:root {
  --bg: #0f1115;
  --bg-soft: #161a22;
  --panel: #ffffff;
  --ink: #1a1f2b;
  --ink-soft: #5a6478;
  --line: #e6e9f0;
  --brand: #4f46e5;
  --brand-2: #7c3aed;
  --brand-ink: #eef0ff;
  --accent: #0ea5a4;
  --warn: #d97706;
  --ok: #16a34a;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(20, 24, 40, .10);
  --shadow-sm: 0 2px 10px rgba(20, 24, 40, .06);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background: #f5f6fa;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
.wrap { width: min(1120px, 92vw); margin: 0 auto; }
a { color: var(--brand); text-decoration: none; }
h1, h2, h3 { line-height: 1.25; margin: 0; }

/* Topbar */
.topbar {
  position: sticky; top: 0; z-index: 20;
  background: rgba(15, 17, 21, .92);
  backdrop-filter: saturate(1.4) blur(8px);
  border-bottom: 1px solid rgba(255,255,255,.06);
}
.topbar-inner { display: flex; align-items: center; justify-content: space-between; height: 62px; }
.brand { display: flex; align-items: center; gap: 12px; }
.brand-mark { font-size: 26px; }
.brand-name { color: #fff; font-weight: 700; font-size: 17px; letter-spacing: .3px; }
.brand-sub { color: #8b93a7; font-size: 11px; letter-spacing: 1.5px; text-transform: uppercase; }
.topnav { display: flex; gap: 22px; }
.topnav a { color: #c7ccda; font-size: 14px; }
.topnav a:hover { color: #fff; }

/* Hero */
.hero {
  background: radial-gradient(1200px 400px at 15% -10%, rgba(124,58,237,.35), transparent 60%),
              radial-gradient(900px 380px at 100% 0%, rgba(14,165,164,.25), transparent 55%),
              var(--bg);
  color: #fff;
  padding: 72px 0 64px;
}
.hero-inner { max-width: 760px; }
.hero h1 { font-size: clamp(28px, 4.4vw, 46px); font-weight: 800; letter-spacing: -.5px; }
.hero-lead { margin-top: 20px; font-size: clamp(15px, 1.8vw, 18px); color: #c9cee0; }
.hero-lead strong { color: #fff; }
.hero-actions { margin-top: 30px; display: flex; align-items: center; gap: 18px; flex-wrap: wrap; }
.hero-note { color: #8b93a7; font-size: 13px; }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  border: 1px solid transparent; border-radius: 10px; cursor: pointer;
  font-family: inherit; font-size: 14px; font-weight: 600; padding: 11px 18px;
  transition: transform .06s ease, box-shadow .2s ease, background .2s ease;
}
.btn:active { transform: translateY(1px); }
.btn-primary { background: linear-gradient(135deg, var(--brand), var(--brand-2)); color: #fff; box-shadow: 0 8px 20px rgba(79,70,229,.35); }
.btn-primary:hover { box-shadow: 0 10px 26px rgba(79,70,229,.5); }
.btn-block { width: 100%; padding: 14px; font-size: 15px; }
.btn-ghost { background: #f3f4fb; color: var(--brand); border-color: var(--line); padding: 8px 12px; font-size: 13px; }
.btn-ghost:hover { background: #ecedff; }

/* Builder */
.builder { padding: 46px 0 20px; }
.builder-grid { display: grid; grid-template-columns: 380px 1fr; gap: 26px; align-items: start; }
.panel { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow-sm); }
.form-panel { padding: 24px; position: sticky; top: 82px; }
.panel-title { font-size: 15px; color: var(--ink-soft); font-weight: 700; letter-spacing: .3px; margin-bottom: 16px; }

