:root {
  --bg: #0d1421;
  --card: #16202f;
  --card2: #1c2a3d;
  --line: #2b3b52;
  --text: #e2e8f0;
  --muted: #8fa3bb;
  --accent: #38bdf8;
  --up: #22c55e;
  --down: #ef4444;
  --warn: #f59e0b;
  --radius: 14px;
}
* { margin: 0; padding: 0; box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html, body { height: 100%; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  padding-bottom: 70px;
}

/* ---------- Top bar ---------- */
#topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 10px;
  background: rgba(13,20,33,.92); backdrop-filter: blur(8px);
  padding: 12px 16px; border-bottom: 1px solid var(--line);
}
#topbar h1 { font-size: 18px; font-weight: 700; }
.icon-btn {
  background: var(--card2); color: var(--text); border: 1px solid var(--line);
  width: 36px; height: 36px; border-radius: 10px; font-size: 18px; cursor: pointer;
  transition: transform .12s;
}
.icon-btn:active { transform: scale(.9); }
.hidden { display: none !important; }

/* ---------- Bottom nav ---------- */
#bottomNav {
  position: fixed; bottom: 0; left: 0; right: 0; z-index: 50;
  display: flex; background: rgba(13,20,33,.95); backdrop-filter: blur(8px);
  border-top: 1px solid var(--line);
  padding-bottom: env(safe-area-inset-bottom);
}
.nav-btn {
  flex: 1; background: none; border: none; color: var(--muted);
  font-size: 12px; padding: 8px 0 10px; cursor: pointer;
  display: flex; flex-direction: column; align-items: center; gap: 2px;
  transition: color .15s, transform .1s;
}
.nav-btn .nav-ico { font-size: 20px; }
.nav-btn.active { color: var(--accent); }
.nav-btn:active { transform: scale(.92); }

/* ---------- Layout ---------- */
#content { max-width: 720px; margin: 0 auto; padding: 16px; }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px; margin-bottom: 14px;
  animation: fadeUp .35s ease both;
}
@keyframes fadeUp { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }
.card h2 { font-size: 17px; margin-bottom: 8px; color: var(--accent); }
.card h3 { font-size: 15px; margin: 12px 0 6px; }
.card p { margin-bottom: 8px; color: var(--text); }
.card b { color: #fff; }
.muted { color: var(--muted); font-size: 14px; }
.pill {
  display: inline-block; background: var(--card2); border: 1px solid var(--line);
  border-radius: 999px; padding: 2px 10px; font-size: 12px; color: var(--muted); margin-right: 6px;
}
.goal-box {
  background: linear-gradient(135deg, rgba(56,189,248,.12), rgba(34,197,94,.10));
  border: 1px solid rgba(56,189,248,.35); border-radius: var(--radius);
  padding: 12px 14px; margin-bottom: 14px; font-size: 15px;
}
.analogy {
  background: rgba(245,158,11,.08); border-left: 3px solid var(--warn);
  border-radius: 8px; padding: 10px 12px; margin: 10px 0; font-size: 14.5px;
}
.keypoint {
  background: rgba(34,197,94,.08); border-left: 3px solid var(--up);
  border-radius: 8px; padding: 10px 12px; margin: 10px 0; font-size: 14.5px;
}

/* ---------- Day list ---------- */
.week-head { font-size: 14px; font-weight: 700; color: var(--muted); margin: 18px 4px 8px; text-transform: uppercase; letter-spacing: .5px; }
.day-item {
  display: flex; align-items: center; gap: 12px; width: 100%;
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 12px 14px; margin-bottom: 8px; cursor: pointer; color: var(--text);
  text-align: left; font-size: 15px; transition: transform .12s, border-color .15s;
}
.day-item:active { transform: scale(.98); }
.day-item .day-num {
  min-width: 40px; height: 40px; border-radius: 12px; display: flex; align-items: center; justify-content: center;
  background: var(--card2); font-weight: 700; font-size: 13px; color: var(--accent); flex-direction: column; line-height: 1.1;
}
.day-item.done .day-num { background: rgba(34,197,94,.18); color: var(--up); }
.day-item .day-t { flex: 1; }
.day-item .day-t small { display: block; color: var(--muted); font-size: 12.5px; }
.day-item .day-check { color: var(--up); font-size: 18px; }

/* ---------- Animations (SVG scenes) ---------- */
.anim-box {
  background: var(--card2); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 12px; margin: 12px 0; overflow: hidden;
}
.anim-title { font-size: 13px; font-weight: 700; color: var(--accent); margin-bottom: 8px; }
.anim-svg svg { width: 100%; height: auto; display: block; }
.anim-cap {
  min-height: 44px; font-size: 14px; color: var(--text);
  background: rgba(56,189,248,.08); border-radius: 10px; padding: 8px 12px; margin-top: 10px;
}
.anim-ctrl { display: flex; gap: 8px; margin-top: 10px; }
.ab {
  flex: 1; background: var(--card); color: var(--text); border: 1px solid var(--line);
  border-radius: 10px; padding: 9px 0; font-size: 14px; cursor: pointer; transition: transform .1s, background .15s;
}
.ab:active { transform: scale(.95); }
.ab.play { color: var(--accent); border-color: rgba(56,189,248,.5); }
.ab.play.on { background: rgba(56,189,248,.15); }

