:root {
  color-scheme: light dark;
  --font-display: "Avenir Next", "SF Pro Display", "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", sans-serif;
  --font-body: "Avenir Next", "SF Pro Text", "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-number: "DIN Alternate", "Avenir Next", ui-sans-serif, system-ui, sans-serif;
  --font-code: "SF Mono", "JetBrains Mono", ui-monospace, Menlo, Consolas, monospace;
  --bg: #f7f7f3;
  --bg-elevated: #ffffff;
  --panel: rgba(255, 255, 255, 0.76);
  --panel-strong: rgba(255, 255, 255, 0.94);
  --panel-muted: rgba(239, 238, 231, 0.72);
  --ink: #111111;
  --muted: #676760;
  --muted-2: #8c8b84;
  --line: rgba(18, 18, 18, 0.12);
  --line-strong: rgba(18, 18, 18, 0.18);
  --rain: #10a37f;
  --rain-2: #19c37d;
  --gold: #b8872d;
  --ember: #d44a3a;
  --sky: #2f68ff;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.08);
  --soft-shadow: 0 14px 40px rgba(0, 0, 0, 0.09);
  --focus-ring: 0 0 0 4px rgba(16, 163, 127, 0.18);
  --radius-xl: 34px;
  --radius-lg: 24px;
  --radius-md: 17px;
  --nav-h: 72px;
}

[data-theme="dark"] {
  --bg: #171717;
  --bg-elevated: #212121;
  --panel: rgba(33, 33, 33, 0.78);
  --panel-strong: rgba(45, 45, 45, 0.94);
  --panel-muted: rgba(39, 39, 39, 0.74);
  --ink: #ececec;
  --muted: #a8a8a0;
  --muted-2: #85857d;
  --line: rgba(255, 255, 255, 0.12);
  --line-strong: rgba(255, 255, 255, 0.18);
  --rain: #19c37d;
  --rain-2: #2ed18f;
  --gold: #d6a949;
  --ember: #ff7a66;
  --sky: #8aa7ff;
  --shadow: 0 26px 80px rgba(0, 0, 0, 0.34);
  --soft-shadow: 0 14px 44px rgba(0, 0, 0, 0.32);
  --focus-ring: 0 0 0 4px rgba(25, 195, 125, 0.18);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #171717;
    --bg-elevated: #212121;
    --panel: rgba(33, 33, 33, 0.78);
    --panel-strong: rgba(45, 45, 45, 0.94);
    --panel-muted: rgba(39, 39, 39, 0.74);
    --ink: #ececec;
    --muted: #a8a8a0;
    --muted-2: #85857d;
    --line: rgba(255, 255, 255, 0.12);
    --line-strong: rgba(255, 255, 255, 0.18);
    --rain: #19c37d;
    --rain-2: #2ed18f;
    --gold: #d6a949;
    --ember: #ff7a66;
    --sky: #8aa7ff;
    --shadow: 0 26px 80px rgba(0, 0, 0, 0.34);
    --soft-shadow: 0 14px 44px rgba(0, 0, 0, 0.32);
    --focus-ring: 0 0 0 4px rgba(25, 195, 125, 0.18);
  }
}

* { box-sizing: border-box; }
html { min-height: 100%; background: var(--bg); }
body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family: var(--font-body);
  overflow-x: hidden;
  overflow-wrap: anywhere;
  background:
    radial-gradient(circle at 18% -12%, color-mix(in srgb, var(--rain) 10%, transparent), transparent 34rem),
    radial-gradient(circle at 94% 6%, rgba(0, 0, 0, 0.055), transparent 28rem),
    linear-gradient(180deg, var(--bg), color-mix(in srgb, var(--bg) 78%, var(--bg-elevated) 22%));
  -webkit-font-smoothing: antialiased;
  text-rendering: geometricPrecision;
}
body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: .42;
  background-image:
    linear-gradient(color-mix(in srgb, var(--ink) 4%, transparent) 1px, transparent 1px),
    linear-gradient(90deg, color-mix(in srgb, var(--ink) 4%, transparent) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: linear-gradient(to bottom, rgba(0,0,0,.6), rgba(0,0,0,.16) 48%, transparent 88%);
}
button, input, select, textarea { font: inherit; }
button { cursor: pointer; }
img { max-width: 100%; }
a { color: var(--rain); text-underline-offset: 3px; }
::selection { color: #fff; background: var(--rain); }

