:root{
  --brand:#123f8c;--brand-2:#0f5ed7;--brand-soft:#eef4ff;--ink:#172033;--muted:#667085;
  --bg:#f5f7fb;--surface:#fff;--surface-2:#f8fafc;--border:#dfe5ee;--success:#117a4f;--success-bg:#eaf8f1;
  --danger:#b42318;--danger-bg:#fff0ee;--warning:#9a6700;--shadow:0 8px 28px rgba(16,24,40,.07);
  --radius:16px;--sidebar:232px;
}
body.dark{
  --brand:#7ea7ff;--brand-2:#7ea7ff;--brand-soft:#172b50;--ink:#f4f7fb;--muted:#b4bfd0;
  --bg:#0d1525;--surface:#121d31;--surface-2:#17233a;--border:#2b3b58;--success:#8ce5bd;--success-bg:#153628;
  --danger:#ffaaa3;--danger-bg:#3a1e23;--shadow:none;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;background:var(--bg);color:var(--ink);font-size:15px;line-height:1.5}
a{color:var(--brand-2)}
button,input,select,textarea{font:inherit}
button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid #ffbf47;outline-offset:2px}
button,.btn{min-height:44px;border:0;border-radius:11px;padding:10px 15px;font-weight:700;cursor:pointer;text-decoration:none;display:inline-flex;align-items:center;justify-content:center;gap:8px;transition:transform .15s ease,box-shadow .15s ease}
button:hover,.btn:hover{transform:translateY(-1px)}
button:disabled{opacity:.5;cursor:not-allowed;transform:none}
.primary{background:var(--brand-2);color:#fff}.secondary{background:var(--surface);color:var(--ink);border:1px solid var(--border)}.danger-btn{background:var(--danger-bg);color:var(--danger)}
.hidden{display:none!important}.muted,.small,small{color:var(--muted)}

/* Student login */
.student-gate{min-height:100vh;display:grid;place-items:center;padding:24px;background:linear-gradient(145deg,#eaf1ff 0,var(--bg) 52%)}
body.dark .student-gate{background:var(--bg)}
.login-card{width:min(480px,100%);background:var(--surface);border:1px solid var(--border);border-radius:24px;padding:32px;box-shadow:0 24px 70px rgba(15,44,94,.13)}
.login-mark{width:56px;height:56px;border-radius:16px;background:var(--brand);color:#fff;display:grid;place-items:center;font-weight:900;font-size:1.2rem;margin-bottom:18px}
.login-card h1{margin:0;font-size:2rem}.login-card>p{color:var(--muted);margin:8px 0 22px}.login-card label{font-weight:700;display:block;margin-bottom:7px}.login-card input{margin-bottom:12px}.login-card button{width:100%}.privacy-note{font-size:.82rem;color:var(--muted);margin-top:14px;text-align:center}

/* App shell */
.app-header{height:72px;background:var(--surface);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:30}
.header-inner{height:100%;max-width:1440px;margin:auto;padding:0 24px;display:flex;align-items:center;justify-content:space-between;gap:18px}
.brand-lockup{display:flex;align-items:center;gap:12px}.brand-symbol{width:40px;height:40px;border-radius:12px;background:var(--brand);color:#fff;display:grid;place-items:center;font-weight:900}.brand-text{display:grid}.brand-text strong{font-size:1.05rem}.brand-text span{font-size:.78rem;color:var(--muted)}
.header-actions{display:flex;align-items:center;gap:10px}.student-menu{display:flex;align-items:center;gap:10px;border-left:1px solid var(--border);padding-left:12px}.student-avatar{width:36px;height:36px;border-radius:50%;background:var(--brand-soft);color:var(--brand-2);display:grid;place-items:center;font-weight:800}.student-name{display:grid;line-height:1.2}.student-name span{font-size:.72rem;color:var(--muted)}.student-name strong{font-size:.86rem;max-width:220px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.header-button{min-height:40px;padding:8px 11px;background:var(--surface-2);color:var(--ink);border:1px solid var(--border)}
.app-layout{display:grid;grid-template-columns:var(--sidebar) minmax(0,1fr);max-width:1440px;margin:0 auto;min-height:calc(100vh - 72px)}
.sidebar{padding:20px 14px;border-right:1px solid var(--border);background:var(--surface);position:sticky;top:72px;height:calc(100vh - 72px)}
.nav-label{padding:0 10px 8px;color:var(--muted);font-size:.72rem;font-weight:800;text-transform:uppercase;letter-spacing:.08em}
.side-nav{display:grid;gap:5px}.nav-item{min-height:44px;border-radius:11px;background:transparent;color:var(--ink);justify-content:flex-start;padding:10px 12px;font-weight:650}.nav-item .nav-icon{width:23px;text-align:center}.nav-item.active{background:var(--brand-soft);color:var(--brand-2)}
.sidebar-footer{position:absolute;left:14px;right:14px;bottom:16px;border-top:1px solid var(--border);padding-top:12px}.sidebar-footer a{font-size:.82rem;color:var(--muted);text-decoration:none}
.main-content{padding:26px 30px 48px;min-width:0}.content-wrap{max-width:1120px;margin:0 auto}.page-heading{display:flex;justify-content:space-between;align-items:flex-end;gap:16px;margin-bottom:18px}.page-heading h1{font-size:1.75rem;margin:0}.page-heading p{margin:5px 0 0;color:var(--muted)}
.system-status{display:flex;align-items:center;gap:9px;padding:10px 13px;border-radius:11px;margin-bottom:16px;font-size:.88rem;transition:.2s}.system-status.ok{background:var(--success-bg);color:var(--success)}.system-status.error{background:var(--danger-bg);color:var(--danger)}.system-status.loading{background:var(--brand-soft);color:var(--brand-2)}.system-status.status-collapsed{padding:0;margin:0;height:0;opacity:0;overflow:hidden}.loader{width:14px;height:14px;border:2px solid currentColor;border-right-color:transparent;border-radius:50%;animation:spin .7s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}

