/* ===== Khoa Học Vui – giao diện (phần nền lấy từ Toán Vui) ===== */
:root {
  --bg: #fff8e7;
  --bg2: #ffe9b8;
  --ink: #3b2f2f;
  --muted: #8a7a6a;
  --primary: #ff8a3d;
  --primary-d: #e56a1a;
  --green: #3cc47c;
  --green-d: #25a262;
  --red: #ff5a5f;
  --blue: #4aa3ff;
  --purple: #9b6bff;
  --card: #ffffff;
  --shadow: 0 6px 0 rgba(0,0,0,.08), 0 10px 24px rgba(0,0,0,.08);
  --radius: 22px;
}
* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html, body { margin: 0; height: 100%; }
body {
  font-family: "Baloo 2", "Nunito", system-ui, -apple-system, "Segoe UI", sans-serif;
  background: radial-gradient(circle at 20% 10%, #fffdf5 0, var(--bg) 40%, var(--bg2) 100%);
  color: var(--ink);
  overflow-x: hidden;
  user-select: none; -webkit-user-select: none;
}
button { font-family: inherit; cursor: pointer; border: 0; }
.hidden { display: none !important; }

#app { max-width: 980px; margin: 0 auto; padding: 12px 16px 40px; min-height: 100%; }

/* ---------- thanh trên ---------- */
.topbar { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.topbar .spacer { flex: 1; }
.pill {
  background: var(--card); border-radius: 999px; padding: 6px 14px;
  font-weight: 700; font-size: 20px; box-shadow: var(--shadow);
  display: inline-flex; align-items: center; gap: 6px;
}
.icon-btn {
  width: 52px; height: 52px; border-radius: 16px; background: var(--card);
  font-size: 26px; box-shadow: var(--shadow);
}
.icon-btn:active { transform: translateY(3px); box-shadow: none; }

/* ---------- nút lớn ---------- */
.big-btn {
  font-size: 28px; font-weight: 800; color: #fff; padding: 16px 34px;
  border-radius: 999px; background: var(--primary); box-shadow: 0 7px 0 var(--primary-d);
  transition: transform .08s;
}
.big-btn:active { transform: translateY(5px); box-shadow: 0 2px 0 var(--primary-d); }
.big-btn.green { background: var(--green); box-shadow: 0 7px 0 var(--green-d); }
.big-btn.ghost { background: #fff; color: var(--ink); box-shadow: 0 7px 0 #e4d7c3; }
.big-btn[disabled] { opacity: .45; pointer-events: none; }

/* ---------- màn hình chính ---------- */
.home { text-align: center; padding-top: 4vh; }
.home h1 { font-size: clamp(40px, 8vw, 72px); margin: 8px 0 0; color: var(--primary-d); letter-spacing: 1px; text-shadow: 0 4px 0 #ffd9a8; }
.home .sub { font-size: 22px; color: var(--muted); margin: 0 0 18px; }
.mascot { font-size: 120px; display: inline-block; animation: bob 2.4s ease-in-out infinite; }
.bubble {
  display: inline-block; background: #fff; border-radius: 24px; padding: 12px 20px; font-size: 24px;
  box-shadow: var(--shadow); margin: 6px auto 22px; max-width: 560px; position: relative;
}
.name-input {
  font-family: inherit; font-size: 28px; padding: 10px 18px; border-radius: 18px; border: 3px solid #f1dcc0;
  text-align: center; width: min(320px, 90%); margin-bottom: 16px; outline: none;
}
.home .row { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; margin-top: 12px; }
@keyframes bob { 0%,100% { transform: translateY(0) } 50% { transform: translateY(-10px) } }

