/*
 * CBTDrill Web App — Main Stylesheet
 * Scoped under .cbtdrill-app and .cbt-* to avoid theme conflicts.
 * ─────────────────────────────────────────────────────────────
 * Design tokens → Variables → Base → Layout → Components →
 * Quiz → Calculator → Results → Auth → Responsive
 */

/* ── DESIGN TOKENS ──────────────────────────────────────────── */
:root {
  --cbt-ink:        #0A0E1A;
  --cbt-ink-soft:   #1C2340;
  --cbt-surface:    #F4F6FF;
  --cbt-surface2:   #ECEFFE;
  --cbt-white:      #FFFFFF;
  --cbt-blue:       #1565FF;
  --cbt-blue-dark:  #0D47C8;
  --cbt-blue-lt:    rgba(21,101,255,0.08);
  --cbt-blue-glow:  rgba(21,101,255,0.22);
  --cbt-green:      #16A34A;
  --cbt-green-lt:   #DCFCE7;
  --cbt-red:        #DC2626;
  --cbt-red-lt:     #FEF2F2;
  --cbt-orange:     #EA580C;
  --cbt-orange-lt:  #FFF7ED;
  --cbt-yellow:     #CA8A04;
  --cbt-yellow-lt:  #FEFCE8;
  --cbt-purple:     #7C3AED;
  --cbt-purple-lt:  rgba(124,58,237,0.08);
  --cbt-border:     #E2E7F8;
  --cbt-muted:      #6B7394;
  --cbt-radius:     14px;
  --cbt-radius-sm:  8px;
  --cbt-radius-lg:  20px;
  --cbt-shadow:     0 4px 20px rgba(10,14,26,0.08);
  --cbt-shadow-sm:  0 1px 4px rgba(10,14,26,0.06);
  --cbt-shadow-lg:  0 16px 48px rgba(10,14,26,0.14);
  --cbt-font-disp:  'Clash Display', 'Cabinet Grotesk', system-ui, sans-serif;
  --cbt-font-body:  'Cabinet Grotesk', system-ui, sans-serif;
  --cbt-transition: 0.2s ease;
}

/* ── BASE RESET (scoped) ─────────────────────────────────────── */
.cbtdrill-app *,
.cbtdrill-app *::before,
.cbtdrill-app *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

.cbtdrill-app {
  font-family: var(--cbt-font-body);
  color: var(--cbt-ink);
  background: var(--cbt-surface);
  min-height: 60vh;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

/* ── SCREEN SYSTEM ───────────────────────────────────────────── */
.cbt-screen {
  display: none;
  flex-direction: column;
  min-height: 60vh;
}
.cbt-screen-active { display: flex; }

/* ── ANIMATIONS ─────────────────────────────────────────────── */
@keyframes cbt-fade-up {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes cbt-slide-q {
  from { opacity: 0; transform: translateX(20px); }
  to   { opacity: 1; transform: translateX(0); }
}
@keyframes cbt-spin {
  to { transform: rotate(360deg); }
}
@keyframes cbt-loading-bar {
  0%   { width: 0%;   margin-left: 0%; }
  50%  { width: 70%;  margin-left: 15%; }
  100% { width: 0%;   margin-left: 100%; }
}
@keyframes cbt-pulse {
  0%,100% { transform: scale(1); }
  50%      { transform: scale(1.04); }
}
@keyframes cbt-blink {
  0%,100% { opacity: 1; }
  50%      { opacity: 0.3; }
}

