.topbar { position: sticky; top: 0; z-index: 50; display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: .6rem 1rem; background: var(--surface); border-bottom: 1px solid var(--line); }
.tb-left { display: flex; gap: .7rem; align-items: center; text-decoration: none; color: var(--text); }
.tb-title { font-weight: 700; }
.tb-right { display: flex; gap: .5rem; align-items: center; }
.brand-sm { font-family: var(--mono); background: var(--primary); color: #fff; border-radius: 8px; padding: .15rem .45rem; font-weight: 700; }
main { outline: none; }

/* Portada */
.home { max-width: 64rem; margin: 0 auto; padding: 2rem 1rem 4rem; }
.home h1 { font-size: 2rem; }
.home .lead { font-size: 1.1rem; color: var(--text-2); max-width: 44rem; }
.banks { display: grid; grid-template-columns: repeat(auto-fill, minmax(14.5rem, 1fr)); gap: 1rem; margin-top: 1.5rem; }
.bank-card { display: flex; flex-direction: column; gap: .5rem; min-height: 14rem; }
.bank-card .num { font-family: var(--mono); font-weight: 700; color: var(--primary); }
.bank-card h2 { margin: 0; font-size: 1.2rem; }
.bank-card p { color: var(--text-2); font-size: .95rem; flex: 1; }
.bank-card.off { opacity: .6; }
.bar { height: 8px; border-radius: 4px; background: var(--surface-2); overflow: hidden; }
.bar > i { display: block; height: 100%; background: var(--ok); border-radius: 4px; }

/* Banco */
.bank { display: grid; grid-template-columns: 19rem minmax(0, 1fr); min-height: calc(100vh - 54px); }
.side { border-right: 1px solid var(--line); background: var(--surface); padding: 1.1rem .8rem 2rem; }
.side h2 { font-size: 1.05rem; margin: 0 .4rem .3rem; }
.side .meta { font-size: .85rem; color: var(--muted); margin: 0 .4rem .6rem; }
.side .bar { margin: 0 .4rem 1rem; }
.side h3 { font-size: .78rem; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); margin: 1rem .4rem .35rem; }
.side ol { list-style: none; margin: 0; padding: 0; display: grid; gap: 2px; }
.side a { display: flex; gap: .5rem; align-items: center; padding: .4rem .5rem; border-radius: 8px; color: var(--text); text-decoration: none; font-size: .95rem; }
.side a:hover { background: var(--bg); }
.side a[aria-current="page"] { background: var(--primary-soft); color: var(--primary); font-weight: 700; }
.side .st { width: 1.2rem; text-align: center; flex: none; font-weight: 700; }
.side .st.ok { color: var(--ok); } .side .st.try { color: var(--warn); } .side .st.no { color: #A3AAC0; }
.side .lv { margin-left: auto; font-size: .7rem; color: var(--muted); letter-spacing: 1px; }
.side .reset { margin: 1.4rem .4rem 0; }

.ex { padding: 1.5rem clamp(1rem, 3vw, 2.5rem) 4rem; max-width: 64rem; }
.ex-head { display: flex; gap: .5rem; align-items: center; flex-wrap: wrap; }
.ex h1 { font-size: 1.7rem; margin: .5rem 0 .4rem; }
.ex .prompt { font-size: 1.08rem; color: var(--text); max-width: 48rem; }
.target { background: var(--surface); border: 1px dashed #B9C0D6; border-radius: 10px; padding: .7rem 1rem; font-family: var(--mono); white-space: pre-wrap; margin: .3rem 0 1rem; font-variant-ligatures: none; }
.target-label { font-size: .8rem; font-weight: 700; color: var(--muted); text-transform: uppercase; letter-spacing: .05em; }
.section { margin-top: 1rem; }
textarea.prediction { font-family: var(--mono); font-size: 16px; min-height: 6rem; font-variant-ligatures: none; }
.status-line { display: flex; gap: .6rem; align-items: center; flex-wrap: wrap; margin-top: .8rem; font-size: .92rem; color: var(--muted); }
.choices { display: grid; gap: .6rem; margin-top: .8rem; max-width: 40rem; }
.choice { justify-content: flex-start; text-align: left; font-weight: 400; padding: .8rem 1rem; border-width: 2px; }
.choice code { font-family: var(--mono); font-size: 1rem; font-variant-ligatures: none; }
.choice .k { font-family: var(--mono); font-weight: 700; background: var(--surface-2); border-radius: 6px; padding: 0 .45rem; }
.choice.right { border-color: var(--ok); background: var(--ok-soft); }
.choice.wrong { border-color: var(--err); background: var(--err-soft); }
.nav-ex { display: flex; justify-content: space-between; gap: .5rem; margin-top: 2rem; border-top: 1px solid var(--line); padding-top: 1rem; }
.solution summary { cursor: pointer; font-weight: 700; }
.hint-list { display: grid; gap: .4rem; margin-top: .6rem; }
.hint-list .hint { background: #FFFBEB; border: 1px solid #F3D9B1; border-radius: 8px; padding: .5rem .75rem; }
.hint-list .hint b { color: var(--warn); }
.editor-host { border: 1px solid var(--line); border-radius: 10px; overflow: hidden; min-height: 160px; background: #fff; }
.editor-host textarea.fallback { font-family: var(--mono); font-size: var(--code-size); line-height: 1.6; border: 0; border-radius: 0; min-height: 220px; tab-size: 4; white-space: pre; }
.toolbar { display: flex; gap: .5rem; flex-wrap: wrap; margin-top: .75rem; align-items: center; }
.toolbar .sp { flex: 1; }
.trace-grid { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr) minmax(0, .8fr); gap: .8rem; margin-top: .8rem; align-items: start; }
.trace-grid .card { padding: .8rem; margin-top: 0; }
.trace-grid h3 { font-size: .85rem; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); }
.solved-badge { display: inline-flex; gap: .3rem; align-items: center; }

@media (max-width: 900px) {
  .bank { grid-template-columns: 1fr; }
  .side { border-right: 0; border-bottom: 1px solid var(--line); }
  .side.collapsed ol, .side.collapsed h3, .side.collapsed .reset { display: none; }
  .trace-grid { grid-template-columns: 1fr; }
}
@media (min-width: 901px) { .toggle-side { display: none; } }

.banks > .card { margin-top: 0; }
.tb-right .btn { white-space: nowrap; }
@media (max-width: 520px) { .tb-title { display: none; } }