/* ---------- bản đồ ---------- */
.world {
  background: linear-gradient(180deg, #d9f7d0, #bdeeb0); border-radius: 30px; padding: 18px 16px 26px;
  box-shadow: var(--shadow); margin-bottom: 18px; position: relative; overflow: hidden;
}
.world.w2 { background: linear-gradient(180deg, #d6ecff, #b9dcff); }
.world.w3 { background: linear-gradient(180deg, #ffe0ec, #ffc7dc); }
.world.w4 { background: linear-gradient(180deg, #efe1ff, #dcc6ff); }
.world.w5 { background: linear-gradient(180deg, #fff1c9, #ffe29a); }
.world h2 { margin: 0 0 4px; font-size: 28px; }
.world .wsub { margin: 0 0 12px; color: #4b5b45; font-size: 17px; }
.path { display: flex; flex-wrap: wrap; gap: 16px 14px; }
.node {
  width: 138px; min-height: 150px; background: #fff; border-radius: 24px; padding: 10px 8px;
  display: flex; flex-direction: column; align-items: center; gap: 2px; box-shadow: var(--shadow);
  text-align: center; position: relative;
}
.node .num { font-size: 15px; font-weight: 800; color: #fff; background: var(--primary); border-radius: 999px; padding: 0 10px; }
.node .ico { font-size: 44px; line-height: 1.2; }
.node .t { font-size: 16px; font-weight: 700; line-height: 1.15; }
.node .hint { font-size: 12.5px; line-height: 1.25; color: var(--muted); display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.node .stars { font-size: 18px; letter-spacing: 1px; }
.node.locked { opacity: .55; filter: grayscale(.7); }
.node.locked .ico::after { content: " 🔒"; font-size: 22px; }
.node.soon { opacity: .5; }
.node.current { outline: 4px solid var(--primary); animation: pulse 1.6s infinite; }
.node:active:not(.locked):not(.soon) { transform: scale(.96); }
@keyframes pulse { 0%,100% { outline-color: var(--primary) } 50% { outline-color: #ffd0a8 } }
/* phản hồi */
.feedback {
  position: fixed; left: 50%; top: 42%; transform: translate(-50%, -50%) scale(.6); font-size: 110px;
  pointer-events: none; opacity: 0; transition: all .25s; z-index: 50; text-shadow: 0 6px 20px rgba(0,0,0,.2);
}
.feedback.show { opacity: 1; transform: translate(-50%, -50%) scale(1); }
.toast {
  position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%); background: #fff; border-radius: 999px;
  padding: 10px 22px; font-size: 24px; font-weight: 700; box-shadow: var(--shadow); z-index: 60; transition: opacity .3s;
}
@keyframes shake { 0%,100% { transform: translateX(0) } 25% { transform: translateX(-8px) } 75% { transform: translateX(8px) } }
@keyframes wiggle { 0%,100% { transform: rotate(0) } 25% { transform: rotate(-8deg) } 75% { transform: rotate(8deg) } }
.small-btn { background: #f3eadc; border-radius: 12px; padding: 8px 14px; font-size: 17px; font-weight: 700; margin: 4px 6px 4px 0; }
.small-btn.danger { background: #ffe0e0; color: #b3261e; }

/* pháo giấy */
.confetti { position: fixed; top: -40px; font-size: 30px; z-index: 70; pointer-events: none; animation: fall linear forwards; }
@keyframes fall { to { transform: translateY(110vh) rotate(540deg); } }
html { touch-action: manipulation; -webkit-text-size-adjust: 100%; }
body { -webkit-touch-callout: none; overscroll-behavior: none; }
.draggable { touch-action: none; cursor: grab; -webkit-user-drag: none; }
.dragging { opacity: .25; }
.drag-ghost {
  position: fixed !important; z-index: 100; pointer-events: none; will-change: transform;
  filter: drop-shadow(0 10px 14px rgba(0,0,0,.25)); cursor: grabbing;
  display: flex; align-items: center; justify-content: center;
}
.drop-hover { outline: 5px dashed var(--blue) !important; outline-offset: 3px; background-color: #eef6ff !important; }
.drag-help { font-size: 18px; color: var(--muted); }
.wagon.drop-hover { transform: scale(1.12); }

