/* Browser Tutor — mobile-first, no framework */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;text-size-adjust:100%}
body{margin:0;font:16px/1.55 system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;background:#0d1117;color:#c9d1d9;overflow-wrap:anywhere}
a{color:#58a6ff}
h1{font-size:clamp(1.6rem,6vw,2.2rem);line-height:1.2;margin:.2em 0 .5em}
h2{font-size:1.05rem;color:#e6edf3;margin:1.2em 0 .5em}
.lead{font-size:1.05rem}.muted{color:#8b949e;font-size:.9rem}
code{background:#30363d;padding:0 4px;border-radius:4px;font-size:.9em}
img.av{width:24px;height:24px;border-radius:50%;vertical-align:middle}

/* buttons: >=44px tap targets */
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:44px;min-width:44px;padding:10px 18px;background:#238636;color:#fff;border:0;border-radius:8px;font:inherit;font-weight:600;cursor:pointer;text-decoration:none;touch-action:manipulation}
.btn:hover{background:#2ea043}.btn:disabled{opacity:.55;cursor:default}
.btn.secondary{background:#30363d}
.link{background:none;border:0;color:#58a6ff;cursor:pointer;font:inherit;min-height:44px;padding:0 8px}
:focus-visible{outline:2px solid #58a6ff;outline-offset:2px}

/* landing */
.narrow{max-width:640px;margin:0 auto;padding:max(8vh,24px) max(20px,env(safe-area-inset-right)) max(24px,env(safe-area-inset-bottom)) max(20px,env(safe-area-inset-left))}
.narrow .btn{width:100%;max-width:340px}

/* app shell */
.topbar{position:sticky;top:0;z-index:10;display:flex;flex-wrap:wrap;align-items:center;gap:4px 12px;background:#161b22;border-bottom:1px solid #30363d;
  padding:max(6px,env(safe-area-inset-top)) max(12px,env(safe-area-inset-right)) 0 max(12px,env(safe-area-inset-left))}
.brand{white-space:nowrap;min-height:44px;display:flex;align-items:center}
.who{margin-left:auto;display:flex;align-items:center;gap:6px;min-width:0}
.who .login{max-width:9em;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;display:inline-block;vertical-align:middle}
.tabs{display:flex;order:3;width:100%;overflow-x:auto;scrollbar-width:none}
.tabs::-webkit-scrollbar{display:none}
.tab{flex:0 0 auto;min-height:44px;background:none;border:0;border-bottom:2px solid transparent;color:#8b949e;font:inherit;cursor:pointer;padding:6px 10px}
.tab.active{color:#fff;border-bottom-color:#f78166}
main{max-width:1200px;margin:0 auto;padding:12px max(12px,env(safe-area-inset-right)) max(16px,env(safe-area-inset-bottom)) max(12px,env(safe-area-inset-left))}

/* probe */
.sharebar{display:flex;flex-wrap:wrap;align-items:center;gap:8px 12px;margin:12px 0}
.grid{display:grid;grid-template-columns:minmax(0,1fr);gap:4px 20px}
.col{min-width:0}
.cards{display:flex;flex-direction:column;gap:8px}
.card{background:#161b22;border:1px solid #30363d;border-radius:10px;overflow:hidden}
.card>summary{min-height:44px;display:flex;align-items:center;padding:8px 14px;cursor:pointer;font-weight:600;color:#e6edf3;text-transform:capitalize;list-style:none}
.card>summary::-webkit-details-marker{display:none}
.card>summary::after{content:"▸";margin-left:auto;color:#8b949e;transition:transform .15s}
.card[open]>summary::after{transform:rotate(90deg)}
.card dl{margin:0;padding:0 14px 8px}
.row{display:grid;grid-template-columns:minmax(0,1fr);gap:0;padding:8px 0;border-top:1px solid #21262d}
.row dt{color:#8b949e;font-size:.82rem;text-transform:none}
.row dd{margin:0;min-width:0;font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:.88rem;word-break:break-word;overflow-wrap:anywhere}
.long>summary{cursor:pointer;list-style:none}.long>summary::-webkit-details-marker{display:none}
.long .more{display:inline-block;margin-left:6px;color:#58a6ff;font-family:system-ui,sans-serif;font-size:.85rem;padding:6px 0;min-height:32px}
.long[open]>summary{display:none}
.pill{padding:1px 8px;border-radius:999px;font-size:.8rem}.pill.on{background:#23863633;color:#7ee787}.pill.off{background:#30363d;color:#8b949e}
.raw{margin-top:8px}.raw>summary{min-height:44px;display:flex;align-items:center;cursor:pointer;color:#8b949e}
pre{background:#161b22;border:1px solid #30363d;border-radius:8px;padding:10px;overflow:auto;max-height:60vh;font-size:12px;white-space:pre-wrap;word-break:break-all;max-width:100%}

