/* ════════════════════════════════════════
   STUDYAPP — Design système neumorphique
   Inspiré de StudyOS · Mobile-first
════════════════════════════════════════ */

:root {
  --bg:       #e4e9f2;
  --sh-d:     #bcc3cf;
  --sh-l:     #ffffff;
  --text:     #2d3452;
  --muted:    #8892aa;
  --faint:    #a8b0c4;
  --accent:   #6366f1;
  --r:        18px;
  --r-sm:     12px;
  --r-xs:     8px;
  --raise:    6px 6px 14px var(--sh-d), -6px -6px 14px var(--sh-l);
  --raise-sm: 3px 3px 8px  var(--sh-d), -3px -3px 8px  var(--sh-l);
  --raise-xs: 2px 2px 5px  var(--sh-d), -2px -2px 5px  var(--sh-l);
  --inset:    inset 3px 3px 8px var(--sh-d), inset -3px -3px 8px var(--sh-l);
  --press:    inset 4px 4px 10px var(--sh-d), inset -1px -1px 4px var(--sh-l);
}

/* ── RESET ── */
*, *::before, *::after {
  box-sizing: border-box; margin: 0; padding: 0;
  -webkit-tap-highlight-color: transparent;
}
html, body { height: 100%; overflow: hidden; }
body {
  font-family: 'Inter', -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}
#app { height: 100%; position: relative; }
.screen {
  position: absolute; inset: 0;
  overflow-y: auto; overflow-x: hidden;
  -webkit-overflow-scrolling: touch;
  opacity: 0; pointer-events: none;
  transition: opacity .22s ease;
}
.screen.active { opacity: 1; pointer-events: auto; }
::-webkit-scrollbar { width: 0; }

/* ════════════════════════════════════════
   HOME
════════════════════════════════════════ */
.home-header {
  padding: env(safe-area-inset-top, 48px) 22px 0;
  padding-top: max(env(safe-area-inset-top, 0px), 48px);
  padding-bottom: 0;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  padding: 52px 22px 20px;
}
.home-header-left { flex: 1; }
.home-header .greeting {
  font-size: 12px;
  font-weight: 600;
  color: var(--faint);
  text-transform: uppercase;
  letter-spacing: .08em;
  margin-bottom: 3px;
}
.home-header h1 {
  font-size: 26px;
  font-weight: 900;
  color: var(--text);
  letter-spacing: -.6px;
  line-height: 1.1;
}
.home-stats-btn {
  width: 40px; height: 40px;
  background: var(--bg);
  box-shadow: var(--raise-sm);
  border-radius: var(--r-sm);
  border: none;
  color: var(--muted);
  font-size: 18px;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
  margin-top: 4px;
  transition: box-shadow .15s;
}
.home-stats-btn:active { box-shadow: var(--press); }

/* Leitner widgets */
.leitner-widgets {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  padding: 20px 22px 4px;
}
.lw-card {
  background: var(--bg);
  box-shadow: var(--raise);
  border-radius: var(--r);
  padding: 16px 10px 14px;
  text-align: center;
  cursor: pointer;
  transition: box-shadow .15s, transform .12s;
  position: relative;
  overflow: hidden;
}
.lw-card:active { box-shadow: var(--press); transform: scale(.97); }
.lw-accent {
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  border-radius: var(--r) var(--r) 0 0;
}
.lw-num {
  font-size: 34px;
  font-weight: 900;
  letter-spacing: -1px;
  line-height: 1;
  margin: 8px 0 10px;
}
.lw-bar-wrap {
  height: 4px;
  background: var(--bg);
  box-shadow: var(--inset);
  border-radius: 2px;
  margin-bottom: 8px;
  overflow: hidden;
}
.lw-bar { height: 4px; border-radius: 2px; transition: width .7s cubic-bezier(.4,0,.2,1); }
.lw-label {
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .07em;
  color: var(--muted);
}

/* Section title */
.section-title {
  font-size: 11px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--faint);
  padding: 22px 22px 10px;
}

