:root {
  --ink: #151044;
  --ink-soft: #5d5977;
  --indigo: #24106b;
  --violet: #7530e8;
  --violet-bright: #a63cff;
  --lavender: #f2ecff;
  --lavender-deep: #e2d4ff;
  --gold: #ffbd2e;
  --white: #fff;
  --line: rgba(40, 21, 104, .11);
  --shadow: 0 24px 70px rgba(40, 18, 101, .12);
  --radius-lg: 32px;
  --radius-md: 22px;
  --radius-sm: 14px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  background: #fcfbff;
  font-family: "DM Sans", sans-serif;
  overflow-x: hidden;
}
button, input, select, textarea { font: inherit; }
a { color: inherit; text-decoration: none; }
button, a { -webkit-tap-highlight-color: transparent; }

.ambient {
  position: fixed;
  border-radius: 999px;
  filter: blur(2px);
  pointer-events: none;
  z-index: -1;
}
.ambient-one {
  width: 420px; height: 420px; right: -180px; top: 80px;
  background: radial-gradient(circle, rgba(169, 61, 255, .13), transparent 68%);
}
.ambient-two {
  width: 500px; height: 500px; left: -260px; bottom: -100px;
  background: radial-gradient(circle, rgba(87, 48, 219, .1), transparent 70%);
}

.site-header {
  max-width: 1240px;
  height: 90px;
  margin: 0 auto;
  padding: 0 30px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand { display: flex; align-items: center; gap: 12px; }
.brand img { filter: drop-shadow(0 8px 12px rgba(55, 28, 145, .14)); }
.brand-copy { display: grid; gap: 1px; }
.brand-copy strong {
  font: 800 18px/1 "Manrope", sans-serif;
  letter-spacing: .18em;
}
.brand-copy em { color: var(--violet-bright); font-style: normal; }
.brand-copy small {
  color: var(--ink-soft);
  font-size: 8px;
  letter-spacing: .18em;
  text-transform: uppercase;
}
.top-nav { display: flex; align-items: center; gap: 28px; font-weight: 600; font-size: 14px; }
.top-nav > a:not(.nav-cta) { color: var(--ink-soft); transition: color .2s; }
.top-nav > a:not(.nav-cta):hover, .top-nav > a.active { color: var(--violet); }
.nav-cta, .btn-primary {
  color: white;
  background: linear-gradient(135deg, var(--indigo), var(--violet));
  border: 0;
  box-shadow: 0 12px 28px rgba(81, 42, 185, .22);
}
.nav-cta { padding: 12px 18px; border-radius: 999px; }
.nav-cta span { margin-left: 5px; }

#app { min-height: calc(100vh - 170px); }
.page { max-width: 1240px; margin: 0 auto; padding: 42px 30px 90px; animation: rise .55s ease both; }
.page-loader { min-height: 60vh; display: grid; place-content: center; justify-items: center; gap: 12px; color: var(--ink-soft); }
.page-loader img { width: 70px; animation: breathe 1.7s ease-in-out infinite; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid rgba(107, 51, 222, .15);
  border-radius: 999px;
  color: var(--violet);
  background: rgba(255, 255, 255, .72);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
}
.eyebrow::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: var(--gold); box-shadow: 0 0 0 4px rgba(255, 189, 46, .15); }
h1, h2, h3 { font-family: "Manrope", sans-serif; margin-top: 0; }
h1 { font-size: clamp(46px, 6vw, 82px); line-height: 1.03; letter-spacing: -.055em; }
h2 { font-size: clamp(30px, 3.6vw, 48px); line-height: 1.1; letter-spacing: -.035em; }
h3 { font-size: 20px; letter-spacing: -.02em; }
.gradient-text { background: linear-gradient(110deg, var(--indigo), var(--violet-bright)); -webkit-background-clip: text; color: transparent; }
.lead { color: var(--ink-soft); font-size: 18px; line-height: 1.7; max-width: 640px; }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  min-height: 50px;
  padding: 0 22px;
  border-radius: 14px;
  font-weight: 700;
  cursor: pointer;
  transition: transform .2s, box-shadow .2s, border-color .2s;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary { border: 0; }
.btn-secondary { color: var(--indigo); background: white; border: 1px solid var(--line); box-shadow: 0 8px 25px rgba(40, 18, 101, .06); }
.btn-ghost { color: var(--ink-soft); background: transparent; border: 1px solid var(--line); }
.btn-wide { width: 100%; }

