/* ===========================================================================
   Momentum — visual identity & layout
   Dark-first, high-impact but low-fatigue. Mobile-first, scales up to desktop.
   Structure it styles (all built by the JS views, no innerHTML):
     #app > header.app-header + nav.app-nav + main#view
     views: .hub / .topic / .practice / .insights / .settings / .onboarding
   =========================================================================== */

/* ---- Design tokens -------------------------------------------------------- */
:root{
  --color-base:#0F172A; --color-surface:#1E293B; --color-primary:#6366F1;
  --color-success:#10B981; --color-streak:#F59E0B; --color-error:#F43F5E;
  --color-text:#F8FAFC; --color-muted:#94A3B8;
  /* module accents */
  --accent-tenses:#6366F1; --accent-conditionals:#8B5CF6; --accent-structure:#2DD4BF;
  --accent-verbforms:#38BDF8; --accent-mechanics:#10B981; --accent-functional:#F59E0B;
  --radius:14px; --radius-sm:10px; --tap:44px;
  --font:Inter,system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
  --shadow:0 6px 24px rgba(0,0,0,.35);
  --shadow-sm:0 2px 8px rgba(0,0,0,.25);
  --border:rgba(148,163,184,.16);
  --surface-2:rgba(148,163,184,.08);
  --maxw:900px;
  --sp-1:.35rem; --sp-2:.6rem; --sp-3:1rem; --sp-4:1.5rem; --sp-5:2.25rem;
  --primary-glow:rgba(99,102,241,.35);
}
[data-theme="light"]{
  --color-base:#F1F5F9; --color-surface:#FFFFFF; --color-text:#0F172A; --color-muted:#475569;
  --shadow:0 6px 24px rgba(15,23,42,.12);
  --shadow-sm:0 2px 8px rgba(15,23,42,.08);
  --border:rgba(15,23,42,.1);
  --surface-2:rgba(15,23,42,.04);
  --primary-glow:rgba(99,102,241,.25);
}

/* ---- Reset & base --------------------------------------------------------- */
*{box-sizing:border-box}
html,body{margin:0;min-height:100%}
body{
  background:var(--color-base);
  /* subtle depth without fatigue */
  background-image:
    radial-gradient(1200px 600px at 100% -10%, color-mix(in srgb, var(--color-primary) 14%, transparent), transparent 60%),
    radial-gradient(900px 500px at -10% 110%, color-mix(in srgb, var(--color-streak) 8%, transparent), transparent 55%);
  background-attachment:fixed;
  color:var(--color-text);
  font-family:var(--font);
  line-height:1.55;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
h1,h2,h3{line-height:1.2;margin:0 0 var(--sp-2)}
h2{font-size:1.5rem;letter-spacing:-.01em}
h3{font-size:1.1rem;margin-top:var(--sp-4)}
p{margin:0 0 var(--sp-2)}
a{color:var(--color-primary);text-decoration:none}
:focus-visible{outline:2px solid var(--color-primary);outline-offset:2px;border-radius:6px}
img{max-width:100%;height:auto}

/* ---- Utilities ------------------------------------------------------------ */
.muted{color:var(--color-muted)}
[hidden]{display:none!important}
.visually-hidden{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}
.surface{background:var(--color-surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow)}

/* ---- App shell ------------------------------------------------------------ */
#app{
  max-width:var(--maxw);
  margin-inline:auto;
  padding:var(--sp-3) var(--sp-3) calc(var(--sp-5) + env(safe-area-inset-bottom,0px));
  display:flex;
  flex-direction:column;
  gap:var(--sp-3);
}
.app-header{
  position:sticky;top:var(--sp-2);z-index:10;
  display:flex;align-items:center;justify-content:space-between;gap:var(--sp-3);
  padding:var(--sp-2) var(--sp-3);
  backdrop-filter:saturate(140%) blur(8px);
}
.app-title{
  font-size:1.15rem;font-weight:800;margin:0;letter-spacing:-.02em;
  background:linear-gradient(90deg,var(--color-text),var(--color-primary));
  -webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent;
}
.app-header-actions{display:flex;align-items:center;gap:var(--sp-2)}

