:root{
  --bg:#f4f6f9; --panel:#ffffff; --ink:#1f2733; --muted:#6b7787;
  --line:#e3e8ef; --brand:#296bb1; --brand-soft:#e8f1fb;
  --ok:#1f9d63; --bad:#d4453b; --warn:#e08a1e; --hl:#ffe27a;
  --shadow:0 1px 3px rgba(20,30,50,.08),0 4px 16px rgba(20,30,50,.05);
  --r:14px;
}
@media (prefers-color-scheme:dark){
  :root{ --bg:#12161c; --panel:#1a2029; --ink:#e7edf5; --muted:#93a0b0;
    --line:#28303b; --brand:#57a5f5; --brand-soft:#1c2c40; --hl:#c8a63a; }
}
*{box-sizing:border-box}
html,body{margin:0;height:100%}
body{font:15px/1.5 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;
  background:var(--bg);color:var(--ink);overflow:hidden}
button{font:inherit;cursor:pointer;border:none;border-radius:10px;padding:8px 12px;
  background:var(--brand-soft);color:var(--brand);font-weight:600;transition:.12s}
button:hover{filter:brightness(.97)}
button.primary{background:var(--brand);color:#fff}
button:active{transform:translateY(1px)}

/* top bar */
#topbar{height:60px;display:flex;align-items:center;gap:16px;padding:0 18px;
  background:var(--panel);border-bottom:1px solid var(--line);box-shadow:var(--shadow);z-index:10}
#sidebar-toggle{background:var(--bg);border:1px solid var(--line);font-size:18px;line-height:1;
  padding:7px 12px;border-radius:10px;color:var(--ink)}
#sidebar-toggle:hover{background:var(--brand-soft);color:var(--brand)}
.brand{font-weight:800;font-size:16px;letter-spacing:.2px}
.brand small{color:var(--muted);font-weight:600}
#pomodoro{display:flex;align-items:center;gap:8px;margin-left:8px;
  background:var(--bg);padding:6px 10px;border-radius:12px;border:1px solid var(--line)}
#pomo-mode{font-weight:700;font-size:12px;padding:3px 8px;border-radius:20px;background:var(--brand-soft);color:var(--brand)}
#pomo-mode.break{background:#e9f7ef;color:var(--ok)}
#pomo-time{font-variant-numeric:tabular-nums;font-weight:800;font-size:20px;min-width:62px;text-align:center}
#pomo-count{font-size:13px;color:var(--muted);font-weight:700}
#pomo-cfg{background:transparent;padding:4px 6px;font-size:15px}
#fullscreen-btn{background:var(--bg);border:1px solid var(--line);font-size:16px;line-height:1;
  padding:7px 11px;border-radius:10px;color:var(--ink)}
#fullscreen-btn:hover{background:var(--brand-soft);color:var(--brand)}
#pomo-panel{position:fixed;top:66px;left:50%;transform:translateX(-50%);z-index:70;
  background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:16px 18px;
  box-shadow:0 8px 30px rgba(0,0,0,.3);width:min(340px,92vw)}
#pomo-panel h4{margin:0 0 12px;font-size:15px}
#pomo-panel label{display:flex;justify-content:space-between;align-items:center;gap:10px;
  font-size:13.5px;margin-bottom:10px;font-weight:600}
#pomo-panel input{width:72px;padding:7px 8px;border-radius:8px;border:1px solid var(--line);
  background:var(--bg);color:var(--ink);font:inherit;text-align:center;font-weight:700}
.pomo-panel-actions{display:flex;justify-content:flex-end;gap:8px;margin-top:6px}
#exam-countdown{margin-left:auto;text-align:right;font-size:13px;color:var(--muted)}
#exam-countdown b{color:var(--warn);font-size:18px;display:block}

/* layout */
#layout{display:flex;height:calc(100% - 60px)}
#sidebar{width:270px;flex:0 0 270px;background:var(--panel);border-right:1px solid var(--line);
  overflow-y:auto;padding:12px}
.side-title{font-size:11px;text-transform:uppercase;letter-spacing:.8px;color:var(--muted);
  font-weight:700;margin:6px 8px 6px}
.side-title b{color:var(--brand)}
#progreso-global{margin:0 8px 12px}
#progreso-global .pg-bar{height:7px;border-radius:5px;background:var(--line);overflow:hidden}
#progreso-global .pg-bar>i{display:block;height:100%;background:var(--ok);transition:width .3s}
#progreso-global .pg-txt{font-size:11px;color:var(--muted);margin-top:5px}
#progreso-global .pg-txt b{color:var(--ink)}
.tema-item{display:flex;align-items:center;gap:10px;padding:9px 10px;border-radius:12px;margin-bottom:3px}
.tema-item:hover{background:var(--bg)}
.tema-item.active{background:var(--brand-soft)}
.tema-item .emo{font-size:18px;width:22px;text-align:center}
.tema-item .tt{flex:1;min-width:0}
.tema-item .tt b{display:block;font-size:13.5px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.tema-item .bar{height:4px;border-radius:3px;background:var(--line);margin-top:4px;overflow:hidden}
.tema-item .bar>i{display:block;height:100%;background:var(--brand)}
.tema-item .chk{font-size:15px}