/* Subject grid */
.subject-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  padding: 0 22px 36px;
}
.subject-card {
  background: var(--bg);
  box-shadow: var(--raise);
  border-radius: var(--r);
  padding: 14px 14px 14px;
  cursor: pointer;
  transition: box-shadow .15s, transform .12s;
  position: relative;
  overflow: hidden;
}
.subject-card:active { box-shadow: var(--press); transform: scale(.98); }
.sc-stripe {
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  border-radius: var(--r) var(--r) 0 0;
}
.sc-tag {
  font-size: 9px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: .08em;
  margin-top: 8px;
  margin-bottom: 5px;
}
.sc-name {
  font-size: 15px;
  font-weight: 800;
  line-height: 1.2;
  color: var(--text);
  letter-spacing: -.3px;
  margin-bottom: 10px;
}
.sc-exam {
  font-size: 11px;
  font-weight: 600;
  color: var(--faint);
  margin-bottom: 10px;
}
.sc-bar-bg {
  height: 4px;
  background: var(--bg);
  box-shadow: var(--inset);
  border-radius: 2px;
  overflow: hidden;
  margin-bottom: 6px;
}
.sc-bar {
  height: 4px;
  border-radius: 2px;
  transition: width .7s cubic-bezier(.4,0,.2,1);
}
.sc-stats {
  font-size: 11px;
  font-weight: 700;
}
.countdown-badge {
  position: absolute;
  top: 13px; right: 12px;
  font-size: 11px;
  font-weight: 900;
  letter-spacing: -.3px;
}

/* Mix row */
.mix-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  padding: 0 22px 8px;
}
.mix-card {
  background: var(--bg);
  box-shadow: var(--raise);
  border-radius: var(--r);
  padding: 16px 12px;
  text-align: center;
  cursor: pointer;
  transition: box-shadow .15s, transform .12s;
}
.mix-card:active { box-shadow: var(--press); transform: scale(.97); }
.mix-icon { font-size: 22px; margin-bottom: 6px; }
.mix-label { font-size: 13px; font-weight: 800; color: var(--accent); margin-bottom: 3px; letter-spacing: -.2px; }
.mix-sub { font-size: 10px; color: var(--muted); font-weight: 600; }

/* ════════════════════════════════════════
   SUBJECT SCREEN
════════════════════════════════════════ */
.subject-hero {
  padding: 52px 22px 20px;
}
.subject-hero .sh-tag {
  font-size: 11px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: .08em;
  margin-bottom: 4px;
}
.subject-hero h2 {
  font-size: 30px;
  font-weight: 900;
  color: var(--text);
  letter-spacing: -.6px;
  margin-bottom: 2px;
}
.subject-hero .sh-exam {
  font-size: 13px;
  color: var(--muted);
  font-weight: 600;
  margin-bottom: 20px;
}

.back-btn {
  width: 38px; height: 38px;
  background: var(--bg);
  box-shadow: var(--raise-sm);
  border: none;
  border-radius: var(--r-sm);
  color: var(--text);
  font-size: 16px;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: box-shadow .15s;
  flex-shrink: 0;
}
.back-btn:active { box-shadow: var(--press); }

.progress-row {
  background: var(--bg);
  box-shadow: var(--raise);
  border-radius: var(--r);
  padding: 16px 18px;
  margin-bottom: 18px;
}
.pr-bar-bg {
  height: 7px;
  background: var(--bg);
  box-shadow: var(--inset);
  border-radius: 4px;
  margin-bottom: 12px;
  overflow: hidden;
}
.pr-bar { height: 7px; border-radius: 4px; transition: width .7s cubic-bezier(.4,0,.2,1); }
.pr-nums {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  font-weight: 700;
}

/* Mode cards */
.mode-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  padding: 0 22px 22px;
}
.mode-card {
  background: var(--bg);
  box-shadow: var(--raise);
  border-radius: var(--r);
  padding: 20px 14px 16px;
  cursor: pointer;
  text-align: center;
  transition: box-shadow .15s, transform .12s;
}
.mode-card:active { box-shadow: var(--press); transform: scale(.97); }
.mc-icon { font-size: 26px; margin-bottom: 8px; line-height: 1; }
.mc-name { font-size: 14px; font-weight: 800; color: var(--text); margin-bottom: 3px; letter-spacing: -.2px; }
.mc-desc { font-size: 11px; color: var(--muted); line-height: 1.4; margin-bottom: 10px; }
.mc-count {
  display: inline-block;
  background: var(--bg);
  box-shadow: var(--inset);
  border-radius: 20px;
  padding: 3px 10px;
  font-size: 11px;
  font-weight: 800;
  color: var(--muted);
}

/* Leitner mini boxes (subject screen) */
.leitner-row { padding: 0 22px 32px; }
.leitner-boxes { display: flex; gap: 8px; }
.leitner-box {
  flex: 1;
  background: var(--bg);
  box-shadow: var(--raise-sm);
  border-radius: var(--r-sm);
  padding: 12px 6px;
  text-align: center;
}
.leitner-box .lb-num {
  font-size: 22px;
  font-weight: 900;
  margin-bottom: 3px;
  letter-spacing: -.5px;
}
.leitner-box .lb-label {
  font-size: 9px;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--muted);
  letter-spacing: .06em;
  line-height: 1.3;
}

