:root {
  --bg: #f8f4ee;
  --surface: #fffdf9;
  --ink: #26211d;
  --ink-soft: #6b6259;
  --line: #e7ded2;
  --accent: #b3402e;
  --accent-soft: #f6e3de;
  --accent-ink: #8c2f20;
  --ok: #1f6f54;
  --ok-soft: #dcece4;
  --radius: 14px;
  --font-body: "Manrope", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-display: "Fraunces", Georgia, serif;
  --font-mono: "DM Mono", ui-monospace, monospace;
  --font-hanzi: "Noto Serif SC", "SimSun", serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(1100px 480px at 90% -10%, #f3e4dc 0%, transparent 60%),
    var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

/* ---------- top bar ---------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px clamp(20px, 5vw, 56px);
  background: color-mix(in srgb, var(--bg) 88%, white);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  text-decoration: none;
  color: var(--ink);
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 32px;
  height: 32px;
  border-radius: 9px;
  background: var(--accent);
  color: #fff;
  font-family: var(--font-hanzi);
  font-size: 18px;
}

.topbar-right { display: flex; align-items: center; gap: 12px; }
.account-label { font-family: var(--font-mono); font-size: 12.5px; color: var(--ink-soft); }

.ghost-button {
  padding: 9px 16px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
  font-family: inherit;
  font-weight: 700;
  font-size: 13.5px;
  color: var(--ink);
  cursor: pointer;
  transition: border-color 0.15s;
}
.ghost-button:hover { border-color: var(--accent); }

/* ---------- layout ---------- */

main {
  max-width: 1160px;
  margin: 0 auto;
  padding: clamp(28px, 5vw, 56px) clamp(20px, 5vw, 56px) 90px;
  display: grid;
  gap: clamp(36px, 5vw, 64px);
}

.eyebrow {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent-ink);
}

.intro { max-width: 640px; }

.intro h1 {
  margin: 0 0 14px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(38px, 6vw, 58px);
  line-height: 1.05;
  letter-spacing: -0.015em;
}
.intro h1 em { color: var(--accent); }

.intro-copy { margin: 0; font-size: 17px; color: var(--ink-soft); max-width: 56ch; }

.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 18px;
}
.section-heading h2 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(24px, 3.4vw, 32px);
}
.level-summary { margin: 0; font-family: var(--font-mono); font-size: 12.5px; color: var(--ink-soft); }

/* ---------- level rail ---------- */

.level-rail {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(170px, 1fr));
  gap: 10px;
}

.rung {
  display: grid;
  gap: 3px;
  text-align: left;
  padding: 13px 15px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  cursor: pointer;
  font-family: inherit;
  transition: border-color 0.15s, transform 0.15s, box-shadow 0.15s;
}
.rung:hover { border-color: var(--accent); transform: translateY(-2px); }
.rung.active {
  border-color: var(--accent);
  background: var(--accent-soft);
  box-shadow: 0 6px 18px rgb(179 64 46 / 0.12);
}

.rung-name { font-weight: 800; font-size: 15px; }
.rung-tagline { font-size: 12.5px; color: var(--ink-soft); }
.rung-status { font-family: var(--font-mono); font-size: 11.5px; margin-top: 3px; }
.rung-status.ok { color: var(--ok); }
.rung-status.locked { color: var(--accent-ink); }

/* ---------- workspace ---------- */

.workspace {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: clamp(20px, 3vw, 36px);
  align-items: start;
}

.level-panel {
  position: sticky;
  top: 76px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.stage-label {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-ink);
}
.level-panel h2 {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 26px;
}
.level-panel p { color: var(--ink-soft); font-size: 14.5px; }

.lock-note { margin: 14px 0; font-size: 14.5px; }
.lock-note strong { color: var(--ink); }

#paypalButtons { margin-top: 14px; }

.primary-button {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 18px;
  border: 0;
  border-radius: 11px;
  background: var(--accent);
  color: #fff;
  font-family: inherit;
  font-weight: 700;
  font-size: 14.5px;
  cursor: pointer;
  transition: background 0.15s, transform 0.15s;
}
.primary-button:hover { background: var(--accent-ink); transform: translateY(-1px); }