.app-shell {
  position: relative;
  z-index: 1;
  width: min(1280px, calc(100vw - 40px));
  margin: 0 auto;
  padding: 20px 0 56px;
}

.boot-card {
  min-height: calc(100vh - 80px);
  display: grid;
  place-items: center;
  grid-template-columns: auto minmax(0, 520px);
  gap: 24px;
}
.brand-mark {
  width: 78px;
  height: 78px;
  border-radius: 24px;
  display: grid;
  place-items: center;
  color: white;
  font-family: var(--font-display);
  font-size: 40px;
  font-weight: 800;
  background: #111;
  box-shadow: var(--soft-shadow);
}
.eyebrow {
  margin: 0 0 10px;
  color: var(--muted);
  font-family: var(--font-number);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .17em;
  text-transform: uppercase;
}

.topbar {
  position: sticky;
  top: 14px;
  z-index: 20;
  min-height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 10px 10px 10px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: color-mix(in srgb, var(--panel-strong) 82%, transparent);
  backdrop-filter: blur(24px) saturate(1.2);
  box-shadow: 0 10px 34px rgba(0, 0, 0, 0.055);
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}
.logo {
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  border-radius: 16px;
  color: #fff;
  font-family: var(--font-display);
  font-size: 24px;
  font-weight: 900;
  background: #111;
  box-shadow: inset 0 -1px 0 rgba(255,255,255,.16), 0 10px 24px rgba(0,0,0,.12);
}
[data-theme="dark"] .logo,
[data-theme="dark"] .brand-mark { background: #ececec; color: #111; }
.brand h1 { margin: 0; font: 850 clamp(21px, 3vw, 30px)/1 var(--font-display); letter-spacing: -.045em; }
.brand p { margin: 4px 0 0; color: var(--muted); font-size: 12px; }
.nav-actions { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; justify-content: flex-end; }

.hero {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(320px, .92fr);
  gap: 22px;
  margin: 28px 0 24px;
}
.hero-card, .panel, .course-card, .lesson-stage, .problem-card, .sheet {
  border: 1px solid var(--line);
  background: var(--panel);
  backdrop-filter: blur(24px) saturate(1.12);
  box-shadow: var(--shadow);
}
.hero-card {
  overflow: hidden;
  min-width: 0;
  min-height: 360px;
  padding: clamp(28px, 5vw, 64px);
  border-radius: var(--radius-xl);
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  background:
    linear-gradient(145deg, color-mix(in srgb, var(--panel-strong) 86%, transparent), color-mix(in srgb, var(--panel-muted) 92%, transparent)),
    radial-gradient(circle at 78% 18%, color-mix(in srgb, var(--rain) 15%, transparent), transparent 24rem);
}
.hero-card::before {
  content: "";
  position: absolute;
  right: clamp(22px, 5vw, 76px);
  top: clamp(22px, 5vw, 64px);
  width: clamp(96px, 15vw, 172px);
  aspect-ratio: 1;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: radial-gradient(circle at 35% 35%, color-mix(in srgb, var(--rain) 28%, transparent), transparent 58%);
  opacity: .7;
}
.hero-title {
  position: relative;
  z-index: 1;
  max-width: 780px;
  margin: 50px 0 0;
  font: 850 clamp(44px, 8vw, 98px)/.94 var(--font-display);
  letter-spacing: -.08em;
  overflow-wrap: anywhere;
}
.hero-title span { color: color-mix(in srgb, var(--rain) 88%, var(--ink)); }
.hero-copy {
  position: relative;
  z-index: 1;
  width: min(100%, 670px);
  margin: 24px 0 0;
  color: var(--muted);
  font-size: clamp(16px, 2vw, 19px);
  line-height: 1.72;
  overflow-wrap: anywhere;
}
.hero-metrics {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-top: 34px;
}
.metric {
  min-height: 104px;
  padding: 16px;
  border-radius: 20px;
  background: color-mix(in srgb, var(--panel-strong) 64%, transparent);
  border: 1px solid var(--line);
  transition: transform .2s ease, border-color .2s ease, background .2s ease;
}
.metric:hover { transform: translateY(-2px); border-color: color-mix(in srgb, var(--ink) 26%, var(--line)); }
.metric strong { display: block; font-family: var(--font-display); font-size: clamp(22px, 3vw, 32px); letter-spacing: -.05em; color: var(--ink); }
.metric span { color: var(--muted); font-size: 12px; line-height: 1.5; }

