/* ============================================================
   ครีมวิทยาศาสตร์ — อะตอมและสมบัติของธาตุ (Interactive)
   ============================================================ */
:root {
  --bg: #0c0f24;
  --bg2: #151a3a;
  --card: #1b2148;
  --card2: #242b58;
  --line: #303a6e;
  --text: #e8ecff;
  --muted: #9aa6d8;
  --gold: #ffd166;
  --teal: #4ecdc4;
  --pink: #ff6b9d;
  --green: #7ce38b;
  --red: #ff7575;
  --blue: #6ea8ff;
  --radius: 14px;
  font-size: 16px;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Sarabun', 'Prompt', 'Noto Sans Thai', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  min-height: 100vh;
}
/* animated atom background */
#bgfx {
  position: fixed; inset: 0; z-index: -1; pointer-events: none;
}

/* ---------- layout ---------- */
header.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 14px;
  padding: 10px 22px;
  background: rgba(11,16,38,.85); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
header.topbar .logo { font-size: 1.5rem; }
header.topbar h1 { font-size: 1.05rem; font-weight: 700; color: var(--gold); }
header.topbar .sub { font-size: .78rem; color: var(--muted); }
header.topbar .home-btn {
  margin-left: auto; text-decoration: none; color: var(--text);
  background: var(--card); border: 1px solid var(--line);
  padding: 6px 16px; border-radius: 99px; font-size: .9rem;
}
header.topbar .home-btn:hover { background: var(--card2); border-color: var(--gold); }

main { max-width: 1000px; margin: 0 auto; padding: 28px 18px 90px; }

/* ---------- home ---------- */
.hero { text-align: center; padding: 30px 10px 10px; }
.hero h2 { font-size: 1.9rem; color: var(--gold); margin-bottom: 6px; }
.hero p { color: var(--muted); max-width: 640px; margin: 0 auto 8px; }
.hero .badge-row { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; margin-top: 14px; }
.hero .badge {
  font-size: .8rem; padding: 4px 14px; border-radius: 99px;
  background: var(--card); border: 1px solid var(--line); color: var(--teal);
}
.section-label {
  margin: 34px 0 14px; font-size: 1.15rem; font-weight: 700; color: var(--teal);
  display: flex; align-items: center; gap: 10px;
}
.section-label::after { content: ''; flex: 1; height: 1px; background: var(--line); }

.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(290px, 1fr)); gap: 16px; }
.lesson-card {
  background: linear-gradient(160deg, var(--card), var(--bg2));
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px; cursor: pointer; text-decoration: none; color: var(--text);
  transition: transform .15s, border-color .15s; position: relative; display: block;
}
.lesson-card:hover { transform: translateY(-3px); border-color: var(--gold); }
.lesson-card .icon { font-size: 1.9rem; }
.lesson-card h3 { font-size: 1.02rem; margin: 8px 0 4px; color: var(--gold); }
.lesson-card p { font-size: .85rem; color: var(--muted); }
.lesson-card .tags { margin-top: 10px; display: flex; gap: 6px; flex-wrap: wrap; }
.lesson-card .tag {
  font-size: .72rem; padding: 2px 10px; border-radius: 99px;
  background: rgba(78,205,196,.12); color: var(--teal); border: 1px solid rgba(78,205,196,.3);
}
.lesson-card .tag.quiz { background: rgba(255,209,102,.1); color: var(--gold); border-color: rgba(255,209,102,.3); }
.lesson-card .tag.ws { background: rgba(255,107,157,.1); color: var(--pink); border-color: rgba(255,107,157,.3); }
.lesson-card .done-mark { position: absolute; top: 12px; right: 14px; font-size: 1rem; color: var(--green); }

/* ---------- lesson page ---------- */
.lesson-head { margin-bottom: 18px; }
.lesson-head .crumb { font-size: .82rem; color: var(--muted); margin-bottom: 6px; }
.lesson-head .crumb a { color: var(--teal); text-decoration: none; }
.lesson-head h2 { font-size: 1.55rem; color: var(--gold); }
.lesson-head .desc { color: var(--muted); font-size: .95rem; }