/* main */
#main{flex:1;min-width:0;display:flex;flex-direction:column;overflow:hidden}
#tema-header{padding:16px 22px 10px}
#tema-header h1{margin:0 0 4px;font-size:22px;display:flex;align-items:center;gap:10px}
.peso-pill{font-size:12px;font-weight:700;color:#fff;background:var(--brand);padding:3px 10px;border-radius:20px}
.subtemas{display:flex;flex-wrap:wrap;gap:6px;margin-top:8px}
.subchip{display:inline-flex;align-items:center;gap:6px;font-size:12px;background:var(--panel);
  border:1px solid var(--line);padding:5px 10px;border-radius:20px;cursor:pointer}
.subchip.done{background:#e9f7ef;color:var(--ok);border-color:#bfe6cf;text-decoration:line-through}
#tabs{display:flex;gap:6px;padding:6px 22px;border-bottom:1px solid var(--line)}
#tabs button{background:transparent;color:var(--muted);border-radius:10px 10px 0 0}
#tabs button.active{background:var(--panel);color:var(--brand);box-shadow:inset 0 -2px 0 var(--brand)}
#tab-content{flex:1;overflow-y:auto;padding:18px 22px}

/* resumen */
.res-card{background:var(--panel);border:1px solid var(--line);border-radius:var(--r);
  padding:14px 16px;margin-bottom:12px;box-shadow:var(--shadow)}
.res-card h3{margin:0 0 8px;font-size:15px}
.res-card ul{margin:0;padding-left:18px}
.res-card li{margin:5px 0}

/* flashcards */
.flash-wrap{max-width:620px;margin:0 auto;text-align:center}
.fc-tools{display:flex;gap:8px;justify-content:center;flex-wrap:wrap;margin-bottom:12px}
.fc-tools button{font-size:12.5px;padding:6px 12px;background:var(--bg);border:1px solid var(--line);color:var(--muted)}
.fc-tools button:hover{border-color:var(--brand);color:var(--brand)}
#fc-reset-all:hover{border-color:var(--bad);color:var(--bad)}
.flash-progress{color:var(--muted);font-size:13px;margin-bottom:10px}
.flashcard{background:var(--panel);border:1px solid var(--line);border-radius:18px;
  padding:34px 26px;min-height:220px;display:flex;flex-direction:column;justify-content:center;
  box-shadow:var(--shadow);font-size:18px;cursor:pointer;user-select:none}
.flashcard .lbl{font-size:11px;text-transform:uppercase;letter-spacing:1px;color:var(--muted);margin-bottom:10px}
.flashcard .ans{color:var(--brand);font-size:16px;text-align:left}
.flash-actions{display:flex;gap:10px;justify-content:center;margin-top:16px}
.flash-actions .bad{background:#fdeceb;color:var(--bad)}
.flash-actions .ok{background:#e9f7ef;color:var(--ok)}
.flash-srs{display:flex;gap:10px;justify-content:center;margin-top:18px;flex-wrap:wrap}
.srs{display:flex;flex-direction:column;align-items:center;gap:3px;min-width:132px;padding:11px 14px;font-weight:700;border-radius:12px}
.srs small{font-weight:600;opacity:.8;font-size:11px}
.srs.bad{background:#fdeceb;color:var(--bad)}
.srs.mid{background:#fff4e3;color:var(--warn)}
.srs.ok{background:#e9f7ef;color:var(--ok)}
.due-badge{background:var(--brand);color:#fff;font-size:12px;font-weight:800;padding:2px 8px;border-radius:20px}
.review-item{border:1px dashed var(--line)}
@media (prefers-color-scheme:dark){
  .srs.bad{background:#3a1f1e}.srs.mid{background:#3a2f1c}.srs.ok{background:#183028}
}

