:root {
  --bg: #0f1222;
  --bg2: #171b31;
  --card: #1d2240;
  --line: #2b3157;
  --text: #eef0ff;
  --muted: #9aa0c3;
  --primary: #6c7bff;
  --primary2: #9b6cff;
  --good: #22c58b;
  --warn: #ffb547;
  --bad: #ff5d73;
  --radius: 16px;
  --safe-b: env(safe-area-inset-bottom, 0px);
  --safe-t: env(safe-area-inset-top, 0px);
  color-scheme: dark;
}
@media (prefers-color-scheme: light) {
  :root {
    --bg: #f3f4fb;
    --bg2: #ffffff;
    --card: #ffffff;
    --line: #e1e4f2;
    --text: #1a1d33;
    --muted: #6a7095;
    color-scheme: light;
  }
}

* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html, body { margin: 0; background: var(--bg); color: var(--text); }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "PingFang SC", "Noto Sans JP", sans-serif;
  font-size: 16px;
  line-height: 1.55;
  padding: calc(52px + var(--safe-t)) 0 calc(76px + var(--safe-b));
  -webkit-text-size-adjust: 100%;
}
main { max-width: 640px; margin: 0 auto; padding: 8px 16px 24px; }
h2 { margin: 8px 0 12px; font-size: 22px; }
h3 { margin: 0 0 8px; font-size: 17px; }
h4 { margin: 0 0 8px; font-size: 15px; }
h3.sec { margin: 22px 0 10px; color: var(--muted); font-size: 14px; letter-spacing: .05em; }
.muted { color: var(--muted); }
.small { font-size: 13px; }
.center { text-align: center; }
b { font-weight: 700; }
input, textarea, select {
  width: 100%;
  font: inherit;
  font-size: 16px; /* prevents iOS zoom */
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 10px 12px;
  margin: 4px 0 8px;
  resize: vertical;
}
input[type=date], input[type=number] { width: auto; max-width: 60%; margin: 0; }
.lbl { display: block; font-size: 13px; color: var(--muted); margin-top: 8px; }

/* ---------- HUD ---------- */
#hud {
  position: fixed; top: 0; left: 0; right: 0; z-index: 20;
  padding: calc(8px + var(--safe-t)) 16px 8px;
  display: flex; align-items: center; gap: 10px; justify-content: space-between;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
  font-size: 14px;
}
.hud-l { display: flex; align-items: center; gap: 8px; flex: 1; max-width: 220px; }
.lv { font-weight: 800; background: linear-gradient(135deg, var(--primary), var(--primary2)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.xpbar { flex: 1; height: 8px; border-radius: 8px; background: var(--line); overflow: hidden; }
.xpbar i { display: block; height: 100%; background: linear-gradient(90deg, var(--primary), var(--primary2)); border-radius: 8px; transition: width .4s; }
.hud-r { display: flex; gap: 12px; font-weight: 600; }
.resume { border: 0; border-radius: 99px; padding: 4px 10px; background: var(--warn); color: #222; font-weight: 700; font-size: 13px; }

/* ---------- tab bar ---------- */
#tabbar {
  position: fixed; bottom: 0; left: 0; right: 0; z-index: 20;
  display: flex; justify-content: space-around;
  padding: 6px 4px calc(6px + var(--safe-b));
  background: color-mix(in srgb, var(--bg2) 92%, transparent);
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
  border-top: 1px solid var(--line);
}
#tabbar a { flex: 1; text-align: center; font-size: 11px; color: var(--muted); text-decoration: none; padding: 2px 0; }
#tabbar a span { display: block; font-size: 22px; line-height: 1.2; filter: grayscale(1); opacity: .7; }
#tabbar a.on { color: var(--text); font-weight: 700; }
#tabbar a.on span { filter: none; opacity: 1; }
body[data-view=session] #tabbar, body[data-view=tutor] #tabbar { display: none; }
body[data-view=session], body[data-view=tutor] { padding-bottom: calc(16px + var(--safe-b)); }