/* ════════════════════════════════════════
   FLASHCARD
════════════════════════════════════════ */
.fc-header {
  position: sticky; top: 0; z-index: 10;
  background: var(--bg);
  padding: 52px 20px 14px;
  display: flex; align-items: center; gap: 12px;
}
.fc-progress-bar {
  flex: 1;
  height: 6px;
  background: var(--bg);
  box-shadow: var(--inset);
  border-radius: 3px;
  overflow: hidden;
}
.fc-progress-fill { height: 6px; border-radius: 3px; transition: width .4s ease; }
.fc-counter {
  font-size: 12px;
  font-weight: 800;
  color: var(--muted);
  flex-shrink: 0;
  min-width: 36px;
  text-align: right;
}

.fc-arena {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 8px 20px 36px;
}

.flashcard {
  width: 100%;
  max-width: 440px;
  min-height: 290px;
  border-radius: var(--r);
  cursor: pointer;
  position: relative;
  transform-style: preserve-3d;
  transition: transform .5s cubic-bezier(.4,0,.2,1);
  margin-bottom: 18px;
}
.flashcard.flipped { transform: rotateY(180deg); }

.fc-face {
  position: absolute; inset: 0;
  border-radius: var(--r);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  display: flex;
  flex-direction: column;
}

/* RECTO */
.fc-front {
  background: var(--bg);
  box-shadow: var(--raise);
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 28px 22px 22px;
}
.fc-cat {
  position: absolute; top: 14px; left: 14px;
  font-size: 10px; font-weight: 700;
  text-transform: uppercase; letter-spacing: .07em;
  color: var(--muted);
  background: var(--bg);
  box-shadow: var(--raise-xs);
  border-radius: 20px;
  padding: 4px 10px;
}
.fc-box {
  position: absolute; top: 14px; right: 14px;
  font-size: 10px; font-weight: 700;
  color: var(--muted);
  background: var(--bg);
  box-shadow: var(--raise-xs);
  border-radius: 20px;
  padding: 4px 10px;
}
.fc-term {
  font-size: 30px;
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -.6px;
  color: var(--text);
  margin-bottom: 10px;
}
.fc-hint {
  font-size: 11px;
  color: var(--faint);
  font-weight: 500;
}

/* VERSO */
.fc-back {
  background: var(--bg);
  box-shadow: var(--raise);
  transform: rotateY(180deg);
  padding: 18px 20px;
}
.fc-cat-back {
  font-size: 9px; font-weight: 700;
  text-transform: uppercase; letter-spacing: .08em;
  color: var(--faint); margin-bottom: 3px;
}
.fc-term-back {
  font-size: 17px; font-weight: 800;
  color: var(--text);
  margin-bottom: 14px;
  padding-bottom: 14px;
  border-bottom: 1.5px solid var(--sh-d);
  letter-spacing: -.2px;
}
.fc-def {
  font-size: 14px;
  line-height: 1.7;
  flex: 1;
  color: var(--text);
}
.fc-ex {
  font-size: 12px;
  color: var(--muted);
  line-height: 1.55;
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1.5px solid var(--sh-d);
  font-style: italic;
}

/* Boutons Oui / Bof / Non */
.fc-buttons {
  width: 100%;
  max-width: 440px;
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 10px;
}
.fc-btn {
  padding: 14px 6px;
  border: none;
  border-radius: var(--r);
  cursor: pointer;
  font-family: 'Inter', sans-serif;
  font-size: 13px;
  font-weight: 800;
  background: var(--bg);
  transition: box-shadow .15s, transform .12s;
  letter-spacing: -.1px;
}
.fc-btn:active { box-shadow: var(--press) !important; transform: scale(.97); }
.fc-btn-no  {
  box-shadow: var(--raise);
  color: #dc2626;
  background: linear-gradient(135deg, #fef2f2, var(--bg));
}
.fc-btn-bof {
  box-shadow: var(--raise);
  color: #b45309;
  background: linear-gradient(135deg, #fffbeb, var(--bg));
}
.fc-btn-yes {
  box-shadow: var(--raise);
  color: #15803d;
  background: linear-gradient(135deg, #f0fdf4, var(--bg));
}

.fc-swipe-hint {
  font-size: 11px;
  color: var(--faint);
  text-align: center;
  margin-top: 12px;
}

/* Session end */
.session-end {
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  text-align: center;
  padding: 40px 24px;
  min-height: calc(100vh - 80px);
}
.se-icon { font-size: 56px; margin-bottom: 14px; }
.session-end h2 {
  font-size: 24px; font-weight: 900;
  color: var(--text); margin-bottom: 6px;
  letter-spacing: -.4px;
}
.session-end p { font-size: 14px; color: var(--muted); margin-bottom: 28px; }

