/* ═══════════════ NAV TOGGLE BUTTON ═══════════════ */
/* Used in tracker/index to open learning pages */
.pattern-nav-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 18px;
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--t2);
  font-family: var(--mono);
  font-size: 12px;
  cursor: pointer;
  transition: all .2s;
  text-decoration: none;
  user-select: none;
}
.pattern-nav-btn:hover {
  background: var(--orange-dim);
  border-color: rgba(249,115,22,.4);
  color: var(--orange);
}
.pattern-nav-btn .btn-icon {
  font-size: 15px;
  line-height: 1;
}
.pattern-nav-btn .btn-arrow {
  margin-left: 2px;
  font-size: 10px;
  color: var(--t3);
  transition: transform .2s;
}
.pattern-nav-btn:hover .btn-arrow {
  transform: translateX(3px);
}

/* ═══════════════ CONTENT REVIEW FIXES ═══════════════ */
/* Minor improvements from code review */
.prob-row { cursor: pointer; }
.prob-row:focus-visible { outline: 2px solid var(--orange); outline-offset: 2px; }


:root {
  --bg:      #0b0d12;
  --bg2:     #10131a;
  --bg3:     #161b26;
  --bg4:     #1c2333;
  --border:  #222840;
  --border2: #2d3555;

  --orange: #f97316;
  --orange-dim: rgba(249,115,22,0.12);
  --green:  #22c55e;
  --green-dim: rgba(34,197,94,0.10);
  --blue:   #3b82f6;
  --blue-dim: rgba(59,130,246,0.10);
  --purple: #a855f7;
  --purple-dim: rgba(168,85,247,0.10);
  --red:    #ef4444;
  --red-dim: rgba(239,68,68,0.10);
  --yellow: #eab308;
  --yellow-dim: rgba(234,179,8,0.10);
  --cyan:   #06b6d4;
  --cyan-dim: rgba(6,182,212,0.10);

  --t1: #f1f5f9;
  --t2: #94a3b8;
  --t3: #64748b;
  --t4: #3d4f6b;

  --mono: 'JetBrains Mono', monospace;
  --sans: 'Inter', sans-serif;
  --r: 12px;
}

*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{background:var(--bg);color:var(--t1);font-family:var(--sans);line-height:1.65;font-size:14px}

/* ═══════════════ HERO ═══════════════ */
.hero{
  padding:52px 24px 44px;
  text-align:center;
  background:radial-gradient(ellipse 80% 50% at 50% -20%, rgba(249,115,22,0.14) 0%, transparent 70%), var(--bg);
  border-bottom:1px solid var(--border);
}
.hero-eyebrow{
  display:inline-flex;align-items:center;gap:8px;
  background:var(--orange-dim);border:1px solid rgba(249,115,22,0.3);
  color:var(--orange);font-family:var(--mono);font-size:11px;letter-spacing:2px;text-transform:uppercase;
  padding:5px 14px;border-radius:20px;margin-bottom:20px;
}
.hero h1{font-size:clamp(2rem,5vw,3rem);font-weight:800;color:var(--t1);letter-spacing:-1px;margin-bottom:10px}
.hero h1 span{color:var(--orange)}
.hero-sub{color:var(--t2);max-width:560px;margin:0 auto 28px;font-size:0.95rem}
.hero-pills{display:flex;flex-wrap:wrap;gap:10px;justify-content:center}
.hero-pill{
  background:var(--bg3);border:1px solid var(--border);
  padding:7px 18px;border-radius:8px;font-family:var(--mono);font-size:12px;color:var(--t2)
}
.hero-pill b{color:var(--orange)}

/* ═══════════════ NAV ═══════════════ */
.sticky-nav{
  position:sticky;top:0;z-index:100;
  background:rgba(11,13,18,0.92);backdrop-filter:blur(16px);
  border-bottom:1px solid var(--border);
  padding:0 20px;
  display:flex;gap:4px;overflow-x:auto;scrollbar-width:none;
}
.sticky-nav::-webkit-scrollbar{display:none}
.nav-item{
  flex-shrink:0;padding:12px 14px;
  font-size:12px;font-weight:500;color:var(--t3);
  cursor:pointer;border-bottom:2px solid transparent;
  transition:all .2s;white-space:nowrap;
}
.nav-item:hover{color:var(--t2);border-bottom-color:var(--border2)}
.nav-item.active{color:var(--orange);border-bottom-color:var(--orange)}

/* ═══════════════ LAYOUT ═══════════════ */
.page{max-width:1060px;margin:0 auto;padding:36px 20px 100px;display:flex;flex-direction:column;gap:32px}