/* ── BUTTONS ────────────────────────────────────────────────── */
.cbt-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 20px;
  border-radius: var(--cbt-radius-sm);
  font-family: var(--cbt-font-body);
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--cbt-transition);
  border: 1.5px solid var(--cbt-border);
  background: var(--cbt-white);
  color: var(--cbt-ink);
  text-decoration: none;
  white-space: nowrap;
}
.cbt-btn:hover:not(:disabled) {
  border-color: var(--cbt-blue);
  color: var(--cbt-blue);
}
.cbt-btn:disabled {
  opacity: .5;
  cursor: not-allowed;
}
.cbt-btn-primary {
  background: var(--cbt-blue);
  color: #fff;
  border-color: var(--cbt-blue);
  box-shadow: 0 4px 14px var(--cbt-blue-glow);
}
.cbt-btn-primary:hover:not(:disabled) {
  background: var(--cbt-blue-dark);
  border-color: var(--cbt-blue-dark);
  transform: translateY(-1px);
}
.cbt-btn-orange {
  background: var(--cbt-orange);
  color: #fff;
  border-color: var(--cbt-orange);
}
.cbt-btn-orange:hover:not(:disabled) { background: #c2460a; border-color: #c2460a; }
.cbt-btn-danger {
  background: none;
  border-color: var(--cbt-red);
  color: var(--cbt-red);
}
.cbt-btn-danger:hover:not(:disabled) { background: var(--cbt-red-lt); }
.cbt-btn-sm { padding: 7px 14px; font-size: 12px; border-radius: 8px; }

/* ── CARDS ──────────────────────────────────────────────────── */
.cbt-card {
  background: var(--cbt-white);
  border: 1px solid var(--cbt-border);
  border-radius: var(--cbt-radius);
  padding: 22px;
  box-shadow: var(--cbt-shadow-sm);
  animation: cbt-fade-up 0.3s ease both;
}
.cbt-card-title {
  font-family: var(--cbt-font-disp);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.cbt-card-hint {
  font-family: var(--cbt-font-body);
  font-size: 12px;
  font-weight: 400;
  color: var(--cbt-muted);
  margin-left: 6px;
}

/* ── ALERT ──────────────────────────────────────────────────── */
.cbt-alert {
  padding: 12px 16px;
  border-radius: var(--cbt-radius-sm);
  font-size: 13px;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 10px;
  animation: cbt-fade-up 0.2s ease;
}
.cbt-alert-error   { background: var(--cbt-red-lt);   color: var(--cbt-red);   border: 1px solid rgba(220,38,38,.2); }
.cbt-alert-success { background: var(--cbt-green-lt);  color: var(--cbt-green); border: 1px solid rgba(22,163,74,.2); }
.cbt-alert-info    { background: var(--cbt-blue-lt);  color: var(--cbt-blue);  border: 1px solid rgba(21,101,255,.15); }

/* ── GUEST BANNER ───────────────────────────────────────────── */
.cbt-guest-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  background: var(--cbt-ink);
  color: rgba(255,255,255,.8);
  padding: 12px 24px;
  font-size: 13px;
  font-weight: 500;
  flex-wrap: wrap;
}
.cbt-guest-actions { display: flex; gap: 8px; }

/* ════════════════════════════════════════════════════════════
   SETUP SCREEN
════════════════════════════════════════════════════════════ */
.cbt-setup-header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 24px 24px 0;
  max-width: 740px;
  margin: 0 auto;
  width: 100%;
}
.cbt-back-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--cbt-white);
  border: 1px solid var(--cbt-border);
  border-radius: 10px;
  padding: 8px 14px;
  font-size: 13px;
  font-weight: 600;
  color: var(--cbt-muted);
  text-decoration: none;
  transition: all var(--cbt-transition);
}
.cbt-back-btn:hover { border-color: var(--cbt-blue); color: var(--cbt-blue); }
.cbt-page-title {
  font-family: var(--cbt-font-disp);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.cbt-setup-body {
  max-width: 740px;
  margin: 0 auto;
  width: 100%;
  padding: 24px 24px 80px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

