F3437; margin-bottom: 12px; }
.reg-block-body p:last-child { margin-bottom: 0; }

/* ═══════════════════════════════════════
   CHECK LIST
═══════════════════════════════════════ */
.check-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 6px; }
.check-list li { font-size: 0.95rem; color: #2F3437; padding-left: 24px; position: relative; line-height: 1.5; }
.check-list li::before { content: '✓'; position: absolute; left: 0; color: #2E7D52; font-weight: 700; }

/* ═══════════════════════════════════════
   TWO-COL GRID
═══════════════════════════════════════ */
.two-col-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 16px; }
.tc-col { border-radius: 6px; padding: 14px 16px; }
.tc-col--blue   { background-color: #EBF2FA; border-left: 3px solid #1D3557; }
.tc-col--gold   { background-color: #FEF9EC; border-left: 3px solid #F5B041; }
.tc-col--green  { background-color: #F0F7F4; border-left: 3px solid #2E7D52; }
.tc-col--red    { background-color: #FEF0F0; border-left: 3px solid #E63946; }
.tc-col--slate  { background-color: #ECEFF1; border-left: 3px solid #455A64; }
.tc-col h5 { font-size: 0.85rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.07em; margin-bottom: 10px; color: #1D3557; }
.tc-col ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 6px; }
.tc-col ul li { font-size: 0.9rem; line-height: 1.5; color: #2F3437; padding-left: 16px; position: relative; }
.tc-col ul li::before { content: '•'; position: absolute; left: 0; color: #888; }
.tc-col p { font-size: 0.9rem; line-height: 1.6; color: #2F3437; margin-bottom: 8px; }
.tc-col p:last-child { margin-bottom: 0; }

/* ═══════════════════════════════════════
   CALLOUT
═══════════════════════════════════════ */
.callout { display: flex; gap: 14px; align-items: flex-start; border-radius: 8px; padding: 16px 18px; margin-top: 16px; }
.callout--tip   { background-color: #EBF2FA; border-left: 4px solid #1D3557; }
.callout--warn  { background-color: #FEF9EC; border-left: 4px solid #F5B041; }
.callout--red   { background-color: #FEF0F0; border-left: 4px solid #E63946; }
.callout--green { background-color: #F0F7F4; border-left: 4px solid #2E7D52; }
.callout-icon   { font-size: 1.4rem; flex-shrink: 0; }
.callout strong { display: block; font-size: 0.9rem; color: #1D3557; margin-bottom: 4px; }
.callout p { font-size: 0.9rem; line-height: 1.55; color: #2F3437; margin: 0; }

/* ═══════════════════════════════════════
   FORMULA BOX
═══════════════════════════════════════ */
.formula-box {
  background-color: #f4f1e8; border-left: 4px solid #1D3557;
  border-radius: 6px; padding: 14px 20px; margin: 14px 0;
}
.formula-box p { margin: 4px 0; color: #1D3557; font-size: 1rem; font-weight: 700; }
.formula-note  { font-size: 0.82rem !important; font-weight: 400 !important; color: #555 !important; }

/* ═══════════════════════════════════════
   INDUCTION CHAIN — "transformer chain" visual
═══════════════════════════════════════ */
.induction-chain {
  display: flex; flex-direction: column; gap: 0;
  margin: 20px 0; border-radius: 8px; overflow: hidden;
  border: 1px solid #e0dbd2;
}
.ic-step {
  display: flex; align-items: stretch; gap: 0;
}
.ic-number {
  width: 44px; flex-shrink: 0; display: flex; align-items: center;
  justify-content: center; font-size: 1rem; font-weight: 900;
  color: #fff;
}
.ic-content {
  flex: 1; padding: 12px 16px; border-bottom: 1px solid #e0dbd2;
}
.ic-step:last-child .ic-content { border-bottom: none; }
.ic-title { font-size: 0.88rem; font-weight: 700; color: #1D3557; margin-bottom: 3px; }
.ic-desc  { font-size: 0.85rem; line-height: 1.5; color: #3a3f42; }
.ic-arrow {
  display: flex; align-items: center; justify-content: center;
  padding: 2px 0; background: #f4f1e8; font-size: 1rem; color: #aaa;
}
.ic-n--1 { background: #1D3557; }
.ic-n--2 { background: #2E5F8A; }
.ic-n--3 { background: #2E7D52; }
.ic-n--4 { background: #D4890A; }
.ic-n--5 { background: #E63946; }
.ic-n--6 { background: #6A0DAD; }