/* ═══════════════ CARDS ═══════════════ */
.card{background:var(--bg2);border:1px solid var(--border);border-radius:var(--r);overflow:hidden}
.card-hd{
  display:flex;align-items:center;gap:12px;
  padding:16px 22px;background:var(--bg3);border-bottom:1px solid var(--border);
  cursor:pointer;user-select:none;
}
.card-hd:hover{background:var(--bg4)}
.card-icon{
  width:34px;height:34px;border-radius:9px;
  display:flex;align-items:center;justify-content:center;font-size:17px;flex-shrink:0;
}
.card-title{font-weight:700;font-size:.95rem;flex:1}
.card-badge{
  font-family:var(--mono);font-size:10px;font-weight:700;letter-spacing:1px;
  padding:3px 10px;border-radius:5px;
}
.chev{color:var(--t3);font-size:14px;transition:transform .28s;margin-left:4px}
.card.open .chev{transform:rotate(180deg)}
.card-body{display:none;padding:24px}
.card.open .card-body{display:block}

/* ═══════════════ PROSE ═══════════════ */
.prose{color:var(--t2);font-size:.9rem}
.prose p{margin-bottom:10px}
.prose strong{color:var(--t1)}
.prose ul{list-style:none;margin:6px 0 12px}
.prose li{padding:3px 0 3px 18px;position:relative}
.prose li::before{content:'›';position:absolute;left:0;color:var(--orange)}

/* ═══════════════ CALLOUT ═══════════════ */
.callout{border-radius:10px;padding:16px 18px;margin:14px 0;border:1px solid}
.callout-title{font-family:var(--mono);font-size:10px;font-weight:700;letter-spacing:1.5px;text-transform:uppercase;margin-bottom:8px}
.co-orange{background:var(--orange-dim);border-color:rgba(249,115,22,0.3)}.co-orange .callout-title{color:var(--orange)}
.co-green {background:var(--green-dim); border-color:rgba(34,197,94,0.3)} .co-green  .callout-title{color:var(--green)}
.co-blue  {background:var(--blue-dim);  border-color:rgba(59,130,246,0.3)} .co-blue   .callout-title{color:var(--blue)}
.co-purple{background:var(--purple-dim);border-color:rgba(168,85,247,0.3)}.co-purple .callout-title{color:var(--purple)}
.co-red   {background:var(--red-dim);   border-color:rgba(239,68,68,0.3)} .co-red    .callout-title{color:var(--red)}
.co-yellow{background:var(--yellow-dim);border-color:rgba(234,179,8,0.3)} .co-yellow .callout-title{color:var(--yellow)}
.co-cyan  {background:var(--cyan-dim);  border-color:rgba(6,182,212,0.3)} .co-cyan   .callout-title{color:var(--cyan)}

/* ═══════════════ CODE ═══════════════ */
.code-wrap{background:#070910;border:1px solid var(--border);border-radius:10px;overflow:hidden;margin:14px 0}
.code-bar{
  display:flex;align-items:center;justify-content:space-between;
  background:var(--bg3);border-bottom:1px solid var(--border);padding:8px 16px;
}
.code-bar-tabs{display:flex;gap:0}
.ctab{
  padding:5px 14px;font-family:var(--mono);font-size:11px;color:var(--t3);
  cursor:pointer;border-bottom:2px solid transparent;transition:all .2s;
}
.ctab:hover{color:var(--t2)}
.ctab.on{color:var(--orange);border-bottom-color:var(--orange)}
.cpanel{display:none}
.cpanel.on{display:block}
pre{
  margin:0;padding:18px 20px;
  font-family:var(--mono);font-size:12.5px;line-height:1.8;
  overflow-x:auto;color:#c9d1d9;
}
.kw {color:#ff79c6}
.fn {color:#8be9fd}
.st {color:#50fa7b}
.cm {color:#4a5568;font-style:italic}
.nm {color:#ffb86c}
.tp {color:#f1fa8c}
.pu {color:#ff5555;font-weight:700}  /* prune */
.ch {color:#22c55e;font-weight:700}  /* choose */
.un {color:#f97316;font-weight:700}  /* unchoose */
.bs {color:#60a5fa;font-weight:700}  /* base case */

/* ═══════════════ TYPE CLASSIFIER ═══════════════ */
.classifier{
  background:var(--bg3);border:1px solid var(--border);border-radius:var(--r);
  padding:24px;margin:16px 0;
}
.clf-title{font-size:.75rem;font-family:var(--mono);color:var(--t3);letter-spacing:1px;text-transform:uppercase;margin-bottom:16px}
.clf-question{font-size:.95rem;font-weight:700;color:var(--t1);margin-bottom:4px}
.clf-sub{font-size:.82rem;color:var(--t2);margin-bottom:20px}