/* Màn đã chơi / chưa chơi */
.node.played { background: #f1fff4; border: 3px solid #9fe3b6; }
.node .done-tag {
  position: absolute; top: -10px; right: -8px; background: var(--green); color: #fff; font-size: 14px; font-weight: 800;
  border-radius: 999px; padding: 2px 9px; box-shadow: 0 3px 0 var(--green-d);
}
.node .new-tag { font-size: 14px; color: var(--muted); }
.node .suggest-tag {
  position: absolute; top: -10px; left: -6px; background: var(--primary); color: #fff; font-size: 14px; font-weight: 800;
  border-radius: 999px; padding: 2px 9px;
}
.world-progress { font-size: 17px; font-weight: 700; color: #3c6b3f; margin: -6px 0 12px; }
.legend { display: flex; gap: 14px; flex-wrap: wrap; font-size: 17px; margin: 0 0 14px; color: var(--muted); }

/* iPad (768–1366px): nút và vật to hơn cho ngón tay */
@media (min-width: 740px) and (pointer: coarse), (min-width: 740px) and (max-width: 1366px) {
  .opt { min-width: 104px; height: 104px; font-size: 54px; border-radius: 28px; }
  .opt.word { font-size: 30px; height: 88px; }
  .options { gap: 18px; }
  .wagon { width: 84px; height: 84px; font-size: 46px; }
  .node { width: 150px; min-height: 164px; }
  .tray .item, .container .item { font-size: 62px; }
}

/* Chọn tài khoản */
.accounts { display: flex; flex-wrap: wrap; gap: 18px; justify-content: center; margin-top: 8px; }
.account {
  width: 170px; padding: 16px 10px; background: #fff; border-radius: 28px; box-shadow: 0 7px 0 #e4d7c3;
  display: flex; flex-direction: column; align-items: center; gap: 4px; border: 4px solid transparent;
}
.account:active { transform: translateY(5px); box-shadow: 0 2px 0 #e4d7c3; }
.account.last { border-color: #ffc38f; }
.account .av { font-size: 76px; line-height: 1.1; }
.account .nm { font-size: 28px; font-weight: 800; color: var(--ink); }
.account .sm { font-size: 16px; color: var(--muted); }

/* ===== Trang bài học (4 phần) ===== */
.lesson-head { display: flex; align-items: center; gap: 14px; margin: 6px 0 4px; }
.lesson-head h2 { margin: 0; font-size: 30px; color: var(--primary-d); }
.lesson-head .book { color: var(--muted); font-size: 17px; }
.mascot.small { font-size: 72px; }
.lcards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; margin-top: 8px; }
@media (max-width: 640px) { .lcards { grid-template-columns: 1fr; } }
.lcard {
  display: flex; align-items: center; gap: 14px; text-align: left; background: #fff; border-radius: 26px; padding: 16px 18px;
  box-shadow: 0 7px 0 #e4d7c3; border: 4px solid transparent; font-family: inherit; color: var(--ink); min-height: 110px;
}
.lcard:active { transform: translateY(5px); box-shadow: 0 2px 0 #e4d7c3; }
.lcard.hl { border-color: var(--primary); animation: pulse 1.6s infinite; }
.lcard .li { font-size: 54px; }
.lcard .lt { flex: 1; display: flex; flex-direction: column; }
.lcard .lt b { font-size: 25px; }
.lcard .lt span { font-size: 16px; color: var(--muted); }
.lcard .lt .ls { margin-top: 6px; font-size: 15px; font-weight: 700; color: var(--primary-d); }
.stage-badges { display: flex; gap: 2px; font-size: 16px; }
.stage-badges .sb { opacity: .25; filter: grayscale(1); }
.stage-badges .sb.ok { opacity: 1; filter: none; }
.stage-pill { font-size: 22px; }
@keyframes pulse2 { 0%,100% { transform: scale(1) } 50% { transform: scale(1.08) } }
@keyframes pop { 0% { transform: scale(.3) } 80% { transform: scale(1.15) } 100% { transform: scale(1) } }

