@import url('https://fonts.googleapis.com/css2?family=Kalam:wght@400;700&family=IBM+Plex+Sans:wght@400;500;600&family=IBM+Plex+Mono:wght@400;500;600&display=swap');

:root{
  --paper:#F6F4EE;
  --paper2:#EFEBE0;
  --ink:#232A33;
  --blue:#2B5D8C;
  --red:#B23A2E;
  --green:#2E7D4F;
  --purple:#6C4F9E;
  --amber:#9C7A2E;
  --line:#D8D2C0;
  --muted:#7A7568;
}
*{box-sizing:border-box;}
body{
  margin:0;
  background:
    linear-gradient(var(--line) 1px, transparent 1px) 0 0/100% 32px,
    var(--paper);
  color:var(--ink);
  font-family:'IBM Plex Sans', sans-serif;
  min-height:100vh;
  padding:24px 16px 60px;
}
.wrap{max-width:640px;margin:0 auto;}

header{display:flex;justify-content:space-between;align-items:flex-end;margin-bottom:18px;flex-wrap:wrap;gap:10px;}
h1{
  font-family:'Kalam', cursive;
  font-weight:700;
  font-size:30px;
  margin:0;
  color:var(--ink);
  transform:rotate(-1deg);
}
.sub{font-size:13px;color:var(--muted);margin-top:2px;}

.stats{display:flex;gap:8px;flex-wrap:wrap;}
.chip{
  background:#fff;
  border:1px solid var(--line);
  border-radius:3px;
  padding:5px 10px;
  font-size:12px;
  font-family:'IBM Plex Mono',monospace;
  box-shadow:1px 1px 0 var(--line);
}
.chip b{font-size:14px;}

.controls{display:flex;justify-content:space-between;align-items:center;margin-bottom:14px;font-size:13px;}
.toggle{
  display:flex;align-items:center;gap:6px;cursor:pointer;user-select:none;color:var(--muted);
}
.toggle input{accent-color:var(--purple);}
.reset{
  background:none;border:none;color:var(--muted);text-decoration:underline;
  cursor:pointer;font-size:12px;font-family:inherit;
}

.card{
  position:relative;
  background:var(--paper2);
  border:1px solid var(--line);
  border-radius:2px;
  padding:34px 26px 26px;
  box-shadow:3px 4px 0 var(--line);
  transform:rotate(-0.4deg);
  margin-bottom:16px;
}
.tape{
  position:absolute; top:-10px; left:24px;
  width:70px; height:22px;
  background:rgba(108,79,158,0.22);
  border:1px solid rgba(108,79,158,0.3);
  transform:rotate(-3deg);
}
.timer{
  position:absolute; top:14px; right:18px;
  font-family:'IBM Plex Mono',monospace;
  font-size:13px;
  color:var(--muted);
  display:flex;align-items:center;gap:6px;
}
.dot{width:7px;height:7px;border-radius:50%;background:var(--red);animation:pulse 1s infinite;}
@keyframes pulse{50%{opacity:.25;}}

.prompt{
  font-family:'IBM Plex Mono',monospace;
  font-size:16px;
  line-height:1.75;
  color:var(--ink);
  min-height:70px;
  margin-top:6px;
}

.options{display:grid;gap:10px;margin-top:6px;}
.opt{
  text-align:left;
  background:#fff;
  border:1px solid var(--line);
  border-radius:3px;
  padding:11px 14px;
  font-size:14px;
  font-family:'IBM Plex Sans',sans-serif;
  cursor:pointer;
  transition:transform .08s ease;
  position:relative;
}
.opt:hover:not(:disabled){border-color:var(--blue);}
.opt:active:not(:disabled){transform:scale(0.99);}
.opt:disabled{cursor:default;}
.opt.correct{border-color:var(--green);background:#EFF7F1;box-shadow:inset 0 0 0 1px var(--green);}
.opt.wrong{border-color:var(--red);background:#FBEEEC;box-shadow:inset 0 0 0 1px var(--red);}
.opt.reveal{border-color:var(--green);text-decoration:underline;text-decoration-color:var(--green);}

.unsure{
  margin-top:2px;
  width:100%;
  background:transparent;
  border:1px dashed var(--muted);
  border-radius:3px;
  padding:10px 14px;
  font-size:13px;
  color:var(--muted);
  font-family:'IBM Plex Sans',sans-serif;
  cursor:pointer;
}
.unsure:hover:not(:disabled){border-color:var(--amber);color:var(--amber);}
.unsure:disabled{cursor:default;opacity:.5;}
.unsure.picked{border-color:var(--amber);color:var(--amber);background:#FAF3E4;}