.app-nav{
  display:flex;flex-wrap:wrap;gap:var(--sp-1);
  padding:var(--sp-1);
  background:var(--surface-2);
  border:1px solid var(--border);
  border-radius:calc(var(--radius) + 4px);
}
.app-nav a{
  flex:1 1 auto;text-align:center;white-space:nowrap;
  min-height:var(--tap);display:flex;align-items:center;justify-content:center;
  padding:0 var(--sp-3);border-radius:var(--radius);
  color:var(--color-muted);font-weight:600;font-size:.95rem;
  transition:background .15s ease,color .15s ease;
}
.app-nav a:hover{color:var(--color-text);background:var(--surface-2)}
.app-nav a:active{transform:translateY(1px)}

#view{display:block;animation:fade .2s ease}
@keyframes fade{from{opacity:0;transform:translateY(4px)}to{opacity:1;transform:none}}

/* ---- Buttons -------------------------------------------------------------- */
button{font:inherit;color:inherit;cursor:pointer}
.btn{
  min-height:var(--tap);padding:0 20px;border:1px solid transparent;border-radius:var(--radius);
  background:var(--color-primary);color:#fff;font-weight:700;font-size:.95rem;
  display:inline-flex;align-items:center;justify-content:center;gap:.4rem;
  box-shadow:0 4px 14px var(--primary-glow);
  transition:transform .12s ease,box-shadow .15s ease,filter .15s ease;
}
.btn:hover{filter:brightness(1.06);box-shadow:0 6px 20px var(--primary-glow)}
.btn:active{transform:translateY(1px)}
.btn:disabled{opacity:.5;cursor:not-allowed;box-shadow:none;filter:none}
.btn.ghost{
  background:transparent;border-color:var(--border);color:var(--color-text);
  box-shadow:none;font-weight:600;
}
.btn.ghost:hover{background:var(--surface-2);filter:none}
.btn.ghost[aria-pressed="true"]{
  background:var(--color-primary);border-color:var(--color-primary);color:#fff;
  box-shadow:0 4px 14px var(--primary-glow);
}
.btn.cta{
  width:100%;min-height:64px;font-size:1.15rem;border-radius:calc(var(--radius) + 4px);
  background:linear-gradient(135deg,var(--color-primary),color-mix(in srgb,var(--color-primary) 55%,var(--accent-conditionals)));
}

/* ---- Streak chip ---------------------------------------------------------- */
.streak-chip{
  display:inline-flex;align-items:center;gap:.3rem;
  padding:.3rem .6rem;border-radius:999px;
  background:color-mix(in srgb,var(--color-streak) 18%,transparent);
  color:var(--color-streak);font-weight:700;font-size:.95rem;
}
.streak-flame{font-size:1rem;line-height:1}

/* ---- Banners -------------------------------------------------------------- */
.storage-warning,.backup-reminder{
  padding:var(--sp-2) var(--sp-3);border-radius:var(--radius);
  border:1px solid color-mix(in srgb,var(--color-streak) 40%,transparent);
  background:color-mix(in srgb,var(--color-streak) 12%,transparent);
  color:var(--color-text);font-size:.9rem;
}
.storage-warning{margin:var(--sp-2) auto;max-width:var(--maxw)}