.hero {
  min-height: 650px;
  display: grid;
  grid-template-columns: 1.08fr .92fr;
  align-items: center;
  gap: 68px;
}
.hero h1 { margin: 22px 0; max-width: 700px; }
.hero-actions { display: flex; gap: 12px; margin-top: 34px; flex-wrap: wrap; }
.trust-row { display: flex; align-items: center; gap: 16px; margin-top: 38px; color: var(--ink-soft); font-size: 13px; }
.avatar-stack { display: flex; }
.avatar-stack span {
  width: 31px; height: 31px; display: grid; place-items: center;
  margin-left: -7px; border: 3px solid white; border-radius: 50%;
  background: var(--lavender); font-size: 12px;
}
.avatar-stack span:first-child { margin-left: 0; }

.hero-visual { position: relative; min-height: 510px; display: grid; place-items: center; }
.logo-stage {
  width: min(420px, 90%);
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  border-radius: 44% 56% 47% 53% / 55% 43% 57% 45%;
  background: linear-gradient(145deg, white, #f4eeff);
  box-shadow: var(--shadow);
  animation: float 6s ease-in-out infinite;
}
.logo-stage::before {
  content: "";
  position: absolute;
  width: 74%; aspect-ratio: 1;
  border: 1px solid rgba(120, 56, 226, .12);
  border-radius: 50%;
  box-shadow: 0 0 0 34px rgba(120, 56, 226, .035), 0 0 0 72px rgba(120, 56, 226, .025);
}
.logo-stage img { position: relative; width: 67%; filter: drop-shadow(0 22px 30px rgba(48, 23, 121, .18)); }
.float-card {
  position: absolute;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 16px;
  border: 1px solid rgba(255,255,255,.8);
  border-radius: 16px;
  background: rgba(255,255,255,.86);
  box-shadow: 0 16px 40px rgba(45, 21, 112, .12);
  backdrop-filter: blur(14px);
  font-size: 13px;
  font-weight: 700;
}
.float-card i { width: 34px; height: 34px; display: grid; place-items: center; border-radius: 11px; background: var(--lavender); font-style: normal; }
.float-one { top: 65px; right: -10px; }
.float-two { bottom: 72px; left: -20px; }

.section-heading { display: flex; justify-content: space-between; align-items: end; gap: 24px; margin: 70px 0 26px; }
.section-heading p { max-width: 500px; color: var(--ink-soft); line-height: 1.6; }
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.feature-card, .surface {
  border: 1px solid var(--line);
  background: rgba(255,255,255,.86);
  box-shadow: 0 14px 45px rgba(42, 20, 105, .06);
}
.feature-card { padding: 28px; border-radius: var(--radius-md); }
.feature-icon { width: 48px; height: 48px; display: grid; place-items: center; border-radius: 15px; background: var(--lavender); color: var(--violet); font-size: 22px; margin-bottom: 24px; }
.feature-card p { margin-bottom: 0; color: var(--ink-soft); line-height: 1.65; }

.page-intro { text-align: center; max-width: 760px; margin: 25px auto 38px; }
.page-intro h1 { font-size: clamp(40px, 5vw, 62px); margin: 18px 0; }
.page-intro .lead { margin: auto; }
.setup-shell { max-width: 830px; margin: 0 auto; padding: 10px; border-radius: 34px; background: linear-gradient(135deg, rgba(114,48,226,.12), rgba(255,189,46,.1)); }
.setup-card { padding: 40px; border-radius: 26px; background: white; box-shadow: var(--shadow); }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.form-field { display: grid; gap: 9px; }
.form-field.full { grid-column: 1 / -1; }
.form-field label { font-size: 13px; font-weight: 700; color: var(--ink); }
.form-field input, .form-field select, .form-field textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 15px 16px;
  color: var(--ink);
  background: #fdfcff;
  outline: none;
  transition: border-color .2s, box-shadow .2s;
}
.form-field textarea { resize: vertical; min-height: 100px; }
.form-field input:focus, .form-field select:focus, .form-field textarea:focus { border-color: rgba(117,48,232,.55); box-shadow: 0 0 0 4px rgba(117,48,232,.09); }
.suggestions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 3px; }
.suggestion { border: 1px solid var(--line); background: white; color: var(--ink-soft); padding: 7px 11px; border-radius: 999px; cursor: pointer; font-size: 12px; }
.setup-footer { display: flex; align-items: center; justify-content: space-between; gap: 20px; padding-top: 28px; margin-top: 28px; border-top: 1px solid var(--line); }
.setup-note { color: var(--ink-soft); font-size: 12px; max-width: 380px; }
.optional { color: #8d88a0; font-weight: 500; }