/* reveal elements inside svg */
svg .rv { opacity: 0; transition: opacity .4s ease; }
svg .rv.on { opacity: 1; }
svg g.pt.on circle.dot { animation: pulsePt 1.6s ease-out infinite; }
@keyframes pulsePt { 0% { stroke-width: 2; stroke-opacity: .9; } 70% { stroke-width: 12; stroke-opacity: 0; } 100% { stroke-width: 12; stroke-opacity: 0; } }
svg .vol.on { animation: growBar .5s ease-out both; transform-origin: bottom; transform-box: fill-box; }
@keyframes growBar { from { transform: scaleY(0); } to { transform: scaleY(1); } }
svg .zone.on { animation: zoneIn .6s ease both; }
@keyframes zoneIn { from { opacity: 0; } to { opacity: 1; } }

/* looping svg helpers */
.loopfloat { animation: floatY 2.4s ease-in-out infinite; }
@keyframes floatY { 0%,100% { transform: translateY(0); } 50% { transform: translateY(-8px); } }
.seesaw-g { transform-box: fill-box; transform-origin: center; animation: seesaw 4s ease-in-out infinite; }
@keyframes seesaw { 0%,100% { transform: rotate(-7deg); } 50% { transform: rotate(7deg); } }
.coil-g { transform-box: fill-box; transform-origin: bottom; animation: coil 3.6s ease-in-out infinite; }
@keyframes coil { 0% { transform: scaleY(1); } 45% { transform: scaleY(.45); } 60% { transform: scaleY(.42); } 75% { transform: scaleY(1.15); } 100% { transform: scaleY(1); } }
.rocket { animation: rocket 3.6s ease-in-out infinite; }
@keyframes rocket { 0%,60% { opacity: 0; transform: translateY(0); } 70% { opacity: 1; } 95% { opacity: 1; transform: translateY(-70px); } 100% { opacity: 0; transform: translateY(-70px); } }
.ball-g { animation: ballDip 4s ease-in-out infinite; }
@keyframes ballDip { 0% { transform: translateY(0); } 35% { transform: translateY(46px); } 55% { transform: translateY(46px); } 75% { transform: translateY(-34px); } 90% { transform: translateY(-26px); } 100% { transform: translateY(0); } }
.trapline { stroke-dasharray: 900; animation: trap 5s ease-in-out infinite; }
@keyframes trap { 0% { stroke-dashoffset: 900; } 55% { stroke-dashoffset: 450; } 100% { stroke-dashoffset: 0; } }
.blinkwarn { animation: blinkW 1.2s steps(2) infinite; }
@keyframes blinkW { 50% { opacity: .15; } }
.growloop { transform-box: fill-box; transform-origin: bottom; animation: growLoop 2.8s ease-in-out infinite; }
@keyframes growLoop { 0% { transform: scaleY(.1); } 45%,80% { transform: scaleY(1); } 100% { transform: scaleY(.1); } }
.slideArrowUp { animation: slideAU 2.8s ease-in-out infinite; }
@keyframes slideAU { 0%,40% { opacity: 0; transform: translateY(12px); } 65% { opacity: 1; transform: translateY(0); } 100% { opacity: 1; transform: translateY(0); } }

/* ---------- Exercises ---------- */
.ex-block { border-top: 1px dashed var(--line); padding-top: 14px; margin-top: 14px; }
.ex-tag { font-size: 12px; font-weight: 700; color: var(--warn); letter-spacing: .5px; }
.ex-q { font-size: 15px; margin: 6px 0 10px; }
.opt {
  display: block; width: 100%; text-align: left;
  background: var(--card2); color: var(--text); border: 1px solid var(--line);
  border-radius: 10px; padding: 10px 12px; margin-bottom: 8px; font-size: 14.5px; cursor: pointer;
  transition: transform .1s, border-color .15s, background .15s;
}
.opt:active { transform: scale(.98); }
.opt.correct { background: rgba(34,197,94,.15); border-color: var(--up); color: #d1fae5; }
.opt.wrong { background: rgba(239,68,68,.15); border-color: var(--down); animation: shake .35s; }
.opt:disabled { cursor: default; opacity: .85; }
@keyframes shake { 0%,100% { transform: translateX(0); } 25% { transform: translateX(-5px); } 75% { transform: translateX(5px); } }
.ex-explain {
  background: rgba(56,189,248,.08); border-radius: 10px; padding: 10px 12px;
  font-size: 14px; margin-top: 6px; animation: fadeUp .3s ease both;
}
.ex-explain.ok { background: rgba(34,197,94,.1); }