/* Exam tabs */
.cbt-exam-tabs {
  display: flex;
  gap: 8px;
  background: var(--cbt-white);
  border: 1px solid var(--cbt-border);
  border-radius: var(--cbt-radius);
  padding: 7px;
}
.cbt-exam-tab {
  flex: 1;
  padding: 11px 10px;
  border: none;
  background: none;
  border-radius: 9px;
  font-family: var(--cbt-font-body);
  font-size: 13px;
  font-weight: 700;
  color: var(--cbt-muted);
  cursor: pointer;
  transition: all var(--cbt-transition);
}
.cbt-exam-tab.active {
  background: var(--cbt-ink);
  color: #fff;
  box-shadow: 0 2px 8px rgba(10,14,26,.2);
}
.cbt-exam-tab:hover:not(.active) { color: var(--cbt-ink); }

/* Subject grid */
.cbt-subject-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}
.cbt-subject-chip {
  padding: 10px 8px;
  border: 1.5px solid var(--cbt-border);
  border-radius: 10px;
  background: var(--cbt-surface);
  font-family: var(--cbt-font-body);
  font-size: 12px;
  font-weight: 600;
  color: var(--cbt-muted);
  cursor: pointer;
  transition: all 0.18s;
  text-align: left;
}
.cbt-subject-chip:hover,
.cbt-subject-chip.selected {
  border-color: var(--cbt-blue);
  background: var(--cbt-blue-lt);
  color: var(--cbt-blue);
}

/* Year grid */
.cbt-year-grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 6px;
  max-height: 130px;
  overflow-y: auto;
}
.cbt-year-chip {
  padding: 7px 4px;
  border: 1.5px solid var(--cbt-border);
  border-radius: 8px;
  background: var(--cbt-surface);
  font-size: 12px;
  font-weight: 600;
  color: var(--cbt-muted);
  cursor: pointer;
  transition: all 0.18s;
  text-align: center;
}
.cbt-year-chip:hover,
.cbt-year-chip.selected {
  border-color: var(--cbt-blue);
  background: var(--cbt-blue-lt);
  color: var(--cbt-blue);
}
.cbt-year-chip[data-year="Any"] { grid-column: 1 / -1; }

/* Options row */
.cbt-options-row {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 14px;
}
.cbt-option-group { display: flex; flex-direction: column; gap: 6px; }
.cbt-option-label {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--cbt-muted);
}
.cbt-option-select {
  padding: 11px 14px;
  border: 1.5px solid var(--cbt-border);
  border-radius: 10px;
  font-family: var(--cbt-font-body);
  font-size: 14px;
  font-weight: 600;
  color: var(--cbt-ink);
  background: var(--cbt-surface);
  outline: none;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%236B7394' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 32px;
  cursor: pointer;
  transition: border-color var(--cbt-transition);
}
.cbt-option-select:focus { border-color: var(--cbt-blue); background-color: var(--cbt-white); }

/* Trial notice */
.cbt-trial-notice {
  background: var(--cbt-orange-lt);
  border: 1px solid rgba(234,88,12,.2);
  border-radius: 10px;
  padding: 14px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  font-size: 13px;
  color: var(--cbt-orange);
  font-weight: 600;
}
.cbt-trial-notice small { display: block; font-size: 11px; opacity: .7; font-weight: 400; }

/* Start button */
.cbt-btn-start {
  width: 100%;
  padding: 16px;
  background: var(--cbt-blue);
  color: #fff;
  border: none;
  border-radius: var(--cbt-radius);
  font-family: var(--cbt-font-body);
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  transition: background var(--cbt-transition), transform var(--cbt-transition), box-shadow var(--cbt-transition);
  box-shadow: 0 4px 20px var(--cbt-blue-glow);
}
.cbt-btn-start:hover:not(:disabled) {
  background: var(--cbt-blue-dark);
  transform: translateY(-1px);
  box-shadow: 0 8px 30px var(--cbt-blue-glow);
}
.cbt-btn-start:disabled { opacity: .5; cursor: not-allowed; transform: none; box-shadow: none; }

