/* ── VARIABLES ─────────────────────────────────────────────── */
:root {
  --primary:      #2563eb;
  --primary-dark: #1d4ed8;
  --accent:       #06b6d4;
  --secondary:    #10b981;
  --bg:           #f8fafc;
  --card:         #ffffff;
  --text:         #0f172a;
  --text-light:   #64748b;
  --border:       #e2e8f0;
  --shadow:       0 1px 3px rgba(0,0,0,0.06), 0 4px 20px rgba(37,99,235,0.07);
  --shadow-hover: 0 8px 32px rgba(37,99,235,0.18);
  --radius:       16px;
}

/* ── DARK MODE ─────────────────────────────────────────────── */
[data-theme="dark"] {
  --primary:      #3b82f6;
  --primary-dark: #1d4ed8;
  --accent:       #22d3ee;
  --secondary:    #10b981;
  --bg:           #0f172a;
  --card:         #1e293b;
  --text:         #f1f5f9;
  --text-light:   #94a3b8;
  --border:       #334155;
  --shadow:       0 2px 8px rgba(0,0,0,0.4);
  --shadow-hover: 0 8px 32px rgba(59,130,246,0.22);
}
[data-theme="dark"] nav { background: #0a1628; border-bottom: 1px solid #1e293b; }
[data-theme="dark"] .page-header { background: linear-gradient(135deg, #0a1628 0%, #1e3a8a 70%, #164e63 100%); }
[data-theme="dark"] .hero { background: linear-gradient(135deg, #0a1628 0%, #1e3a8a 60%, #164e63 100%); }
[data-theme="dark"] .tab-btn { background: #1e293b; color: var(--text-light); border-color: var(--border); }
[data-theme="dark"] .tab-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }
[data-theme="dark"] th { background: #1d4ed8; }
[data-theme="dark"] tr:nth-child(even) td { background: #162032; }
[data-theme="dark"] tr:hover td { background: #1e3a5f; }
[data-theme="dark"] .formula-box { background: linear-gradient(135deg, #1e3a5f, #0d2e20); border-color: var(--primary); }
[data-theme="dark"] .info-box { background: #1e3a5f; border-color: var(--primary); border-left-color: var(--accent); }
[data-theme="dark"] .warn-box { background: #2d2008; border-color: #d97706; border-left-color: #f59e0b; }
[data-theme="dark"] .result-box { background: #0d2e20; border-color: var(--secondary); color: #6ee7b7; }
[data-theme="dark"] .result-error { background: #2d0f0f; border-color: #f87171; color: #fca5a5; }
[data-theme="dark"] input, [data-theme="dark"] select { background: #1e293b; color: var(--text); border-color: var(--border); }
[data-theme="dark"] input:focus, [data-theme="dark"] select:focus { border-color: var(--primary); }
[data-theme="dark"] .quiz-opt { background: #1e293b; border-color: var(--border); color: var(--text); }
[data-theme="dark"] .quiz-opt:hover:not(:disabled) { background: #1e3a5f; border-color: var(--primary); }
[data-theme="dark"] .quiz-score-bar { background: #1e293b; border-color: var(--border); }
[data-theme="dark"] .quiz-cat-btn { background: #1e293b; border-color: var(--border); color: var(--text); }
[data-theme="dark"] .quiz-cat-btn.active { background: var(--primary); border-color: var(--primary); color: #fff; }
[data-theme="dark"] .quiz-score-best { background: #0d2e20; border-color: #10b981; color: #6ee7b7; }
[data-theme="dark"] .quiz-review-item.ok { background: #0d2e20; }
[data-theme="dark"] .quiz-review-item.ng { background: #2d0f0f; }
[data-theme="dark"] .quiz-explain.correct { background: #0d2e20; color: #6ee7b7; }
[data-theme="dark"] .quiz-explain.wrong { background: #2d0f0f; color: #fca5a5; }
[data-theme="dark"] .page-nav a { background: #1e293b; border-color: var(--border); color: var(--text); }
[data-theme="dark"] .page-nav a:hover { background: #1e3a5f; border-color: var(--primary); color: var(--primary); }
[data-theme="dark"] .pdf-card { background: #1e293b; border-color: var(--border); color: var(--text); }
[data-theme="dark"] .pdf-card:hover { border-color: var(--primary); }
[data-theme="dark"] .topic-card { background: #1e293b; border-color: var(--border); color: var(--text); }
[data-theme="dark"] .topic-card:hover { border-color: var(--primary); }
[data-theme="dark"] ul.content-list li { border-color: var(--border); }
[data-theme="dark"] footer { background: #060d1a; }
[data-theme="dark"] .section-title::after { opacity: 0.9; }
[data-theme="dark"] .card:hover { box-shadow: var(--shadow-hover); }
[data-theme="dark"] .quiz-box { background: #1e293b; border-color: var(--border); }
[data-theme="dark"] .quiz-score-bar { background: #1e293b; }

/* ── DARK TOGGLE ───────────────────────────────────────────── */
.dark-toggle { background: none; border: 1.5px solid rgba(255,255,255,0.22); color: #fff; border-radius: 20px; padding: 0.28rem 0.85rem; cursor: pointer; font-size: 0.85rem; font-family: inherit; transition: all 0.2s; white-space: nowrap; }
.dark-toggle:hover { background: rgba(255,255,255,0.12); border-color: rgba(255,255,255,0.5); }

/* ── RESET ─────────────────────────────────────────────────── */
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body { font-family: 'Anuphan', sans-serif; background: var(--bg); color: var(--text); font-size: 16px; line-height: 1.75; }

.skip-link { position: fixed; top: 0.5rem; left: 0.5rem; z-index: 1000; padding: 0.65rem 1rem; border-radius: 10px; background: #fff; color: #0f172a; font-weight: 700; text-decoration: none; transform: translateY(-150%); transition: transform 0.15s; }
.skip-link:focus { transform: translateY(0); }
:where(a, button, input, select, textarea, [tabindex]):focus-visible { outline: 3px solid #fbbf24 !important; outline-offset: 3px; }

