:root {
  --bg: #f6f7fb;
  --card: #ffffff;
  --text: #1f2430;
  --muted: #6b7280;
  --line: #e5e7eb;
  --accent: #4f46e5;
  --accent-soft: #eef2ff;
  --success: #157f3b;
  --success-soft: #ecfdf3;
  --danger: #b42318;
  --danger-soft: #fef3f2;
  --shadow: 0 12px 30px rgba(31, 36, 48, 0.08);
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: linear-gradient(180deg, #f8f9ff 0%, var(--bg) 40%);
  color: var(--text);
}
button, input { font: inherit; }
button { cursor: pointer; }

.app-shell {
  width: min(960px, calc(100% - 32px));
  margin: 0 auto;
  padding: 32px 0 56px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border-radius: 12px;
  background: var(--accent);
  color: white;
  font-weight: 800;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 20px;
  box-shadow: var(--shadow);
}

.hero {
  padding: 28px;
  margin-bottom: 22px;
}

.hero h1, .hero h2 { margin: 0 0 8px; }
.hero p { margin: 0; color: var(--muted); line-height: 1.6; }

.progress-wrap { margin-top: 20px; }
.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 14px;
  color: var(--muted);
  margin-bottom: 8px;
}
.progress-bar {
  height: 10px;
  background: #eceef6;
  border-radius: 999px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: var(--accent);
  border-radius: inherit;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.lesson-card { padding: 20px; }
.lesson-card h3 { margin: 8px 0 8px; }
.lesson-card p { color: var(--muted); line-height: 1.5; min-height: 48px; }
.badge {
  display: inline-block;
  border-radius: 999px;
  padding: 5px 9px;
  font-size: 12px;
  font-weight: 700;
  background: var(--accent-soft);
  color: var(--accent);
}
.badge.done {
  background: var(--success-soft);
  color: var(--success);
}

.primary, .secondary, .danger-btn {
  border: 0;
  border-radius: 12px;
  padding: 12px 16px;
  font-weight: 700;
}
.primary { background: var(--accent); color: white; }
.secondary { background: #f3f4f6; color: var(--text); }
.danger-btn { background: var(--danger-soft); color: var(--danger); }
.primary:disabled { opacity: .45; cursor: not-allowed; }

.onboarding {
  min-height: 78vh;
  display: grid;
  place-items: center;
}
.onboarding .card {
  width: min(520px, 100%);
  padding: 32px;
}
.onboarding h1 { margin-top: 0; }
.onboarding p { color: var(--muted); line-height: 1.6; }
.input {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 13px 14px;
  margin: 12px 0;
  outline: none;
}
.input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }

.lesson { max-width: 760px; margin: 0 auto; }
.lesson .card { padding: 28px; }
.lesson h1 { margin-top: 0; }
.cn {
  background: #fafafa;
  border-left: 4px solid var(--accent);
  padding: 14px 16px;
  border-radius: 10px;
  line-height: 1.7;
  margin: 16px 0;
}
.example {
  background: var(--accent-soft);
  padding: 16px;
  border-radius: 14px;
  margin: 18px 0 24px;
}
.question-count { color: var(--muted); font-size: 14px; }
.options { display: grid; gap: 10px; margin: 18px 0; }
.option {
  border: 1px solid var(--line);
  background: white;
  border-radius: 12px;
  padding: 14px;
  text-align: left;
}
.option:hover { border-color: #b8bcef; }
.option.selected { border-color: var(--accent); background: var(--accent-soft); }
.option.correct { border-color: var(--success); background: var(--success-soft); }
.option.wrong { border-color: var(--danger); background: var(--danger-soft); }
.feedback {
  border-radius: 12px;
  padding: 12px 14px;
  margin: 12px 0;
  font-weight: 650;
}
.feedback.good { background: var(--success-soft); color: var(--success); }
.feedback.bad { background: var(--danger-soft); color: var(--danger); }
.actions { display: flex; gap: 10px; justify-content: flex-end; margin-top: 20px; }

.score {
  text-align: center;
  padding: 28px 10px;
}
.score strong { font-size: 52px; display: block; margin-bottom: 4px; }
.muted { color: var(--muted); }

@media (max-width: 760px) {
  .app-shell { width: min(100% - 20px, 960px); padding-top: 18px; }
  .grid { grid-template-columns: 1fr; }
  .topbar { align-items: flex-start; }
  .hero { padding: 22px; }
  .lesson .card { padding: 20px; }
}