/* ---------- basics ---------- */
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px 16px;
  margin: 10px 0;
}
.card.warn { border-color: var(--warn); }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  font: inherit; font-weight: 600; font-size: 15px;
  color: var(--text); background: var(--bg2);
  border: 1px solid var(--line); border-radius: 12px;
  padding: 11px 16px; min-height: 44px;
  cursor: pointer; text-decoration: none;
  transition: transform .08s;
}
.btn:active { transform: scale(.97); }
.btn.primary { background: linear-gradient(135deg, var(--primary), var(--primary2)); border: 0; color: #fff; }
.btn.danger { color: var(--bad); border-color: color-mix(in srgb, var(--bad) 40%, var(--line)); }
.btn.ghost { background: transparent; }
.btn.small { padding: 6px 12px; min-height: 34px; font-size: 13px; }
.btn.block { display: flex; width: 100%; }
.btn.big { min-height: 56px; font-size: 17px; }
.btn[disabled], .big-btn[disabled] { opacity: .45; pointer-events: none; }
.row { display: flex; gap: 8px; margin: 8px 0; }
.row.wrap { flex-wrap: wrap; }
.row > .btn { flex: 1; }
.stack { display: flex; flex-direction: column; gap: 8px; margin: 12px 0; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0; }
.chip {
  font: inherit; font-size: 13px; font-weight: 600;
  padding: 6px 12px; border-radius: 99px;
  border: 1px solid var(--line); background: var(--bg2); color: var(--text);
}
.chip.on { background: var(--c, var(--primary)); border-color: var(--c, var(--primary)); color: #fff; }
.seg { display: flex; background: var(--bg2); border: 1px solid var(--line); border-radius: 12px; padding: 3px; margin: 10px 0; }
.seg button { flex: 1; font: inherit; font-size: 14px; font-weight: 600; border: 0; background: transparent; color: var(--muted); padding: 9px 4px; border-radius: 9px; }
.seg button.on { background: var(--card); color: var(--text); box-shadow: 0 1px 4px rgba(0,0,0,.25); }
.seg.small button { font-size: 13px; }
.tag { display: inline-block; font-size: 11px; padding: 1px 8px; border-radius: 99px; background: var(--line); margin-left: 4px; }
.kv { display: flex; align-items: center; justify-content: space-between; gap: 8px; padding: 4px 0; }
.empty { text-align: center; color: var(--muted); padding: 32px 8px; }
.back { font: inherit; color: var(--primary); background: none; border: 0; padding: 4px 0; font-size: 15px; }
details { margin: 6px 0; }
summary { cursor: pointer; font-weight: 600; padding: 6px 0; }
ul { margin: 4px 0; padding-left: 1.3em; }
.md-h { font-weight: 700; margin-top: 6px; }
.md-gap { height: 6px; }
.note { margin-top: 10px; padding: 8px 10px; border-radius: 10px; background: color-mix(in srgb, var(--warn) 14%, transparent); font-size: 14px; }

/* ---------- home ---------- */
.hero { display: flex; gap: 14px; align-items: center; padding: 16px; border-radius: 20px; margin: 6px 0 10px;
  background: linear-gradient(135deg, #3b2ff0, #8a3cff 55%, #ff5d9e); color: #fff; }
.hero-days { text-align: center; min-width: 80px; }
.hero-days b { display: block; font-size: 48px; line-height: 1; }
.hero-days span { font-size: 12px; opacity: .9; }
.hero-txt .phase { font-weight: 800; font-size: 17px; }
.hero .muted { color: rgba(255,255,255,.85); }
.today { display: flex; gap: 16px; align-items: center; }
.today-body { flex: 1; }
.today-body .btn { margin-top: 8px; }
.ring { --p: 0; width: 88px; height: 88px; border-radius: 50%; flex-shrink: 0;
  background: conic-gradient(var(--rc, var(--good)) calc(var(--p) * 360deg), var(--line) 0);
  display: grid; place-items: center; }
.ring > div { width: 70px; height: 70px; border-radius: 50%; background: var(--card); display: grid; place-items: center; align-content: center; }
.ring b { font-size: 22px; line-height: 1; }
.ring small { color: var(--muted); font-size: 11px; }
.subjects { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; }
.subj { text-align: left; font: inherit; color: var(--text); background: var(--card); border: 1px solid var(--line);
  border-left: 4px solid var(--c); border-radius: 14px; padding: 10px 12px; }
.subj-top { display: flex; justify-content: space-between; }
.subj-ic { font-size: 20px; color: var(--c); }
.subj-d { font-size: 12px; color: var(--muted); }
.subj-name { font-weight: 800; font-size: 16px; }
.subj-meta { font-size: 12px; color: var(--muted); }
.subj-meta b { color: var(--warn); }
.bar { height: 6px; background: var(--line); border-radius: 6px; margin-top: 6px; overflow: hidden; }
.bar i { display: block; height: 100%; background: var(--c); }
.hbar { display: grid; grid-template-columns: 80px 1fr 28px; gap: 8px; align-items: center; font-size: 14px; margin: 4px 0; }
.hbar div { height: 10px; background: var(--line); border-radius: 6px; overflow: hidden; }
.hbar i { display: block; height: 100%; background: var(--bad); }
.week { display: flex; justify-content: space-between; gap: 6px; }
.wk { flex: 1; text-align: center; display: flex; flex-direction: column; align-items: center; }
.wk-bar { width: 100%; max-width: 26px; height: 70px; background: var(--line); border-radius: 6px; display: flex; align-items: flex-end; overflow: hidden; }
.wk-bar i { display: block; width: 100%; background: linear-gradient(0deg, var(--primary), var(--primary2)); }
.wk small { font-size: 11px; }
.onboarding ol { padding-left: 1.2em; margin: 6px 0; }