/* ── NAV ───────────────────────────────────────────────────── */
nav {
  background: linear-gradient(90deg, #1d4ed8 0%, #1e40af 100%);
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 20px rgba(0,0,0,0.22);
  border-bottom: 1px solid rgba(255,255,255,0.06);
}
.nav-inner { max-width: 1200px; margin: auto; padding: 0 1.5rem; display: flex; align-items: center; gap: 0.35rem; height: 60px; }
.nav-brand { font-size: 1.08rem; font-weight: 800; color: #fff; text-decoration: none; white-space: nowrap; margin-right: auto; letter-spacing: -0.02em; display: flex; align-items: center; gap: 0.35rem; }
.nav-menu { display: flex; align-items: center; gap: 0.2rem; position: relative; }
.nav-link { color: rgba(255,255,255,0.75); text-decoration: none; padding: 0.42rem 0.9rem; border-radius: 20px; font-size: 0.875rem; transition: background 0.15s, color 0.15s; white-space: nowrap; }
.nav-link:hover { background: rgba(255,255,255,0.12); color: #fff; }
.nav-link.active { background: rgba(255,255,255,0.2); color: #fff; font-weight: 700; }
.nav-sep { width: 1px; height: 18px; background: rgba(255,255,255,0.15); margin: 0 0.4rem; }

/* Dropdown */
.nav-dropdown { position: relative; }
.nav-dropdown-toggle { background: none; border: none; color: rgba(255,255,255,0.75); padding: 0.42rem 0.9rem; border-radius: 20px; cursor: pointer; font-size: 0.875rem; font-family: inherit; display: flex; align-items: center; gap: 0.3rem; transition: background 0.15s, color 0.15s; white-space: nowrap; line-height: 1.7; }
.nav-dropdown-toggle:hover, .nav-dropdown.open .nav-dropdown-toggle { background: rgba(255,255,255,0.12); color: #fff; }
.nav-dropdown-toggle.active { background: rgba(255,255,255,0.2); color: #fff; font-weight: 700; }
.nav-chevron { font-size: 0.6rem; opacity: 0.7; transition: transform 0.2s; display: inline-block; }
.nav-dropdown.open .nav-chevron { transform: rotate(180deg); }
.nav-dropdown-menu { display: none; position: absolute; top: calc(100% + 10px); left: 0; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 0.4rem; min-width: 200px; box-shadow: 0 12px 40px rgba(0,0,0,0.15); }
.nav-dropdown-menu-end { right: 0; left: auto; }
.nav-dropdown.open .nav-dropdown-menu { display: block; animation: dd-in 0.15s ease; }
@keyframes dd-in { from { opacity:0; transform:translateY(-8px); } to { opacity:1; transform:translateY(0); } }
.nav-dropdown-menu a { display: flex; align-items: center; gap: 0.5rem; color: var(--text); text-decoration: none; padding: 0.5rem 0.85rem; border-radius: 10px; font-size: 0.9rem; transition: background 0.12s; white-space: nowrap; }
.nav-dropdown-menu a:hover { background: var(--bg); }
.nav-dropdown-menu a.active { background: #eff6ff; color: var(--primary); font-weight: 700; }
/* หน้าลูกที่อยู่ใต้หน้าฮับในดรอปดาวน์ (เช่น เครื่องซักผ้า 3 แบบ) — เยื้องเข้าไปให้เห็นว่าเป็นกลุ่มเดียวกัน */
.nav-dropdown-menu a.nav-sub { padding-left: 1.75rem; position: relative; font-size: 0.86rem; }
/* เส้นไกด์ใช้ currentColor เพื่อให้อ่านออกทั้งดรอปดาวน์บนพื้นสว่าง โหมดมืด และเมนูมือถือที่พื้นเป็นสีทึบ */
.nav-dropdown-menu a.nav-sub::before { content: ""; position: absolute; left: 0.95rem; top: 0.35rem; bottom: 0.35rem;
  width: 2px; border-radius: 2px; background: currentColor; opacity: 0.3; }
.nav-dropdown-menu a.nav-sub.active::before { opacity: 0.75; }
[data-theme="dark"] .nav-dropdown-menu a.active { background: #1e3a5f; color: #93c5fd; }
/* mega panel anchors to the nav-menu's right edge (not the toggle) so a wide
   4-column menu grows leftward and never overflows the right viewport edge */
.nav-dropdown-mega { position: static; }
.nav-mega-menu { width: min(900px, calc(100vw - 2rem)); grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0.65rem; padding: 0.8rem; left: auto; right: 0; }
.nav-dropdown.open .nav-mega-menu { display: grid; }
.nav-mega-group { min-width: 0; padding: 0.25rem; }
.nav-mega-group-toggle { width: 100%; display: flex; align-items: center; justify-content: space-between; gap: 0.5rem; padding: 0.45rem 0.65rem 0.6rem; border: 0; border-bottom: 2px solid var(--border); background: none; color: var(--primary-dark); font: inherit; font-size: 0.83rem; font-weight: 800; text-align: left; }
.nav-group-chevron { display: none; font-size: 0.58rem; transition: transform 0.2s; }
.nav-mega-group-links { display: block; padding-top: 0.3rem; }
.nav-mega-group-links a { white-space: normal; line-height: 1.45; }
[data-theme="dark"] .nav-mega-group-toggle { color: #93c5fd; }

/* Hamburger */
.nav-hamburger { display: none; background: none; border: 1.5px solid rgba(255,255,255,0.25); color: #fff; font-size: 1.1rem; cursor: pointer; padding: 0.3rem 0.65rem; border-radius: 10px; line-height: 1; margin-left: 0.5rem; }

/* ── HERO (home only) ──────────────────────────────────────── */
.hero {
  background: linear-gradient(135deg, #1d4ed8 0%, #2563eb 40%, #0891b2 100%);
  color: #fff;
  text-align: center;
  padding: 5rem 1rem 6rem;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle, rgba(255,255,255,0.07) 1px, transparent 1px);
  background-size: 28px 28px;
  pointer-events: none;
}
.hero h1 { font-size: 2.6rem; font-weight: 800; margin-bottom: 0.75rem; position: relative; letter-spacing: -0.03em; }
.hero p { font-size: 1.15rem; opacity: 0.9; max-width: 580px; margin: auto; position: relative; }

/* ── PAGE HEADER (inner pages) ─────────────────────────────── */
.page-header {
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 65%, var(--accent) 100%);
  color: #fff;
  padding: 2.25rem 1rem 2.5rem;
  position: relative;
  overflow: hidden;
}
.page-header::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle, rgba(255,255,255,0.06) 1px, transparent 1px);
  background-size: 24px 24px;
  pointer-events: none;
}
.page-header-inner { max-width: 1200px; margin: auto; display: flex; align-items: center; gap: 1.25rem; position: relative; }
.page-header-icon { font-size: 2.5rem; filter: drop-shadow(0 2px 8px rgba(0,0,0,0.2)); }
.page-header h1 { font-size: 1.6rem; font-weight: 800; letter-spacing: -0.02em; }
.page-header p { font-size: 0.93rem; opacity: 0.85; margin-top: 0.2rem; }