/* ═══════════════════════════════════════
   ROTATING FIELD DIAGRAM (CSS visual)
═══════════════════════════════════════ */
.rf-diagram {
  display: grid; grid-template-columns: repeat(4, 1fr);
  gap: 8px; margin: 16px 0 8px;
}
.rf-frame {
  background: #EBF2FA; border: 1px solid #c4d5e8;
  border-radius: 8px; padding: 10px 8px; text-align: center;
}
.rf-label {
  font-size: 0.65rem; font-weight: 700; letter-spacing: 0.08em;
  text-transform: uppercase; color: #555; margin-bottom: 6px; display: block;
}
.rf-circle {
  width: 56px; height: 56px; border-radius: 50%;
  border: 3px solid #1D3557; margin: 0 auto 6px;
  position: relative; background: #f0f5fa;
  display: flex; align-items: center; justify-content: center;
}
.rf-arrow-n, .rf-arrow-s {
  position: absolute; font-size: 1rem; font-weight: 900; color: #1D3557;
}
.rf-caption { font-size: 0.7rem; color: #555; line-height: 1.3; }

/* ═══════════════════════════════════════
   STARTING SEQUENCE TIMELINE
═══════════════════════════════════════ */
.start-timeline {
  position: relative; padding-left: 36px;
  margin: 16px 0;
}
.start-timeline::before {
  content: ''; position: absolute; left: 16px; top: 16px;
  bottom: 16px; width: 3px; background: linear-gradient(to bottom, #1D3557, #2E7D52);
  border-radius: 2px;
}
.st-step {
  position: relative; margin-bottom: 16px;
}
.st-step:last-child { margin-bottom: 0; }
.st-dot {
  position: absolute; left: -28px; top: 10px;
  width: 20px; height: 20px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.72rem; font-weight: 900; color: #fff;
  z-index: 1;
}
.st-dot--blue   { background: #1D3557; }
.st-dot--teal   { background: #1D7A7A; }
.st-dot--green  { background: #2E7D52; }
.st-dot--gold   { background: #D4890A; }
.st-dot--red    { background: #E63946; }
.st-card {
  background: #ffffff; border: 1px solid #e0dbd2;
  border-radius: 6px; padding: 12px 14px;
  box-shadow: 0 1px 4px rgba(0,0,0,0.05);
}
.st-phase {
  font-size: 0.68rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.1em; color: #E63946; margin-bottom: 3px;
}
.st-title { font-size: 0.9rem; font-weight: 700; color: #1D3557; margin-bottom: 4px; }
.st-detail { font-size: 0.85rem; line-height: 1.5; color: #3a3f42; }
.st-metric {
  display: inline-block; background: #1D3557; color: #F8F3E7;
  font-size: 0.72rem; font-weight: 700; padding: 2px 8px;
  border-radius: 3px; margin-top: 4px;
}

/* ═══════════════════════════════════════
   TORQUE-SPEED CURVE (CSS bar chart)
═══════════════════════════════════════ */
.torque-chart-wrap {
  background: #f9f7f2; border: 1px solid #e0dbd2;
  border-radius: 8px; padding: 20px 16px; margin: 16px 0;
}
.tq-chart-title {
  font-size: 0.78rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.08em; color: #555; margin-bottom: 16px; text-align: center;
}
.tq-chart {
  display: flex; align-items: flex-end; gap: 6px;
  height: 140px; position: relative;
}
.tq-bar-group {
  flex: 1; display: flex; flex-direction: column;
  align-items: center; gap: 4px;
}
.tq-bar {
  width: 100%; border-radius: 4px 4px 0 0;
  transition: opacity 0.2s;
}
.tq-bar--lrt  { background: #E63946; }
.tq-bar--put  { background: #F5B041; }
.tq-bar--bdt  { background: #2E7D52; }
.tq-bar--flt  { background: #1D3557; }
.tq-bar--op   { background: #6A0DAD; }
.tq-bar-label {
  font-size: 0.64rem; text-align: center; color: #555; line-height: 1.3;
  word-break: break-word;
}
.tq-bar-val {
  font-size: 0.7rem; font-weight: 700; color: #1D3557; margin-bottom: 2px;
}
.tq-legend {
  display: flex; flex-wrap: wrap; gap: 8px;
  margin-top: 14px; justify-content: center;
}
.tq-legend-item {
  display: flex; align-items: center; gap: 5px; font-size: 0.75rem; color: #555;
}
.tq-legend-dot {
  width: 10px; height: 10px; border-radius: 2px; flex-shrink: 0;
}
.tq-arrow {
  position: absolute; bottom: 22px; left: 0; right: 0;
  display: flex; align-items: center;
  font-size: 0.65rem; color: #aaa; pointer-events: none;
}
.tq-arrow::before {
  content: ''; flex: 1; height: 1px; background: #ddd; margin-right: 4px;
}
.tq-arrow::after {
  content: '▶'; font-size: 0.6rem;
}