/* ════════════════════════════════════════════════════════════
   LOADING SCREEN
════════════════════════════════════════════════════════════ */
#cbt-screen-loading {
  align-items: center;
  justify-content: center;
  gap: 18px;
  padding: 60px 20px;
}
.cbt-loading-icon {
  font-size: 52px;
  animation: cbt-pulse 1s ease-in-out infinite alternate;
}
.cbt-loading-title {
  font-family: var(--cbt-font-disp);
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.cbt-loading-sub { font-size: 13px; color: var(--cbt-muted); }
.cbt-loading-bar {
  width: 240px;
  height: 4px;
  background: var(--cbt-surface2);
  border-radius: 99px;
  overflow: hidden;
}
.cbt-loading-bar-fill {
  height: 100%;
  background: var(--cbt-blue);
  border-radius: 99px;
  animation: cbt-loading-bar 1.8s ease-in-out infinite;
}

/* ════════════════════════════════════════════════════════════
   QUIZ SCREEN
════════════════════════════════════════════════════════════ */
#cbt-screen-quiz { background: var(--cbt-surface); }

/* Topbar */
.cbt-quiz-topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--cbt-white);
  border-bottom: 1px solid var(--cbt-border);
  height: 60px;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 0 20px;
}
.cbt-quiz-meta { display: flex; align-items: center; gap: 10px; flex: 1; }
.cbt-subject-tag {
  font-size: 12px;
  font-weight: 700;
  color: var(--cbt-blue);
  background: var(--cbt-blue-lt);
  padding: 4px 12px;
  border-radius: 99px;
}
.cbt-progress-text { font-size: 12px; font-weight: 600; color: var(--cbt-muted); }

/* Timer */
.cbt-timer-wrap {
  display: flex;
  align-items: center;
  gap: 7px;
  background: var(--cbt-surface);
  border: 1.5px solid var(--cbt-border);
  border-radius: 10px;
  padding: 5px 12px;
  transition: all 0.3s;
}
.cbt-timer-wrap.cbt-timer-warning { border-color: var(--cbt-orange); background: var(--cbt-orange-lt); }
.cbt-timer-wrap.cbt-timer-danger  {
  border-color: var(--cbt-red);
  background: var(--cbt-red-lt);
  animation: cbt-pulse 0.8s ease infinite;
}
.cbt-timer-display {
  font-family: var(--cbt-font-disp);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--cbt-ink);
  min-width: 50px;
  text-align: center;
}
.cbt-timer-wrap.cbt-timer-warning .cbt-timer-display { color: var(--cbt-orange); }
.cbt-timer-wrap.cbt-timer-danger  .cbt-timer-display { color: var(--cbt-red); }

.cbt-quiz-controls { display: flex; gap: 6px; }
.cbt-icon-btn {
  background: none;
  border: 1.5px solid var(--cbt-border);
  border-radius: 8px;
  padding: 6px 10px;
  font-size: 14px;
  cursor: pointer;
  color: var(--cbt-muted);
  transition: all var(--cbt-transition);
}
.cbt-icon-btn:hover { border-color: var(--cbt-ink); color: var(--cbt-ink); }

/* Progress bar */
.cbt-progress-bar {
  height: 3px;
  background: var(--cbt-surface2);
  position: sticky;
  top: 60px;
  z-index: 49;
}
.cbt-progress-fill {
  height: 100%;
  background: var(--cbt-blue);
  transition: width 0.4s ease;
}

/* Question body */
.cbt-quiz-body {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 28px 20px 80px;
}
.cbt-question-card {
  width: 100%;
  max-width: 680px;
  background: var(--cbt-white);
  border: 1px solid var(--cbt-border);
  border-radius: 20px;
  padding: 30px;
  box-shadow: var(--cbt-shadow);
  animation: cbt-slide-q 0.28s ease both;
}
.cbt-q-number {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--cbt-muted);
  margin-bottom: 12px;
}
.cbt-q-text {
  font-size: 17px;
  font-weight: 600;
  color: var(--cbt-ink);
  line-height: 1.6;
  margin-bottom: 24px;
}