/* ── CONTAINER ─────────────────────────────────────────────── */
.container { max-width: 1200px; margin: 0 auto; padding: 2.5rem 1.25rem; }

/* ── SECTION ───────────────────────────────────────────────── */
.section { margin-bottom: 3rem; }
.section-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--primary-dark);
  margin-bottom: 1.5rem;
  padding-bottom: 0.85rem;
  border-bottom: 2px solid var(--border);
  position: relative;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.section-title::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 3.5rem;
  height: 2px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  border-radius: 999px;
}
.section-subtitle { font-size: 1.05rem; font-weight: 700; color: var(--secondary); margin: 1.5rem 0 0.85rem; }

/* ── CARDS ─────────────────────────────────────────────────── */
.card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.75rem;
  margin-bottom: 1.5rem;
  border: 1px solid var(--border);
  transition: box-shadow 0.2s, transform 0.18s;
}
.card:hover { box-shadow: var(--shadow-hover); transform: translateY(-2px); }
.card h3 { font-size: 1.05rem; font-weight: 700; margin-bottom: 0.85rem; color: var(--primary-dark); }
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.5rem; }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 1.25rem; }

/* ── TABLE ─────────────────────────────────────────────────── */
table { width: 100%; border-collapse: collapse; font-size: 0.95rem; }
th { background: var(--primary); color: #fff; padding: 0.7rem 0.9rem; text-align: left; font-weight: 600; }
td { padding: 0.6rem 0.9rem; border-bottom: 1px solid var(--border); transition: background 0.12s; }
tr:nth-child(even) td { background: #f8fafc; }
tr:hover td { background: #eff6ff; }

/* ── FORMULA ───────────────────────────────────────────────── */
.formula-box { background: linear-gradient(135deg, #eff6ff, #ecfeff); border: 2px solid var(--primary); border-radius: 14px; padding: 1.25rem 1.5rem; margin: 1rem 0; }
.formula-box .formula { font-size: 1.18rem; font-weight: 700; color: var(--primary-dark); font-family: monospace; }

/* ── INFO / WARN BOXES ─────────────────────────────────────── */
.info-box { background: #eff6ff; border: 1px solid #bfdbfe; border-left: 4px solid var(--primary); border-radius: 12px; padding: 1rem 1.25rem; margin: 1rem 0; font-size: 0.95rem; }
.warn-box { background: #fffbeb; border: 1px solid #fde68a; border-left: 4px solid #f59e0b; border-radius: 12px; padding: 1rem 1.25rem; margin: 1rem 0; font-size: 0.95rem; }

/* ── LIST ──────────────────────────────────────────────────── */
ul.content-list { list-style: none; padding: 0; }
ul.content-list li { padding: 0.45rem 0 0.45rem 1.4rem; border-bottom: 1px solid var(--border); position: relative; }
ul.content-list li::before { content: "▸"; color: var(--accent); font-weight: 700; position: absolute; left: 0; top: 0.45rem; }

/* ── COLOR STRIP ───────────────────────────────────────────── */
.color-strip { display: inline-block; width: 28px; height: 20px; border-radius: 5px; border: 1px solid #ccc; vertical-align: middle; margin-right: 6px; }

/* ── STEPS ─────────────────────────────────────────────────── */
.steps { counter-reset: step; }
.step { display: flex; gap: 1rem; margin-bottom: 1.25rem; align-items: flex-start; }
.step-num { background: linear-gradient(135deg, var(--primary), var(--accent)); color: #fff; border-radius: 50%; width: 34px; height: 34px; min-width: 34px; display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 0.95rem; box-shadow: 0 2px 8px rgba(37,99,235,0.3); }
.step-content { flex: 1; padding-top: 0.35rem; }

/* ── ANNOUNCEMENTS (หน้าแรก) ───────────────────────────────── */
.announcements { margin: 0 0 2rem; }
.ann-head { font-weight: 700; font-size: 1.1rem; color: var(--text); margin: 0 0 0.75rem; }
.ann-item { display: flex; align-items: flex-start; gap: 0.85rem; background: var(--card); border: 1px solid var(--border); border-left: 4px solid var(--primary); border-radius: 12px; padding: 0.85rem 1rem; margin-bottom: 0.6rem; box-shadow: var(--shadow); }
.ann-lesson   { border-left-color: var(--primary); }
.ann-download { border-left-color: var(--secondary); }
.ann-update   { border-left-color: var(--accent); }
.ann-icon { font-size: 1.5rem; line-height: 1.4; }
.ann-body { flex: 1; min-width: 0; }
.ann-tag { display: inline-block; font-size: 0.72rem; font-weight: 600; padding: 0.12rem 0.5rem; border-radius: 999px; background: rgba(37,99,235,0.1); color: var(--primary); margin-right: 0.4rem; }
.ann-download .ann-tag { background: rgba(16,185,129,0.12); color: var(--secondary); }
.ann-update .ann-tag { background: rgba(6,182,212,0.12); color: var(--accent); }
.ann-new { display: inline-block; font-size: 0.66rem; font-weight: 700; color: #fff; background: #ef4444; padding: 0.1rem 0.4rem; border-radius: 999px; margin-right: 0.4rem; animation: annPulse 1.6s ease-in-out infinite; }
@keyframes annPulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.45; } }
.ann-date { font-size: 0.75rem; color: var(--text-light); }
.ann-text { margin-top: 0.2rem; color: var(--text); line-height: 1.5; }
.ann-cta { align-self: center; white-space: nowrap; font-weight: 600; font-size: 0.9rem; color: var(--primary); text-decoration: none; padding: 0.4rem 0.7rem; border: 1px solid var(--border); border-radius: 8px; transition: all 0.2s; }
.ann-cta:hover { background: var(--primary); color: #fff; border-color: var(--primary); }
.ann-x { background: none; border: none; cursor: pointer; font-size: 1.4rem; line-height: 1; color: var(--text-light); padding: 0 0.2rem; align-self: flex-start; }
.ann-x:hover { color: #ef4444; }
@media (max-width: 640px) {
  .ann-cta { align-self: stretch; text-align: center; }
  .ann-item { flex-wrap: wrap; }
}

