* { box-sizing: border-box; }
body { margin: 0; font-family: -apple-system, "Segoe UI", "Microsoft YaHei", sans-serif; background: #f5f6f8; color: #1f2329; }
header { display: flex; justify-content: space-between; gap: 16px; align-items: center; padding: 12px 22px; color: #fff; flex-wrap: wrap;
  background: linear-gradient(90deg,#0A1220,#0F1B30 60%,#121F38); border-bottom: 1px solid rgba(255,255,255,.06); }
header .brand { display: flex; align-items: center; gap: 11px; }
header .logo { width: 34px; height: 34px; border-radius: 10px; display: grid; place-items: center;
  background: linear-gradient(145deg,#2F5BFF,#6D5BFF); box-shadow: 0 8px 22px -10px rgba(47,91,255,.9); }
header .logo svg { width: 18px; height: 18px; }
header b { font-size: 15px; letter-spacing: .4px; display: block; }
header small { display: block; font-size: 10.5px; color: #8FA1BE; margin-top: 1px; }
header .muted { color: #8FA1BE; font-size: 12px; }
main { max-width: 980px; margin: 18px auto 60px; padding: 0 16px; }
.card { background: #fff; border: 1px solid #E7EBF3; border-radius: 16px; padding: 18px 20px; margin-bottom: 16px; box-shadow: 0 1px 2px rgba(16,24,40,.04), 0 14px 34px -28px rgba(16,24,40,.4); }
h2 { font-size: 16px; margin: 0 0 10px; }
label { display: block; font-size: 13px; margin: 8px 0; }
input { padding: 8px 10px; border: 1px solid #d1d5db; border-radius: 6px; font-size: 14px; }
input.typing { width: 100%; font-size: 22px; font-family: ui-monospace, Menlo, Consolas, monospace; }
button { padding: 8px 14px; border-radius: 6px; border: 1px solid #d1d5db; background: #fff; cursor: pointer; font-size: 14px; }
button.primary { background: linear-gradient(180deg,#3D68FF,#2F5BFF); border-color: #2A52E8; color: #fff; box-shadow: 0 8px 18px -12px rgba(47,91,255,.9); }
button.mini { padding: 3px 10px; font-size: 12px; }
button:disabled { opacity: .5; cursor: not-allowed; }
.muted { color: #6b7280; font-size: 12px; }
.err { color: #b3261e; font-size: 13px; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 10px; }
.lesson { border: 1px solid #e5e7eb; border-radius: 8px; padding: 12px; cursor: pointer; }
.lesson:hover { border-color: #2b5cff; background: #f7f9ff; }
.lesson b { display: block; margin-bottom: 4px; }
.target { font-family: ui-monospace, Menlo, Consolas, monospace; font-size: 30px; letter-spacing: 2px; margin: 10px 0; color: #111827; }
.kv { font-size: 13px; margin: 4px 0; }
.row { display: flex; gap: 10px; align-items: center; margin-top: 10px; }
.progress { height: 6px; background: #eef1f5; border-radius: 4px; overflow: hidden; margin-bottom: 8px; }
.progress > i { display: block; height: 100%; width: 0; background: #2b5cff; transition: width .2s; }
.tip { font-family: ui-monospace, monospace; font-size: 13px; min-height: 20px; margin: 8px 0 0; }
.tip.ok { color: #15803d; }
.tip.bad { color: #b3261e; }
.kb { margin: 10px 0 4px; }
.kb-row { display: flex; gap: 4px; margin-bottom: 4px; }
.key { width: 34px; height: 34px; display: flex; align-items: center; justify-content: center; border: 1px solid #e5e7eb; border-radius: 6px; font-family: ui-monospace, monospace; font-size: 14px; color: #9ca3af; background: #fafafa; }
.key.on { color: #1f2a44; background: #eef3ff; border-color: #2b5cff; font-weight: 600; }
.key.home { border-bottom: 3px solid #f59e0b; }
.key.next { background: #fde68a; border-color: #f59e0b; }