.panel, .sheet { border-radius: var(--radius-lg); padding: 22px; }
.panel, .sheet, .course-card, .lesson-stage, .problem-card { min-width: 0; }
.panel h2, .sheet h2, .problem-card h2 { margin: 0 0 14px; font-size: 22px; line-height: 1.2; letter-spacing: -.045em; }
.panel p, .sheet p { color: var(--muted); line-height: 1.65; }

.card-stack { display: grid; gap: 16px; align-content: start; }
.card-stack .panel:first-child {
  padding: 24px;
  border-radius: 28px;
  background: color-mix(in srgb, var(--panel-strong) 88%, transparent);
}
.form-grid { display: grid; gap: 14px; }
.field { display: grid; gap: 7px; }
.field label { color: var(--muted); font-size: 13px; font-weight: 760; }
.login-switch {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
  margin: 16px 0 18px;
  padding: 4px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: color-mix(in srgb, var(--panel-muted) 72%, transparent);
}
.login-tab {
  min-height: 38px;
  border: 0;
  border-radius: 999px;
  color: var(--muted);
  background: transparent;
  font-weight: 850;
  transition: background .18s ease, color .18s ease, box-shadow .18s ease, transform .18s ease;
}
.login-tab:hover { color: var(--ink); }
.login-tab.active {
  color: var(--ink);
  background: var(--panel-strong);
  box-shadow: 0 8px 22px rgba(0,0,0,.08);
}
.input-action-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 10px;
  align-items: center;
}
.input, .select, .textarea {
  width: 100%;
  border: 1px solid transparent;
  border-radius: 18px;
  color: var(--ink);
  background: color-mix(in srgb, var(--panel-muted) 74%, var(--panel-strong));
  padding: 14px 15px;
  outline: none;
  box-shadow: inset 0 0 0 1px var(--line);
  transition: border-color .18s ease, box-shadow .18s ease, transform .18s ease, background .18s ease;
}
.input::placeholder, .textarea::placeholder { color: var(--muted-2); }
.textarea { min-height: 96px; resize: vertical; }
.file-input {
  width: 100%;
  border: 1px dashed var(--line-strong);
  border-radius: 18px;
  color: var(--muted);
  background: color-mix(in srgb, var(--panel-muted) 74%, transparent);
  padding: 12px;
}
.input:focus, .select:focus, .textarea:focus {
  border-color: var(--rain);
  box-shadow: inset 0 0 0 1px var(--rain), var(--focus-ring);
  background: var(--panel-strong);
}
.row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.row-between { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.divider { height: 1px; background: var(--line); margin: 16px 0; }
.compact-status { padding: 16px 18px; }
.compact-status p { margin: 10px 0 0; font-size: 13px; }