/* ── DOWNLOADS: ค้นหา + กรองหมวด ────────────────────────────── */
.dl-toolbar { position: sticky; top: 60px; z-index: 40; background: var(--bg); padding: 0.85rem 0; margin-bottom: 1.25rem; border-bottom: 1px solid var(--border); }
.dl-search-wrap { position: relative; margin-bottom: 0.75rem; }
.dl-search-icon { position: absolute; left: 0.9rem; top: 50%; transform: translateY(-50%); font-size: 0.95rem; opacity: 0.6; pointer-events: none; }
.dl-search { width: 100%; padding: 0.7rem 1rem 0.7rem 2.5rem; font-family: inherit; font-size: 0.95rem; color: var(--text); background: var(--card); border: 1px solid var(--border); border-radius: 12px; transition: border-color 0.15s, box-shadow 0.15s; }
.dl-search:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px rgba(37,99,235,0.15); }
.dl-chips { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.dl-chip { display: inline-flex; align-items: center; gap: 0.35rem; padding: 0.4rem 0.85rem; border: 1px solid var(--border); background: var(--card); color: var(--text); border-radius: 999px; cursor: pointer; font-family: inherit; font-size: 0.85rem; transition: background 0.15s, color 0.15s, border-color 0.15s; }
.dl-chip:hover { border-color: var(--primary); color: var(--primary); }
.dl-chip.active { background: var(--primary); border-color: var(--primary); color: #fff; }
.dl-chip-n { font-size: 0.72rem; font-weight: 700; background: rgba(0,0,0,0.08); border-radius: 999px; padding: 0.05rem 0.45rem; }
.dl-chip.active .dl-chip-n { background: rgba(255,255,255,0.25); }
[data-theme="dark"] .dl-chip-n { background: rgba(255,255,255,0.12); }
.dl-noresult { text-align: center; color: var(--text-light); font-size: 0.95rem; padding: 2rem 0; }
.dl-credit { background: var(--card); border: 1px solid var(--border); border-left: 4px solid var(--secondary); border-radius: 12px; padding: 0.7rem 1rem; margin-bottom: 1rem; font-size: 0.9rem; color: var(--text); }
.dl-credit strong { color: var(--primary); }
.pdf-card.dl-hidden, .section.dl-hidden { display: none; }

/* ── TABS ──────────────────────────────────────────────────── */
.tabs { display: flex; gap: 0.5rem; margin-bottom: 1.25rem; flex-wrap: wrap; }
.tab-btn { padding: 0.5rem 1.25rem; border-radius: 20px; border: 2px solid var(--border); background: var(--card); cursor: pointer; font-family: inherit; font-size: 0.92rem; font-weight: 600; color: var(--text-light); transition: all 0.2s; }
.tab-btn:hover { border-color: var(--primary); color: var(--primary); }
.tab-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); box-shadow: 0 4px 12px rgba(37,99,235,0.25); }
.tab-content { display: none; }
.tab-content.active { display: block; }

/* ── INTERACTIVE TOOLS ─────────────────────────────────────── */
.tool-box { background: var(--card); border-radius: var(--radius); box-shadow: var(--shadow); padding: 1.75rem; border: 2px solid var(--border); margin-bottom: 1.75rem; transition: border-color 0.2s, box-shadow 0.2s; }
.tool-box:hover { border-color: var(--primary); box-shadow: var(--shadow-hover); }
.tool-title { font-size: 1.15rem; font-weight: 700; color: var(--primary-dark); margin-bottom: 1.25rem; display: flex; align-items: center; gap: 0.65rem; }
.tool-title > span:first-child { background: linear-gradient(135deg, var(--primary), var(--accent)); color: #fff; border-radius: 50%; width: 30px; height: 30px; display: flex; align-items: center; justify-content: center; font-size: 0.88rem; min-width: 30px; box-shadow: 0 2px 8px rgba(37,99,235,0.3); }
label { display: block; font-weight: 600; margin-bottom: 0.3rem; margin-top: 0.85rem; font-size: 0.95rem; }
input[type=number], input[type=text], select { width: 100%; padding: 0.6rem 0.85rem; border: 2px solid var(--border); border-radius: 10px; font-size: 1rem; font-family: inherit; transition: border-color 0.2s, box-shadow 0.2s; }
input[type=number]:focus, input[type=text]:focus, select:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px rgba(37,99,235,0.12); }
.btn { display: inline-block; background: linear-gradient(135deg, var(--primary), var(--primary-dark)); color: #fff; border: none; padding: 0.7rem 1.75rem; border-radius: 20px; font-size: 1rem; font-weight: 700; cursor: pointer; margin-top: 1rem; transition: all 0.2s; font-family: inherit; text-decoration: none; box-shadow: 0 4px 14px rgba(37,99,235,0.3); }
.btn:hover { background: linear-gradient(135deg, var(--primary-dark), #1e3a8a); box-shadow: 0 6px 20px rgba(37,99,235,0.4); transform: translateY(-1px); }
.btn:active { transform: scale(0.97); }
.btn-green { background: linear-gradient(135deg, var(--secondary), #059669); box-shadow: 0 4px 14px rgba(16,185,129,0.3); }
.btn-green:hover { background: linear-gradient(135deg, #059669, #047857); box-shadow: 0 6px 20px rgba(16,185,129,0.4); }
.result-box { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0fdf4; border: 2px solid var(--secondary); border-radius: 12px; font-size: 1rem; font-weight: 700; color: #065f46; min-height: 2.75rem; }
.result-error { background: #fef2f2; border-color: #f87171; color: #991b1b; }

/* ── RESISTOR VISUAL ───────────────────────────────────────── */
#r4_b1, #r4_b2, #r4_b3, #r4_b4 { width: 24px; }

/* ── TOPIC CARDS (home page) ───────────────────────────────── */
.topic-card { background: var(--card); border-radius: 20px; box-shadow: var(--shadow); padding: 1.75rem 1.25rem; border: 1px solid var(--border); cursor: pointer; transition: box-shadow 0.2s, transform 0.18s, border-color 0.2s; text-align: center; text-decoration: none; color: var(--text); display: block; }
.topic-card:hover { box-shadow: var(--shadow-hover); transform: translateY(-5px); border-color: var(--primary); }
.topic-card .icon { font-size: 2.5rem; margin-bottom: 0.75rem; display: block; }
.topic-card h3 { font-size: 0.97rem; font-weight: 700; color: var(--primary-dark); margin-bottom: 0.35rem; }
.topic-card p { font-size: 0.82rem; color: var(--text-light); }
.topic-card-blue   { border-top: 4px solid var(--primary); }
.topic-card-teal   { border-top: 4px solid var(--accent); }
.topic-card-orange { border-top: 4px solid #f59e0b; }
.topic-card-green  { border-top: 4px solid var(--secondary); }