/* quiz */
.quiz-wrap{max-width:680px;margin:0 auto}
.quiz-q{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:20px;box-shadow:var(--shadow)}
.quiz-q h3{margin:0 0 14px;font-size:17px}
.opt{display:block;width:100%;text-align:left;background:var(--bg);border:1.5px solid var(--line);
  color:var(--ink);font-weight:500;padding:12px 14px;border-radius:12px;margin-bottom:9px}
.opt:hover{border-color:var(--brand)}
.opt.correct{background:#e9f7ef;border-color:var(--ok);color:var(--ok);font-weight:700}
.opt.wrong{background:#fdeceb;border-color:var(--bad);color:var(--bad)}
.quiz-expl{margin-top:12px;padding:12px 14px;background:var(--brand-soft);border-radius:12px;font-size:14px}
.quiz-foot{display:flex;justify-content:space-between;align-items:center;margin-top:14px}
.empty{color:var(--muted);text-align:center;padding:40px;font-size:15px}

/* pdf — scroll continuo */
#tab-content{background:var(--bg)}
#pdf-toolbar{position:sticky;top:-18px;z-index:6;display:flex;align-items:center;gap:8px;flex-wrap:wrap;
  background:var(--bg);margin:-18px 0 6px;padding:18px 0 10px}
#pdf-toolbar select{padding:8px;border-radius:10px;border:1px solid var(--line);background:var(--panel);color:var(--ink);max-width:52vw}
#pdf-pages{display:flex;flex-direction:column;align-items:center;gap:14px;padding-bottom:40px}
.pdf-page{position:relative;background:#fff;box-shadow:var(--shadow);border-radius:4px;max-width:100%}
.pdf-page canvas{display:block;max-width:100%}
.pdf-page .tl{position:absolute;inset:0;overflow:hidden;line-height:1}
.pdf-page .tl span{position:absolute;white-space:pre;transform-origin:0 0;color:transparent;cursor:text}
.pdf-page .tl span::selection{background:rgba(255,205,50,.55)}
.pdf-page .tl span::-moz-selection{background:rgba(255,205,50,.55)}
.pdf-page .hll{position:absolute;inset:0;pointer-events:none}
.hl-rect{position:absolute;background:var(--hl);opacity:.45;border-radius:2px;mix-blend-mode:multiply}
#hl-toggle.on{background:var(--hl);color:#5a4300}
/* modo enfoque: al esconder el menú, ocultar también el título del tema */
#sidebar.hidden ~ #main #tema-header{display:none}
.pdf-hint{font-size:12px;color:var(--muted)}
.pdf-center{text-align:center}

/* guided mode */
.hidden{display:none !important}
#btn-guided{margin-left:auto}
#guided-bar{flex:0 0 auto;background:var(--panel);border-top:2px solid var(--brand);
  padding:10px 22px;box-shadow:0 -2px 10px rgba(20,30,50,.06)}
.gb-top{display:flex;align-items:center;gap:12px}
.gb-steps{display:flex;gap:6px;flex:1;flex-wrap:wrap}
.gb-step{display:flex;align-items:center;gap:6px;font-size:12.5px;font-weight:700;
  padding:5px 11px;border-radius:20px;background:var(--bg);color:var(--muted);border:1.5px solid var(--line);cursor:pointer}
.gb-step.done{color:var(--ok);border-color:#bfe6cf}
.gb-step.cur{background:var(--brand);color:#fff;border-color:var(--brand)}
.gb-hint{font-size:12.5px;color:var(--muted);margin-top:7px}
.gb-hint b{color:var(--ink)}
#toast{position:fixed;left:50%;bottom:26px;transform:translateX(-50%);
  background:var(--brand);color:#fff;padding:12px 20px;border-radius:14px;font-weight:600;
  box-shadow:var(--shadow);z-index:50;max-width:80vw;text-align:center}
.done-screen{max-width:560px;margin:30px auto;text-align:center}
.done-screen .big{font-size:44px}
.done-screen h2{margin:6px 0}