.why{
  margin-top:16px;
  padding-top:14px;
  border-top:1px dashed var(--line);
  font-size:13.5px;
  color:var(--ink);
  line-height:1.6;
  display:none;
}
.why b{color:var(--purple);}
.framework-link{color:var(--purple);font-weight:600;text-decoration:none;border-bottom:1px solid currentColor;}
.framework-link:hover{color:var(--blue);}
.why .leet{
  display:inline-block;
  margin-top:10px;
  font-family:'IBM Plex Mono',monospace;
  font-size:12.5px;
}
.why .leet a{color:var(--blue);text-decoration:none;border-bottom:1px solid var(--blue);}
.why .leet a:hover{color:var(--ink);border-color:var(--ink);}
.why.show{display:block;}
.mistake-note{
  margin-top:10px;
  padding:8px 10px;
  border-left:3px solid var(--red);
  background:#FBEEEC;
}
.mistake-note b{color:var(--red);}
.mistake-note code,.solution code{
  font-family:'IBM Plex Mono',monospace;
  font-size:.92em;
}
.solution{
  margin-top:12px;
  padding:10px 12px;
  background:#F7F3FB;
  border-left:3px solid var(--purple);
}
.solution-title{font-weight:600;color:var(--purple);}
.solution ol{margin:6px 0 0;padding-left:20px;}
.solution li{margin:4px 0;}
.solution pre{
  overflow:auto;
  margin:10px 0 0;
  padding:10px;
  background:#232A33;
  color:#F6F4EE;
  border-radius:2px;
  font-size:12px;
  line-height:1.5;
}

.next{
  margin-top:14px;
  width:100%;
  background:var(--ink);
  color:var(--paper);
  border:none;
  border-radius:3px;
  padding:12px;
  font-size:14px;
  font-family:'Kalam',cursive;
  font-weight:700;
  letter-spacing:.5px;
  cursor:pointer;
  display:none;
}
.next.show{display:block;}
.next:hover{background:#3a4553;}

.weak{
  margin-top:22px;
  font-size:12.5px;
  color:var(--muted);
}
.weak b{color:var(--ink);}

/* —— tabs —— */
.tabs{
  display:flex;
  gap:0;
  margin-bottom:16px;
  border-bottom:1px solid var(--line);
}
.tab{
  flex:1;
  background:transparent;
  border:none;
  border-bottom:2px solid transparent;
  margin-bottom:-1px;
  padding:10px 12px;
  font-family:'Kalam',cursive;
  font-weight:700;
  font-size:16px;
  color:var(--muted);
  cursor:pointer;
  letter-spacing:.3px;
}
.tab:hover{color:var(--ink);}
.tab.active{
  color:var(--ink);
  border-bottom-color:var(--purple);
}
.mode[hidden]{display:none;}

/* —— framework rewrite —— */
.rewrite-intro{font-size:13px;color:var(--muted);margin:0 0 12px;line-height:1.5;}
.rewrite-card{
  position:relative;background:var(--paper2);border:1px solid var(--line);border-radius:2px;
  padding:30px 22px 22px;box-shadow:3px 4px 0 var(--line);transform:rotate(-0.3deg);
}
.rewrite-label{font-size:15px;color:var(--purple);font-family:'IBM Plex Mono',monospace;font-weight:600;line-height:1.6;margin-bottom:14px;}
.code-label{display:block;margin:16px 0 7px;font-size:13px;font-weight:600;}
.code-editor{
  display:block;width:100%;min-height:260px;resize:vertical;border:1px solid var(--line);border-radius:3px;
  padding:12px;background:#232A33;color:#F6F4EE;font:13px/1.6 'IBM Plex Mono',monospace;
}
.code-editor:focus{outline:2px solid var(--blue);outline-offset:1px;}
.code-editor:disabled{opacity:.82;cursor:not-allowed;}
.submit-code,.retry-code,.reference-code,.next-code{
  border-radius:3px;padding:10px 14px;font:600 13px 'IBM Plex Sans',sans-serif;cursor:pointer;
}
.submit-code{width:100%;margin-top:12px;background:var(--ink);color:var(--paper);border:1px solid var(--ink);}
.submit-code:hover:not(:disabled){background:#3a4553;}
.submit-code:disabled{opacity:.55;cursor:default;}
.reference-code{width:100%;margin-top:10px;background:#F7F3FB;border:1px solid var(--purple);color:var(--purple);}
.reference-code:hover{background:#EFE6FA;}
.rewrite-feedback{display:none;margin-top:12px;padding:10px 12px;font-size:13px;line-height:1.6;}
.rewrite-feedback.show{display:block;}
.rewrite-feedback.warning{color:#765a17;background:#FAF3E4;border-left:3px solid var(--amber);}
.rewrite-feedback.pending{background:#F7F3FB;border-left:3px solid var(--purple);}
.rewrite-feedback.success{background:#EFF7F1;border-left:3px solid var(--green);}
.rewrite-feedback.needs-practice{background:#FBEEEC;border-left:3px solid var(--red);}
.rewrite-feedback b{color:var(--purple);}
.rewrite-feedback.success b{color:var(--green);}
.rewrite-feedback.needs-practice b{color:var(--red);}
.self-evaluate{display:grid;grid-template-columns:1fr 1fr;gap:8px;margin-top:12px;}
.self-evaluate-title{grid-column:1 / -1;font-size:13px;font-weight:600;}
.self-correct,.self-wrong{border-radius:3px;padding:10px;border:1px solid;font:600 13px 'IBM Plex Sans',sans-serif;cursor:pointer;}
.self-correct{color:var(--green);border-color:var(--green);background:#EFF7F1;}
.self-wrong{color:var(--red);border-color:var(--red);background:#FBEEEC;}
.self-correct:hover{background:#DDEFE2;}
.self-wrong:hover{background:#F7DEDA;}
.rewrite-actions{display:flex;gap:8px;margin-top:12px;}
.retry-code{flex:1;background:#fff;border:1px solid var(--purple);color:var(--purple);}
.next-code{flex:1;background:transparent;border:1px dashed var(--muted);color:var(--muted);}
.retry-code:hover{background:#F7F3FB;}
.next-code:hover{color:var(--blue);border-color:var(--blue);}
.reference-answer{margin-top:14px;border:1px solid var(--line);background:#fff;}
.reference-title{padding:8px 10px;font-size:12px;font-weight:600;color:var(--purple);background:#F7F3FB;border-bottom:1px solid var(--line);}
.reference-answer pre{overflow:auto;margin:0;padding:12px;background:#232A33;color:#F6F4EE;font:12px/1.55 'IBM Plex Mono',monospace;}