/* ---- Hub ------------------------------------------------------------------ */
.hub{display:flex;flex-direction:column;gap:var(--sp-3)}
.topic-search{
  width:100%;min-height:var(--tap);padding:0 var(--sp-3);
  border-radius:var(--radius);border:1px solid var(--border);
  background:var(--color-surface);color:var(--color-text);font:inherit;
}
.topic-search::placeholder{color:var(--color-muted)}
.topic-cards{
  list-style:none;margin:0;padding:0;
  display:grid;grid-template-columns:repeat(auto-fill,minmax(140px,1fr));gap:var(--sp-3);
}
.topic-card{padding:0;overflow:hidden;transition:transform .12s ease,box-shadow .15s ease}
.topic-card:hover{transform:translateY(-3px);box-shadow:0 10px 28px rgba(0,0,0,.4)}
.topic-card-btn{
  width:100%;height:100%;background:none;border:0;
  display:flex;flex-direction:column;align-items:center;gap:var(--sp-2);
  padding:var(--sp-3);
}
.topic-title{font-weight:600;text-align:center;font-size:.95rem}
.progress-ring{display:block}

/* ---- Module roadmap cards ------------------------------------------------- */
.module-cards{
  list-style:none;margin:0;padding:0;
  display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:var(--sp-3);
}
.module-card{position:relative;padding:0;overflow:hidden;transition:transform .12s ease,box-shadow .15s ease}
.module-card[data-status="available"]:hover{transform:translateY(-3px);box-shadow:0 10px 28px rgba(0,0,0,.4)}
.module-card[data-next="true"]{outline:2px solid var(--color-primary);outline-offset:-2px}
.module-card-btn,.module-card-soon{
  width:100%;height:100%;background:none;border:0;
  display:flex;flex-direction:column;align-items:center;gap:var(--sp-2);
  padding:var(--sp-3);text-align:center;
}
.module-order{
  align-self:flex-start;font-size:.75rem;font-weight:800;color:var(--color-muted);
  width:22px;height:22px;border-radius:999px;background:var(--surface-2);
  display:inline-flex;align-items:center;justify-content:center;
}
.module-title{font-weight:700;font-size:1rem}
.module-next-badge{
  font-size:.7rem;font-weight:800;letter-spacing:.04em;text-transform:uppercase;
  color:var(--color-primary);
  background:color-mix(in srgb,var(--color-primary) 16%,transparent);
  padding:.15rem .5rem;border-radius:999px;
}
.module-card[data-status="coming-soon"]{opacity:.6}
.module-coming{
  font-size:.72rem;font-weight:700;color:var(--color-muted);
  padding:.15rem .5rem;border-radius:999px;border:1px dashed var(--border);
}

/* ---- Module view (topic list) --------------------------------------------- */
.module{display:flex;flex-direction:column;gap:var(--sp-3)}
.module>header{margin-bottom:var(--sp-1)}
.module-subtitle{margin:0;font-size:.95rem}
.topic-rows{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:var(--sp-2);counter-reset:topic}
.topic-row{padding:0;overflow:hidden;transition:transform .12s ease,box-shadow .15s ease}
.topic-row:hover{transform:translateY(-2px);box-shadow:0 8px 22px rgba(0,0,0,.35)}
.topic-row-btn{
  width:100%;background:none;border:0;
  display:flex;align-items:center;justify-content:space-between;gap:var(--sp-3);
  padding:var(--sp-3);text-align:left;min-height:var(--tap);
}
.topic-row-title{font-weight:600;font-size:1rem}
.topic-status{
  flex:none;font-size:.75rem;font-weight:700;letter-spacing:.02em;
  padding:.2rem .6rem;border-radius:999px;white-space:nowrap;
  background:var(--surface-2);color:var(--color-muted);border:1px solid var(--border);
}
.topic-status[data-status="learned"]{color:var(--color-primary);background:color-mix(in srgb,var(--color-primary) 14%,transparent);border-color:transparent}
.topic-status[data-status="practicing"]{color:var(--color-streak);background:color-mix(in srgb,var(--color-streak) 14%,transparent);border-color:transparent}
.topic-status[data-status="mastered"]{color:var(--color-success);background:color-mix(in srgb,var(--color-success) 16%,transparent);border-color:transparent}
/* Topic families: a small uppercase heading over each group of topic rows. */
.topic-group{display:flex;flex-direction:column;gap:var(--sp-2);margin-bottom:var(--sp-3)}
.topic-group-title{margin:0 0 var(--sp-1);font-size:.8rem;font-weight:800;letter-spacing:.08em;text-transform:uppercase;color:var(--color-muted)}
.topic-group-en{font-weight:600;letter-spacing:0;text-transform:none}
/* Contextual back control (module/topic headers): small, left-aligned. */
.btn.back{align-self:flex-start;padding:.35rem .7rem;font-size:.85rem;margin-bottom:var(--sp-1)}