/* ---------- word grid ---------- */

.word-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 12px;
}

.word-card {
  display: grid;
  gap: 2px;
  padding: 18px 18px 15px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  transition: border-color 0.15s, box-shadow 0.15s;
}
.word-card:hover { border-color: #d8c8b4; box-shadow: 0 4px 14px rgb(38 33 29 / 0.06); }

.word-card .hanzi { margin: 0; font-family: var(--font-hanzi); font-weight: 700; font-size: 30px; line-height: 1.25; }
.word-card .pinyin { margin: 0; font-size: 14.5px; color: var(--accent-ink); }
.word-card .part { margin: 4px 0 0; font-family: var(--font-mono); font-size: 10.5px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-soft); }
.word-card .meaning { margin: 1px 0 8px; font-size: 14.5px; font-weight: 600; }
.word-card .example { margin: 0; font-family: var(--font-hanzi); font-size: 15px; }
.word-card .example-pinyin { margin: 0; font-size: 12.5px; color: var(--ink-soft); }
.word-card .example-meaning { margin: 2px 0 0; font-size: 12.5px; color: var(--ink-soft); font-style: italic; }

.empty-note { grid-column: 1 / -1; margin: 24px 0; text-align: center; color: var(--ink-soft); font-size: 14.5px; }

.word-pager {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  margin-top: 20px;
}
.word-pager:empty { display: none; }
.pager-button {
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
  color: var(--ink);
  font-family: inherit;
  font-weight: 600;
  font-size: 13.5px;
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s;
}
.pager-button:hover:not(:disabled) { border-color: var(--accent); }
.pager-button:disabled { opacity: 0.4; cursor: default; }
.pager-status { font-size: 13px; color: var(--ink-soft); font-family: var(--font-mono); }

.teaser {
  grid-column: 1 / -1;
  padding: 44px 24px;
  text-align: center;
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  color: var(--ink-soft);
  background: repeating-linear-gradient(-45deg, transparent 0 14px, rgb(179 64 46 / 0.03) 14px 28px);
}
.teaser-hanzi {
  margin: 0 0 8px;
  font-family: var(--font-hanzi);
  font-size: 56px;
  color: var(--line);
  filter: blur(2px);
  user-select: none;
}
.teaser p { margin: 4px 0; }
.teaser-sub { font-size: 13px; }

/* ---------- auth dialog ---------- */

.auth-dialog {
  position: relative;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 26px;
  width: min(92vw, 380px);
  background: var(--surface);
  color: var(--ink);
  font-family: var(--font-body);
}
.auth-dialog::backdrop { background: rgb(38 33 29 / 0.4); backdrop-filter: blur(2px); }

.auth-close {
  position: absolute;
  top: 10px;
  right: 12px;
  width: 32px;
  height: 32px;
  border: none;
  background: transparent;
  color: var(--ink);
  font-size: 22px;
  line-height: 1;
  cursor: pointer;
  border-radius: 8px;
}
.auth-close:hover { background: var(--bg); }

.auth-dialog h3 { margin: 0 0 14px; font-family: var(--font-display); font-size: 22px; }
.auth-dialog label { display: grid; gap: 5px; margin-bottom: 12px; font-size: 13.5px; font-weight: 600; }
.auth-dialog input {
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  font-family: inherit;
  font-size: 14.5px;
  background: var(--bg);
  color: var(--ink);
}
.auth-dialog input:focus { outline: 2px solid var(--accent-soft); border-color: var(--accent); }

.auth-error { min-height: 1.3em; margin: 0 0 10px; font-size: 13px; color: var(--accent-ink); }
.auth-actions { display: flex; gap: 10px; flex-wrap: wrap; }

/* ---------- responsive ---------- */

@media (max-width: 860px) {
  .workspace { grid-template-columns: 1fr; }
  .level-panel { position: static; }
  .section-heading { flex-direction: column; align-items: start; gap: 6px; }
}