.field { display: block; margin-bottom: 16px; }
.field-label { display: block; font-size: 13px; font-weight: 600; color: var(--ink); margin-bottom: 7px; }
.field-label em { color: var(--brand-2); font-style: normal; }
.field-label b { color: var(--brand); font-size: 15px; }
input[type=text], input[type=number], select {
  width: 100%; padding: 11px 12px; border: 1px solid var(--line); border-radius: 10px;
  font-family: inherit; font-size: 14px; color: var(--ink); background: #fbfbfe; transition: border .15s, box-shadow .15s;
}
input[type=text]:focus, input[type=number]:focus, select:focus {
  outline: none; border-color: var(--brand); box-shadow: 0 0 0 3px rgba(79,70,229,.14);
}
input[type=range] { width: 100%; accent-color: var(--brand); }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }

.chips { display: flex; flex-wrap: wrap; gap: 7px; align-items: center; margin: -6px 0 16px; }
.chips-label { font-size: 12px; color: var(--ink-soft); }
.chip {
  border: 1px solid var(--line); background: #fff; color: var(--brand);
  border-radius: 999px; padding: 5px 11px; font-size: 12.5px; cursor: pointer; font-family: inherit;
}
.chip:hover { background: var(--brand-ink); border-color: #c7c9ff; }

.form-hint, .form-actions { margin-top: 4px; }
.form-hint { font-size: 12px; color: var(--ink-soft); margin-top: 12px; }

/* Output */
.output-panel { padding: 24px; min-height: 420px; }
.output-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; margin-bottom: 8px; }
.output-tools { display: flex; gap: 8px; flex-wrap: wrap; }
.output-body { margin-top: 8px; }

.course-head { border-bottom: 1px dashed var(--line); padding-bottom: 18px; margin-bottom: 18px; }
.course-title { font-size: 22px; font-weight: 800; letter-spacing: -.3px; }
.course-tagline { color: var(--ink-soft); margin-top: 6px; font-size: 14.5px; }
.course-meta { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.tag { font-size: 12px; background: var(--brand-ink); color: var(--brand); border-radius: 8px; padding: 4px 10px; font-weight: 600; }
.tag.alt { background: #e6f7f6; color: var(--accent); }

.course-block { margin-bottom: 18px; }
.course-block h4 { font-size: 13px; text-transform: uppercase; letter-spacing: 1px; color: var(--ink-soft); margin-bottom: 8px; }
.outcome-list { margin: 0; padding-left: 18px; }
.outcome-list li { margin-bottom: 4px; font-size: 14px; }

.phase-label {
  display: inline-block; font-size: 11.5px; font-weight: 700; letter-spacing: .5px;
  color: #fff; background: var(--brand); border-radius: 6px; padding: 2px 9px; margin: 20px 0 10px;
}
.phase-label.p0 { background: #6366f1; } .phase-label.p1 { background: #0ea5a4; }
.phase-label.p2 { background: #7c3aed; } .phase-label.p3 { background: #db2777; }
.phase-label.p4 { background: #ea580c; }

.lesson {
  border: 1px solid var(--line); border-radius: 12px; padding: 16px 16px 14px; margin-bottom: 12px;
  background: #fcfcff; transition: box-shadow .2s, border .2s;
}
.lesson:hover { box-shadow: var(--shadow-sm); border-color: #d7dbe8; }
.lesson-top { display: flex; align-items: baseline; gap: 10px; }
.lesson-no { font-size: 12px; font-weight: 800; color: #fff; background: var(--brand); border-radius: 7px; padding: 3px 8px; white-space: nowrap; }
.lesson-title { font-size: 16px; font-weight: 700; flex: 1; }
.lesson-dur { font-size: 12px; color: var(--ink-soft); white-space: nowrap; }
.lesson-obj { margin: 10px 0 0; font-size: 13.5px; color: var(--ink); background: #f4f4fd; border-left: 3px solid var(--brand); padding: 8px 12px; border-radius: 0 8px 8px 0; }
.lesson-obj b { color: var(--brand-2); }
.lesson-points { margin: 12px 0 0; padding-left: 18px; }
.lesson-points li { font-size: 13.5px; margin-bottom: 3px; }
.lesson-foot { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 12px; }
.lesson-foot .cell { background: #fff; border: 1px solid var(--line); border-radius: 9px; padding: 9px 11px; }
.lesson-foot .cell .lbl { font-size: 11px; font-weight: 700; letter-spacing: .5px; text-transform: uppercase; color: var(--ink-soft); display: block; margin-bottom: 3px; }
.lesson-foot .cell.ex .lbl { color: var(--accent); }
.lesson-foot .cell.hw .lbl { color: var(--warn); }
.lesson-foot .cell .txt { font-size: 13px; }
[contenteditable="true"]:focus { outline: 2px solid rgba(79,70,229,.4); outline-offset: 2px; border-radius: 4px; }