.content-card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px 26px; margin-bottom: 18px;
}
.content-card h3 {
  color: var(--teal); font-size: 1.18rem; margin-bottom: 12px;
  padding-bottom: 8px; border-bottom: 1px dashed var(--line);
}
.content-card h4 { color: var(--gold); font-size: 1.02rem; margin: 16px 0 6px; }
.content-card p { margin-bottom: 10px; }
.content-card ul, .content-card ol { margin: 4px 0 12px 24px; }
.content-card li { margin-bottom: 4px; }
.content-card table {
  width: 100%; border-collapse: collapse; margin: 10px 0 16px; font-size: .92rem;
}
.content-card th, .content-card td {
  border: 1px solid var(--line); padding: 7px 12px; text-align: left; vertical-align: top;
}
.content-card th { background: var(--card2); color: var(--gold); font-weight: 600; }
.content-card tr:nth-child(even) td { background: rgba(255,255,255,.02); }
.kw { color: var(--gold); font-weight: 600; }
.en { color: var(--muted); font-style: italic; }
.formula {
  display: block; background: var(--bg2); border: 1px solid var(--line);
  border-left: 4px solid var(--teal); border-radius: 8px;
  padding: 10px 16px; margin: 10px 0; font-size: 1.02rem;
}
.callout {
  border-radius: 10px; padding: 12px 16px; margin: 12px 0; font-size: .94rem;
  background: rgba(255,209,102,.08); border: 1px solid rgba(255,209,102,.35);
}
.callout.tip { background: rgba(78,205,196,.08); border-color: rgba(78,205,196,.35); }
.callout.warn { background: rgba(255,117,117,.08); border-color: rgba(255,117,117,.35); }
.callout .ct { font-weight: 700; color: var(--gold); }
.callout.tip .ct { color: var(--teal); }
.callout.warn .ct { color: var(--red); }

.example-box {
  background: var(--bg2); border: 1px solid var(--line); border-radius: 10px;
  padding: 14px 18px; margin: 12px 0;
}
.example-box .ex-title { font-weight: 700; color: var(--pink); margin-bottom: 6px; }
details.solution { margin-top: 8px; }
details.solution summary {
  cursor: pointer; color: var(--teal); font-weight: 600; font-size: .92rem;
  user-select: none;
}
details.solution[open] summary { margin-bottom: 6px; }
details.solution .sol-body {
  background: rgba(78,205,196,.06); border-left: 3px solid var(--teal);
  padding: 10px 14px; border-radius: 6px; font-size: .94rem;
}

/* ---------- simulator ---------- */
.sim-box {
  background: var(--bg2); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px; margin: 16px 0;
}
.sim-box .sim-title {
  font-weight: 700; color: var(--gold); margin-bottom: 4px; font-size: 1.02rem;
  display: flex; align-items: center; gap: 8px;
}
.sim-box .sim-hint { font-size: .82rem; color: var(--muted); margin-bottom: 10px; }
.sim-box canvas {
  width: 100%; border-radius: 10px; background: #060a1c; display: block;
  touch-action: none; cursor: grab;
}
.sim-controls {
  display: flex; flex-wrap: wrap; gap: 14px 22px; margin-top: 12px; align-items: center;
}
.sim-controls .ctrl { display: flex; flex-direction: column; gap: 2px; min-width: 160px; flex: 1; }
.sim-controls .ctrl.row { flex-direction: row; align-items: center; gap: 8px; min-width: auto; flex: 0; }
.sim-controls label { font-size: .82rem; color: var(--muted); }
.sim-controls label b { color: var(--gold); }
.sim-controls input[type=range] { width: 100%; accent-color: var(--teal); }
.sim-controls select, .sim-controls button {
  background: var(--card); color: var(--text); border: 1px solid var(--line);
  border-radius: 8px; padding: 5px 12px; font-family: inherit; font-size: .88rem;
}
.sim-controls button { cursor: pointer; }
.sim-controls button:hover { border-color: var(--gold); }
.sim-controls button.active { background: var(--teal); color: #06281f; border-color: var(--teal); font-weight: 700; }
.sim-readout {
  margin-top: 10px; display: flex; flex-wrap: wrap; gap: 8px; font-size: .85rem;
}
.sim-readout span {
  background: var(--card); border: 1px solid var(--line); border-radius: 8px; padding: 3px 12px;
}
.sim-readout b { color: var(--teal); }