/* ---- Topic (teach) -------------------------------------------------------- */
.topic{display:flex;flex-direction:column;gap:var(--sp-2)}
.topic>header{margin-bottom:var(--sp-2)}
.topic-subtitle{color:var(--color-muted);font-style:italic;margin:0}
.topic-p,.topic-quote{margin:0 0 var(--sp-2)}
.topic-quote{
  border-left:3px solid var(--color-primary);padding:var(--sp-2) var(--sp-3);
  background:var(--surface-2);border-radius:0 var(--radius-sm) var(--radius-sm) 0;
}
.topic-p p,.topic-quote p{margin:.15rem 0}
.topic-diagram{border-radius:var(--radius);border:1px solid var(--border);margin:var(--sp-2) 0}
.topic-table{width:100%;border-collapse:collapse;margin:var(--sp-2) 0;font-size:.92rem}
.topic-table th,.topic-table td{padding:.55rem .7rem;text-align:left;border-bottom:1px solid var(--border)}
.topic-table th{color:var(--color-muted);font-weight:700}
.topic-examples{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:var(--sp-2)}
.topic-examples li{
  display:flex;flex-wrap:wrap;align-items:center;gap:.5rem;
  padding:var(--sp-2) var(--sp-3);background:var(--surface-2);border-radius:var(--radius-sm);
}
.example-en{font-weight:600}
.example-es{color:var(--color-muted);width:100%}
.topic-generate{
  margin-top:var(--sp-3);padding:var(--sp-3);border:1px dashed var(--border);
  border-radius:var(--radius);display:flex;flex-direction:column;gap:var(--sp-2);align-items:flex-start;
}
.ai-status{margin:0;font-size:.9rem}

/* ---- Core idea (topic essence) -------------------------------------------- */
.topic-core-idea{
  margin:0 0 var(--sp-3);padding:var(--sp-3) var(--sp-4);
  border-left:4px solid var(--color-primary);border-radius:0 var(--radius) var(--radius) 0;
  background:color-mix(in srgb,var(--color-primary) 12%,transparent);
}
.core-idea-es{margin:0;font-size:1.2rem;font-weight:700;line-height:1.35}
.core-idea-en{display:flex;align-items:center;gap:.4rem;margin:.35rem 0 0;font-size:.95rem}

/* ---- Bilingual callout ---------------------------------------------------- */
.callout{
  border-left:3px solid var(--color-primary);
  background:color-mix(in srgb,var(--color-primary) 10%,transparent);
  padding:var(--sp-2) var(--sp-3);border-radius:0 var(--radius-sm) var(--radius-sm) 0;
  margin:var(--sp-2) 0;
}
.callout-why{border-left-color:var(--color-success);background:color-mix(in srgb,var(--color-success) 10%,transparent)}
.callout-pitfall{border-left-color:var(--color-error);background:color-mix(in srgb,var(--color-error) 10%,transparent)}
.callout-pitfall .callout-en::before{content:"⚠ ";}
.callout-en{display:flex;align-items:center;gap:.4rem;font-weight:600;margin:0}
.callout-es{color:var(--color-muted);margin:.15rem 0 0}

/* ---- Audio button --------------------------------------------------------- */
.audio-btn{
  flex:none;width:32px;height:32px;padding:0;border-radius:999px;border:1px solid var(--border);
  background:var(--surface-2);font-size:.9rem;line-height:1;
  display:inline-flex;align-items:center;justify-content:center;
}
.audio-btn:hover{background:var(--color-surface)}