/* ---------- add ---------- */
.photos { display: flex; flex-wrap: wrap; gap: 8px; margin: 6px 0; }
.ph { position: relative; }
.ph img { width: 84px; height: 112px; object-fit: cover; border-radius: 10px; border: 1px solid var(--line); }
.ph button { position: absolute; top: -6px; right: -6px; width: 24px; height: 24px; border-radius: 50%; border: 0; background: var(--bad); color: #fff; font-weight: 700; }
.pv.del { opacity: .35; }
.pv-top { display: flex; align-items: center; gap: 6px; }
.pv-top .x { margin-left: auto; border: 0; background: var(--line); color: var(--text); width: 28px; height: 28px; border-radius: 50%; font-size: 16px; }
.stars { color: var(--warn); font-size: 12px; }
.pv-f { font-weight: 600; margin-top: 6px; }
.pv-b { color: var(--good); margin-top: 4px; }
.summary { font-size: 14px; }
.sticky-bottom { position: sticky; bottom: calc(76px + var(--safe-b)); background: var(--bg); padding: 8px 0; margin: 0; }

/* ---------- review ---------- */
.big-btn { display: flex; flex-direction: column; align-items: flex-start; gap: 2px; width: 100%; text-align: left;
  font: inherit; color: var(--text); background: var(--card); border: 1px solid var(--line); border-radius: 16px; padding: 14px; margin: 0; }
.big-btn b { font-size: 16px; }
.big-btn span { font-size: 12px; color: var(--muted); }
.big-btn.primary { background: linear-gradient(135deg, var(--primary), var(--primary2)); border: 0; color: #fff; margin: 6px 0 10px; }
.big-btn.primary span { color: rgba(255,255,255,.85); }
.big-btn.danger { border-color: color-mix(in srgb, var(--bad) 50%, var(--line)); }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin: 10px 0; }
.list { display: flex; flex-direction: column; gap: 6px; margin: 8px 0; }
.li { display: flex; align-items: center; gap: 10px; width: 100%; text-align: left; font: inherit; color: var(--text);
  background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 10px 12px; }
.li .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--c); flex-shrink: 0; }
.li-t { flex: 1; min-width: 0; overflow: hidden; }
.card-li .li-t { max-height: 5.2em; }
.card-li .li-t small { display: block; }
.mini-m { font-size: 12px; color: var(--muted); }
.search { margin: 4px 0; }