/* ---------- quiz ---------- */
.quiz-top {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-bottom: 16px;
}
.quiz-top .score-pill {
  background: var(--card); border: 1px solid var(--line); border-radius: 99px;
  padding: 5px 18px; font-size: .92rem;
}
.quiz-top .score-pill b { color: var(--gold); }
.btn {
  cursor: pointer; border: 1px solid var(--line); border-radius: 10px;
  background: var(--card); color: var(--text); padding: 8px 20px;
  font-family: inherit; font-size: .92rem; text-decoration: none; display: inline-block;
}
.btn:hover { border-color: var(--gold); }
.btn.primary { background: var(--gold); color: #2b1d00; font-weight: 700; border-color: var(--gold); }
.btn.primary:hover { filter: brightness(1.1); }
.btn.teal { background: var(--teal); color: #06281f; font-weight: 700; border-color: var(--teal); }
.btn.ghost { background: transparent; }

.q-item {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px 22px; margin-bottom: 14px;
}
.q-item .q-text { font-weight: 600; margin-bottom: 12px; }
.q-item .q-num { color: var(--teal); font-weight: 700; margin-right: 6px; }
.choices { display: grid; gap: 8px; }
.choice {
  border: 1px solid var(--line); border-radius: 10px; padding: 9px 14px;
  cursor: pointer; background: var(--bg2); transition: border-color .12s;
  display: flex; gap: 10px; align-items: baseline;
}
.choice:hover { border-color: var(--teal); }
.choice .letter {
  font-weight: 700; color: var(--teal); flex: 0 0 auto;
}
.choice.selected { border-color: var(--gold); background: rgba(255,209,102,.08); }
.choice.correct { border-color: var(--green); background: rgba(124,227,139,.1); }
.choice.wrong { border-color: var(--red); background: rgba(255,117,117,.1); }
.choice.disabled { pointer-events: none; opacity: .85; }
.q-feedback { margin-top: 10px; font-size: .9rem; border-radius: 8px; padding: 8px 14px; display: none; }
.q-feedback.show { display: block; }
.q-feedback.ok { background: rgba(124,227,139,.1); border: 1px solid rgba(124,227,139,.4); }
.q-feedback.no { background: rgba(255,117,117,.08); border: 1px solid rgba(255,117,117,.4); }
.quiz-result {
  text-align: center; background: var(--card); border: 1px solid var(--gold);
  border-radius: var(--radius); padding: 22px; margin-top: 18px; display: none;
}
.quiz-result.show { display: block; }
.quiz-result .big { font-size: 1.6rem; color: var(--gold); font-weight: 700; }

/* ---------- workshop ---------- */
.ws-item {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px 22px; margin-bottom: 16px;
}
.ws-item .ws-q { font-weight: 600; margin-bottom: 10px; }
.ws-item .ws-q .q-num { color: var(--pink); font-weight: 700; margin-right: 6px; }
.ws-item img.ws-fig { max-width: 100%; border-radius: 10px; margin: 8px 0; }
.ws-blank-row { display: flex; flex-wrap: wrap; gap: 10px 18px; align-items: center; margin-bottom: 8px; }
.ws-blank-row label { font-size: .92rem; }
input.ws-input, select.ws-select, textarea.ws-area {
  background: var(--bg2); border: 1px solid var(--line); color: var(--text);
  border-radius: 8px; padding: 6px 10px; font-family: inherit; font-size: .92rem;
  min-width: 110px;
}
textarea.ws-area { width: 100%; min-height: 70px; resize: vertical; }
input.ws-input:focus, select.ws-select:focus { outline: none; border-color: var(--teal); }
input.ws-input.ok, select.ws-select.ok { border-color: var(--green); background: rgba(124,227,139,.08); }
input.ws-input.no, select.ws-select.no { border-color: var(--red); background: rgba(255,117,117,.08); }
.ws-table { width: 100%; border-collapse: collapse; margin: 10px 0; font-size: .9rem; }
.ws-table th, .ws-table td { border: 1px solid var(--line); padding: 6px 10px; }
.ws-table th { background: var(--card2); color: var(--gold); }
.ws-table input.ws-input, .ws-table select.ws-select { min-width: 80px; width: 100%; }
.ws-actions { display: flex; gap: 10px; margin-top: 12px; flex-wrap: wrap; }
.ws-solution {
  display: none; margin-top: 12px; background: rgba(78,205,196,.06);
  border-left: 3px solid var(--teal); border-radius: 6px; padding: 10px 16px; font-size: .92rem;
}
.ws-solution.show { display: block; }
.ws-solution .st { color: var(--teal); font-weight: 700; }
.ws-score { font-size: .9rem; color: var(--muted); margin-top: 8px; }
.ws-score b { color: var(--gold); }