/* Version 0.2 additions */
.version-badge {
  display: inline-block;
  margin: 18px 0 0;
  padding: 5px 9px;
  border-radius: 999px;
  background: #f3f4f6;
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}
.hero-copy {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}
.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 16px;
  margin: 28px 2px 12px;
}
.section-heading h2 { margin: 0 0 4px; }
.section-heading p { margin: 0; color: var(--muted); }
.lessons-heading { margin-top: 34px; }
.mastery-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}
.mastery-card { padding: 18px; }
.mastery-top {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: flex-start;
}
.mastery-card h3 { margin: 0 0 4px; font-size: 16px; }
.mastery-card p { color: var(--muted); line-height: 1.45; font-size: 14px; }
.mastery-status {
  white-space: nowrap;
  border-radius: 999px;
  padding: 4px 8px;
  font-size: 11px;
  font-weight: 800;
  background: #f3f4f6;
  color: var(--muted);
}
.mastery-status.weak { background: var(--danger-soft); color: var(--danger); }
.mastery-status.developing { background: #fff7ed; color: #b45309; }
.mastery-status.strong { background: var(--success-soft); color: var(--success); }
.mastery-number { font-size: 30px; font-weight: 800; margin-top: 14px; }
.mini-progress {
  height: 7px;
  background: #eceef6;
  border-radius: 999px;
  overflow: hidden;
  margin: 8px 0 4px;
}
.mini-progress-fill { height: 100%; background: #c4c7d4; border-radius: inherit; }
.mini-progress-fill.weak { background: #d92d20; }
.mini-progress-fill.developing { background: #f59e0b; }
.mini-progress-fill.strong { background: #16a34a; }
.concept-note { color: var(--muted); font-size: 12px; display: block; margin-top: 4px; }
.lesson-meta { display: flex; justify-content: space-between; gap: 8px; align-items: center; }
.mastery-pill {
  font-size: 11px;
  font-weight: 700;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
  padding: 5px 8px;
}
.concept-list { display: flex; gap: 6px; flex-wrap: wrap; margin: 12px 0 16px; }
.concept-list span, .question-concepts span {
  display: inline-block;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 4px 7px;
  font-size: 11px;
  color: var(--muted);
  background: #fafafa;
}
.question-concepts { color: var(--muted); font-size: 12px; display: flex; gap: 6px; flex-wrap: wrap; align-items: center; margin: 0 0 18px; }
.feedback-why { font-weight: 500; }
.feedback-mastery { margin-top: 8px; font-size: 12px; opacity: .85; }
.completion-mastery { margin: 14px auto 8px; background: var(--accent-soft); border-radius: 12px; padding: 12px; width: fit-content; }
.loading, .error-card { width: min(560px, 100%); padding: 28px; }
.error-card code { background: #f3f4f6; padding: 2px 5px; border-radius: 5px; }

@media (max-width: 760px) {
  .hero-copy { align-items: stretch; flex-direction: column; }
  .hero-copy .primary { width: 100%; }
  .mastery-grid { grid-template-columns: 1fr; }
  .section-heading { align-items: flex-start; flex-direction: column; }
}

/* Version 0.3 additions */
.dashboard-actions { display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:14px; margin:20px 0 8px; }
.action-card { padding:20px; display:flex; align-items:center; justify-content:space-between; gap:18px; }
.action-card h3 { margin:4px 0 6px; }
.action-card p { margin:0; color:var(--muted); line-height:1.45; }
.eyebrow { font-size:11px; font-weight:800; letter-spacing:.08em; color:var(--accent); }
.diagnostic-intro { max-width:620px; }
.clean-list { color:var(--muted); line-height:1.8; padding-left:22px; }
.diagnostic-progress { display:flex; align-items:center; justify-content:space-between; gap:12px; margin-bottom:18px; }
.result-columns { display:grid; grid-template-columns:1fr 1fr; gap:16px; text-align:left; margin:24px 0; }
.result-columns > div { border:1px solid var(--line); border-radius:14px; padding:16px; }
.result-columns h3 { margin-top:0; }
.result-chip { display:inline-block; border-radius:999px; padding:6px 9px; margin:3px; font-size:12px; font-weight:700; }
.result-chip.strong { background:var(--success-soft); color:var(--success); }
.result-chip.weak { background:var(--danger-soft); color:var(--danger); }
.small { font-size:13px; }
@media (max-width:760px){ .dashboard-actions,.result-columns{grid-template-columns:1fr}.action-card{align-items:flex-start;flex-direction:column}.action-card button{width:100%} }