/* ── PDF CARDS ─────────────────────────────────────────────── */
.pdf-card { display:flex; align-items:center; gap:1rem; background:var(--card); border:1px solid var(--border); border-radius:var(--radius); padding:1.1rem 1.4rem; text-decoration:none; color:var(--text); box-shadow:var(--shadow); transition:box-shadow 0.2s, transform 0.18s, border-color 0.2s; }
.pdf-card:hover { box-shadow:var(--shadow-hover); transform:translateY(-2px); border-color:var(--primary); }
.pdf-icon { font-size:1.75rem; min-width:2rem; text-align:center; }
.pdf-info { flex:1; }
.pdf-title { font-weight:700; font-size:0.97rem; color:var(--primary-dark); margin-bottom:0.2rem; }
.pdf-sub { font-size:0.82rem; color:var(--text-light); }
.pdf-dl { font-size:1.3rem; color:var(--primary); min-width:1.5rem; text-align:center; }

/* ── QUIZ ──────────────────────────────────────────────────── */
.quiz-cat-grid { display:grid; grid-template-columns:repeat(auto-fit,minmax(160px,1fr)); gap:0.85rem; margin-bottom:1.75rem; }
.quiz-cat-btn { background:var(--card); border:2px solid var(--border); border-radius:var(--radius); padding:1.1rem 0.75rem; cursor:pointer; text-align:center; transition:all 0.2s; font-family:inherit; }
.quiz-cat-btn:hover { border-color:var(--primary); box-shadow:0 4px 16px rgba(37,99,235,0.14); transform:translateY(-2px); }
.quiz-cat-btn.active { border-color:var(--primary); background:var(--primary); color:#fff; box-shadow:0 4px 16px rgba(37,99,235,0.3); }
.quiz-cat-btn .cat-icon { font-size:1.7rem; display:block; margin-bottom:0.4rem; }
.quiz-cat-btn .cat-name { font-size:0.85rem; font-weight:700; }
.quiz-cat-btn .cat-count { font-size:0.75rem; opacity:0.7; }
.quiz-score-bar { display:flex; gap:1rem; align-items:center; background:var(--card); border:1px solid var(--border); border-radius:var(--radius); padding:0.85rem 1.4rem; margin-bottom:1.4rem; flex-wrap:wrap; }
.quiz-score-item { text-align:center; }
.quiz-score-item .sq-num { font-size:1.5rem; font-weight:800; color:var(--primary-dark); line-height:1; }
.quiz-score-item .sq-label { font-size:0.75rem; color:var(--text-light); }
.quiz-score-best { margin-left:auto; background:#f0fdf4; border:1px solid #a7f3d0; border-radius:20px; padding:0.4rem 1rem; font-size:0.88rem; font-weight:700; color:#065f46; }
.quiz-box { background:var(--card); border:1px solid var(--border); border-radius:var(--radius); padding:1.75rem; box-shadow:var(--shadow); }
.quiz-progress { height:6px; background:#e2e8f0; border-radius:999px; margin-bottom:1.4rem; overflow:hidden; }
.quiz-progress-fill { height:100%; background:linear-gradient(90deg,var(--primary),var(--accent)); border-radius:999px; transition:width 0.4s; }
.quiz-qnum { font-size:0.82rem; color:var(--text-light); margin-bottom:0.5rem; }
.quiz-question { font-size:1.08rem; font-weight:700; color:var(--text); margin-bottom:1.4rem; line-height:1.65; }
.quiz-options { display:flex; flex-direction:column; gap:0.7rem; }
.quiz-opt { display:flex; align-items:center; gap:0.75rem; padding:0.8rem 1.1rem; border:2px solid var(--border); border-radius:12px; cursor:pointer; font-family:inherit; font-size:0.97rem; background:var(--card); text-align:left; transition:all 0.15s; width:100%; }
.quiz-opt:hover:not(:disabled) { border-color:var(--primary); background:#eff6ff; transform:translateX(2px); }
.quiz-opt.correct { border-color:#10b981; background:#d1fae5; color:#065f46; font-weight:700; }
.quiz-opt.wrong { border-color:#ef4444; background:#fee2e2; color:#991b1b; }
.quiz-opt.reveal { border-color:#10b981; background:#d1fae5; color:#065f46; }
.quiz-opt:disabled { cursor:default; }
.quiz-opt-letter { width:28px; height:28px; min-width:28px; border-radius:50%; border:2px solid currentColor; display:flex; align-items:center; justify-content:center; font-weight:700; font-size:0.82rem; }
.quiz-explain { margin-top:1rem; padding:1rem 1.25rem; border-radius:12px; font-size:0.93rem; line-height:1.65; }
.quiz-explain.correct { background:#d1fae5; border-left:4px solid #10b981; color:#065f46; }
.quiz-explain.wrong { background:#fee2e2; border-left:4px solid #ef4444; color:#991b1b; }
.quiz-nav { display:flex; gap:0.75rem; margin-top:1.4rem; align-items:center; flex-wrap:wrap; }
.quiz-finish { text-align:center; padding:2.5rem 1rem; }
.quiz-finish .big-score { font-size:3.75rem; font-weight:800; color:var(--primary-dark); line-height:1; }
.quiz-finish .score-label { font-size:1rem; color:var(--text-light); margin-bottom:1rem; }
.quiz-finish .score-msg { font-size:1.1rem; font-weight:700; margin-bottom:1.75rem; }
.quiz-review { margin-top:1rem; text-align:left; }
.quiz-review-item { padding:0.85rem; border-radius:12px; margin-bottom:0.6rem; font-size:0.9rem; }
.quiz-review-item.ok { background:#d1fae5; }
.quiz-review-item.ng { background:#fee2e2; }