/* màn chơi */
/* ---------- màn chơi ---------- */
.progress { flex: 1; height: 22px; background: #fff; border-radius: 999px; overflow: hidden; box-shadow: inset 0 2px 4px rgba(0,0,0,.08); }
.progress > div { height: 100%; background: linear-gradient(90deg, #7be495, var(--green)); border-radius: 999px; transition: width .4s; }
.diff { font-size: 22px; }
.question {
  background: #fff; border-radius: var(--radius); box-shadow: var(--shadow);
  padding: 14px 18px; display: flex; align-items: center; gap: 12px; margin: 8px 0 14px;
}
.question .q-text { font-size: clamp(22px, 3.6vw, 30px); font-weight: 700; flex: 1; line-height: 1.25; }
.question .speak { flex: none; }
.review-tag { display: inline-block; background: var(--purple); color: #fff; font-size: 15px; border-radius: 999px; padding: 0 10px; margin-bottom: 4px; }

/* =====================================================================
   PHẦN RIÊNG CỦA KHOA HỌC VUI
   ===================================================================== */
:root { --sky: #4aa3ff; --sky-d: #2a7fd6; }
body { background: radial-gradient(circle at 20% 10%, #f7fcff 0, #e6f4ff 45%, #cfe8ff 100%); }
.home h1 { color: #2a7fd6; text-shadow: 0 4px 0 #bfe0ff; }
.node .num { background: var(--sky); }
.world.w6 { background: linear-gradient(180deg, #ffe7d6, #ffd2b3); }
.world.w7 { background: linear-gradient(180deg, #e3f0ff, #c8defa); }
.world.w8 { background: linear-gradient(180deg, #e5e4ff, #cfcdfb); }
.world.w9 { background: linear-gradient(180deg, #fff6c2, #ffe98a); }
.stage-badges { display: flex; gap: 3px; font-size: 15px; margin-top: 2px; }
.stage-badges .sb { opacity: .28; filter: grayscale(1); }
.stage-badges .sb.ok { opacity: 1; filter: none; }
.lcard { display: flex; align-items: center; gap: 14px; background: #fff; border-radius: 26px; padding: 16px 18px; box-shadow: 0 7px 0 #d9e6f2; border: 4px solid transparent; text-align: left; }
.lcard .lt span { color: var(--muted); font-size: 17px; }
.lcard .lt .ls { color: var(--sky-d); font-weight: 700; }
.needs { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin: 4px 0 8px; font-size: 18px; }
.needs b { color: #7a5c00; }
.need-btn { border: 2px solid #ffd35c; background: #fff8dc; border-radius: 16px; padding: 6px 12px; font-size: 17px; cursor: pointer; font-family: inherit; }
.need-btn.done { border-color: #9bd8a5; background: #eefaf0; }
.bigidea { background: #fffbe6; border: 3px solid #ffe08a; border-radius: 24px; padding: 12px 18px; font-size: 22px; margin: 8px 0 16px; box-shadow: var(--shadow); }
.bigidea b { display: block; color: #c07a00; font-size: 18px; }
.part-title { font-size: 32px; color: var(--sky-d); margin: 8px 0 14px; }
.muted { color: var(--muted); }