/* Version 0.4 additions */
.topbar-actions { display:flex; align-items:center; gap:10px; flex-wrap:wrap; justify-content:flex-end; }
.ai-status { font-size:11px; font-weight:800; border-radius:999px; padding:6px 9px; border:1px solid var(--line); background:#fff; color:var(--muted); }
.ai-status.live { color:#166534; background:#f0fdf4; border-color:#bbf7d0; }
.ai-status.demo { color:#92400e; background:#fffbeb; border-color:#fde68a; }
.dashboard-actions.three-up { grid-template-columns:repeat(3,minmax(0,1fr)); }
.ai-card { background:linear-gradient(180deg,#fff 0%,#faf7ff 100%); }
.small-button { width:auto; padding:8px 11px; font-size:12px; margin-top:10px; }
.feedback-actions { margin-top:10px; }
.feedback-cn { margin-top:8px; }
.ai-explanation { margin-top:14px; border:1px solid #ddd6fe; background:#faf5ff; border-radius:14px; padding:16px; line-height:1.55; }
.ai-explanation h3 { margin:10px 0 8px; }
.ai-explanation p { margin:8px 0; }
.ai-heading { display:flex; align-items:center; justify-content:space-between; gap:12px; }
.ai-examples { margin:12px 0; padding:12px; border-radius:10px; background:#fff; border:1px solid #ede9fe; }
.ai-loading { margin-top:14px; border:1px dashed #c4b5fd; background:#faf5ff; border-radius:12px; padding:14px; color:var(--muted); }
@media (max-width:980px){ .dashboard-actions.three-up{grid-template-columns:1fr} }
@media (max-width:760px){ .topbar-actions{align-items:flex-end;flex-direction:column}.ai-heading{align-items:flex-start;flex-direction:column} }

/* Version 0.5 additions */
.dashboard-actions.four-up { grid-template-columns:repeat(2,minmax(0,1fr)); }
.production-card { background:linear-gradient(180deg,#fff 0%,#f0fdfa 100%); }
.error-summary { margin:16px 0 6px; padding:20px; }
.error-summary h3 { margin:4px 0 10px; }
.error-list { display:grid; gap:8px; }
.error-list > div { display:flex; justify-content:space-between; gap:16px; align-items:center; padding:10px 12px; border:1px solid var(--line); border-radius:10px; background:#fafafa; }
.error-list span { display:flex; flex-direction:column; gap:2px; }
.error-list small { color:var(--muted); }
.error-list b { color:var(--danger); white-space:nowrap; }
.card-mini-actions { display:flex; gap:7px; flex-wrap:wrap; }
.production-prompt { margin:18px 0 12px; border:1px solid #99f6e4; background:#f0fdfa; border-radius:14px; padding:15px; line-height:1.55; }
.production-input { width:100%; min-height:110px; resize:vertical; font:inherit; line-height:1.5; }
.production-result { display:grid; grid-template-columns:auto 1fr; gap:14px; margin-top:18px; border-radius:14px; padding:16px; border:1px solid var(--line); }
.production-result.good-result { background:#f0fdf4; border-color:#bbf7d0; }
.production-result.needs-work { background:#fff7ed; border-color:#fed7aa; }
.result-icon { width:34px; height:34px; border-radius:50%; display:grid; place-items:center; font-weight:900; background:#fff; border:1px solid var(--line); }
.production-result h3 { margin:0 0 8px; }
.production-result p { margin:8px 0; line-height:1.5; }
.correction { display:flex; flex-direction:column; gap:6px; margin:8px 0 10px; }
.correction span { text-decoration:line-through; color:var(--muted); }
.correction strong { font-size:18px; }
.error-code { display:inline-block; margin-top:10px; padding:5px 8px; border-radius:999px; background:#ffedd5; color:#9a3412; font-size:12px; font-weight:800; }
@media (max-width:760px){ .dashboard-actions.four-up{grid-template-columns:1fr}.production-result{grid-template-columns:1fr}.result-icon{width:30px;height:30px} }