/* ── FORMULA SHEET ─────────────────────────────────────────── */
.formula-sheet-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; margin-bottom: 2.25rem; }
.fs-card { border-radius: var(--radius); padding: 1.4rem; border: 2px solid transparent; }
.fs-card-title { font-weight: 700; font-size: 0.92rem; margin-bottom: 0.9rem; display: flex; align-items: center; gap: 0.4rem; }
.fs-main { font-size: 1.9rem; font-weight: 800; text-align: center; padding: 0.4rem 0 0.6rem; letter-spacing: -0.02em; }
.fs-variants { display: flex; gap: 0.6rem; justify-content: center; flex-wrap: wrap; margin-top: 0.4rem; }
.fs-variants span { background: rgba(0,0,0,0.07); padding: 0.2rem 0.8rem; border-radius: 20px; font-size: 0.9rem; font-weight: 600; }
.fs-sub { text-align: center; font-size: 1.05rem; font-weight: 700; margin-top: 0.65rem; padding: 0.35rem 0.5rem; background: rgba(0,0,0,0.06); border-radius: 10px; }
.fs-legend { font-size: 0.76rem; color: var(--text-light); margin-top: 0.55rem; text-align: center; line-height: 1.6; }
.fs-tbl { width: 100%; border-collapse: collapse; margin-top: 0.5rem; font-size: 0.84rem; }
.fs-tbl th { padding: 0.3rem 0.5rem; background: rgba(0,0,0,0.09); font-size: 0.78rem; text-align: center; }
.fs-tbl td { padding: 0.35rem 0.5rem; text-align: center; border-top: 1px solid rgba(0,0,0,0.06); }
/* Card color themes */
.fs-blue  { background:#eff6ff; border-color:#3b82f6; } .fs-blue .fs-card-title { color:#1d4ed8; } .fs-blue .fs-main { color:#1e40af; }
.fs-green { background:#f0fdf4; border-color:#22c55e; } .fs-green .fs-card-title { color:#15803d; } .fs-green .fs-main { color:#166534; }
.fs-orange{ background:#fff7ed; border-color:#f97316; } .fs-orange .fs-card-title { color:#c2410c; }
.fs-purple{ background:#faf5ff; border-color:#a855f7; } .fs-purple .fs-card-title { color:#7e22ce; }
.fs-teal  { background:#f0fdfa; border-color:#14b8a6; } .fs-teal .fs-card-title { color:#0f766e; }
.fs-red   { background:#fef2f2; border-color:#ef4444; } .fs-red .fs-card-title { color:#b91c1c; } .fs-red .fs-main { color:#991b1b; font-size:1.35rem; }
[data-theme="dark"] .fs-blue   { background:#1e3a5f; } [data-theme="dark"] .fs-blue .fs-main { color:#93c5fd; }
[data-theme="dark"] .fs-green  { background:#0d2e20; } [data-theme="dark"] .fs-green .fs-main { color:#6ee7b7; }
[data-theme="dark"] .fs-orange { background:#2d1a0a; } [data-theme="dark"] .fs-orange .fs-card-title { color:#fb923c; }
[data-theme="dark"] .fs-purple { background:#2e1a47; } [data-theme="dark"] .fs-purple .fs-card-title { color:#c084fc; }
[data-theme="dark"] .fs-teal   { background:#0d2e2a; } [data-theme="dark"] .fs-teal .fs-card-title { color:#5eead4; }
[data-theme="dark"] .fs-red    { background:#2d0f0f; } [data-theme="dark"] .fs-red .fs-main { color:#fca5a5; }
[data-theme="dark"] .fs-variants span { background: rgba(255,255,255,0.1); }
[data-theme="dark"] .fs-sub { background: rgba(255,255,255,0.08); }
[data-theme="dark"] .fs-tbl th { background: rgba(255,255,255,0.1); color: var(--text); }
[data-theme="dark"] .fs-tbl td { border-color: rgba(255,255,255,0.06); }

/* Reference tables */
.fs-ref-section { margin-bottom: 2.25rem; }
.fs-ref-title { font-size: 1.05rem; font-weight: 700; color: var(--primary-dark); margin-bottom: 0.85rem; display: flex; align-items: center; gap: 0.4rem; }
.fs-ref-table { width: 100%; border-collapse: collapse; font-size: 0.88rem; border-radius: 12px; overflow: hidden; }
.fs-ref-table th { background: var(--primary-dark); color: #fff; padding: 0.5rem 0.85rem; text-align: left; font-weight: 600; }
.fs-ref-table td { padding: 0.45rem 0.85rem; border-bottom: 1px solid var(--border); }
.fs-ref-table tr:last-child td { border-bottom: none; }
.fs-ref-table tr:nth-child(even) td { background: var(--bg); }
.rc-dot { display: inline-block; width: 14px; height: 14px; border-radius: 3px; vertical-align: middle; margin-right: 0.4rem; border: 1px solid rgba(0,0,0,0.15); }

/* Print-only header */
.print-sheet-header { display: none; text-align: center; margin-bottom: 1rem; padding-bottom: 0.75rem; border-bottom: 2px solid #000; }
.print-sheet-header h2 { font-size: 1.1rem; font-weight: 800; }
.print-sheet-header p { font-size: 0.85rem; margin-top: 0.4rem; }

/* ── BACK TO TOP ───────────────────────────────────────────── */
#back-to-top { position:fixed; bottom:2rem; right:2rem; width:46px; height:46px; border-radius:50%; background:linear-gradient(135deg,var(--primary),var(--accent)); color:#fff; border:none; cursor:pointer; font-size:1.3rem; box-shadow:0 4px 16px rgba(37,99,235,0.35); opacity:0; pointer-events:none; transform:translateY(12px); transition:opacity 0.3s,transform 0.3s; z-index:998; display:flex; align-items:center; justify-content:center; line-height:1; }
#back-to-top.visible { opacity:1; pointer-events:auto; transform:translateY(0); }
#back-to-top:hover { box-shadow:0 6px 24px rgba(37,99,235,0.5); transform:translateY(-3px); }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; scroll-behavior: auto !important; transition-duration: 0.01ms !important; }
}

/* ── PRINT ─────────────────────────────────────────────────── */
@media print {
  nav, .page-header, .print-hide, footer, .page-nav { display: none !important; }
  .print-sheet-header { display: block !important; }
  body { background: #fff !important; color: #000 !important; font-size: 10.5pt; }
  .container { padding: 0; max-width: 100%; }
  .formula-sheet-grid { grid-template-columns: 1fr 1fr; gap: 0.6rem; margin-bottom: 1rem; }
  .fs-card { background: #fff !important; border: 1.5px solid #999 !important; padding: 0.7rem; break-inside: avoid; }
  .fs-card-title { color: #000 !important; font-size: 0.82rem; }
  .fs-main { color: #000 !important; font-size: 1.5rem; }
  .fs-variants span { background: #eee !important; }
  .fs-sub { background: #f2f2f2 !important; color: #000; }
  .fs-legend { color: #555; }
  .fs-tbl th { background: #ddd !important; color: #000 !important; -webkit-print-color-adjust: exact; print-color-adjust: exact; }
  .fs-ref-table th { background: #333 !important; -webkit-print-color-adjust: exact; print-color-adjust: exact; }
  .rc-dot { -webkit-print-color-adjust: exact; print-color-adjust: exact; }
  .fs-ref-section { break-inside: avoid; }
}