/* ---------- 🔍 Khám phá: khung hình minh hoạ ---------- */
.scene-wrap { position: relative; margin: 4px auto 8px; width: min(100%, calc((100vh - 300px) * 1.6)); }
.scene-wrap.small { width: min(100%, 520px); }
.scene-box { position: relative; width: 100%; aspect-ratio: 8 / 5; background: #fff; border-radius: 26px; overflow: hidden; box-shadow: var(--shadow); touch-action: none; }
.scene-svg { width: 100%; height: 100%; display: block; }
.scene-cap { position: absolute; left: 50%; top: 12px; transform: translateX(-50%); background: rgba(255,255,255,.93); border-radius: 999px; padding: 4px 18px; font-size: clamp(18px, 2.8vw, 26px); font-weight: 800; color: var(--sky-d); box-shadow: 0 3px 10px rgba(0,0,0,.12); pointer-events: none; white-space: nowrap; max-width: 94%; overflow: hidden; text-overflow: ellipsis; }
.pic-big { display: flex; align-items: center; justify-content: center; height: 100%; font-size: clamp(60px, 12vw, 130px); gap: 10px; flex-wrap: wrap; text-align: center; }
.task-bar { margin: 0 auto 8px; width: fit-content; max-width: 100%; background: #fff3c4; border: 3px solid #ffd35a; border-radius: 999px; padding: 4px 18px; font-size: 22px; font-weight: 700; animation: pulse2 1.8s infinite; }
.task-bar.ok { background: #dcf8e6; border-color: #7ad9a0; animation: none; }
.ex-bottom { display: flex; align-items: center; gap: 12px; }
.ex-bubble { flex: 1; background: #fff; border-radius: 22px; padding: 10px 16px; font-size: clamp(19px, 2.6vw, 24px); line-height: 1.3; box-shadow: var(--shadow); display: flex; gap: 10px; align-items: flex-start; min-height: 64px; }
.ex-bubble .ow { font-size: 34px; line-height: 1; }
.big-btn.nav { padding: 14px 22px; font-size: 24px; flex: none; }
.big-btn.locked { opacity: .4; }
.big-btn.pulse { animation: pulse2 .8s 3; }
.dots { display: flex; gap: 5px; }
.dots span { width: 12px; height: 12px; border-radius: 50%; background: #fff; box-shadow: inset 0 0 0 2px #b9d7f2; }
.dots span.past { background: #9fd3ff; box-shadow: none; }
.dots span.on { background: var(--sky); box-shadow: none; transform: scale(1.3); }
.summary { height: 100%; display: flex; flex-direction: column; align-items: center; justify-content: center; padding: 18px; gap: 12px; background: linear-gradient(180deg, #fffdf0, #fff4c9); overflow: auto; }
.sum-title { font-size: 28px; font-weight: 800; color: #c07a00; }
.sum-idea { font-size: clamp(20px, 3vw, 28px); font-weight: 700; text-align: center; max-width: 640px; line-height: 1.3; }
.words { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; }
.word { background: #fff; border-radius: 18px; padding: 8px 14px; box-shadow: 0 4px 0 #efdca0; display: flex; flex-direction: column; max-width: 240px; text-align: left; }
.word b { font-size: 20px; color: var(--sky-d); }
.word span { font-size: 15px; color: var(--muted); line-height: 1.25; }

/* các lớp dùng trong hình SVG */
.k-text { font-family: "Baloo 2", system-ui, sans-serif; font-weight: 700; pointer-events: none; }
.k-emoji { pointer-events: none; }
.k-label { pointer-events: none; }
.k-label.k-tap { pointer-events: auto; }
.k-tap, .k-drag { cursor: pointer; }
.k-drag { cursor: grab; }
.k-dragging { cursor: grabbing; filter: drop-shadow(0 8px 8px rgba(0,0,0,.25)); }
.k-pressed { opacity: .8; }
.k-hint { animation: khint 1s ease-in-out 4; }
@keyframes khint { 0%,100% { opacity: 1 } 50% { opacity: .35 } }
.sun-rays { animation: spin 18s linear infinite; }
.k-sun.hot .sun-rays { animation-duration: 4s; }
.k-sun.hot .sun-glow { opacity: .7; }
@keyframes spin { to { transform: rotate(360deg); } }
.k-waves { animation: waves 3s linear infinite; }
@keyframes waves { to { transform: translateX(40px); } }
.k-flow { stroke-dasharray: 14 12; animation: flow 1s linear infinite; }
@keyframes flow { to { stroke-dashoffset: -26; } }
.k-steam > path { animation: steam 2.4s ease-in infinite; }
@keyframes steam { 0% { transform: translateY(0); opacity: 0 } 25% { opacity: .9 } 100% { transform: translateY(-40px); opacity: 0 } }
.k-bob { animation: kbob 2.4s ease-in-out infinite; }
@keyframes kbob { 0%,100% { transform: translateY(0) } 50% { transform: translateY(-8px) } }
.k-blink { animation: khint 1.2s ease-in-out infinite; }
.k-fade { transition: opacity .6s; }