/* Options */
.cbt-options-list { display: flex; flex-direction: column; gap: 10px; margin-bottom: 24px; }
.cbt-option-btn {
  width: 100%;
  padding: 14px 18px;
  border: 1.5px solid var(--cbt-border);
  border-radius: 12px;
  background: var(--cbt-surface);
  font-family: var(--cbt-font-body);
  font-size: 14px;
  font-weight: 500;
  color: var(--cbt-ink);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 12px;
  text-align: left;
  transition: all 0.18s;
}
.cbt-option-btn:hover:not(:disabled) {
  border-color: var(--cbt-blue);
  background: var(--cbt-blue-lt);
  color: var(--cbt-blue);
}
.cbt-option-btn:disabled { cursor: default; }
.cbt-option-btn.selected { border-color: var(--cbt-blue); background: var(--cbt-blue-lt); }
.cbt-option-btn.correct  { border-color: var(--cbt-green); background: var(--cbt-green-lt); color: var(--cbt-green); }
.cbt-option-btn.wrong    { border-color: var(--cbt-red);   background: var(--cbt-red-lt);   color: var(--cbt-red); }

.cbt-option-letter {
  width: 28px; height: 28px;
  border-radius: 7px;
  background: var(--cbt-surface2);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 700;
  color: var(--cbt-muted);
  flex-shrink: 0;
  transition: all 0.18s;
}
.cbt-option-btn.selected .cbt-option-letter { background: var(--cbt-blue); color: #fff; }
.cbt-option-btn.correct  .cbt-option-letter { background: var(--cbt-green); color: #fff; }
.cbt-option-btn.wrong    .cbt-option-letter { background: var(--cbt-red);   color: #fff; }
.cbt-option-btn:hover:not(:disabled):not(.selected):not(.correct):not(.wrong) .cbt-option-letter {
  background: var(--cbt-blue); color: #fff;
}

/* Explanation */
.cbt-explanation-box {
  background: var(--cbt-surface);
  border: 1px solid var(--cbt-border);
  border-radius: 10px;
  padding: 13px 16px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--cbt-ink-soft);
  margin-top: 4px;
  margin-bottom: 20px;
  animation: cbt-fade-up 0.2s ease;
}
.cbt-explanation-box strong { color: var(--cbt-blue); }

/* Navigation */
.cbt-q-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.cbt-btn-nav {
  padding: 11px 22px;
  border-radius: 10px;
  font-family: var(--cbt-font-body);
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--cbt-transition);
  border: 1.5px solid var(--cbt-border);
  background: var(--cbt-white);
  color: var(--cbt-muted);
}
.cbt-btn-nav:hover:not(:disabled) { border-color: var(--cbt-ink); color: var(--cbt-ink); }
.cbt-btn-nav:disabled { opacity: .3; cursor: not-allowed; }
.cbt-btn-nav.cbt-btn-primary { background: var(--cbt-blue); color: #fff; border-color: var(--cbt-blue); box-shadow: 0 4px 12px var(--cbt-blue-glow); }
.cbt-btn-nav.cbt-btn-finish  { background: var(--cbt-green); color: #fff; border-color: var(--cbt-green); box-shadow: 0 4px 12px rgba(22,163,74,.25); }

.cbt-q-dots {
  display: flex;
  gap: 5px;
  flex-wrap: wrap;
  justify-content: center;
  flex: 1;
}
.cbt-q-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--cbt-surface2);
  transition: all 0.2s;
  cursor: pointer;
}
.cbt-q-dot.answered { background: var(--cbt-blue); }
.cbt-q-dot.current  { background: var(--cbt-blue); transform: scale(1.45); }
.cbt-q-dot.correct  { background: var(--cbt-green); }
.cbt-q-dot.wrong    { background: var(--cbt-red); }