.clf-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:14px}
.clf-type{
  border-radius:10px;border:1.5px solid;padding:16px 16px 14px;cursor:pointer;
  transition:transform .18s,box-shadow .18s;
}
.clf-type:hover{transform:translateY(-2px);box-shadow:0 8px 24px rgba(0,0,0,0.4)}
.clf-type-tag{
  display:inline-block;font-family:var(--mono);font-size:9px;font-weight:700;
  letter-spacing:1.5px;text-transform:uppercase;padding:3px 9px;border-radius:4px;margin-bottom:10px;
}
.clf-type-name{font-size:.9rem;font-weight:700;margin-bottom:6px;color:var(--t1)}
.clf-type-signal{font-size:.78rem;color:var(--t2);margin-bottom:10px;line-height:1.5}
.clf-type-eg{font-family:var(--mono);font-size:.75rem;padding:6px 10px;border-radius:6px;color:var(--t3)}
.clf-type-key{
  margin-top:10px;padding-top:10px;border-top:1px solid;
  font-family:var(--mono);font-size:.75rem;color:var(--t2);
}
.clf-type-key b{display:block;font-size:.65rem;letter-spacing:1px;text-transform:uppercase;margin-bottom:3px}

/* colors per type */
.t-sub   {border-color:rgba(34,197,94,0.4); background:rgba(34,197,94,0.05)}
.t-sub   .clf-type-tag{background:rgba(34,197,94,0.15);color:var(--green)}
.t-sub   .clf-type-eg{background:rgba(34,197,94,0.08)}
.t-sub   .clf-type-key{border-color:rgba(34,197,94,0.2)}

.t-perm  {border-color:rgba(168,85,247,0.4); background:rgba(168,85,247,0.05)}
.t-perm  .clf-type-tag{background:rgba(168,85,247,0.15);color:var(--purple)}
.t-perm  .clf-type-eg{background:rgba(168,85,247,0.08)}
.t-perm  .clf-type-key{border-color:rgba(168,85,247,0.2)}

.t-cst   {border-color:rgba(249,115,22,0.4); background:rgba(249,115,22,0.05)}
.t-cst   .clf-type-tag{background:rgba(249,115,22,0.15);color:var(--orange)}
.t-cst   .clf-type-eg{background:rgba(249,115,22,0.08)}
.t-cst   .clf-type-key{border-color:rgba(249,115,22,0.2)}

.t-grid  {border-color:rgba(59,130,246,0.4); background:rgba(59,130,246,0.05)}
.t-grid  .clf-type-tag{background:rgba(59,130,246,0.15);color:var(--blue)}
.t-grid  .clf-type-eg{background:rgba(59,130,246,0.08)}
.t-grid  .clf-type-key{border-color:rgba(59,130,246,0.2)}

.t-part  {border-color:rgba(6,182,212,0.4);  background:rgba(6,182,212,0.05)}
.t-part  .clf-type-tag{background:rgba(6,182,212,0.15);color:var(--cyan)}
.t-part  .clf-type-eg{background:rgba(6,182,212,0.08)}
.t-part  .clf-type-key{border-color:rgba(6,182,212,0.2)}

/* ═══════════════ DECISION FLOWCHART ═══════════════ */
.flow{
  background:#070910;border:1px solid var(--border);border-radius:10px;
  padding:28px 20px;margin:16px 0;overflow-x:auto;
}
.flow-inner{min-width:600px;display:flex;flex-direction:column;align-items:center;gap:0}
.f-node{
  padding:10px 22px;border-radius:8px;font-size:.82rem;font-weight:600;
  text-align:center;max-width:320px;border:1px solid;
}
.f-node.question{
  background:var(--bg3);border-color:var(--border2);color:var(--t1);
  font-size:.85rem;
}
.f-node.answer-sub   {background:rgba(34,197,94,0.12); border-color:rgba(34,197,94,0.4); color:var(--green)}
.f-node.answer-perm  {background:rgba(168,85,247,0.12);border-color:rgba(168,85,247,0.4);color:var(--purple)}
.f-node.answer-cst   {background:rgba(249,115,22,0.12);border-color:rgba(249,115,22,0.4);color:var(--orange)}
.f-node.answer-grid  {background:rgba(59,130,246,0.12);border-color:rgba(59,130,246,0.4);color:var(--blue)}
.f-node.answer-part  {background:rgba(6,182,212,0.12); border-color:rgba(6,182,212,0.4); color:var(--cyan)}