/* ---------- 💡 Em có biết ---------- */
.fact-box { background: #fff; border-radius: 30px; box-shadow: var(--shadow); padding: 24px; text-align: center; max-width: 720px; margin: 0 auto; }
.fact-e { font-size: 110px; line-height: 1.1; animation: bob 2.4s ease-in-out infinite; }
.fact-t { font-size: clamp(22px, 3.2vw, 30px); font-weight: 700; line-height: 1.35; margin: 10px 0 20px; }
.fact-n { color: var(--muted); margin-top: 10px; }
.row { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; align-items: center; }
.row.left { justify-content: flex-start; gap: 8px; }

/* ---------- 🧪 Thử ở nhà ---------- */
.safe { background: #fff0e0; border: 3px solid #ffc38f; border-radius: 18px; padding: 8px 14px; font-size: 18px; margin-bottom: 12px; }
.lab { display: grid; grid-template-columns: 1fr 1.6fr; gap: 14px; }
@media (max-width: 640px) { .lab { grid-template-columns: 1fr; } }
.lab > div, .lab-q, .lab-why { background: #fff; border-radius: 22px; padding: 12px 18px; box-shadow: var(--shadow); font-size: 21px; }
.lab b { font-size: 22px; color: var(--sky-d); }
.lab ul, .lab ol { margin: 6px 0 0; padding-left: 26px; line-height: 1.4; }
.lab li { margin-bottom: 4px; }
.lab-q { margin-top: 14px; }
.lab-why { margin-top: 12px; }
.lab-why summary { font-weight: 700; cursor: pointer; }
.lab-why div { margin-top: 8px; line-height: 1.4; }

/* ---------- ❓ Đố vui ---------- */
.q-pic { text-align: center; font-size: clamp(56px, 10vw, 96px); margin: 0 0 10px; }
.qbody { display: flex; flex-direction: column; align-items: center; gap: 16px; }
.opts { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 14px; width: 100%; max-width: 860px; }
.opts.four { grid-template-columns: repeat(2, 1fr); }
.opt, .opt.tf { height: auto; min-height: 76px; min-width: 0; font-size: clamp(19px, 2.6vw, 24px); font-weight: 700; padding: 12px 16px; border-radius: 22px; background: #fff; box-shadow: 0 7px 0 #d9e6f2; display: flex; align-items: center; gap: 10px; justify-content: center; text-align: left; line-height: 1.25; color: var(--ink); }
.opt .oe { font-size: 40px; line-height: 1; }
.opt.emoji .oe { font-size: 64px; }
.opt.tf { font-size: 28px; }
.opt[disabled] { opacity: .5; }
.why { background: #fffbe6; border: 3px solid #ffe08a; border-radius: 24px; padding: 14px 18px; margin: 16px auto 0; max-width: 860px; text-align: center; }
.why-h { font-size: 26px; font-weight: 800; color: #c07a00; }
.why-t { font-size: clamp(19px, 2.6vw, 24px); line-height: 1.35; margin: 6px 0 12px; }
.pool { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; min-height: 70px; }
.chip { background: #fff; border-radius: 18px; padding: 8px 14px; box-shadow: 0 5px 0 #d9e6f2; display: inline-flex; align-items: center; gap: 8px; font-size: 21px; font-weight: 700; color: var(--ink); }
.chip .ce { font-size: 40px; line-height: 1; }
.chip.big { font-size: 20px; flex-direction: column; padding: 10px 12px; max-width: 170px; text-align: center; line-height: 1.2; }
.chip.sel { outline: 4px solid var(--sky); }
.chip.in { box-shadow: none; background: #eafff1; }
.chip.shake, .shake { animation: shake .4s; }
.bins { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; width: 100%; max-width: 860px; }
.bins.three { grid-template-columns: repeat(3, 1fr); }
.bin { background: rgba(255,255,255,.7); border: 4px dashed #a9cdf5; border-radius: 24px; min-height: 150px; padding: 10px; }
.bin-h { font-size: 22px; font-weight: 800; text-align: center; color: var(--sky-d); margin-bottom: 6px; }
.bin-items { display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; }
.slots { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; justify-content: center; }
.slot { min-width: 130px; min-height: 120px; border: 4px dashed #a9cdf5; border-radius: 20px; position: relative; display: flex; align-items: center; justify-content: center; background: rgba(255,255,255,.6); }
.slot .sn { position: absolute; top: -12px; left: -8px; background: var(--sky); color: #fff; border-radius: 50%; width: 28px; height: 28px; display: flex; align-items: center; justify-content: center; font-weight: 800; }
.slot .chip { box-shadow: none; }
.sarrow { font-size: 28px; color: var(--sky-d); }