.classroom-page { max-width: 1440px; padding-top: 20px; }
.lesson-bar { display: flex; align-items: center; justify-content: space-between; gap: 18px; margin-bottom: 18px; }
.lesson-title { display: flex; align-items: center; gap: 14px; }
.lesson-title .mini-mark { width: 42px; height: 42px; border-radius: 14px; display: grid; place-items: center; background: var(--lavender); }
.lesson-title h1 { font-size: 20px; letter-spacing: -.02em; margin: 0 0 3px; }
.lesson-title p { color: var(--ink-soft); font-size: 12px; margin: 0; }
.lesson-actions { display: flex; align-items: center; gap: 10px; }
.hidden { display: none !important; }
.status-pill { display: inline-flex; align-items: center; gap: 7px; padding: 8px 12px; border-radius: 999px; background: #ecfbf5; color: #178359; font-size: 12px; font-weight: 700; }
.status-pill::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: #22ba7c; }
.status-pill.connecting, .status-pill.thinking { color: #80550c; background: #fff8e7; }
.status-pill.connecting::before, .status-pill.thinking::before { background: var(--gold); animation: breathe 1s infinite; }
.status-pill.listening { color: #a22647; background: #fff0f4; }
.status-pill.listening::before { background: #e54470; animation: breathe .65s infinite; }
.status-pill.speaking { color: #6531b5; background: #f2ebff; }
.status-pill.speaking::before { background: var(--violet); animation: breathe .55s infinite; }
.status-pill.error { color: #a22647; background: #fff0f4; }
.status-pill.error::before { background: #e54470; }
.classroom-grid { display: grid; grid-template-columns: minmax(300px,.82fr) minmax(440px,1.35fr) minmax(270px,.72fr); gap: 16px; height: clamp(620px, calc(100vh - 150px), 760px); min-height: 0; }
.class-panel { min-height: 0; border-radius: 24px; overflow: hidden; }
.teacher-panel { position: relative; display: flex; flex-direction: column; justify-content: space-between; padding: 26px; color: white; background: radial-gradient(circle at 50% 35%, #7143d7, #2a126f 62%, #190d4e); }
.teacher-panel::before { content: ""; position: absolute; inset: 18% -30% -40%; border-radius: 50%; border: 1px solid rgba(255,255,255,.13); box-shadow: 0 0 0 55px rgba(255,255,255,.035), 0 0 0 110px rgba(255,255,255,.025); }
.teacher-top { position: relative; display: flex; justify-content: space-between; font-size: 12px; color: rgba(255,255,255,.75); }
.avatar-placeholder { position: relative; display: grid; place-items: center; flex: 1; min-height: 0; }
.avatar-placeholder canvas { position: absolute; inset: 0; width: 100%; height: 100%; z-index: 2; transform: scale(calc(1 + var(--talk-level, 0) * .012)); transition: transform .08s linear; }
.avatar-placeholder img { position: relative; width: 68%; filter: brightness(0) invert(1) drop-shadow(0 22px 30px rgba(0,0,0,.22)); opacity: .94; transform: scale(calc(1 + var(--talk-level, 0) * .025)); transition: transform .08s linear; z-index: 2; }
.avatar-placeholder span { position: absolute; bottom: 9%; z-index: 3; padding: 7px 11px; border-radius: 999px; background: rgba(255,255,255,.12); border: 1px solid rgba(255,255,255,.16); font-size: 11px; }
.avatar-placeholder.live2d-ready span { background: rgba(34,186,124,.2); border-color: rgba(255,255,255,.25); }
.voice-rings { position: absolute; inset: 18%; display: grid; place-items: center; }
.voice-rings i { position: absolute; width: 76%; aspect-ratio: 1; border: 1px solid rgba(255,255,255,.12); border-radius: 50%; transform: scale(calc(1 + var(--talk-level, 0) * .35)); transition: transform .1s linear, opacity .2s; }
.voice-rings i:nth-child(2) { width: 94%; opacity: .65; }
.voice-rings i:nth-child(3) { width: 112%; opacity: .35; }
.teacher-panel[data-state="listening"] .voice-rings i { animation: listening-ring 1.5s infinite; border-color: rgba(255,255,255,.3); }
.teacher-panel[data-state="speaking"] .voice-rings i { border-color: rgba(255,255,255,.28); }
.voice-control { position: relative; z-index: 6; text-align: center; }
.mic-button {
  position: relative;
  z-index: 7;
  width: 66px; height: 66px; border: 0; border-radius: 50%; color: var(--indigo); background: white;
  box-shadow: 0 0 0 10px rgba(255,255,255,.09), 0 12px 35px rgba(0,0,0,.2);
  cursor: pointer; font-size: 25px; transition: transform .2s;
}
.mic-button:hover { transform: scale(1.05); }
.mic-button.recording { color: white; background: #e54470; animation: mic-pulse 1.2s infinite; }
.voice-control p { margin: 16px 0 0; font-size: 12px; color: rgba(255,255,255,.72); }
.voice-control small { display: block; margin-top: 5px; color: rgba(255,255,255,.48); font-size: 10px; }
.whiteboard-panel { display: flex; flex-direction: column; background: white; border: 1px solid var(--line); box-shadow: 0 18px 55px rgba(40,18,101,.08); }
.panel-head { padding: 18px 22px; border-bottom: 1px solid var(--line); display: flex; align-items: center; justify-content: space-between; }
.panel-head h2 { font-size: 15px; margin: 0; }
.panel-head span { color: var(--ink-soft); font-size: 11px; }
.whiteboard-content { min-height: 0; flex: 1; padding: 34px; overflow: auto; background-image: linear-gradient(rgba(80,45,170,.045) 1px, transparent 1px), linear-gradient(90deg, rgba(80,45,170,.045) 1px, transparent 1px); background-size: 24px 24px; }
.empty-board { min-height: 480px; display: grid; place-content: center; text-align: center; color: var(--ink-soft); }
.empty-board .sketch { margin: auto auto 22px; width: 90px; height: 90px; display: grid; place-items: center; border-radius: 26px; background: var(--lavender); font-size: 38px; transform: rotate(-3deg); }
.empty-board h3 { color: var(--ink); margin-bottom: 8px; }
.empty-board p { max-width: 330px; line-height: 1.6; margin: 0 auto; font-size: 13px; }
.board-block { margin-bottom: 19px; }
.board-block.heading { color: var(--indigo); font: 800 25px/1.25 "Manrope", sans-serif; }
.board-block.text { color: var(--ink-soft); line-height: 1.7; }
.board-block.equation { padding: 0; text-align: center; border-radius: 14px; color: var(--indigo); font: 800 18px/1.35 "Manrope", sans-serif; }
.equation-card { display: inline-flex; max-width: 100%; align-items: center; justify-content: center; gap: 14px; padding: 22px 28px; border-radius: 16px; background: var(--lavender); box-shadow: inset 0 0 0 1px rgba(117,48,232,.07); overflow-x: auto; }
.eq-prefix, .eq-suffix, .eq-inline { white-space: nowrap; }
.eq-fraction { display: inline-grid; min-width: min(420px, 68vw); align-items: center; justify-items: stretch; color: var(--ink); }
.eq-top, .eq-bottom { display: block; padding: 4px 14px; white-space: normal; overflow-wrap: anywhere; }
.eq-top { border-bottom: 2px solid currentColor; }
.eq-bottom { color: var(--ink-soft); }
.board-block.diagram { padding: 16px; border: 1px solid var(--lavender-deep); border-radius: 14px; background: #faf8ff; }
.board-block.diagram span { display: block; margin-bottom: 8px; color: var(--violet); font-size: 10px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.board-block.diagram pre { margin: 0; color: var(--ink-soft); white-space: pre-wrap; font: 12px/1.6 ui-monospace, SFMono-Regular, Consolas, monospace; }
.mermaid-flow { display: grid; gap: 12px; }
.flow-row { display: grid; grid-template-columns: minmax(120px, 1fr) minmax(84px, .45fr) minmax(120px, 1fr); align-items: center; gap: 10px; }
.flow-node { min-height: 46px; display: grid; place-items: center; padding: 10px 12px; border: 1px solid rgba(117,48,232,.22); border-radius: 12px; color: var(--indigo); background: white; font: 800 12px/1.35 "Manrope", sans-serif; text-align: center; box-shadow: 0 8px 22px rgba(40,18,101,.06); }
.flow-link { display: grid; grid-template-rows: auto 1fr; align-items: center; gap: 4px; color: var(--violet); text-align: center; }
.flow-link small { font-size: 10px; font-weight: 800; }
.flow-link b { position: relative; display: block; height: 2px; background: var(--lavender-deep); }
.flow-link b::after { content: ""; position: absolute; right: -1px; top: 50%; width: 8px; height: 8px; border-top: 2px solid var(--lavender-deep); border-right: 2px solid var(--lavender-deep); transform: translateY(-50%) rotate(45deg); }
.board-block ul { margin: 0; padding-left: 20px; color: var(--ink-soft); line-height: 1.8; }
.side-panel { display: flex; flex-direction: column; background: white; border: 1px solid var(--line); }
.transcript { min-height: 0; flex: 1; padding: 18px; overflow: auto; }
.message { display: grid; gap: 5px; padding: 12px; margin-bottom: 10px; border-radius: 14px; font-size: 12px; line-height: 1.5; }
.message strong { font-size: 10px; text-transform: uppercase; letter-spacing: .08em; }
.message.student { background: #f6f3fc; }
.message.teacher { color: #fff; background: linear-gradient(135deg, var(--indigo), #5130b5); }
.transcript-empty { padding: 30px 10px; text-align: center; color: var(--ink-soft); font-size: 12px; line-height: 1.6; }
.ask-box { padding: 14px; border-top: 1px solid var(--line); }
.ask-box form { display: flex; gap: 8px; }
.ask-box input { min-width: 0; flex: 1; border: 1px solid var(--line); border-radius: 12px; padding: 11px; outline: none; }
.send-btn { width: 40px; border: 0; border-radius: 12px; color: white; background: var(--violet); cursor: pointer; }