.blank {
  display: inline-block; min-width: 76px; text-align: center;
  border-bottom: 2px dashed var(--accent); color: var(--accent);
  padding: 0 6px; margin: 0 2px; cursor: pointer; font-weight: 700;
}
.blank.filled { border-bottom-style: solid; }
.blank.good { color: var(--up); border-color: var(--up); }
.blank.bad { color: var(--down); border-color: var(--down); animation: shake .35s; }
.bank { display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0; }
.chip {
  background: var(--card2); border: 1px solid var(--line); color: var(--text);
  border-radius: 999px; padding: 6px 14px; font-size: 14px; cursor: pointer; transition: transform .1s;
}
.chip:active { transform: scale(.92); }
.chip.used { opacity: .3; pointer-events: none; }

.btn {
  display: inline-block; background: var(--accent); color: #06233a; border: none;
  border-radius: 10px; padding: 10px 18px; font-size: 14.5px; font-weight: 700; cursor: pointer;
  transition: transform .1s, opacity .15s;
}
.btn:active { transform: scale(.95); }
.btn.ghost { background: var(--card2); color: var(--text); border: 1px solid var(--line); }
.btn.success { background: var(--up); color: #06230f; }
.btn:disabled { opacity: .4; cursor: default; }

.task-item { display: flex; align-items: flex-start; gap: 10px; padding: 8px 0; font-size: 14.5px; }
.task-item input { width: 20px; height: 20px; margin-top: 2px; accent-color: var(--up); }
.task-item.done-t { color: var(--muted); text-decoration: line-through; }

/* diagram tap quiz */
.dq-prompt { font-size: 15px; margin: 8px 0; }
.dq-prompt b { color: var(--warn); }
svg .qdot { cursor: pointer; }
svg .qdot circle { transition: fill .2s; }
svg .qdot.found circle { fill: var(--up) !important; }
svg .qdot.missfx circle { animation: shakeDot .3s; }
@keyframes shakeDot { 0%,100% { transform: translateX(0); } 50% { transform: translateX(-6px); } }

/* ---------- Flashcards ---------- */
.fc-stage { perspective: 1000px; margin: 10px 0; }
.fc-card {
  position: relative; width: 100%; height: 240px; cursor: pointer;
  transform-style: preserve-3d; transition: transform .5s;
}
.fc-card.flipped { transform: rotateY(180deg); }
.fc-face {
  position: absolute; inset: 0; backface-visibility: hidden;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  background: var(--card2); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 20px; text-align: center;
}
.fc-face.back { transform: rotateY(180deg); background: #1a2c42; }
.fc-face .fc-term { font-size: 22px; font-weight: 800; color: var(--accent); }
.fc-face .fc-vi { font-size: 15px; color: var(--warn); margin-top: 4px; }
.fc-face .fc-def { font-size: 15px; }
.fc-btns { display: flex; gap: 10px; margin-top: 12px; }
.fc-btns .btn { flex: 1; }
.fc-meta { text-align: center; color: var(--muted); font-size: 13px; margin-top: 8px; }

/* ---------- Progress ---------- */
.prog-bar { background: var(--card2); border-radius: 999px; height: 14px; overflow: hidden; margin: 8px 0 4px; }
.prog-fill { height: 100%; background: linear-gradient(90deg, var(--accent), var(--up)); border-radius: 999px; transition: width .6s ease; }
.day-grid { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.dg-cell {
  width: 40px; height: 40px; border-radius: 10px; display: flex; align-items: center; justify-content: center;
  background: var(--card2); border: 1px solid var(--line); font-size: 13px; color: var(--muted);
}
.dg-cell.done { background: rgba(34,197,94,.2); border-color: var(--up); color: var(--up); font-weight: 700; }

.seg { display: flex; gap: 8px; margin-bottom: 12px; }
.seg .btn { flex: 1; }
.seg .btn.off { background: var(--card2); color: var(--muted); border: 1px solid var(--line); }

.lesson-nav { display: flex; gap: 10px; margin-top: 4px; }
.lesson-nav .btn { flex: 1; }

.legend-item { display: flex; gap: 10px; padding: 8px 0; border-bottom: 1px dashed var(--line); font-size: 14px; }
.legend-item:last-child { border-bottom: none; }
.legend-badge {
  min-width: 54px; height: 26px; border-radius: 8px; display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 800; color: #06233a; background: var(--accent);
}
.legend-badge.red { background: var(--down); color: #fff; }

.score-banner {
  text-align: center; padding: 16px; border-radius: var(--radius); margin-top: 12px;
  background: rgba(34,197,94,.12); border: 1px solid var(--up); animation: fadeUp .4s ease both;
}
.score-banner .big { font-size: 28px; font-weight: 800; color: var(--up); }