/* Version 0.6 additions */
.speech-card { background:linear-gradient(180deg,#fff 0%,#eff6ff 100%); }
.speech-lab .card { overflow:hidden; }
.speech-head { display:flex; justify-content:space-between; align-items:flex-start; gap:20px; }
.speech-head h1 { margin:5px 0 6px; }
.speech-mini-score { min-width:92px; border:1px solid #bfdbfe; background:#eff6ff; border-radius:16px; padding:12px; font-size:25px; font-weight:850; text-align:center; }
.speech-mini-score small { display:block; font-size:11px; color:var(--muted); font-weight:700; margin-top:2px; }
.speech-target { margin:22px 0 16px; padding:18px; border:1px solid #bfdbfe; background:#f8fbff; border-radius:16px; }
.target-line { font-size:27px; font-weight:800; line-height:1.3; margin-bottom:10px; }
.speech-target .cn { margin:10px 0 14px; }
.speech-instructions { display:flex; justify-content:space-between; gap:14px; align-items:center; padding:10px 0; }
.speech-status { margin:10px 0; padding:10px 12px; border-radius:10px; background:#f3f4f6; color:var(--muted); text-align:center; }
.speech-actions { justify-content:center; margin:12px 0 20px; }
.speech-actions .primary { min-width:190px; }
.speech-result { display:grid; grid-template-columns:120px 1fr; gap:18px; margin-top:20px; border:1px solid #bfdbfe; border-radius:16px; padding:18px; background:#f8fbff; }
.speech-score { display:flex; flex-direction:column; justify-content:center; align-items:center; gap:4px; background:white; border:1px solid #dbeafe; border-radius:14px; min-height:110px; }
.speech-score strong { font-size:34px; }
.speech-score span { font-size:12px; color:var(--muted); font-weight:800; }
.speech-result p { margin:8px 0; line-height:1.5; }
.pron-metrics { display:grid; grid-template-columns:repeat(4,minmax(0,1fr)); gap:8px; margin-bottom:12px; }
.pron-metrics span { display:flex; flex-direction:column; align-items:center; gap:2px; padding:9px 6px; border:1px solid var(--border); border-radius:10px; background:white; }
.pron-metrics b { font-size:18px; }
.pron-metrics small { color:var(--muted); font-weight:700; font-size:10px; }
.pron-tip { margin-top:12px; padding:13px; border-radius:12px; background:#fff7ed; border:1px solid #fed7aa; line-height:1.5; }
.pron-tip p { margin:5px 0; }
.speech-nav { display:flex; align-items:center; justify-content:space-between; gap:12px; margin-top:20px; padding-top:16px; border-top:1px solid var(--line); }
@media (max-width:760px){
  .speech-head,.speech-instructions,.speech-nav{align-items:stretch;flex-direction:column}
  .speech-mini-score{width:100%;}
  .speech-result{grid-template-columns:1fr}
  .pron-metrics{grid-template-columns:repeat(2,minmax(0,1fr))}
  .target-line{font-size:23px}
}

/* Version 0.7 account + cloud-sync additions */
.account-card { max-width: 560px; }
.account-submit { width: 100%; margin-top: 10px; }
.adult-check { display: flex; align-items: flex-start; gap: 10px; margin: 14px 2px; color: var(--muted); line-height: 1.45; }
.adult-check input { margin-top: 4px; }
.account-divider { display: flex; align-items: center; gap: 12px; color: var(--muted); font-size: 12px; margin: 18px 0 8px; }
.account-divider::before, .account-divider::after { content: ''; height: 1px; background: var(--line); flex: 1; }
.account-email { max-width: 210px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; color: var(--muted); font-size: 12px; }
.sync-status { display: inline-flex; align-items: center; border-radius: 999px; padding: 5px 9px; font-size: 11px; font-weight: 800; background: #f3f4f6; color: var(--muted); }
.sync-status.synced { background: var(--success-soft); color: var(--success); }
.sync-status.syncing, .sync-status.pending { background: #fff7ed; color: #b45309; }
.sync-status.error { background: var(--danger-soft); color: var(--danger); }
@media (max-width: 760px) {
  .topbar-actions { width: 100%; justify-content: flex-start; }
  .account-email { max-width: 100%; }
}


/* Version 0.9 public-beta account flows */
.text-button { border:0; background:transparent; color:var(--primary); font:inherit; font-weight:750; cursor:pointer; padding:8px 4px; }
.text-button:hover { text-decoration:underline; }
.account-link { width:100%; text-align:center; margin-top:6px; }
.account-card a { color:var(--primary); }
.legal-page { max-width:820px; margin:42px auto; padding:0 18px 60px; }
.legal-page .card { padding:30px; }
.legal-page h1 { margin-top:10px; }
.legal-page h2 { margin-top:26px; }
.legal-page p, .legal-page li { line-height:1.65; }
.inline-action { display:inline-flex; text-decoration:none; width:auto; }
.settings-rule { border:0; border-top:1px solid var(--line); margin:28px 0; }
.danger-wide { width:100%; margin-top:12px; padding:12px 16px; }