/* chat: fills the dynamic viewport, composer pinned to the bottom above the keyboard / home indicator */
body.in-chat{height:100vh;height:100dvh;display:flex;flex-direction:column;overflow:hidden}
body.in-chat main{flex:1;min-height:0;display:flex;flex-direction:column;width:100%;padding-bottom:0}
.chat{flex:1;min-height:0;display:flex;flex-direction:column;position:relative}
.chat[hidden]{display:none}
#log{flex:1;min-height:0;overflow-y:auto;overscroll-behavior:contain;-webkit-overflow-scrolling:touch;display:flex;flex-direction:column;gap:10px;padding:4px 0 12px}
.msg{padding:10px 14px;border-radius:12px;max-width:min(85%,760px);min-width:0}
.msg.user{align-self:flex-end;background:#1f6feb33;border:1px solid #1f6feb;white-space:pre-wrap}
.msg.bot{align-self:flex-start;background:#161b22;border:1px solid #30363d}
.msg.tool{align-self:flex-start;color:#8b949e;font-size:.85rem;padding:0 14px}
.msg pre{max-height:none;white-space:pre-wrap}
.msg h3,.msg h4{margin:.4em 0;font-size:1rem;color:#e6edf3}
.composer{position:sticky;bottom:0;background:#0d1117;border-top:1px solid #21262d;padding:6px 0 max(10px,env(safe-area-inset-bottom))}
.composer .muted{margin:0 0 6px;font-size:.8rem}
#form{display:flex;gap:8px;align-items:flex-end}
#q{flex:1;min-width:0;min-height:44px;max-height:160px;resize:none;padding:10px 12px;border-radius:10px;border:1px solid #30363d;background:#0d1117;color:#c9d1d9;font:inherit;font-size:16px;line-height:1.4}
.jump{position:absolute;right:8px;bottom:110px;min-height:44px;padding:0 14px;border-radius:999px;border:1px solid #30363d;background:#161b22;color:#c9d1d9;font:inherit;font-size:.9rem;cursor:pointer;box-shadow:0 2px 8px #0008}

/* tablets and up */
@media (min-width:600px){
  .row{grid-template-columns:minmax(120px,38%) minmax(0,1fr);gap:12px}
  .row dt{font-size:.88rem}
}
@media (min-width:768px){
  .topbar{flex-wrap:nowrap;padding-bottom:0}
  .tabs{order:0;width:auto;flex:0 1 auto}
  .tab{flex:0 0 auto}
}
@media (min-width:1000px){
  .grid{grid-template-columns:minmax(0,1fr) minmax(0,1fr)}
  main{padding-left:24px;padding-right:24px}
  .chat{max-width:900px;margin:0 auto;width:100%}
}
@media (prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}

/* nav links styled as tabs */
a.tab{display:inline-flex;align-items:center;justify-content:center;text-decoration:none;text-align:center}
a.brand{color:#e6edf3;text-decoration:none}
.tab{white-space:nowrap;padding:6px 8px}

/* gotchas lesson */
.lesson{max-width:900px}
.badge{display:inline-block;font-size:.72rem;font-weight:600;padding:2px 8px;border-radius:999px;white-space:nowrap;vertical-align:middle}
.badge.build{background:#23863633;color:#7ee787}.badge.docs{background:#1f6feb33;color:#79c0ff}.badge.unverified{background:#bb800933;color:#e3b341}
.gotchas{list-style:none;padding:0;margin:12px 0 0}
.gotchas .card>summary{flex-wrap:wrap;gap:6px 10px;text-transform:none;padding:10px 14px;line-height:1.35}
.gt-num{flex:0 0 auto;width:28px;height:28px;border-radius:50%;background:#30363d;display:inline-flex;align-items:center;justify-content:center;font-size:.85rem}
.gt-title{flex:1 1 200px;min-width:0}
.gotchas .card>summary .badge{order:3;margin-left:38px}
.gotchas .card>summary::after{order:2}
.gt-body{padding:0 14px 12px}
.gt-body h3{font-size:.85rem;text-transform:uppercase;letter-spacing:.04em;color:#8b949e;margin:14px 0 4px}
.gt-body p{margin:0}
.src{margin:4px 0 0;padding-left:1.2em}.src li{margin:2px 0}.src a{display:inline-flex;align-items:center;min-height:44px}
.gt-tools{display:flex;justify-content:flex-end}
@media (min-width:600px){.gotchas .card>summary .badge{order:0;margin-left:0}}

/* live demos */
.demos .card>summary{text-transform:none}
.demo-run{margin:12px 0}
.demo-out{margin-top:8px}.demo-out:empty{display:none}
.demo-out.ok{border-left:3px solid #238636;padding-left:10px}
.demo-out.warn{border-left:3px solid #bb8009;padding-left:10px;color:#e3b341}
.demo-out .kv{font-size:.9rem;margin:6px 0}
.preview{width:100%;max-width:320px;border-radius:10px;background:#000;display:block;margin:4px 0}
.meter{height:14px;background:#30363d;border-radius:7px;overflow:hidden;margin:6px 0;max-width:320px}
.meter span{display:block;height:100%;width:0;background:#2ea043;transition:width .05s}
.demo-out .btn{margin-top:8px}

/* gotcha status badges */
.status{display:inline-block;font-size:11px;font-weight:700;line-height:1;padding:4px 8px;border-radius:999px;white-space:nowrap;border:1px solid transparent;vertical-align:middle}
.st-fixed{background:#0f2e1a;color:#4ade80;border-color:#1f7a44}
.st-mitigated{background:#2e2a0f;color:#facc15;border-color:#7a6a1f}
.st-accepted{background:#1a2230;color:#7aa2d6;border-color:#3b5a82}
.st-needs{background:#331616;color:#f87171;border-color:#7a2f2f}
.gt-fix{background:#0d1117;border:1px solid #30363d;border-radius:8px;padding:10px 12px;font-size:14px}
summary .status{margin-left:6px}