.quiz-shell, .summary-shell { max-width: 900px; margin: 0 auto; }
.inline-quiz { max-width: 760px; margin: 0 auto; }
.inline-quiz .progress-row { margin-top: 0; }
.progress-row { display: flex; justify-content: space-between; align-items: center; margin: 20px 0 34px; color: var(--ink-soft); font-size: 13px; }
.progress-track { flex: 1; max-width: 390px; height: 7px; margin: 0 18px; border-radius: 99px; background: var(--lavender); overflow: hidden; }
.progress-fill { height: 100%; width: 33%; border-radius: inherit; background: linear-gradient(90deg, var(--violet), var(--violet-bright)); transition: width .3s; }
.quiz-card { padding: 38px; border-radius: var(--radius-lg); }
.question-number { color: var(--violet); font-size: 12px; font-weight: 800; text-transform: uppercase; letter-spacing: .1em; }
.question-title { font-size: 27px; margin: 12px 0 28px; }
.answer-list { display: grid; gap: 11px; }
.answer-option { display: flex; align-items: center; gap: 12px; padding: 15px; border: 1px solid var(--line); border-radius: 14px; cursor: pointer; transition: border-color .2s, background .2s; }
.answer-option:hover, .answer-option.selected { border-color: rgba(117,48,232,.5); background: var(--lavender); }
.answer-option input { accent-color: var(--violet); }
.quiz-actions { display: flex; justify-content: space-between; margin-top: 28px; }