.btn {
  --btn-bg: color-mix(in srgb, var(--panel-strong) 72%, transparent);
  --btn-ink: var(--ink);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 42px;
  padding: 10px 16px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--btn-ink);
  background: var(--btn-bg);
  text-decoration: none;
  font-weight: 820;
  letter-spacing: -.01em;
  transition: transform .18s ease, box-shadow .18s ease, background .18s ease, opacity .18s ease, border-color .18s ease;
}
.btn:hover { transform: translateY(-1px); box-shadow: var(--soft-shadow); border-color: color-mix(in srgb, var(--ink) 24%, var(--line)); }
.btn:disabled { opacity: .48; cursor: not-allowed; transform: none; box-shadow: none; }
.btn.primary { --btn-bg: #111; --btn-ink: #fff; border-color: transparent; }
.btn.primary:hover { background: color-mix(in srgb, #111 86%, var(--rain)); }
.btn.gold { --btn-bg: color-mix(in srgb, var(--gold) 16%, var(--panel-strong)); --btn-ink: var(--ink); }
.btn.danger { --btn-bg: color-mix(in srgb, var(--ember) 12%, var(--panel-strong)); --btn-ink: var(--ember); }
.btn.ghost { background: transparent; }
.btn.small { min-height: 34px; padding: 7px 11px; font-size: 13px; }
[data-theme="dark"] .btn.primary { --btn-bg: #ececec; --btn-ink: #111; }
[data-theme="dark"] .btn.primary:hover { background: #fff; }
.pill {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 7px 11px;
  border-radius: 999px;
  border: 1px solid var(--line);
  color: var(--muted);
  background: color-mix(in srgb, var(--panel-strong) 58%, transparent);
  font-size: 12px;
  font-weight: 820;
}
.pill.live { color: #fff; background: #111; border-color: transparent; }
.pill.ok { color: var(--rain); }
.pill.warn { color: var(--gold); }
[data-theme="dark"] .pill.live { color: #111; background: #ececec; }

.workspace {
  display: grid;
  grid-template-columns: minmax(280px, 360px) minmax(0, 1fr);
  gap: 18px;
  align-items: start;
  margin-top: 24px;
}
.problem-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 350px);
  gap: 18px;
  align-items: start;
}
.side { display: grid; gap: 14px; position: sticky; top: calc(var(--nav-h) + 34px); }
.main-grid { display: grid; gap: 18px; }
.course-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(248px, 1fr)); gap: 14px; }
.course-card {
  position: relative;
  overflow: hidden;
  padding: 18px;
  border-radius: var(--radius-lg);
  min-height: 224px;
  display: grid;
  align-content: space-between;
  background: color-mix(in srgb, var(--panel-strong) 78%, transparent);
  transition: transform .22s ease, box-shadow .22s ease, border-color .22s ease;
}
.course-card:hover { transform: translateY(-3px); box-shadow: var(--shadow); border-color: color-mix(in srgb, var(--ink) 24%, var(--line)); }
.course-card::before {
  content: "";
  position: absolute;
  inset: 0;
  opacity: .66;
  pointer-events: none;
  background: radial-gradient(circle at 92% 0%, color-mix(in srgb, var(--rain) 15%, transparent), transparent 10rem);
}
.course-head { position: relative; display: flex; gap: 13px; align-items: flex-start; }
.avatar {
  width: 54px;
  height: 54px;
  border-radius: 18px;
  object-fit: cover;
  background: linear-gradient(135deg, #111, color-mix(in srgb, #111 70%, var(--rain)));
  display: grid;
  place-items: center;
  color: #fff;
  font-weight: 900;
  flex: 0 0 auto;
  box-shadow: inset 0 -1px 0 rgba(255,255,255,.18);
}
[data-theme="dark"] .avatar { background: linear-gradient(135deg, #ececec, color-mix(in srgb, #ececec 78%, var(--rain))); color: #111; }
.course-card h3 { margin: 0; font-size: 18px; line-height: 1.25; letter-spacing: -.03em; }
.course-card p { margin: 7px 0 0; color: var(--muted); font-size: 13px; line-height: 1.45; }
.course-actions { position: relative; display: flex; justify-content: space-between; align-items: center; gap: 8px; margin-top: 18px; }
.auto-enter-copy { margin: 0; font-size: 13px; }