/* ---- Practice ------------------------------------------------------------- */
.practice{display:flex;flex-direction:column;align-items:center;gap:var(--sp-3)}
.practice-progress{align-self:center;margin:0;font-weight:600;letter-spacing:.05em}
.practice-card{
  width:100%;max-width:620px;padding:var(--sp-4);
  display:flex;flex-direction:column;gap:var(--sp-2);
}
.practice-prompt{font-size:1.35rem;font-weight:700;margin:0}
.practice-prompt-es{margin:0 0 var(--sp-2)}
.practice-answer{display:flex;flex-wrap:wrap;gap:var(--sp-2)}
.answer-input{
  flex:1 1 220px;min-height:var(--tap);padding:0 var(--sp-3);
  border-radius:var(--radius);border:1px solid var(--border);
  background:var(--color-base);color:var(--color-text);font:inherit;font-size:1.05rem;
}
.choice{flex:1 1 45%;justify-content:flex-start;text-align:left}
.practice-feedback{display:flex;flex-direction:column;gap:var(--sp-2)}
.verdict{font-weight:800;font-size:1.05rem;margin:0}
.verdict.ok{color:var(--color-success)}
.verdict.no{color:var(--color-error)}
.practice-ratings{display:grid;grid-template-columns:repeat(2,1fr);gap:var(--sp-2)}
.btn.rating{background:var(--surface-2);border:1px solid var(--border);color:var(--color-text);box-shadow:none;font-weight:600}
.btn.rating:hover{filter:none;background:var(--color-surface)}
.rating[data-rating="again"]{border-color:var(--color-error);color:var(--color-error)}
.rating[data-rating="hard"]{border-color:var(--color-streak);color:var(--color-streak)}
.rating[data-rating="good"]{border-color:var(--color-primary);color:var(--color-primary)}
.rating[data-rating="easy"]{border-color:var(--color-success);color:var(--color-success)}
.practice-ai{margin-top:var(--sp-2);display:flex;flex-direction:column;gap:var(--sp-2)}
.practice-ai-actions{display:flex;flex-wrap:wrap;gap:var(--sp-2)}
.practice-ai-output{margin:0;font-size:.92rem;min-height:1.2em}
.practice-summary{
  max-width:480px;margin:var(--sp-4) auto 0;padding:var(--sp-5);text-align:center;
}
.practice-summary h2{color:var(--color-success)}

/* ---- Insights ------------------------------------------------------------- */
.insights{display:flex;flex-direction:column;gap:var(--sp-2)}
.insights-tiles{display:grid;grid-template-columns:repeat(2,1fr);gap:var(--sp-3)}
.insight-tile{padding:var(--sp-4);display:flex;flex-direction:column;gap:.25rem;align-items:flex-start}
.insight-value{font-size:2rem;font-weight:800;line-height:1;color:var(--color-primary)}
.insight-label{font-size:.85rem}
.forecast-chart{
  display:flex;align-items:flex-end;gap:var(--sp-2);
  padding:var(--sp-4) var(--sp-2) var(--sp-2);
  background:var(--surface-2);border-radius:var(--radius);border:1px solid var(--border);
}
.forecast-col{flex:1;height:150px;display:flex;flex-direction:column;align-items:center;justify-content:flex-end;gap:.3rem}
.forecast-count{font-size:.75rem;color:var(--color-muted);font-weight:700}
.forecast-bar{
  width:min(70%,34px);min-height:4px;border-radius:6px 6px 0 0;
  background:linear-gradient(180deg,var(--color-primary),color-mix(in srgb,var(--color-primary) 60%,transparent));
}
.forecast-label{font-size:.72rem}
.weak-topics{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:var(--sp-2)}
.weak-topic{
  display:flex;align-items:center;gap:var(--sp-3);
  padding:var(--sp-2) var(--sp-3);background:var(--surface-2);border-radius:var(--radius-sm);
}
.weak-topic-name{flex:1;font-weight:600}
.weak-topic-ratio{font-variant-numeric:tabular-nums}
.insights-empty{padding:var(--sp-5) var(--sp-3);text-align:center}