/* ── LANGUAGE SWITCHING ────────────────────────────────────── */
html[lang="en"] .th-only { display: none !important; }
html:not([lang="en"]) .en-only { display: none !important; }
.lang-toggle { display: flex; align-items: center; gap: 0.15rem; }
.lang-btn { background: none; border: 1.5px solid rgba(255,255,255,0.22); color: rgba(255,255,255,0.65); border-radius: 20px; padding: 0.22rem 0.65rem; cursor: pointer; font-size: 0.78rem; font-family: inherit; transition: all 0.15s; line-height: 1.4; }
.lang-btn:hover { background: rgba(255,255,255,0.12); color: #fff; }
.lang-btn.active { background: rgba(255,255,255,0.22); color: #fff; border-color: rgba(255,255,255,0.5); font-weight: 700; }

/* ── PAGE NAV (prev / next) ────────────────────────────────── */
.page-nav { display:flex; justify-content:space-between; gap:1rem; margin-top:2.5rem; padding-top:2rem; border-top:2px solid var(--border); flex-wrap:wrap; }
.page-nav a { display:flex; align-items:center; gap:0.6rem; padding:0.85rem 1.4rem; border-radius:var(--radius); border:2px solid var(--border); text-decoration:none; color:var(--text); font-weight:700; font-size:0.92rem; background:var(--card); transition:all 0.2s; }
.page-nav a:hover { border-color:var(--primary); color:var(--primary); background:#eff6ff; transform:translateY(-1px); box-shadow:0 4px 16px rgba(37,99,235,0.12); }
.page-nav .next { margin-left:auto; }

/* ── FOOTER ────────────────────────────────────────────────── */
footer { background: linear-gradient(90deg, #0f172a 0%, #1d4ed8 100%); color: #94a3b8; text-align: center; padding: 2rem 1.5rem; font-size: 0.9rem; margin-top: 2.5rem; }
footer strong { color: #fff; }
.footer-topics { margin-top: 0.35rem; font-size: 0.9rem; }
.footer-credit { margin-top: 0.75rem; font-size: 0.85rem; }
.footer-credit strong { color: #fff; }
.footer-credit a { color: inherit; text-decoration: underline; text-underline-offset: 2px; }
.footer-credit a:hover { color: #fff; }
.footer-license { margin-top: 0.75rem; font-size: 0.78rem; opacity: 0.85; }
.footer-license a { color: inherit; text-decoration: underline; text-underline-offset: 2px; }
.footer-license a:hover { color: #fff; opacity: 1; }

/* ── RESPONSIVE ────────────────────────────────────────────── */
@media (max-width: 768px) {
  .nav-hamburger { display: flex; }
  .nav-menu {
    display: none; position: absolute; top: 60px; left: 0; right: 0;
    background: #1d4ed8; flex-direction: column; align-items: stretch;
    padding: 1rem 1.25rem 1.25rem; gap: 0.2rem;
    border-top: 1px solid rgba(255,255,255,0.1);
    box-shadow: 0 12px 32px rgba(0,0,0,0.35);
  }
  .nav-menu.open { display: flex; }
  .nav-link, .nav-dropdown-toggle { width: 100%; text-align: left; border-radius: 10px; }
  .nav-sep { width: 100%; height: 1px; margin: 0.35rem 0; }
  .nav-dropdown-menu { position: static; background: rgba(0,0,0,0.22); border: none; border-radius: 10px; box-shadow: none; margin-top: 0.15rem; }
  .nav-dropdown.open .nav-mega-menu { display: block; width: auto; padding: 0.4rem; }
  .nav-mega-group { padding: 0; }
  .nav-mega-group + .nav-mega-group { border-top: 1px solid rgba(255,255,255,0.12); }
  .nav-mega-group-toggle { padding: 0.65rem 0.75rem; border: 0; color: #fff; cursor: pointer; font-size: 0.86rem; }
  .nav-group-chevron { display: inline-block; }
  .nav-mega-group.open .nav-group-chevron { transform: rotate(180deg); }
  .nav-mega-group-links { display: none; padding: 0 0.25rem 0.45rem; }
  .nav-mega-group.open .nav-mega-group-links { display: block; }
  [data-theme="dark"] .nav-mega-group-toggle { color: #fff; }
  .nav-dropdown-menu a { color: rgba(255,255,255,0.82); }
  .nav-dropdown-menu a:hover { background: rgba(255,255,255,0.1); color: #fff; }
  .nav-dropdown-menu a.active { background: rgba(255,255,255,0.18); color: #fff; }
  [data-theme="dark"] .nav-dropdown-menu a.active { background: rgba(255,255,255,0.15); color: #fff; }
  .dark-toggle { width: 100%; margin-top: 0.5rem; text-align: center; }
  .lang-toggle { justify-content: center; margin-top: 0.25rem; }
}
@media (max-width: 640px) {
  .hero h1 { font-size: 1.65rem; }
  .page-header h1 { font-size: 1.25rem; }
  .formula-sheet-grid { grid-template-columns: 1fr; }
  .container { padding: 1.75rem 1rem; }
}

/* ── SLIDER SIM (shared: water-heater.html; หน้าเก่าอย่าง thyristor/igbt/op-amp
   ยังมีสำเนา .sim-* ใน <style> ของตัวเอง — กฎเดียวกับ .bs-* คือหน้าใหม่ใช้ชุดนี้ ห้ามก๊อปไปฝัง) ── */
.sim-wrap { display:grid; grid-template-columns:1fr 285px; gap:1.25rem; align-items:start; }
@media (max-width:860px){ .sim-wrap{ grid-template-columns:1fr; } }
.sim-screen { width:100%; height:auto; display:block; border-radius:12px; background:#0b1220; border:1px solid var(--border); }
.sim-panel { background:var(--card); border:1px solid var(--border); border-radius:var(--radius); padding:.9rem 1rem; }
.sim-ctrl { margin-bottom:.9rem; }
.sim-ctrl-row { display:flex; justify-content:space-between; align-items:center; font-size:.84rem; font-weight:600; margin-bottom:.25rem; }
.sim-ctrl-row span { color:var(--primary); font-size:.9rem; }
.sim-ctrl input[type=range] { width:100%; cursor:pointer; accent-color:var(--primary); }
.sim-readout { display:grid; grid-template-columns:1fr 1fr; gap:.45rem; margin-top:.4rem; }
.sim-rb { background:var(--bg); border:1px solid var(--border); border-radius:9px; padding:.45rem .6rem; text-align:center; }
.sim-rl { font-size:.72rem; color:var(--text-light); margin-bottom:.12rem; }
.sim-rv { font-size:1.02rem; font-weight:700; color:var(--text); }
.sim-modes { display:flex; gap:.4rem; margin-bottom:.9rem; }
.sim-modes button { flex:1; padding:.45rem .3rem; font-family:inherit; font-size:.85rem; font-weight:600; cursor:pointer;
  border:1px solid var(--border); background:var(--bg); color:var(--text); border-radius:9px; }
.sim-modes button.active { background:var(--primary); border-color:var(--primary); color:#fff; }
.sim-verdict { margin-top:.7rem; padding:.5rem .65rem; border-radius:9px; font-size:.83rem; font-weight:600; text-align:center;
  background:var(--bg); border:1px solid var(--border); color:var(--text); }
.sim-btn { width:100%; margin-top:.2rem; padding:.45rem .3rem; font-family:inherit; font-size:.85rem; font-weight:700; cursor:pointer;
  border:1px solid var(--border); background:var(--bg); color:var(--text); border-radius:9px; }
.sim-btn:hover { border-color:var(--primary); color:var(--primary); }