/* Generic */
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:22px}.section-head{display:flex;align-items:flex-end;justify-content:space-between;gap:16px;margin-bottom:16px}.section-head h2,.section-head h3{margin:0}.section-head p{margin:4px 0 0;color:var(--muted)}
.pill{display:inline-flex;align-items:center;border-radius:999px;padding:5px 9px;background:var(--brand-soft);color:var(--brand-2);font-size:.76rem;font-weight:750}
input[type=text],input[type=password],input[type=file],select,textarea{width:100%;min-height:44px;padding:10px 12px;border:1px solid var(--border);border-radius:10px;background:var(--surface);color:var(--ink)}
label{display:block;font-weight:700;margin-bottom:7px}.grid-2{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}.empty-state,.error-panel,.success-panel{border:1px dashed var(--border);border-radius:12px;padding:18px;text-align:center;color:var(--muted);margin-top:14px}.error-panel{background:var(--danger-bg);color:var(--danger);border-style:solid}.success-panel{background:var(--success-bg);color:var(--success);border-style:solid}

/* Dashboard */
.hero{background:linear-gradient(120deg,var(--brand),#0f5ed7);color:#fff;border-radius:20px;padding:26px;display:flex;align-items:center;justify-content:space-between;gap:24px;margin-bottom:16px;box-shadow:var(--shadow)}.hero h2{font-size:1.7rem;margin:4px 0 7px}.hero p{margin:0;opacity:.9;max-width:660px}.hero .eyebrow{font-size:.75rem;text-transform:uppercase;letter-spacing:.08em;font-weight:800;opacity:.75}.hero .primary{background:#fff;color:#123f8c;white-space:nowrap}
.metrics{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;margin-bottom:16px}.metric{background:var(--surface);border:1px solid var(--border);border-radius:14px;padding:17px}.metric span{display:block;color:var(--muted);font-size:.8rem}.metric strong{display:block;font-size:1.65rem;margin-top:3px}.metric small{font-size:.76rem}
.action-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.action-card{background:var(--surface);border:1px solid var(--border);border-radius:14px;padding:17px;text-align:left;color:var(--ink);display:grid;gap:6px;min-height:132px;align-content:start}.action-icon{width:38px;height:38px;border-radius:10px;background:var(--brand-soft);display:grid;place-items:center;font-size:1.15rem}.action-card strong{font-size:1rem}.action-card small{font-weight:400}

/* Modules */
.search-row{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:10px;align-items:center}.module-result-count{color:var(--muted);font-size:.85rem;text-align:right;min-height:20px}.modules-list{display:grid;gap:12px;margin-top:14px}.module-panel{background:var(--surface);border:1px solid var(--border);border-radius:14px;overflow:hidden}.module-panel summary{list-style:none;display:flex;align-items:center;gap:12px;padding:16px 18px;cursor:pointer;font-weight:750}.module-panel summary::-webkit-details-marker{display:none}.module-icon{width:40px;height:40px;border-radius:10px;background:var(--brand-soft);display:grid;place-items:center}.module-title{display:grid;flex:1}.module-title small{font-weight:500}.module-files{border-top:1px solid var(--border);padding:10px 14px 14px;display:grid;gap:7px}.file-row{display:grid;grid-template-columns:auto minmax(0,1fr) auto;gap:11px;align-items:center;padding:10px;border-radius:10px}.file-row:hover{background:var(--surface-2)}.file-type{min-width:42px;text-align:center;padding:6px 7px;border-radius:8px;background:var(--brand-soft);color:var(--brand-2);font-size:.7rem;font-weight:800}.file-info{min-width:0;display:grid}.file-info strong{font-size:.88rem;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.file-info small{font-size:.76rem}.file-row .btn{min-height:38px;padding:7px 11px;font-size:.82rem}