.session-score {
  display: flex;
  gap: 0;
  margin-bottom: 32px;
  background: var(--bg);
  box-shadow: var(--raise);
  border-radius: var(--r);
  overflow: hidden;
  width: 100%;
  max-width: 300px;
}
.ss-item {
  flex: 1;
  text-align: center;
  padding: 18px 10px;
}
.ss-item:not(:last-child) {
  border-right: 1.5px solid var(--sh-d);
}
.ss-num { font-size: 32px; font-weight: 900; letter-spacing: -.8px; line-height: 1; margin-bottom: 4px; }
.ss-label { font-size: 10px; color: var(--muted); font-weight: 700; text-transform: uppercase; letter-spacing: .06em; }

.btn-primary {
  background: var(--bg);
  box-shadow: var(--raise);
  color: var(--accent);
  border: none;
  border-radius: var(--r);
  cursor: pointer;
  font-family: 'Inter', sans-serif;
  font-size: 15px; font-weight: 800;
  padding: 16px 32px;
  width: 100%; max-width: 300px;
  transition: box-shadow .15s;
  letter-spacing: -.3px;
}
.btn-primary:active { box-shadow: var(--press); }
.btn-secondary {
  background: var(--bg);
  box-shadow: var(--raise-sm);
  color: var(--muted);
  border: none;
  border-radius: var(--r);
  cursor: pointer;
  font-family: 'Inter', sans-serif;
  font-size: 14px; font-weight: 700;
  padding: 14px 24px;
  width: 100%; max-width: 300px;
  margin-top: 10px;
  transition: box-shadow .15s;
}
.btn-secondary:active { box-shadow: var(--press); }

/* ════════════════════════════════════════
   QCM
════════════════════════════════════════ */
.qcm-header {
  position: sticky; top: 0; z-index: 10;
  background: var(--bg);
  padding: 52px 20px 14px;
  display: flex; align-items: center; gap: 12px;
}
.qcm-arena { padding: 10px 20px 130px; }

.qcm-question {
  background: var(--bg);
  box-shadow: var(--raise);
  border-radius: var(--r);
  padding: 20px;
  margin-bottom: 14px;
  font-size: 16px;
  font-weight: 700;
  line-height: 1.6;
  color: var(--text);
  letter-spacing: -.2px;
}

.qcm-options { display: flex; flex-direction: column; gap: 9px; }
.qcm-opt {
  background: var(--bg);
  box-shadow: var(--raise-sm);
  border: none;
  border-radius: var(--r-sm);
  padding: 15px 18px;
  cursor: pointer;
  text-align: left;
  font-family: 'Inter', sans-serif;
  font-size: 14px;
  font-weight: 600;
  color: var(--text);
  line-height: 1.45;
  transition: box-shadow .15s, transform .1s;
  position: relative;
}
.qcm-opt:active:not(.disabled) { transform: scale(.99); box-shadow: var(--press); }

.qcm-opt.correct {
  box-shadow: 4px 4px 10px rgba(21,128,61,.15), -4px -4px 10px rgba(255,255,255,.9) !important;
  background: linear-gradient(135deg, #f0fdf4, var(--bg)) !important;
  color: #15803d !important;
  font-weight: 800;
}
.qcm-opt.wrong {
  box-shadow: 4px 4px 10px rgba(220,38,38,.12), -4px -4px 10px rgba(255,255,255,.9) !important;
  background: linear-gradient(135deg, #fef2f2, var(--bg)) !important;
  color: #dc2626 !important;
  font-weight: 800;
}
.qcm-opt.disabled { pointer-events: none; }

.qcm-explanation {
  background: var(--bg);
  box-shadow: var(--inset);
  border-radius: var(--r-sm);
  padding: 14px 16px 14px 20px;
  margin-top: 12px;
  font-size: 13px;
  color: var(--muted);
  line-height: 1.65;
  border-left: 3px solid var(--accent);
  animation: fadeIn .3s ease;
}
@keyframes fadeIn { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