.summary-hero { padding: 44px; border-radius: 34px; color: white; background: linear-gradient(135deg, #21105f, #6c2bd7); box-shadow: var(--shadow); overflow: hidden; position: relative; }
.summary-hero::after { content: ""; position: absolute; width: 260px; height: 260px; right: -60px; top: -100px; border: 1px solid rgba(255,255,255,.16); border-radius: 50%; box-shadow: 0 0 0 38px rgba(255,255,255,.04), 0 0 0 76px rgba(255,255,255,.025); }
.summary-hero > * { position: relative; z-index: 1; }
.summary-hero h1 { font-size: 45px; margin: 16px 0 8px; }
.summary-hero p { color: rgba(255,255,255,.75); }
.summary-grid { display: grid; grid-template-columns: 1.15fr .85fr; gap: 18px; margin-top: 18px; }
.summary-card { padding: 28px; border-radius: var(--radius-md); }
.summary-card h3 { display: flex; align-items: center; gap: 10px; }
.summary-card p, .summary-card li { color: var(--ink-soft); line-height: 1.65; font-size: 14px; }
.summary-card ul { padding-left: 20px; }
.stat-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 20px; }
.stat { padding: 16px; border-radius: 15px; background: var(--lavender); }
.stat strong { display: block; font: 800 24px "Manrope", sans-serif; color: var(--violet); }
.stat span { color: var(--ink-soft); font-size: 11px; }
.empty-state { text-align: center; padding: 60px 24px; }
.empty-state img { width: 80px; margin-bottom: 16px; }
.empty-copy { margin: 0 auto 24px; }
.summary-eyebrow { color: white; background: rgba(255,255,255,.12); border-color: rgba(255,255,255,.15); }
.summary-new { color: var(--indigo); background: white; }