/* v1.2 no-cost beta */
.field-label{display:block;margin:14px 0 6px;font-size:12px;font-weight:800;color:var(--muted)}
.main-nav{display:flex;gap:8px;margin:14px 0 18px;padding:6px;background:#f3f4f6;border-radius:14px;overflow:auto}
.nav-tab{border:0;background:transparent;border-radius:10px;padding:10px 16px;cursor:pointer;display:flex;flex-direction:column;align-items:flex-start;min-width:105px;color:var(--muted)}
.nav-tab b{font-size:14px}.nav-tab small{font-size:10px}.nav-tab.active{background:white;color:var(--ink);box-shadow:0 1px 4px rgba(0,0,0,.08)}
.daily-plan{padding:22px;margin:18px 0}.daily-plan-head{display:flex;justify-content:space-between;gap:20px;align-items:center}.daily-plan-head h2{margin:4px 0}.daily-plan-head p{margin:0;color:var(--muted)}
.goal-ring{width:72px;height:72px;border-radius:50%;display:grid;place-items:center;border:8px solid #e9d5ff;background:#faf5ff;font-weight:900;color:var(--accent)}
.plan-list{display:grid;gap:8px;margin-top:18px}.plan-row{width:100%;display:grid;grid-template-columns:auto 1fr auto;gap:12px;align-items:center;text-align:left;border:1px solid var(--line);background:#fff;border-radius:12px;padding:12px;cursor:pointer}.plan-row:hover{background:#fafafa}.plan-row span:nth-child(2){display:flex;flex-direction:column}.plan-row small{color:var(--muted);margin-top:2px}.plan-number{width:28px;height:28px;border-radius:50%;display:grid;place-items:center;background:#f3e8ff;color:#6b21a8;font-weight:900}
.practice-layout,.two-col{display:grid;grid-template-columns:minmax(0,2fr) minmax(260px,1fr);gap:16px}.practice-main{padding:26px}.practice-type,.vocab-category{font-size:11px;font-weight:900;letter-spacing:.06em;color:var(--accent);text-transform:uppercase}.practice-main h2{line-height:1.5}.vocab-tools{display:grid;grid-template-columns:2fr 1fr;gap:12px;padding:16px;margin-bottom:16px}.vocab-tools .input{margin:0}.vocab-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.vocab-card{padding:16px;display:flex;justify-content:space-between;gap:12px;align-items:center}.vocab-card.learning{border-color:#f59e0b}.vocab-card.known{border-color:#22c55e;background:#f0fdf4}.vocab-card h3{margin:4px 0}.vocab-actions{display:flex;gap:4px;align-items:center;flex-wrap:wrap;justify-content:flex-end}.vocab-fav{font-size:22px;margin:0;padding:4px}
.stat-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;margin-bottom:16px}.stat-card{padding:18px;display:flex;flex-direction:column}.stat-card b{font-size:30px}.stat-card span{color:var(--muted);font-size:12px}.progress-panel{padding:20px;margin-bottom:16px}.week-chart{height:180px;display:flex;gap:12px;align-items:flex-end}.day-bar{flex:1;display:flex;flex-direction:column;align-items:center;gap:4px}.bar-track{height:120px;width:28px;background:#f3f4f6;border-radius:8px;display:flex;align-items:flex-end;overflow:hidden}.bar-fill{width:100%;background:#8b5cf6;border-radius:8px}.day-bar small{color:var(--muted)}.mastery-breakdown{display:grid;grid-template-columns:repeat(2,1fr);gap:10px}.mastery-breakdown div{border:1px solid var(--line);border-radius:10px;padding:12px;display:flex;flex-direction:column}.mastery-breakdown b{font-size:24px}.mastery-breakdown span{color:var(--muted);font-size:12px}.achievement-grid{display:grid;gap:8px}.achievement{display:flex;gap:10px;align-items:center;opacity:.45}.achievement.earned{opacity:1}.achievement>span{width:28px;height:28px;border-radius:50%;display:grid;place-items:center;background:#f3f4f6}.achievement.earned>span{background:#dcfce7;color:#166534}.achievement div{display:flex;flex-direction:column}.achievement small{color:var(--muted)}.roadmap,.mistake-list{display:grid;gap:8px}.roadmap>div,.mistake-list>div{display:flex;justify-content:space-between;gap:14px;padding:11px 0;border-bottom:1px solid var(--line)}.roadmap span,.mistake-list div{display:flex;flex-direction:column}.roadmap small,.mistake-list small{color:var(--muted)}
@media(max-width:900px){.practice-layout,.two-col{grid-template-columns:1fr}.vocab-grid{grid-template-columns:repeat(2,1fr)}.stat-grid{grid-template-columns:repeat(2,1fr)}}
@media(max-width:620px){.daily-plan-head{align-items:flex-start;flex-direction:column}.vocab-tools,.vocab-grid,.stat-grid{grid-template-columns:1fr}.week-chart{gap:5px}.bar-track{width:20px}.nav-tab{min-width:90px;padding:8px 12px}}