/* ---------- session ---------- */
.sess-top { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.icon { border: 0; background: var(--line); color: var(--text); width: 34px; height: 34px; border-radius: 50%; font-size: 15px; }
.prog { flex: 1; height: 8px; background: var(--line); border-radius: 8px; overflow: hidden; }
.prog i { display: block; height: 100%; background: linear-gradient(90deg, var(--good), #7be0b8); transition: width .3s; }
.combo { font-weight: 800; color: var(--warn); animation: pop .3s; }
@keyframes pop { from { transform: scale(1.6); } to { transform: scale(1); } }
.flash {
  min-height: 46vh; background: var(--card); border: 1px solid var(--line); border-top: 5px solid var(--c);
  border-radius: 20px; padding: 18px; margin-bottom: 14px; font-size: 19px;
  display: flex; flex-direction: column; animation: cardIn .25s ease-out;
}
.flash.method { background: linear-gradient(180deg, color-mix(in srgb, var(--primary) 12%, var(--card)), var(--card)); }
@keyframes cardIn { from { transform: translateY(12px) scale(.98); opacity: 0; } to { transform: none; opacity: 1; } }
.flash-meta { display: flex; justify-content: space-between; font-size: 12px; color: var(--muted); margin-bottom: 10px; }
.flash-front { font-weight: 600; }
.flash-sep { border-top: 1px dashed var(--line); margin: 16px 0; }
.flash-back { color: var(--good); font-weight: 600; animation: cardIn .2s; }
.tap-hint { margin-top: auto; text-align: center; color: var(--muted); font-size: 13px; padding-top: 20px; }
.grades { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; }
.g { font: inherit; font-weight: 700; font-size: 15px; border: 0; border-radius: 14px; padding: 16px 4px; color: #fff; }
.g:active { transform: scale(.95); }
.g0 { background: var(--bad); }
.g1 { background: #f08a3c; }
.g2 { background: var(--good); }
.g3 { background: #2aa4ff; }
.prob .thumbs.big img { width: 100%; height: auto; max-height: 60vh; object-fit: contain; }
.think { display: flex; align-items: center; gap: 10px; justify-content: space-between; margin: 12px 0 4px; padding: 10px 12px;
  border-radius: 12px; background: color-mix(in srgb, var(--primary) 15%, transparent); font-size: 14px; }
.think b { font-size: 26px; min-width: 44px; text-align: center; }
.think b.late { color: var(--bad); }
.hint { padding: 8px 10px; border-radius: 10px; background: color-mix(in srgb, var(--warn) 15%, transparent); margin: 6px 0; font-size: 15px; }
.kp { margin: 8px 0; }
.kp > span { display: block; font-size: 12px; color: var(--muted); font-weight: 600; }
.steps { padding-left: 1.3em; }
.steps li { margin: 8px 0; }
.thumbs { display: flex; gap: 8px; overflow-x: auto; margin: 8px 0; }
.thumbs img { height: 160px; border-radius: 10px; border: 1px solid var(--line); flex-shrink: 0; }
.done { text-align: center; padding-top: 20px; }
.done-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin: 16px 0; }
.done-grid div { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 12px 4px; }
.done-grid b { display: block; font-size: 22px; }
.done-grid small { color: var(--muted); }
.confetti { font-size: 34px; height: 50px; }
.confetti span { display: inline-block; animation: jump 1s ease-in-out infinite; animation-delay: calc(var(--i) * .12s); }
@keyframes jump { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-14px) rotate(10deg); } }

/* ---------- tutor ---------- */
.tutor-top { display: flex; justify-content: space-between; align-items: center; }
.chat { display: flex; flex-direction: column; gap: 8px; margin: 10px 0; padding-bottom: 8px; }
.bubble { max-width: 88%; padding: 10px 12px; border-radius: 16px; font-size: 15px; word-break: break-word; }
.bubble.user { align-self: flex-end; background: linear-gradient(135deg, var(--primary), var(--primary2)); color: #fff; border-bottom-right-radius: 4px; }
.bubble.assistant { align-self: flex-start; background: var(--card); border: 1px solid var(--line); border-bottom-left-radius: 4px; }
.chat-img img { max-width: 200px; border-radius: 10px; }
.typing i { display: inline-block; width: 7px; height: 7px; margin: 0 2px; border-radius: 50%; background: var(--muted); animation: jump 1s infinite; }
.typing i:nth-child(2) { animation-delay: .15s; }
.typing i:nth-child(3) { animation-delay: .3s; }
.quick { display: flex; gap: 6px; overflow-x: auto; padding: 4px 0; }
.quick .chip { white-space: nowrap; }
.composer { position: sticky; bottom: calc(8px + var(--safe-b)); display: flex; gap: 6px; align-items: flex-end;
  background: var(--bg); padding: 6px 0; }
.composer textarea { margin: 0; min-height: 44px; resize: none; }
.composer .btn { white-space: nowrap; flex-shrink: 0; }
.icon-btn { display: grid; place-items: center; min-width: 44px; height: 44px; border-radius: 12px; background: var(--card); border: 1px solid var(--line); font-size: 20px; }
#attach-prev img { height: 70px; border-radius: 8px; vertical-align: middle; }