.checklist { margin-top: 22px; background: #f7f8fc; border: 1px solid var(--line); border-radius: 12px; padding: 16px; }
.checklist h4 { font-size: 13px; margin: 0 0 10px; color: var(--ink-soft); text-transform: uppercase; letter-spacing: 1px; }
.check-item { display: flex; gap: 9px; font-size: 13.5px; margin-bottom: 6px; align-items: flex-start; }
.check-item .ic { flex: none; width: 18px; }
.check-item.ok .ic { color: var(--ok); }
.check-item.warn .ic { color: var(--warn); }

/* Empty state */
.empty { text-align: center; color: var(--ink-soft); padding: 40px 10px; }
.empty .big { font-size: 42px; }
.empty p { margin: 12px 0 0; font-size: 14px; }

/* Sections */
.how, .faq { padding: 54px 0; }
.faq { background: #fff; border-top: 1px solid var(--line); }
.section-title { font-size: 26px; font-weight: 800; letter-spacing: -.3px; }
.section-lead { color: var(--ink-soft); margin-top: 8px; margin-bottom: 26px; }
.how-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.how-card { background: #fff; border: 1px solid var(--line); border-radius: 12px; padding: 20px; box-shadow: var(--shadow-sm); }
.how-num { font-size: 13px; font-weight: 800; color: var(--brand); letter-spacing: 1px; }
.how-card h3 { font-size: 16px; margin: 8px 0 8px; }
.how-card p { font-size: 13.5px; color: var(--ink-soft); margin: 0; }

.faq-list { display: grid; gap: 12px; max-width: 820px; }
.faq details { border: 1px solid var(--line); border-radius: 10px; padding: 4px 16px; background: #fbfbfe; }
.faq summary { cursor: pointer; font-weight: 600; padding: 12px 0; font-size: 15px; }
.faq details[open] summary { color: var(--brand); }
.faq details p { margin: 0 0 14px; color: var(--ink-soft); font-size: 14px; }

/* Footer */
.site-footer { background: var(--bg); color: #8b93a7; padding: 26px 0; }
.footer-inner { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; font-size: 13px; }
.footer-dim { color: #5a6478; }

/* Toast */
.toast {
  position: fixed; left: 50%; bottom: 30px; transform: translate(-50%, 20px);
  background: #1a1f2b; color: #fff; padding: 11px 20px; border-radius: 10px; font-size: 14px;
  opacity: 0; pointer-events: none; transition: opacity .25s, transform .25s; z-index: 50; box-shadow: var(--shadow);
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

/* Responsive */
@media (max-width: 900px) {
  .builder-grid { grid-template-columns: 1fr; }
  .form-panel { position: static; }
  .how-grid { grid-template-columns: 1fr 1fr; }
  .topnav { display: none; }
}
@media (max-width: 560px) {
  .how-grid { grid-template-columns: 1fr; }
  .lesson-foot { grid-template-columns: 1fr; }
  .hero { padding: 52px 0 44px; }
  .output-tools { width: 100%; }
}

/* Print */
@media print {
  .topbar, .hero, .how, .faq, .site-footer, .form-panel, .output-tools, .toast, .chips { display: none !important; }
  body { background: #fff; }
  .builder { padding: 0; }
  .builder-grid { display: block; }
  .output-panel { border: none; box-shadow: none; padding: 0; }
  .lesson { break-inside: avoid; }
}