.site-footer {
  max-width: 1240px;
  margin: 0 auto;
  padding: 28px 30px 38px;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--ink-soft);
  font-size: 12px;
}
.footer-brand { display: flex; align-items: center; gap: 8px; color: var(--ink); font-weight: 800; }
.toast { position: fixed; right: 22px; bottom: 22px; max-width: 340px; padding: 14px 17px; border-radius: 14px; color: white; background: var(--ink); box-shadow: var(--shadow); transform: translateY(120px); opacity: 0; transition: .3s; z-index: 20; }
.toast.show { transform: translateY(0); opacity: 1; }

@keyframes rise { from { opacity: 0; transform: translateY(14px); } to { opacity: 1; transform: none; } }
@keyframes float { 0%,100% { transform: translateY(0) rotate(-1deg); } 50% { transform: translateY(-12px) rotate(1deg); } }
@keyframes breathe { 50% { transform: scale(1.08); } }
@keyframes mic-pulse { 50% { box-shadow: 0 0 0 18px rgba(229,68,112,.12), 0 12px 35px rgba(0,0,0,.2); } }
@keyframes listening-ring { 50% { transform: scale(1.13); opacity: .25; } }

@media (max-width: 1050px) {
  .hero { grid-template-columns: 1fr 1fr; gap: 30px; }
  .classroom-grid { grid-template-columns: .75fr 1.25fr; }
  .side-panel { grid-column: 1 / -1; min-height: 320px; }
}
@media (max-width: 760px) {
  .site-header { height: 76px; padding: 0 18px; }
  .brand-copy small { display: none; }
  .top-nav > a:not(.nav-cta) { display: none; }
  .page { padding: 28px 18px 65px; }
  .hero { grid-template-columns: 1fr; min-height: auto; padding-top: 38px; }
  .hero-visual { min-height: 430px; }
  .hero h1 { font-size: 50px; }
  .feature-grid, .form-grid, .summary-grid { grid-template-columns: 1fr; }
  .section-heading, .setup-footer { align-items: flex-start; flex-direction: column; }
  .form-field.full { grid-column: auto; }
  .setup-card { padding: 25px; }
  .classroom-grid { grid-template-columns: 1fr; height: auto; }
  .teacher-panel { min-height: 520px; }
  .whiteboard-panel { min-height: 570px; }
  .lesson-bar { align-items: flex-start; }
  .lesson-actions .btn { display: none; }
  .summary-hero { padding: 30px; }
  .site-footer { gap: 14px; flex-wrap: wrap; padding-inline: 18px; }
  .site-footer p { order: 3; flex-basis: 100%; }
}