/* ---------- modal / overlay ---------- */
#modal { position: fixed; inset: 0; z-index: 50; background: rgba(0,0,0,.5); display: none; align-items: flex-end; justify-content: center; }
#modal.show { display: flex; }
.sheet { position: relative; width: 100%; max-width: 640px; max-height: 88vh; overflow-y: auto; background: var(--bg2);
  border-radius: 22px 22px 0 0; padding: 20px 16px calc(20px + var(--safe-b)); animation: up .22s ease-out; }
@keyframes up { from { transform: translateY(40px); opacity: 0; } to { transform: none; opacity: 1; } }
.sheet-x { position: absolute; top: 12px; right: 12px; border: 0; width: 32px; height: 32px; border-radius: 50%; background: var(--line); color: var(--text); font-size: 15px; z-index: 2; }
#overlay { position: fixed; inset: 0; z-index: 60; background: rgba(10,12,30,.82); color: #fff; display: none;
  flex-direction: column; align-items: center; justify-content: center; gap: 10px; text-align: center; padding: 24px; }
#overlay.show { display: flex; }
#overlay .muted { color: #b9bde0; }
.spinner { width: 48px; height: 48px; border-radius: 50%; border: 5px solid rgba(255,255,255,.2); border-top-color: #fff; animation: spin 1s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }
#viewer { position: fixed; inset: 0; z-index: 70; background: #000; display: none; overflow: auto; }
#viewer.show { display: block; }
#viewer img { width: 100%; display: block; }
#viewer img.big { width: 250%; max-width: none; }
#viewer .sheet-x { position: fixed; top: calc(12px + var(--safe-t)); }
#toast { position: fixed; left: 50%; bottom: calc(90px + var(--safe-b)); transform: translateX(-50%) translateY(20px); z-index: 80;
  background: #222849; color: #fff; padding: 10px 16px; border-radius: 99px; font-size: 14px; opacity: 0; pointer-events: none;
  transition: all .25s; max-width: 90vw; text-align: center; box-shadow: 0 6px 20px rgba(0,0,0,.3); }
#toast.show { opacity: 1; transform: translateX(-50%); }

.katex { font-size: 1.05em; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 4px 0; }

/* ---------- feynman ---------- */
.big-btn.fey { margin: 0 0 10px; border-color: color-mix(in srgb, var(--good) 45%, var(--line));
  background: linear-gradient(135deg, color-mix(in srgb, var(--good) 16%, var(--card)), var(--card)); }
.fey-score { display: flex; gap: 14px; align-items: center; }
.fey-pill { min-width: 36px; text-align: center; padding: 2px 8px; border-radius: 99px; background: var(--sc); color: #fff; font-size: 13px; }
.bubble .who { font-size: 11px; color: var(--muted); font-weight: 700; margin-bottom: 2px; }
.fc { display: flex; gap: 10px; padding: 10px 0; border-top: 1px solid var(--line); }
.fc.off { opacity: .4; }
.fc-box { font-size: 20px; line-height: 1.2; color: var(--good); }
.fey-wrong { padding: 8px 0; border-top: 1px solid var(--line); }
.fey-wrong:first-of-type { border-top: 0; }
.bubble.teacher { border-color: color-mix(in srgb, var(--good) 55%, var(--line)); background: color-mix(in srgb, var(--good) 10%, var(--card)); }
.chip.hot { background: var(--good); border-color: var(--good); color: #fff; }
.toggle { display: flex; gap: 10px; align-items: flex-start; margin: 4px 0 10px; font-size: 14px; }
.toggle input { width: 22px; height: 22px; margin: 2px 0 0; flex-shrink: 0; accent-color: var(--primary); }

/* ---------- exam banner / lesson ---------- */
.exam-banner { border-color: var(--warn); background: color-mix(in srgb, var(--warn) 14%, var(--card)); }
.exam-banner.today-exam { border-color: var(--good); background: color-mix(in srgb, var(--good) 14%, var(--card)); }
.next-exam { font-weight: 700; margin: 2px 0; }
.seg3 button { line-height: 1.25; padding: 7px 2px; }
.seg3 small { font-size: 11px; font-weight: 500; opacity: .8; }
.lesson-prog { margin: 8px 0; }
.lesson-sec { border-top: 4px solid var(--primary); }
.lesson-sec h3 { margin-top: 4px; }
.example, .more, .check { margin-top: 12px; padding: 10px 12px; border-radius: 12px; }
.example { background: color-mix(in srgb, var(--primary) 10%, transparent); }
.more { background: color-mix(in srgb, var(--good) 12%, transparent); }
.check { background: color-mix(in srgb, var(--warn) 14%, transparent); }
.example h4, .more h4, .check h4 { margin-bottom: 4px; }
.lesson-done { border-color: var(--good); }
.big-btn.pack-entry { margin: 0 0 10px; border-color: color-mix(in srgb, var(--warn) 55%, var(--line));
  background: linear-gradient(135deg, color-mix(in srgb, var(--warn) 16%, var(--card)), var(--card)); }