/* calendario */
.cal-wrap{max-width:840px;margin:0 auto}
.cal-today{display:flex;gap:14px;flex-wrap:wrap;justify-content:space-between;align-items:center;
  background:var(--brand-soft);border:1px solid var(--line);border-radius:16px;padding:16px 18px;margin-bottom:14px}
.cal-today-l{min-width:200px;flex:1}
.cal-big{font-size:19px;font-weight:800;margin:2px 0 4px}
.cal-lbl{font-size:11px;text-transform:uppercase;letter-spacing:.6px;color:var(--muted);font-weight:700}
.cal-today-r{display:flex;gap:16px}
.cal-metric{text-align:center;background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:10px 14px;min-width:96px}
.cal-num{font-size:22px;font-weight:800;display:block}
.cal-ok{color:var(--ok)}
.cal-temas{display:grid;grid-template-columns:1fr 1fr;gap:6px;margin:4px 0 8px}
.cal-tema{display:flex;align-items:center;gap:8px;padding:8px 10px;border-radius:10px;background:var(--bg);
  border:1px solid var(--line);cursor:pointer;font-size:13.5px;font-weight:600;user-select:none}
.cal-tema:hover{border-color:var(--brand)}
.cal-tema.done{background:#e9f7ef;color:var(--ok);border-color:#bfe6cf}
.cal-check{font-size:16px}
.cal-wk{font-size:14px}
.cal-tbl{width:100%;border-collapse:collapse;font-size:13px}
.cal-tbl td{padding:8px 8px;border-top:1px solid var(--line);vertical-align:top}
.cal-d{white-space:nowrap;color:var(--muted);font-size:12px;width:52px}
.cal-det{font-size:12px;color:var(--muted);margin-top:2px}
.cal-h{white-space:nowrap;font-weight:700;color:var(--brand);text-align:right;width:44px}
.cal-row-today{background:var(--brand-soft)}
.cal-row-today td{border-top:2px solid var(--brand)}
@media (prefers-color-scheme:dark){ .cal-tema.done{background:#183028;border-color:#2a5a48} }
@media (max-width:640px){ .cal-temas{grid-template-columns:1fr} }

/* banco de quizzes / examen / progreso */
.qb-wrap,.ex-wrap,.prog-wrap{max-width:760px;margin:0 auto}
.qb-head{margin-bottom:12px}
.qb-chips{display:flex;gap:6px;flex-wrap:wrap;margin-bottom:6px}
.qb-chip{font-size:12px;padding:5px 10px;background:var(--bg);border:1px solid var(--line);color:var(--muted);border-radius:20px}
.qb-chip.on{background:var(--brand);color:#fff;border-color:var(--brand)}
.qb-chip b{opacity:.8}
.dif-facil{color:var(--ok);font-weight:700}
.dif-media{color:var(--warn);font-weight:700}
.dif-dificil{color:var(--bad);font-weight:700}
.q-rate{display:flex;gap:8px;justify-content:center;flex-wrap:wrap;margin-top:14px;align-items:center}
.q-rate .pdf-hint{width:100%;text-align:center;margin-bottom:2px}
.expl-src{margin-top:10px;font-size:12px;color:var(--muted);border-top:1px dashed var(--line);padding-top:8px}
.pdf-link{color:var(--brand);font-weight:700;cursor:pointer;text-decoration:underline}
.opt.sel{border-color:var(--brand);background:var(--brand-soft);font-weight:700}
/* examen */
.ex-row{display:flex;justify-content:space-between;align-items:center;gap:10px;margin:12px 0;flex-wrap:wrap}
.ex-opt{background:var(--bg);border:1px solid var(--line);color:var(--ink);padding:8px 14px;border-radius:10px;font-weight:700}
.ex-opt.on{background:var(--brand);color:#fff;border-color:var(--brand)}
#ex-min{width:80px;padding:8px;border-radius:10px;border:1px solid var(--line);background:var(--bg);color:var(--ink);text-align:center;font-weight:700}
.ex-bar{position:sticky;top:0;background:var(--bg);display:flex;align-items:center;gap:12px;padding:10px 0;border-bottom:1px solid var(--line);margin-bottom:12px;z-index:5}
.ex-timer-w b{font-size:20px;font-variant-numeric:tabular-nums;color:var(--warn)}
.ex-fin{margin-left:auto;background:#fdeceb;color:var(--bad);font-weight:700}
.ex-nav{display:flex;justify-content:space-between;gap:10px;margin-top:14px}
.ex-nav button{flex:1}
.dif-pill{font-size:12px;font-weight:700;padding:3px 10px;border-radius:20px;background:var(--bg);border:1px solid var(--line)}
/* progreso */
.prog-top{display:flex;gap:14px;flex-wrap:wrap;align-items:center;justify-content:space-between;margin-bottom:14px}
.prob-box{text-align:center;background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:14px 22px;box-shadow:var(--shadow)}
.prob-num{font-size:42px;font-weight:900;line-height:1}
.prog-metrics{display:flex;gap:12px}
.prog-chart{width:100%;height:110px;background:var(--bg);border-radius:10px;padding:8px}