/* ---------- phần thưởng, album, phụ huynh ---------- */
.reward { text-align: center; padding-top: 5vh; }
.reward h1 { font-size: clamp(34px, 6vw, 56px); color: var(--sky-d); margin: 6px 0; }
.big-stars { font-size: 64px; letter-spacing: 6px; }
.stk { background: #fff; border-radius: 20px; box-shadow: var(--shadow); height: 116px; display: flex; flex-direction: column; align-items: center; justify-content: center; }
.stk .se { font-size: 54px; }
.stk .sn { font-size: 14px; color: var(--muted); }
.stk.no { background: #e9f1f8; }
.stk.no .se { opacity: .3; }
.pcard { background: #fff; border-radius: 22px; padding: 14px 18px; box-shadow: var(--shadow); margin-bottom: 16px; font-size: 18px; }
.pcard > b { font-size: 22px; display: block; margin-bottom: 6px; }
.small-btn.on { background: var(--sky); color: #fff; }
.plesson { border-top: 1px solid #e6eef6; padding: 8px 2px; }
.plesson summary { font-weight: 700; cursor: pointer; font-size: 19px; }
.plesson.soon summary { color: var(--muted); font-weight: 500; }
.plesson .pst { float: right; letter-spacing: 2px; }
.pbody { padding: 6px 4px 4px 16px; display: flex; flex-direction: column; gap: 5px; line-height: 1.35; }
.pbody .src { color: var(--muted); font-size: 15px; }

@media (max-width: 640px) {
  .ex-bottom { flex-wrap: wrap; }
  .ex-bubble { order: -1; flex-basis: 100%; }
  .ex-bottom .nav { flex: 1; }
  .opts.four { grid-template-columns: 1fr; }
  .bins.three { grid-template-columns: 1fr; }
  .dots { display: none; }
}
.lesson-head h2 { color: var(--sky-d); }
.lcard.hl { border-color: var(--sky); }
.slots.many .slot { min-width: 92px; min-height: 100px; }
.slots.many .chip.big { max-width: 96px; font-size: 16px; padding: 6px; }
.slots.many .sarrow { font-size: 18px; }

/* Màn thấp (iPad ngang, laptop 768px): lời Cú dài 4 dòng vẫn phải nằm trọn trong màn hình */
@media (max-height: 820px) {
  .ex-bubble { font-size: 20px; line-height: 1.28; padding: 8px 14px; }
  .task-bar { font-size: 19px; margin-bottom: 6px; }
}