/* mcq letter circles (เลือกหลายตัว เช่น A–L) */
.letter-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 8px 0; }
.letter-chip {
  width: 38px; height: 38px; border-radius: 50%; border: 1px solid var(--line);
  background: var(--bg2); color: var(--text); display: flex; align-items: center;
  justify-content: center; cursor: pointer; font-weight: 700; user-select: none;
}
.letter-chip:hover { border-color: var(--teal); }
.letter-chip.sel { background: var(--gold); color: #2b1d00; border-color: var(--gold); }
.letter-chip.ok { background: var(--green); color: #06281f; border-color: var(--green); }
.letter-chip.no { background: var(--red); color: #fff; border-color: var(--red); }
.letter-chip.miss { outline: 2px dashed var(--green); }

/* ---------- nav footer ---------- */
.page-nav { display: flex; justify-content: space-between; gap: 12px; margin-top: 30px; flex-wrap: wrap; }
.footer-note { text-align: center; color: var(--muted); font-size: .78rem; margin-top: 50px; }

@media (max-width: 640px) {
  :root { font-size: 15px; }
  .content-card { padding: 16px; }
  main { padding: 18px 10px 70px; }
  header.topbar .sub { display: none; }
}

/* ============================================================
   ส่วนเพิ่มเติมเฉพาะวิชาเคมี
   ============================================================ */

/* ---------- เทคนิคช่วยจำ ---------- */
.mnemonic {
  border-radius: 12px; padding: 14px 18px; margin: 14px 0;
  background: linear-gradient(135deg, rgba(255,107,157,.1), rgba(255,209,102,.08));
  border: 1px solid rgba(255,107,157,.4);
}
.mnemonic .mn-title { font-weight: 700; color: var(--pink); margin-bottom: 4px; }
.mnemonic .mn-key {
  display: inline-block; background: rgba(255,209,102,.15); border: 1px dashed var(--gold);
  color: var(--gold); border-radius: 8px; padding: 2px 12px; margin: 4px 6px 4px 0;
  font-weight: 700; font-size: .95rem;
}

/* ---------- ภาพประกอบ (hotlink) ---------- */
.figure-row { display: flex; flex-wrap: wrap; gap: 14px; justify-content: center; margin: 14px 0; }
.figure { text-align: center; max-width: 150px; }
.figure img {
  width: 110px; height: 130px; object-fit: cover; border-radius: 10px;
  border: 2px solid var(--line); background: var(--bg2);
}
.figure .cap { font-size: .76rem; color: var(--muted); line-height: 1.4; margin-top: 4px; }
.figure-wide { text-align: center; margin: 12px 0; }
.figure-wide img { max-width: 100%; border-radius: 10px; background: #fff; padding: 6px; }
.figure-wide .cap { font-size: .78rem; color: var(--muted); margin-top: 4px; }

/* ---------- เกมจับคู่ (flashcard matching) ---------- */
.match-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(95px, 1fr)); gap: 8px; margin: 12px 0; }
.match-card {
  background: var(--bg2); border: 1.5px solid var(--line); border-radius: 10px;
  padding: 10px 4px; text-align: center; cursor: pointer; user-select: none;
  font-weight: 600; transition: transform .12s, border-color .12s; min-height: 56px;
  display: flex; align-items: center; justify-content: center; font-size: .92rem;
}
.match-card:hover { border-color: var(--teal); transform: translateY(-2px); }
.match-card.sel { border-color: var(--gold); background: rgba(255,209,102,.12); }
.match-card.ok { border-color: var(--green); background: rgba(124,227,139,.12); opacity: .55; pointer-events: none; }
.match-card.shake { animation: shake .3s; border-color: var(--red); }
@keyframes shake { 0%,100%{transform:translateX(0)} 25%{transform:translateX(-5px)} 75%{transform:translateX(5px)} }