/* ── PAUSE OVERLAY ───────────────────────────────────────────── */
.cbt-pause-overlay {
  position: fixed;
  inset: 0;
  background: rgba(10,14,26,.82);
  backdrop-filter: blur(8px);
  z-index: 200;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}
.cbt-pause-card {
  background: var(--cbt-white);
  border-radius: 20px;
  padding: 40px 44px;
  text-align: center;
  box-shadow: var(--cbt-shadow-lg);
  animation: cbt-fade-up 0.2s ease;
}
.cbt-pause-icon  { font-size: 44px; margin-bottom: 12px; }
.cbt-pause-title { font-family: var(--cbt-font-disp); font-size: 22px; font-weight: 700; margin-bottom: 6px; }
.cbt-pause-sub   { font-size: 13px; color: var(--cbt-muted); margin-bottom: 22px; }
.cbt-pause-btns  { display: flex; gap: 12px; justify-content: center; }

/* ── CALCULATOR ──────────────────────────────────────────────── */
.cbt-calc-modal {
  position: fixed;
  bottom: 24px;
  right: 20px;
  width: 296px;
  background: #1a1d2e;
  border-radius: 20px;
  box-shadow: 0 20px 60px rgba(10,14,26,.55);
  z-index: 100;
  flex-direction: column;
  overflow: hidden;
  animation: cbt-fade-up 0.22s ease;
  user-select: none;
}
/* display:none/flex toggled by JS */

.cbt-calc-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 14px 8px;
}
.cbt-calc-mode-tabs {
  display: flex;
  background: rgba(255,255,255,.07);
  border-radius: 8px;
  padding: 3px;
  gap: 2px;
}
.cbt-calc-tab {
  padding: 5px 13px;
  border: none;
  background: none;
  border-radius: 6px;
  font-family: var(--cbt-font-body);
  font-size: 11px;
  font-weight: 700;
  color: rgba(255,255,255,.4);
  cursor: pointer;
  transition: all 0.2s;
}
.cbt-calc-tab.active { background: var(--cbt-blue); color: #fff; }
.cbt-calc-close {
  background: rgba(255,255,255,.08);
  border: none;
  border-radius: 8px;
  width: 28px; height: 28px;
  color: rgba(255,255,255,.5);
  font-size: 14px;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: all 0.2s;
}
.cbt-calc-close:hover { background: rgba(255,255,255,.15); color: #fff; }

.cbt-calc-display { padding: 6px 16px 12px; text-align: right; border-bottom: 1px solid rgba(255,255,255,.06); }
.cbt-calc-expr  { font-size: 11px; color: rgba(255,255,255,.3); min-height: 16px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.cbt-calc-value {
  font-family: var(--cbt-font-disp);
  font-size: 30px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: #fff;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  transition: color 0.2s;
}
.cbt-calc-value.error { color: var(--cbt-red); font-size: 14px; padding-top: 8px; }

.cbt-calc-sci-rows  { padding: 8px 10px 0; flex-direction: column; gap: 4px; }
.cbt-calc-basic-rows{ padding: 8px 10px 12px; display: flex; flex-direction: column; gap: 4px; }
.cbt-calc-row       { display: flex; gap: 4px; }

.cbt-cb {
  flex: 1;
  height: 50px;
  border: none;
  border-radius: 10px;
  font-family: var(--cbt-font-body);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  background: rgba(255,255,255,.08);
  color: #fff;
  transition: background 0.15s, transform 0.1s;
  display: flex; align-items: center; justify-content: center;
}
.cbt-cb:hover  { background: rgba(255,255,255,.14); }
.cbt-cb:active { transform: scale(0.93); }
.cbt-cb-op    { background: rgba(21,101,255,.25); color: var(--cbt-blue); }
.cbt-cb-op:hover { background: rgba(21,101,255,.4); }
.cbt-cb-eq    { background: var(--cbt-blue); flex: 1; }
.cbt-cb-eq:hover { background: var(--cbt-blue-dark); }
.cbt-cb-clear { background: rgba(220,38,38,.2); color: #f87171; }
.cbt-cb-clear:hover { background: rgba(220,38,38,.35); }
.cbt-cb-gray  { background: rgba(255,255,255,.05); color: rgba(255,255,255,.6); }
.cbt-cb-fn    { height: 40px; font-size: 11px; background: rgba(124,58,237,.2); color: #c4b5fd; border-radius: 8px; }
.cbt-cb-fn:hover { background: rgba(124,58,237,.35); }
.cbt-cb-zero  { flex: 2; }