.lesson-stage { border-radius: var(--radius-xl); overflow: hidden; }
.stage-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 18px 20px;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--panel-strong) 74%, transparent);
}
.stage-head h2 { margin: 0; font-size: 20px; letter-spacing: -.04em; }
.stage-body { display: grid; grid-template-columns: minmax(0, 1fr) 218px; min-height: 520px; }
.slide-view {
  position: relative;
  display: grid;
  place-items: center;
  padding: clamp(14px, 3vw, 28px);
  background:
    radial-gradient(circle at 50% 8%, color-mix(in srgb, var(--rain) 9%, transparent), transparent 42%),
    color-mix(in srgb, var(--ink) 4%, transparent);
}
.slide-frame {
  width: 100%;
  max-width: 980px;
  aspect-ratio: 16 / 9;
  display: grid;
  place-items: center;
  border-radius: 22px;
  overflow: hidden;
  background: #111;
  box-shadow: 0 28px 90px rgba(0,0,0,.22);
}
.slide-frame img { width: 100%; height: 100%; object-fit: contain; background: #0a0a0a; }
.empty-slide { padding: 28px; text-align: center; color: var(--muted); }
.empty-slide h2 { color: var(--ink); letter-spacing: -.05em; }
.slide-toolbar {
  position: absolute;
  left: 50%;
  bottom: 18px;
  transform: translateX(-50%);
  display: flex;
  gap: 8px;
  align-items: center;
  padding: 8px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--panel-strong) 78%, transparent);
  border: 1px solid var(--line);
  backdrop-filter: blur(18px);
  box-shadow: 0 12px 36px rgba(0,0,0,.12);
}
.thumb-rail {
  overflow-y: auto;
  padding: 12px;
  border-left: 1px solid var(--line);
  background: color-mix(in srgb, var(--panel-muted) 58%, transparent);
}
.thumb {
  width: 100%;
  padding: 0;
  margin: 0 0 10px;
  border: 2px solid transparent;
  border-radius: 15px;
  background: transparent;
  overflow: hidden;
  text-align: left;
  color: var(--ink);
  transition: border-color .18s ease, box-shadow .18s ease, transform .18s ease;
}
.thumb:hover { transform: translateY(-1px); }
.thumb.active { border-color: var(--rain); box-shadow: var(--focus-ring); }
.thumb img { width: 100%; aspect-ratio: 16/9; object-fit: cover; display: block; background: #111; }
.thumb span { display: block; padding: 7px 8px; color: var(--muted); font-size: 12px; }

.problem-card { border-radius: var(--radius-lg); padding: 20px; background: color-mix(in srgb, var(--panel-strong) 72%, transparent); }
.problem-body { line-height: 1.75; color: var(--ink); }
.problem-body img { border-radius: 12px; }
.options { display: grid; gap: 10px; margin-top: 14px; }
.option {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  padding: 13px 14px;
  border: 1px solid var(--line);
  border-radius: 17px;
  background: color-mix(in srgb, var(--panel-strong) 66%, transparent);
  transition: border-color .18s ease, background .18s ease, transform .18s ease;
}
.option:hover { border-color: color-mix(in srgb, var(--ink) 22%, var(--line)); background: var(--panel-strong); }
.option input { margin-top: 5px; accent-color: var(--rain); }
.option-key { font-weight: 900; color: var(--rain); }
.timeline { max-height: 360px; overflow: auto; display: grid; gap: 10px; padding-right: 4px; }
.event {
  border: 1px solid var(--line);
  border-radius: 17px;
  padding: 12px;
  background: color-mix(in srgb, var(--panel-strong) 58%, transparent);
}
.event strong { display: block; }
.event span { color: var(--muted); font-size: 12px; }
.event.problem { border-color: color-mix(in srgb, var(--rain) 46%, var(--line)); }