/* ═══════════════════════════════════════
   LOAD-EFFECT TABLE
═══════════════════════════════════════ */
.styled-table { width: 100%; border-collapse: collapse; font-size: 0.88rem; }
.styled-table th {
  background-color: #1D3557; color: #F8F3E7; padding: 10px 12px;
  text-align: left; font-size: 0.8rem; font-weight: 700; letter-spacing: 0.04em;
}
.styled-table td { padding: 9px 12px; border-bottom: 1px solid #e8e2d6; color: #2F3437; vertical-align: middle; }
.styled-table tbody tr:nth-child(even) { background-color: #f9f7f2; }
.styled-table tbody tr:hover { background-color: #EBF2FA; }
.data-table-wrap { overflow-x: auto; margin-bottom: 4px; }

.trend-up   { color: #E63946; font-weight: 700; }
.trend-down { color: #2E7D52; font-weight: 700; }
.trend-flat { color: #888; font-weight: 700; }

/* ═══════════════════════════════════════
   WINDING CIRCUIT DIAGRAM (CSS)
═══════════════════════════════════════ */
.winding-diagram {
  display: grid; grid-template-columns: 1fr 1fr 1fr;
  gap: 12px; margin: 16px 0;
}
.wd-box {
  border-radius: 8px; border: 2px solid #e0dbd2;
  padding: 14px 12px; text-align: center; position: relative;
}
.wd-box--run    { background: #EBF2FA; border-color: #1D3557; }
.wd-box--start  { background: #FEF0F0; border-color: #E63946; }
.wd-box--cap    { background: #F3EFF8; border-color: #6A0DAD; }
.wd-box--switch { background: #ECEFF1; border-color: #455A64; }
.wd-label {
  font-size: 0.7rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.1em; color: #555; display: block; margin-bottom: 6px;
}
.wd-symbol { font-size: 1.6rem; display: block; margin-bottom: 6px; }
.wd-name { font-size: 0.82rem; font-weight: 700; color: #1D3557; display: block; margin-bottom: 4px; }
.wd-desc { font-size: 0.78rem; line-height: 1.4; color: #3a3f42; }
.wd-badge {
  position: absolute; top: -10px; right: 8px;
  font-size: 0.65rem; font-weight: 700; padding: 2px 8px;
  border-radius: 20px; border: 1px solid;
}
.wd-badge--always { background: #F0F7F4; color: #2E7D52; border-color: #2E7D52; }
.wd-badge--start  { background: #FEF0F0; color: #E63946; border-color: #E63946; }

/* ═══════════════════════════════════════
   HEAT DISSIPATION BAR
═══════════════════════════════════════ */
.heat-bar-wrap {
  background: #f9f7f2; border: 1px solid #e0dbd2;
  border-radius: 8px; padding: 16px; margin: 16px 0;
}
.heat-bar-title {
  font-size: 0.78rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.08em; color: #555; margin-bottom: 12px;
}
.heat-row { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; }
.heat-row:last-child { margin-bottom: 0; }
.heat-source { font-size: 0.82rem; font-weight: 600; color: #2F3437; width: 180px; flex-shrink: 0; }
.heat-track { flex: 1; height: 10px; background: #e0dbd2; border-radius: 5px; overflow: hidden; }
.heat-fill { height: 100%; border-radius: 5px; }
.heat-fill--high { background: linear-gradient(to right, #F5B041, #E63946); }
.heat-fill--med  { background: linear-gradient(to right, #1D3557, #2E7D52); }
.heat-fill--low  { background: #2E7D52; }
.heat-pct { font-size: 0.78rem; font-weight: 700; color: #555; width: 36px; text-align: right; }