/* Concepts */
.search-box{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:10px}.result-count{color:var(--muted);font-size:.82rem;margin:14px 0 7px}.concept-results{display:grid;gap:9px}.concept-card{border:1px solid var(--border);border-radius:12px;padding:15px;margin-top:9px;background:var(--surface)}.concept-top{display:flex;align-items:center;justify-content:space-between;gap:10px}.concept-card p{margin:7px 0 0;color:var(--ink)}

/* Quiz */
.quiz-shell{max-width:900px}.quiz-setup-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin:18px 0}.info-note{border-left:4px solid var(--brand-2);background:var(--brand-soft);padding:12px 14px;border-radius:10px;margin:14px 0 18px}.quiz-top{display:flex;justify-content:space-between;align-items:center;gap:12px}.quiz-meta{display:flex;align-items:center;gap:8px}.progress-wrap{height:10px;background:var(--surface-2);border:1px solid var(--border);border-radius:999px;overflow:hidden;margin:14px 0 20px}.progress{height:100%;background:var(--brand-2);width:0;transition:width .2s}.question{font-size:1.16rem;font-weight:750;line-height:1.55;margin:13px 0 18px}.options{display:grid;gap:9px}.option{min-height:54px;justify-content:flex-start;text-align:left;background:var(--surface);color:var(--ink);border:1px solid var(--border);padding:10px 12px}.option-letter{width:32px;height:32px;border-radius:9px;background:var(--surface-2);display:grid;place-items:center;flex:0 0 auto}.option:hover{border-color:var(--brand-2);box-shadow:0 0 0 2px var(--brand-soft)}.option.correct{border-color:var(--success);background:var(--success-bg);color:var(--success)}.option.wrong{border-color:var(--danger);background:var(--danger-bg);color:var(--danger)}.answer-feedback{border-radius:12px;padding:14px;margin-top:15px}.correct-feedback{background:var(--success-bg);color:var(--success)}.wrong-feedback{background:var(--danger-bg);color:var(--danger)}.feedback-title{font-weight:800}.answer-feedback p{margin:5px 0 0}.next-area{display:flex;justify-content:flex-end;margin-top:14px}.result-score{display:flex;align-items:baseline;gap:6px;margin:8px 0}.result-score strong{font-size:3.3rem;color:var(--brand-2)}.result-score span{color:var(--muted)}.rank{font-size:1.25rem;font-weight:800}.stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:9px;margin:18px 0}.stat{border:1px solid var(--border);border-radius:12px;padding:13px}.stat strong{font-size:1.4rem;display:block}.stat span{font-size:.76rem;color:var(--muted)}.review-header{margin-top:22px}.review-header h3{margin-bottom:3px}.review-header p{margin-top:0;color:var(--muted)}.review-item{border:1px solid var(--border);border-radius:12px;padding:15px;margin-top:8px}.review-item h4{margin:9px 0}.review-item p{margin:5px 0}

/* Progress */
.progress-summary{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:10px}.progress-score-card{border:1px solid var(--border);border-radius:13px;padding:15px}.progress-score-card span{display:block;color:var(--muted);font-size:.78rem}.progress-score-card strong{font-size:1.65rem;display:block}.progress-score-card small{font-size:.74rem}.progress-meta{display:flex;gap:16px;flex-wrap:wrap;background:var(--surface-2);border-radius:11px;padding:12px 14px;margin:14px 0}.progress-pending{color:var(--warning)}.topic-section{margin-top:20px}.topic-row{display:grid;grid-template-columns:minmax(220px,1.4fr) 2fr 52px;gap:12px;align-items:center;border-top:1px solid var(--border);padding:11px 0}.topic-label{display:grid}.topic-label span{font-size:.76rem;color:var(--muted)}.topic-track{height:8px;background:var(--surface-2);border-radius:999px;overflow:hidden}.topic-track span{display:block;height:100%;background:var(--brand-2);border-radius:999px}.skeleton-block{height:210px;border-radius:14px;background:linear-gradient(90deg,var(--surface-2),var(--surface),var(--surface-2));background-size:200% 100%;animation:skeleton 1.4s infinite}@keyframes skeleton{to{background-position:-200% 0}}