.qr-video { width: 100%; aspect-ratio: 4/3; border-radius: 18px; object-fit: cover; background: #111; border: 1px solid var(--line); }
.fallback-entry {
  margin-top: 14px;
  padding: 12px 14px;
  border: 1px dashed var(--line-strong);
  border-radius: 18px;
  background: color-mix(in srgb, var(--panel-muted) 48%, transparent);
}
.fallback-entry summary {
  color: var(--muted);
  font-weight: 820;
  cursor: pointer;
}
.fallback-entry form { margin-top: 12px; }
.cookie-import { margin-top: 16px; }
.cookie-import-note { margin: 0; font-size: 12.5px; line-height: 1.58; }
.status-list { display: grid; gap: 8px; margin: 0; padding: 0; list-style: none; }
.status-list li { display: flex; justify-content: space-between; gap: 12px; padding: 9px 0; border-bottom: 1px solid var(--line); color: var(--muted); }
.status-list strong { color: var(--ink); font-family: var(--font-number); }
.code { font-family: var(--font-code); font-size: 12px; word-break: break-all; }

.toast-region { position: fixed; right: 18px; bottom: 18px; z-index: 100; display: grid; gap: 10px; width: min(380px, calc(100vw - 36px)); }
.toast {
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--panel-strong);
  box-shadow: var(--shadow);
  animation: toast-in .22s ease-out;
}
.toast strong { display: block; margin-bottom: 3px; }
.toast.error { border-color: color-mix(in srgb, var(--ember) 60%, var(--line)); }
.toast.success { border-color: color-mix(in srgb, var(--rain) 60%, var(--line)); }
@keyframes toast-in { from { opacity: 0; transform: translateY(8px) scale(.98); } }

.hidden { display: none !important; }
.muted { color: var(--muted); }
.text-danger { color: var(--ember); }
.text-success { color: var(--rain); }
.nowrap { white-space: nowrap; }

@media (prefers-reduced-motion: no-preference) {
  .topbar, .hero-card, .card-stack, .workspace { animation: page-in .42s cubic-bezier(.2,.7,.2,1) both; }
  .card-stack { animation-delay: .06s; }
  .workspace { animation-delay: .03s; }
  @keyframes page-in { from { opacity: 0; transform: translateY(10px); } }
}

@media (max-width: 1060px) {
  .hero, .workspace, .problem-layout { grid-template-columns: 1fr; }
  .side { position: static; }
  .stage-body { grid-template-columns: 1fr; }
  .thumb-rail { display: flex; gap: 10px; overflow-x: auto; overflow-y: hidden; border-left: 0; border-top: 1px solid var(--line); }
  .thumb { width: 156px; flex: 0 0 auto; }
}

@media (max-width: 680px) {
  .app-shell { width: min(100vw - 18px, 1280px); padding-top: 10px; padding-bottom: 86px; }
  .topbar { top: 8px; border-radius: 24px; align-items: flex-start; flex-wrap: wrap; }
  .brand h1 { font-size: 24px; }
  .nav-actions { width: 100%; justify-content: flex-start; }
  .hero { margin-top: 16px; }
  .hero-card { padding: 26px 20px; min-height: auto; }
  .hero-card::before { display: none; }
  .hero-title { max-width: 100%; margin-top: 0; font-size: clamp(34px, 12vw, 50px); line-height: 1.02; letter-spacing: -.06em; }
  .hero-title span { display: block; }
  .hero-copy { width: calc(100vw - 58px); max-width: 100%; font-size: 15.5px; line-height: 1.7; word-break: break-all; }
  .panel p, .sheet p { word-break: break-all; }
  .hero-metrics { grid-template-columns: 1fr; margin-top: 22px; }
  .metric { min-height: auto; }
  .panel, .sheet, .problem-card { padding: 17px; border-radius: 22px; }
  .input-action-row { grid-template-columns: 1fr; }
  .course-grid { grid-template-columns: 1fr; }
  .stage-head { align-items: flex-start; }
  .slide-toolbar { position: static; transform: none; margin: 12px auto 0; width: max-content; max-width: 100%; flex-wrap: wrap; justify-content: center; }
  .slide-view { display: block; }
  .row > .btn { flex: 1 1 auto; }
}