/* ---------- ตารางธาตุ ---------- */
.ptable-wrap { overflow-x: auto; padding-bottom: 6px; }
.ptable {
  display: grid; grid-template-columns: repeat(18, minmax(34px, 1fr));
  gap: 3px; min-width: 700px; margin: 10px 0;
}
.pt-cell {
  border-radius: 5px; text-align: center; padding: 3px 1px; cursor: pointer;
  border: 1px solid transparent; line-height: 1.15; transition: transform .1s;
  background: var(--card2);
}
.pt-cell:hover { transform: scale(1.12); border-color: #fff; z-index: 2; position: relative; }
.pt-cell .z { font-size: .55rem; opacity: .75; display: block; }
.pt-cell .sym { font-size: .82rem; font-weight: 700; display: block; }
.pt-cell.dim { opacity: .25; }
.pt-cell.hl { outline: 2px solid #fff; z-index: 2; }
.pt-spacer { pointer-events: none; }
.pt-legend { display: flex; flex-wrap: wrap; gap: 6px 12px; font-size: .78rem; margin: 8px 0; }
.pt-legend span { display: inline-flex; align-items: center; gap: 5px; color: var(--muted); }
.pt-legend i { width: 13px; height: 13px; border-radius: 3px; display: inline-block; }
.pt-detail {
  background: var(--bg2); border: 1px solid var(--line); border-radius: 12px;
  padding: 14px 18px; margin-top: 10px; min-height: 90px; font-size: .92rem;
}
.pt-detail .big-sym {
  font-size: 2rem; font-weight: 700; margin-right: 14px; padding: 4px 16px;
  border-radius: 10px; display: inline-block; vertical-align: middle;
}
.pt-detail table.mini { font-size: .85rem; margin-top: 8px; border-collapse: collapse; width: 100%; }
.pt-detail table.mini td { border: 1px solid var(--line); padding: 4px 10px; }

/* ---------- กล่องออร์บิทัล (electron configuration) ---------- */
.orb-area { display: flex; flex-wrap: wrap; gap: 14px 22px; align-items: flex-end; margin: 12px 0; }
.orb-group { text-align: center; }
.orb-row { display: flex; gap: 4px; justify-content: center; }
.orb-box {
  width: 34px; height: 34px; border: 2px solid var(--muted); border-radius: 6px;
  display: flex; align-items: center; justify-content: center; gap: 1px;
  background: var(--bg2); font-size: 1rem; font-weight: 700;
}
.orb-box .up { color: var(--teal); }
.orb-box .dn { color: var(--pink); }
.orb-label { font-size: .8rem; color: var(--gold); margin-top: 3px; font-weight: 700; }
.config-str {
  font-size: 1.05rem; background: var(--bg2); border: 1px solid var(--line);
  border-left: 4px solid var(--gold); border-radius: 8px; padding: 8px 16px; margin: 8px 0;
  overflow-x: auto; white-space: nowrap;
}
.config-str sup { color: var(--gold); }

/* ---------- ไทม์ไลน์ ---------- */
.timeline { position: relative; margin: 16px 0 16px 14px; padding-left: 24px; border-left: 3px solid var(--line); }
.tl-item { position: relative; margin-bottom: 18px; }
.tl-item::before {
  content: ''; position: absolute; left: -33px; top: 6px; width: 14px; height: 14px;
  border-radius: 50%; background: var(--gold); border: 3px solid var(--bg);
}
.tl-item .tl-year { font-weight: 700; color: var(--teal); font-size: .9rem; }
.tl-item .tl-title { font-weight: 700; color: var(--gold); }
.tl-item p { font-size: .92rem; color: var(--text); }

/* ---------- แถบสเปกตรัม ---------- */
.spectrum-strip {
  height: 34px; border-radius: 8px; margin: 8px 0;
  background: linear-gradient(90deg, #7600bc 0%, #4b0fd1 9%, #1731e8 17%, #00b7eb 30%, #00c853 45%, #d4e157 62%, #ffb300 74%, #ff6d00 84%, #d50000 100%);
  position: relative; border: 1px solid var(--line);
}
.spectrum-strip .mark { position: absolute; top: -4px; bottom: -4px; width: 3px; background: #fff; border-radius: 2px; }

/* ---------- ปุ่มเลือกสารเคมี (flame test) ---------- */
.chem-bottles { display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0; }
.bottle {
  border: 1.5px solid var(--line); border-radius: 10px; background: var(--bg2);
  padding: 8px 14px; cursor: pointer; text-align: center; font-size: .85rem; line-height: 1.3;
}
.bottle b { display: block; font-size: 1rem; }
.bottle:hover { border-color: var(--gold); }
.bottle.active { border-color: var(--teal); background: rgba(78,205,196,.12); }

@media (max-width: 640px) {
  .pt-cell .z { display: none; }
  .ptable { min-width: 620px; }
}