.qcm-next-btn {
  position: fixed;
  bottom: 28px; left: 50%;
  transform: translateX(-50%);
  width: calc(100% - 44px);
  max-width: 420px;
  background: var(--bg);
  box-shadow: var(--raise);
  color: var(--accent);
  border: none;
  border-radius: var(--r);
  padding: 17px;
  font-family: 'Inter', sans-serif;
  font-size: 15px; font-weight: 800;
  cursor: pointer;
  display: none;
  z-index: 20;
  animation: slideUp .28s cubic-bezier(.4,0,.2,1);
  transition: box-shadow .15s;
  letter-spacing: -.2px;
}
.qcm-next-btn:active { box-shadow: var(--press); }
.qcm-next-btn.show { display: block; }
@keyframes slideUp {
  from { transform: translateX(-50%) translateY(20px); opacity: 0; }
  to   { transform: translateX(-50%); opacity: 1; }
}

/* ════════════════════════════════════════
   STATS
════════════════════════════════════════ */
.stats-header {
  padding: 52px 22px 20px;
  display: flex; align-items: center; gap: 12px;
}
.stats-header h1 {
  font-size: 26px; font-weight: 900;
  color: var(--text); letter-spacing: -.5px;
  flex: 1;
}

.stats-subject {
  background: var(--bg);
  box-shadow: var(--raise);
  border-radius: var(--r);
  padding: 16px 18px;
  margin: 0 22px 12px;
  overflow: hidden;
  position: relative;
}
.stats-subject .ss-stripe {
  position: absolute; top: 0; left: 0; right: 0; height: 3px;
  border-radius: var(--r) var(--r) 0 0;
}
.stats-subject .ss-name {
  font-size: 14px; font-weight: 800;
  color: var(--text); margin-top: 6px; margin-bottom: 10px;
  letter-spacing: -.2px;
}
.ss-bar-bg {
  height: 6px;
  background: var(--bg);
  box-shadow: var(--inset);
  border-radius: 3px;
  margin-bottom: 10px;
  overflow: hidden;
}
.ss-bar { height: 6px; border-radius: 3px; transition: width .7s cubic-bezier(.4,0,.2,1); }
.ss-detail {
  display: flex; gap: 12px;
  font-size: 11px; font-weight: 700;
}
.ss-row-label {
  font-size: 10px; font-weight: 700;
  text-transform: uppercase; letter-spacing: .07em;
  color: var(--faint); margin-bottom: 5px;
}

.stats-actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 4px 22px 16px;
}
.action-btn {
  background: var(--bg);
  box-shadow: var(--raise-sm);
  border: none;
  border-radius: var(--r);
  padding: 14px 18px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 14px;
  text-align: left;
  width: 100%;
  transition: box-shadow .15s, transform .12s;
  font-family: 'Inter', sans-serif;
}
.action-btn:active { box-shadow: var(--press); transform: scale(.99); }
.action-btn:disabled { opacity: .5; pointer-events: none; }
.ab-icon { font-size: 22px; flex-shrink: 0; }
.ab-title { font-size: 14px; font-weight: 800; color: var(--text); margin-bottom: 2px; letter-spacing: -.2px; }
.ab-desc { font-size: 11px; color: var(--muted); font-weight: 500; }
.action-sync .ab-title { color: var(--accent); }
.action-export .ab-title { color: #059669; }

.reset-btn {
  display: block;
  margin: 20px 22px 48px;
  background: var(--bg);
  box-shadow: var(--raise-sm);
  color: #dc2626;
  border: none;
  border-radius: var(--r);
  padding: 14px;
  font-family: 'Inter', sans-serif;
  font-size: 13px; font-weight: 700;
  cursor: pointer;
  text-align: center;
  width: calc(100% - 44px);
  transition: box-shadow .15s;
}
.reset-btn:active { box-shadow: var(--press); }

/* ════════════════════════════════════════
   TOAST
════════════════════════════════════════ */
#toast {
  position: fixed;
  bottom: 36px; left: 50%;
  transform: translateX(-50%) translateY(16px);
  background: var(--text);
  color: var(--bg);
  border-radius: 24px;
  padding: 10px 20px;
  font-size: 13px; font-weight: 700;
  opacity: 0;
  transition: opacity .25s, transform .25s;
  pointer-events: none;
  z-index: 100;
  white-space: nowrap;
  letter-spacing: -.1px;
}
#toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* Update banner */
.update-banner {
  position: fixed; bottom: 80px; left: 50%;
  transform: translateX(-50%);
  background: var(--text); color: var(--bg);
  border-radius: 20px; padding: 10px 16px;
  font-size: 13px; font-weight: 600;
  z-index: 200; display: flex; align-items: center; gap: 10px;
  box-shadow: 0 4px 20px rgba(0,0,0,.2);
  animation: fadeIn .3s;
}
.update-banner button {
  background: var(--accent); color: #fff;
  border: none; border-radius: 10px;
  padding: 4px 10px; font-size: 12px;
  font-weight: 700; cursor: pointer;
  font-family: 'Inter', sans-serif;
}