.f-arrow{display:flex;flex-direction:column;align-items:center;gap:0;width:100%}
.f-branch{display:flex;justify-content:center;gap:40px;width:100%;flex-wrap:wrap}
.f-branch-item{display:flex;flex-direction:column;align-items:center;gap:0;flex:1;min-width:140px}
.f-line{width:1px;background:var(--border2);height:24px;margin:0 auto}
.f-label{
  font-family:var(--mono);font-size:10px;color:var(--t3);
  background:var(--bg3);padding:2px 8px;border-radius:4px;margin:4px 0;
}
.f-row{display:flex;align-items:flex-start;gap:40px;justify-content:center;width:100%;flex-wrap:wrap}
.f-col{display:flex;flex-direction:column;align-items:center;flex:1;min-width:140px}

/* ═══════════════ TREES ═══════════════ */
.tree-tabs{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:16px}
.tree-tab{
  padding:7px 16px;border-radius:7px;font-size:.8rem;font-weight:600;
  cursor:pointer;border:1.5px solid var(--border);color:var(--t3);
  transition:all .2s;
}
.tree-tab:hover{color:var(--t2);border-color:var(--border2)}
.tree-tab.on{color:var(--t1);border-color:currentColor}
.tree-tab.tt-sub  {color:var(--green)}.tree-tab.tt-sub.on{background:rgba(34,197,94,0.1)}
.tree-tab.tt-perm {color:var(--purple)}.tree-tab.tt-perm.on{background:rgba(168,85,247,0.1)}
.tree-tab.tt-comb {color:var(--orange)}.tree-tab.tt-comb.on{background:rgba(249,115,22,0.1)}
.tree-tab.tt-grid {color:var(--blue)}.tree-tab.tt-grid.on{background:rgba(59,130,246,0.1)}

.tree-panel{display:none}
.tree-panel.on{display:block}
.tree-canvas{
  background:#070910;border:1px solid var(--border);border-radius:10px;
  overflow-x:auto;padding:24px 20px;
}
.tree-pre{
  font-family:var(--mono);font-size:12px;line-height:2;
  white-space:pre;color:var(--t2);
}
.tc-r  {color:var(--t3)}          /* connector lines */
.tc-n  {color:var(--t1)}          /* normal node */
.tc-ch {color:var(--green);font-weight:700}   /* choose */
.tc-un {color:var(--orange);font-weight:700}  /* unchoose */
.tc-lf {color:var(--green);font-weight:700}   /* leaf result */
.tc-pr {color:var(--red);font-weight:700}     /* pruned */
.tc-cu {color:var(--blue)}         /* current path */
.tc-cm {color:var(--t4);font-style:italic}    /* comment */

/* ═══════════════ PROBLEMS ═══════════════ */
.prob-filter{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:16px}
.pf-btn{
  padding:6px 14px;border-radius:20px;font-size:.78rem;font-weight:600;
  cursor:pointer;border:1.5px solid var(--border);color:var(--t3);
  transition:all .2s;background:transparent;
}
.pf-btn:hover{color:var(--t2)}
.pf-btn.on{color:var(--t1)}
.pf-btn.f-all.on  {background:var(--bg3);border-color:var(--border2)}
.pf-btn.f-sub.on  {background:rgba(34,197,94,0.12); border-color:rgba(34,197,94,0.5); color:var(--green)}
.pf-btn.f-perm.on {background:rgba(168,85,247,0.12);border-color:rgba(168,85,247,0.5);color:var(--purple)}
.pf-btn.f-cst.on  {background:rgba(249,115,22,0.12);border-color:rgba(249,115,22,0.5);color:var(--orange)}
.pf-btn.f-grid.on {background:rgba(59,130,246,0.12);border-color:rgba(59,130,246,0.5);color:var(--blue)}
.pf-btn.f-part.on {background:rgba(6,182,212,0.12); border-color:rgba(6,182,212,0.5); color:var(--cyan)}

.prob-list{display:flex;flex-direction:column;gap:8px}
.prob-row{
  display:flex;align-items:center;gap:10px;
  background:var(--bg3);border:1px solid var(--border);border-radius:9px;
  padding:11px 14px;cursor:pointer;transition:border-color .2s;
}
.prob-row:hover{border-color:var(--border2)}
.prob-row.hidden{display:none}