/* ── INTERACTIVE STEP-BY-STEP (shared: transistor.html, switching-psu.html) ── */
.bs-wrap { background:var(--bg); border:1px solid var(--border); border-radius:var(--radius); padding:1rem; }
.bs-tabs { display:grid; grid-template-columns:repeat(auto-fit,minmax(125px,1fr)); gap:.4rem; margin-bottom:.9rem; }
.bs-tab { display:flex; align-items:center; gap:.45rem; justify-content:center; text-align:center;
  background:var(--card); border:1px solid var(--border); border-radius:10px; padding:.5rem .5rem;
  font:inherit; font-size:.82rem; font-weight:600; color:var(--text-light); cursor:pointer; transition:.15s; }
.bs-tab:hover { border-color:var(--primary); color:var(--text); }
.bs-tab .bs-n { display:flex; align-items:center; justify-content:center; min-width:22px; height:22px;
  border-radius:50%; background:var(--border); color:var(--text); font-size:.78rem; font-weight:800; }
.bs-tab.active { background:var(--primary); border-color:var(--primary); color:#fff; box-shadow:0 2px 8px rgba(37,99,235,.3); }
.bs-tab.active .bs-n { background:rgba(255,255,255,.28); color:#fff; }
.bs-canvas { width:100%; height:auto; aspect-ratio:680/320; display:block;
  background:var(--card); border:1px solid var(--border); border-radius:12px; }
.bs-nav { display:flex; gap:.5rem; justify-content:center; margin:.75rem 0; }
.bs-navbtn { background:var(--card); border:1px solid var(--border); border-radius:9px; padding:.4rem .9rem;
  font:inherit; font-size:.85rem; font-weight:600; color:var(--text); cursor:pointer; transition:.15s; }
.bs-navbtn:hover { border-color:var(--primary); color:var(--primary); }
.bs-navbtn.active { background:var(--primary); border-color:var(--primary); color:#fff; }
.bs-desc { display:none; background:var(--card); border:1px solid var(--border); border-left:4px solid var(--accent);
  border-radius:12px; padding:.9rem 1.1rem; font-size:.93rem; }
.bs-desc.active { display:block; }
.bs-desc p { margin:0; }
/* ช่องเลือกอาการเสีย + แถบเตือนของซิมทีละขั้น (switching-psu ยังใช้ .sp-* ของตัวเองอยู่;
   ซิมใหม่ให้ใช้ 2 คลาสนี้แทน จะได้ไม่ต้องก๊อป CSS ไปฝังในแต่ละหน้า) */
.bs-select { background:var(--card); border:1px solid var(--border); border-radius:9px; padding:.4rem .7rem;
  font-family:inherit; font-size:.85rem; font-weight:600; color:var(--text); cursor:pointer; }
.bs-select:hover { border-color:var(--primary); }
.bs-faultnote { display:none; background:#fef2f2; border:1px solid #fecaca; border-left:4px solid #dc2626;
  border-radius:10px; padding:.6rem .85rem; margin:.75rem 0 0; font-size:.87rem; color:#b91c1c; }
.bs-faultnote.active { display:block; }
[data-theme="dark"] .bs-faultnote { background:rgba(220,38,38,.12); border-color:rgba(220,38,38,.35); color:#fca5a5; }
@media (max-width:700px){ .bs-tabs{ grid-template-columns:repeat(2,1fr); } }

/* ── WASHING MACHINE (shared: washing-machine.html + หน้าลูก 2 ถัง / ฝาบน / ฝาหน้า) ──
   ห้ามก๊อปกลับไปฝังใน <style> ของหน้าตัวเอง — ทั้ง 4 หน้าใช้ชุดนี้ร่วมกัน */
.wm-steps { display:grid; grid-template-columns:repeat(4,1fr); gap:.5rem; align-items:stretch; }
@media (max-width:760px){ .wm-steps{ grid-template-columns:1fr 1fr; } }
.wm-step { background:var(--bg); border:1px solid var(--border); border-radius:12px; padding:.85rem .6rem; text-align:center; }
.wm-step .wm-num { display:inline-block; width:24px; height:24px; line-height:24px; border-radius:50%; background:var(--primary); color:#fff; font-weight:700; font-size:.82rem; margin-bottom:.4rem; }
.wm-step h4 { margin:.2rem 0 .35rem; font-size:.9rem; color:var(--primary-dark); }
.wm-step p { margin:0; font-size:.78rem; color:var(--text-light); }
/* ห้ามใส่ white-space:nowrap กับช่องเหล่านี้ — มันเก็บประโยค ไม่ใช่ค่าสั้นๆ ตารางจะดันออกนอกจอ */
.wm-tbl td.hi { font-weight:700; color:var(--primary-dark); }
.wm-tbl td.val { font-weight:700; color:var(--secondary); }
.wm-tbl td.bad { font-weight:700; color:#dc2626; }
.wm-tbl th, .wm-tbl td { vertical-align:top; line-height:1.45; }
.wm-scroll { overflow-x:auto; -webkit-overflow-scrolling:touch; margin-top:1rem; }
.wm-scroll table { min-width:600px; margin-top:0; }
@media (max-width:640px){ .wm-tbl { font-size:.8rem; } }
.wm-fault { border:1px solid var(--border); border-radius:12px; padding:1rem 1.15rem; margin:0 0 1rem; border-left-width:5px; border-left-style:solid; }
.wm-fault:last-child { margin-bottom:0; }
.wm-fault-title { font-weight:700; margin-bottom:.4rem; display:block; }
.wm-formula { background:var(--bg); border:1px dashed var(--border); border-radius:10px; padding:.8rem 1rem; text-align:center; font-size:1.05rem; font-weight:700; color:var(--primary-dark); margin:.8rem 0; }
.wm-wire { display:inline-block; width:14px; height:14px; border-radius:4px; vertical-align:-2px; margin-right:.4rem; border:1px solid rgba(0,0,0,.15); }