/* —— frameworks cheat-sheet —— */
.fw-intro{
  font-size:13px;
  color:var(--muted);
  margin:0 0 12px;
  line-height:1.5;
}
.fw-list{display:grid;gap:8px;}
.fw-item{
  display:flex;
  align-items:center;
  gap:12px;
  width:100%;
  text-align:left;
  background:#fff;
  border:1px solid var(--line);
  border-radius:3px;
  padding:11px 14px;
  font-family:'IBM Plex Sans',sans-serif;
  cursor:pointer;
  box-shadow:1px 1px 0 var(--line);
  transition:transform .08s ease;
}
.fw-item:hover{border-color:var(--blue);}
.fw-item:active{transform:scale(0.99);}
.fw-item.open{border-color:var(--purple);background:#F7F3FB;}
.fw-idx{
  font-family:'IBM Plex Mono',monospace;
  font-size:12px;
  color:var(--muted);
  min-width:1.5em;
}
.fw-names{flex:1;min-width:0;display:flex;flex-direction:column;gap:2px;}
.fw-en{font-size:14px;font-weight:500;color:var(--ink);}
.fw-zh{font-size:12px;color:var(--muted);}
.fw-meta{display:flex;flex-direction:column;align-items:flex-end;gap:2px;flex-shrink:0;}
.fw-stars{
  font-size:12px;
  color:var(--amber);
  letter-spacing:1px;
  font-family:'IBM Plex Mono',monospace;
}
.fw-diff{
  font-size:11px;
  color:var(--muted);
  font-family:'IBM Plex Mono',monospace;
}

.fw-detail{margin-top:4px;}
.fw-detail-card{
  position:relative;
  background:var(--paper2);
  border:1px solid var(--line);
  border-radius:2px;
  padding:28px 22px 22px;
  box-shadow:3px 4px 0 var(--line);
  transform:rotate(-0.3deg);
}
.fw-back{
  background:none;
  border:none;
  color:var(--muted);
  text-decoration:underline;
  cursor:pointer;
  font-size:12px;
  font-family:inherit;
  padding:0;
  margin-bottom:10px;
}
.fw-back:hover{color:var(--blue);}
.fw-detail-title{
  font-family:'Kalam',cursive;
  font-weight:700;
  font-size:24px;
  margin:0 0 6px;
  color:var(--ink);
}
.fw-detail-zh{
  font-family:'IBM Plex Sans',sans-serif;
  font-weight:500;
  font-size:14px;
  color:var(--muted);
  margin-left:10px;
}
.fw-detail-meta{
  display:flex;
  align-items:center;
  gap:10px;
  margin-bottom:12px;
}
.fw-cue{
  font-size:13.5px;
  line-height:1.6;
  color:var(--ink);
  margin:0 0 16px;
  padding-bottom:14px;
  border-bottom:1px dashed var(--line);
}
.fw-snippet{margin-bottom:14px;}
.fw-snippet:last-child{margin-bottom:0;}
.fw-code-title{
  font-size:12px;
  color:var(--purple);
  font-weight:600;
  margin-bottom:6px;
}
.fw-code{
  margin:0;
  padding:14px 16px;
  background:#fff;
  border:1px solid var(--line);
  border-radius:3px;
  overflow-x:auto;
  box-shadow:inset 0 0 0 1px rgba(0,0,0,0.02);
}
.fw-code code{
  font-family:'IBM Plex Mono',monospace;
  font-size:12.5px;
  line-height:1.65;
  color:var(--ink);
  white-space:pre;
}