.prob-check{
  width:20px;height:20px;border-radius:50%;
  border:2px solid var(--border2);flex-shrink:0;
  display:flex;align-items:center;justify-content:center;
  font-size:10px;transition:all .2s;
}
.prob-check.done{background:var(--green);border-color:var(--green);color:#000;font-weight:700}

.diff-badge{
  font-family:var(--mono);font-size:9px;font-weight:700;
  padding:3px 8px;border-radius:4px;flex-shrink:0;
}
.d-easy  {background:rgba(34,197,94,0.15); color:var(--green)}
.d-med   {background:rgba(234,179,8,0.15); color:var(--yellow)}
.d-hard  {background:rgba(239,68,68,0.15); color:var(--red)}

.prob-name{flex:1;font-size:.87rem;color:var(--t1)}
.type-chip{
  font-family:var(--mono);font-size:9px;font-weight:700;letter-spacing:.5px;
  padding:3px 9px;border-radius:4px;flex-shrink:0;
}
.tc-sub  {background:rgba(34,197,94,0.12); color:var(--green)}
.tc-perm {background:rgba(168,85,247,0.12);color:var(--purple)}
.tc-cst  {background:rgba(249,115,22,0.12);color:var(--orange)}
.tc-grid {background:rgba(59,130,246,0.12);color:var(--blue)}
.tc-part {background:rgba(6,182,212,0.12); color:var(--cyan)}

/* ═══════════════ PROGRESS ═══════════════ */
.prog-wrap{margin-bottom:16px}
.prog-meta{display:flex;justify-content:space-between;font-size:.78rem;color:var(--t3);margin-bottom:6px}
.prog-meta span{color:var(--orange);font-weight:700}
.prog-bar{height:5px;background:var(--bg4);border-radius:3px}
.prog-fill{height:100%;background:linear-gradient(90deg,var(--orange),#fbbf24);border-radius:3px;transition:width .4s}

/* ═══════════════ QUIZ ═══════════════ */
.quiz-q{background:var(--bg3);border:1px solid var(--border);border-radius:10px;padding:18px 20px;margin-bottom:14px}
.quiz-num{font-family:var(--mono);font-size:10px;color:var(--t3);margin-bottom:6px}
.quiz-text{font-size:.9rem;font-weight:600;color:var(--t1);margin-bottom:14px}
.quiz-opts{display:flex;flex-direction:column;gap:7px}
.quiz-opt{
  background:var(--bg4);border:1px solid var(--border);border-radius:8px;
  padding:9px 14px;font-size:.83rem;color:var(--t2);cursor:pointer;text-align:left;
  transition:all .2s;
}
.quiz-opt:hover:not(:disabled){border-color:var(--border2);color:var(--t1)}
.quiz-opt.correct{border-color:var(--green);background:rgba(34,197,94,0.1);color:var(--green)}
.quiz-opt.wrong  {border-color:var(--red);  background:rgba(239,68,68,0.1); color:var(--red)}
.quiz-explain{
  margin-top:10px;padding:10px 14px;border-radius:7px;
  background:var(--bg);border-left:3px solid var(--orange);
  font-size:.8rem;color:var(--t2);display:none;line-height:1.6;
}

/* ═══════════════ TABLE ═══════════════ */
.t-table{width:100%;border-collapse:collapse;font-size:.82rem;margin:12px 0}
.t-table th{
  background:var(--bg3);padding:10px 14px;text-align:left;
  font-family:var(--mono);font-size:.72rem;letter-spacing:1px;text-transform:uppercase;
  color:var(--orange);border-bottom:1px solid var(--border);
}
.t-table td{padding:10px 14px;color:var(--t2);border-bottom:1px solid var(--border)}
.t-table tr:last-child td{border:none}
.t-table tr:hover td{background:var(--bg3)}
.t-table td:first-child{color:var(--t1);font-weight:600}

/* ═══════════════ STEPS ═══════════════ */
.steps{display:flex;flex-direction:column;gap:10px;margin:12px 0}
.step{display:flex;gap:14px;align-items:flex-start}
.step-n{
  width:26px;height:26px;border-radius:50%;flex-shrink:0;
  background:var(--orange);color:#000;font-weight:800;font-size:11px;
  display:flex;align-items:center;justify-content:center;
}
.step-body strong{display:block;color:var(--t1);font-size:.88rem;margin-bottom:2px}
.step-body p{color:var(--t2);font-size:.82rem}

/* ═══════════════ RESPONSIVE ═══════════════ */
@media(max-width:600px){
  .clf-grid{grid-template-columns:1fr}
  .f-branch{flex-direction:column;align-items:center}
  .f-row{flex-direction:column;align-items:center}
}