/* ---- Settings ------------------------------------------------------------- */
.settings{display:flex;flex-direction:column;gap:var(--sp-3)}
.setting-group{display:flex;flex-direction:column;gap:var(--sp-2)}
.setting-label{font-weight:600;color:var(--color-muted);font-size:.9rem}
.setting-choices{display:flex;flex-wrap:wrap;gap:var(--sp-2)}
.setting-choices .btn{flex:1 1 auto;min-width:90px}
.settings-actions{display:flex;flex-wrap:wrap;gap:var(--sp-2)}
.import-label{cursor:pointer}
.text-input{
  width:100%;min-height:var(--tap);padding:0 var(--sp-3);margin-top:.35rem;
  border-radius:var(--radius);border:1px solid var(--border);
  background:var(--color-base);color:var(--color-text);font:inherit;
}
.settings-ai{
  display:flex;flex-direction:column;gap:var(--sp-2);
  padding:var(--sp-3);background:var(--surface-2);border-radius:var(--radius);border:1px solid var(--border);
}
.ai-note{font-size:.82rem;color:var(--color-muted);margin:0}
.toast-area{position:sticky;bottom:var(--sp-3)}
.toast{padding:var(--sp-2) var(--sp-3);border-radius:var(--radius);font-weight:600;box-shadow:var(--shadow-sm)}
.toast-ok{background:color-mix(in srgb,var(--color-success) 20%,var(--color-surface));color:var(--color-success)}
.toast-error{background:color-mix(in srgb,var(--color-error) 20%,var(--color-surface));color:var(--color-error)}

/* ---- Onboarding ----------------------------------------------------------- */
.onboarding{
  min-height:70vh;display:flex;flex-direction:column;align-items:center;justify-content:center;
  gap:var(--sp-4);text-align:center;max-width:520px;margin-inline:auto;padding:var(--sp-4);
}
.onboarding-slides{width:100%}
.onboarding-slide{display:flex;flex-direction:column;gap:var(--sp-2)}
.onboarding-slide h2{font-size:1.8rem}
.onboarding-slide p{color:var(--color-muted);font-size:1.05rem}
.onboarding-dots{display:flex;gap:.5rem}
.dot{width:9px;height:9px;border-radius:999px;background:var(--border);transition:background .2s,transform .2s}
.dot.active{background:var(--color-primary);transform:scale(1.3)}
.goal-chooser{display:flex;flex-wrap:wrap;gap:var(--sp-2);justify-content:center;margin-top:var(--sp-3)}
.onboarding .btn[data-role="advance"]{min-width:180px}

/* ---- Pronounce feedback --------------------------------------------------- */
/* Palabras ok/off del intento. El color NUNCA es el único indicador (WCAG
   1.4.1): "off" lleva subrayado ondulado además del color de error, y en el
   DOM cada palabra off arrastra un marcador " (revisar)" para lectores de
   pantalla. "ok" usa el color de éxito. */
.phrase-words{display:flex;flex-wrap:wrap;gap:var(--sp-1)}
.word{font-weight:600}
.word.ok{color:var(--color-success)}
.word.off{color:var(--color-error);text-decoration:underline wavy var(--color-error);text-underline-offset:3px}

/* ---- Responsive ----------------------------------------------------------- */
@media (min-width:640px){
  #app{padding:var(--sp-4) var(--sp-4) var(--sp-5)}
  .app-title{font-size:1.35rem}
  .practice-ratings{grid-template-columns:repeat(4,1fr)}
  .insights-tiles{gap:var(--sp-4)}
  h2{font-size:1.7rem}
}
@media (max-width:400px){
  .topic-cards,.module-cards{grid-template-columns:repeat(2,1fr)}
  .app-nav a{padding:0 var(--sp-2);font-size:.88rem}
}

/* ---- Motion preference ---------------------------------------------------- */
@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}}