/* ═══════════════════════════════════════
   STEP LIST
═══════════════════════════════════════ */
.step-list {
  list-style: none; margin: 12px 0 0; padding: 0;
  display: flex; flex-direction: column; gap: 10px;
  counter-reset: step-counter;
}
.step-list li {
  font-size: 0.95rem; color: #2F3437; padding-left: 36px;
  position: relative; line-height: 1.55; counter-increment: step-counter;
}
.step-list li::before {
  content: counter(step-counter); position: absolute; left: 0; top: 0;
  width: 24px; height: 24px; background-color: #1D3557; color: #fff;
  font-size: 0.75rem; font-weight: 700; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
}


/* QUIZ NAV */
.quiz-nav-container {
  text-align: center;
  margin-bottom: 0.75rem;
}

.quiz-nav {
  display: flex;
  justify-content: center;
}

.quiz-nav-btn {
  display: inline-block;
  background-color: #E63946;
  color: #F8F3E7;
  text-decoration: none;
  padding: 0.85rem 1.4rem;
  border-radius: 0.5rem;
  font-weight: 600;
  transition: background-color 0.2s, transform 0.2s, box-shadow 0.2s;
  box-shadow: 0 4px 12px rgba(29, 53, 87, 0.18);
  border: 2px solid transparent;
}

.quiz-nav-btn:hover {
  background-color: #C92F3B;
  transform: translateY(-1px);
  box-shadow: 0 6px 14px rgba(29, 53, 87, 0.24);
}

.quiz-nav-btn:focus {
  outline: none;
  border-color: #F1C40F;
}

/* FOOTER NAV */
.main-footer-nav {
  background-color: #1D3557; display: flex; justify-content: center;
  gap: 12px; padding: 16px 24px; flex-wrap: wrap;
}
.main-footer-nav-btn {
  display: inline-block; background-color: #F5B041; color: #2F3437;
  font-weight: 700; font-size: 0.9rem; padding: 10px 24px;
  border-radius: 4px; transition: background-color 0.2s; text-decoration: none;
}
.main-footer-nav-btn:hover { background-color: #F8C471; }

/* ═══════════════════════════════════════
   SITE FOOTER
═══════════════════════════════════════ */
.site-footer { background-color: #2F3437; color: #F8F3E7; padding: 40px 24px 24px; }
.footer-container { display: flex; align-items: flex-start; justify-content: center; color: #F1C40F; gap: 32px; max-width: 1200px; margin: 0 auto; }
.footer-col { text-align: left; color: #F1C40F; margin: 0 50px; }
.footer-col a { color: #F1C40F; text-decoration: underline; transition: opacity 0.2s; }
.footer-col a:hover { opacity: 0.5; }
.footer-col h3 { font-size: 1.05rem; color: #F1C40F; margin-bottom: 10px; }
.footer-col p { font-size: 0.9rem; opacity: 0.8; line-height: 1.7; }
.footer-credit { text-align: center; font-size: 0.8rem; opacity: 0.6; margin-top: 24px; padding-top: 16px; border-top: 1px solid rgba(255,255,255,0.15); max-width: 1200px; margin-left: auto; margin-right: auto; }

/* ═══════════════════════════════════════
   RESPONSIVE
═══════════════════════════════════════ */
@media (max-width: 768px) {
  .page-title-main { font-size: 1.5rem; }
  .page-title-block { padding: 24px 20px; }
  .section-art-txt { padding: 20px 16px; }
  .section-art-title { font-size: 1rem; }
  .definition-cards { grid-template-columns: 1fr; }
  .two-col-grid { grid-template-columns: 1fr; }
  .quick-nav-grid { grid-template-columns: repeat(3, 1fr); }
  .footer-container { flex-direction: column; gap: 20px; }
  .rf-diagram { grid-template-columns: repeat(2, 1fr); }
  .winding-diagram { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 480px) {
  .quick-nav-grid { grid-template-columns: repeat(2, 1fr); }
  .rf-diagram { grid-template-columns: repeat(2, 1fr); }
  .winding-diagram { grid-template-columns: 1fr; }
  .heat-source { width: 130px; font-size: 0.76rem; }
  .tq-chart { height: 110px; }
}

/* ── Back to Top ── */
.back-to-top {
  position: fixed; bottom: 28px; right: 24px; z-index: 999;
  padding: 10px 18px; font-size: 0.85rem; opacity: 0; pointer-events: none;
  transition: opacity 0.3s ease, transform 0.3s ease;
  transform: translateY(10px); border-radius: 4px; box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}
.back-to-top.visible { opacity: 1; pointer-events: auto; transform: translateY(0); }

/* ── Scroll Margin ── */
.section-art-txt[id], article[id] { scroll-margin-top: 80px; }