/* Admin additions */
.admin-layout{max-width:1320px;margin:auto;padding:26px}.admin-header{background:var(--surface);border-bottom:1px solid var(--border);padding:16px 24px}.admin-header-inner{max-width:1320px;margin:auto;display:flex;align-items:center;justify-content:space-between}.admin-tabs{display:flex;gap:6px;background:var(--surface);border:1px solid var(--border);border-radius:13px;padding:5px;margin-bottom:14px;overflow:auto}.admin-tab{background:transparent;color:var(--muted);white-space:nowrap}.admin-tab.active{background:var(--brand-soft);color:var(--brand-2)}

@media(max-width:980px){
  :root{--sidebar:78px}.sidebar .nav-text,.nav-label,.sidebar-footer{display:none}.nav-item{justify-content:center}.metrics,.progress-summary{grid-template-columns:repeat(2,1fr)}.action-grid{grid-template-columns:repeat(2,1fr)}
}
@media(max-width:720px){
  .app-header{height:auto;position:static}.header-inner{padding:12px 14px;align-items:flex-start}.brand-text span,.student-name span{display:none}.student-name strong{max-width:120px}.header-button span{display:none}.app-layout{display:block}.sidebar{position:fixed;left:0;right:0;bottom:0;top:auto;height:68px;padding:6px 8px;border-right:0;border-top:1px solid var(--border);z-index:40}.side-nav{grid-template-columns:repeat(5,1fr);height:100%}.nav-item{min-height:54px;padding:5px;display:grid;justify-items:center;gap:0;font-size:.68rem}.sidebar .nav-text{display:block}.nav-item .nav-icon{font-size:1.05rem}.main-content{padding:18px 14px 88px}.page-heading{display:none}.hero{align-items:flex-start;flex-direction:column;padding:20px}.hero h2{font-size:1.4rem}.hero .primary{width:100%}.metrics,.action-grid,.progress-summary,.stats,.quiz-setup-grid,.grid-2{grid-template-columns:1fr}.search-row,.search-box{grid-template-columns:1fr}.modules-list{gap:9px}.file-row{grid-template-columns:auto minmax(0,1fr)}.file-row .btn{grid-column:1/-1;width:100%}.concept-top{align-items:flex-start;flex-direction:column}.topic-row{grid-template-columns:1fr}.header-actions{gap:6px}.student-menu{padding-left:6px}.student-avatar{display:none}.app-header .brand-symbol{width:36px;height:36px}.app-header .brand-text strong{font-size:.95rem}.login-card{padding:24px}.admin-layout{padding:16px}
}


/* V3.2 - Contexto de estudio para preguntas procedimentales */
.study-context{
  margin:4px 0 18px;
  border:1px solid var(--border);
  border-radius:14px;
  background:var(--blue3);
  overflow:hidden;
}
.study-context summary{
  list-style:none;
  display:flex;
  align-items:center;
  gap:10px;
  padding:12px 14px;
  cursor:pointer;
  font-weight:800;
  color:var(--text);
}
.study-context summary::-webkit-details-marker{display:none}
.context-icon{
  width:24px;height:24px;border-radius:50%;
  display:inline-flex;align-items:center;justify-content:center;
  background:var(--blue2);color:white;font-size:.8rem;
  flex:0 0 auto;
}
.context-action{
  margin-left:auto;
  color:var(--blue2);
  font-size:.82rem;
}
.study-context[open] .context-action::after{content:""; }
.study-context-body{
  padding:0 14px 14px 48px;
  color:var(--text);
  line-height:1.6;
}
.exam-context-note{
  margin:4px 0 16px;
  padding:10px 12px;
  border-radius:10px;
  background:var(--blue3);
  color:var(--muted);
  font-size:.86rem;
}
@media(max-width:700px){
  .study-context-body{padding:0 13px 13px}
  .context-action{font-size:.76rem}
}


/* V3.3 - Navegación Atrás y comportamiento móvil */
.quiz-nav-row{
  display:flex;
  align-items:center;
  justify-content:flex-start;
  margin-bottom:12px;
}
.back-btn{
  min-height:38px;
  padding:8px 13px;
}
.result-actions{
  display:flex;
  gap:10px;
  margin-top:18px;
  flex-wrap:wrap;
}
@media(max-width:700px){
  .quiz-nav-row{
    margin-bottom:10px;
  }
  .back-btn{
    width:auto !important;
    min-width:92px;
    min-height:42px;
    font-size:.95rem;
  }
  .result-actions{
    display:grid;
    grid-template-columns:1fr 1fr;
  }
  .result-actions button{
    width:100%;
  }
}