/* ════════════════════════════════════════════════════════════
   RESULTS SCREEN
════════════════════════════════════════════════════════════ */
#cbt-screen-results { align-items: center; padding: 40px 20px 80px; }
.cbt-results-wrap   { width: 100%; max-width: 640px; display: flex; flex-direction: column; gap: 18px; }

.cbt-score-hero {
  background: var(--cbt-white);
  border: 1px solid var(--cbt-border);
  border-radius: 22px;
  padding: 36px 28px;
  text-align: center;
  box-shadow: var(--cbt-shadow);
  position: relative;
  overflow: hidden;
  animation: cbt-fade-up 0.4s ease both;
}
.cbt-score-hero::before {
  content: '';
  position: absolute; top: -60px; left: -60px;
  width: 220px; height: 220px; border-radius: 50%;
  background: radial-gradient(circle, var(--cbt-blue-glow), transparent 70%);
  pointer-events: none;
}
.cbt-score-grade {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: 8px;
}
.cbt-score-grade.grade-A { color: var(--cbt-green); }
.cbt-score-grade.grade-B { color: var(--cbt-blue); }
.cbt-score-grade.grade-C { color: var(--cbt-yellow); }
.cbt-score-grade.grade-D { color: var(--cbt-orange); }
.cbt-score-grade.grade-F { color: var(--cbt-red); }

.cbt-score-circle {
  width: 126px; height: 126px;
  margin: 0 auto 14px;
  position: relative;
}
.cbt-score-circle svg { width: 126px; height: 126px; transform: rotate(-90deg); }
.cbt-arc-bg   { fill: none; stroke: var(--cbt-surface2); stroke-width: 10; }
.cbt-arc-fill { fill: none; stroke-width: 10; stroke-linecap: round; transition: stroke-dashoffset 1.2s cubic-bezier(.4,0,.2,1); }
.cbt-score-circle-text {
  position: absolute; inset: 0;
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
}
.cbt-score-pct  { font-family: var(--cbt-font-disp); font-size: 30px; font-weight: 700; letter-spacing: -.04em; line-height: 1; }
.cbt-score-frac { font-size: 11px; color: var(--cbt-muted); margin-top: 3px; }
.cbt-score-title{ font-family: var(--cbt-font-disp); font-size: 20px; font-weight: 700; margin-bottom: 3px; }
.cbt-score-sub  { font-size: 13px; color: var(--cbt-muted); }

.cbt-result-chips {
  display: grid;
  grid-template-columns: repeat(3,1fr);
  gap: 10px;
  margin-top: 20px;
}
.cbt-result-chip { background: var(--cbt-surface); border-radius: 10px; padding: 12px; text-align: center; }
.cbt-chip-val   { font-family: var(--cbt-font-disp); font-size: 20px; font-weight: 700; letter-spacing: -.02em; display: block; }
.cbt-chip-label { font-size: 11px; color: var(--cbt-muted); margin-top: 2px; display: block; }

.cbt-paywall-strip {
  background: var(--cbt-ink);
  border-radius: var(--cbt-radius);
  padding: 18px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  color: rgba(255,255,255,.7);
  font-size: 13px;
}
.cbt-paywall-strip strong { color: #fff; }

.cbt-result-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

/* Review */
.cbt-review-card {
  background: var(--cbt-white);
  border: 1px solid var(--cbt-border);
  border-radius: var(--cbt-radius);
  overflow: hidden;
  box-shadow: var(--cbt-shadow-sm);
}
.cbt-review-header {
  padding: 14px 18px;
  border-bottom: 1px solid var(--cbt-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}
.cbt-review-header h3 { font-family: var(--cbt-font-disp); font-size: 14px; font-weight: 700; }
.cbt-review-filter { display: flex; gap: 5px; }
.cbt-filter-btn {
  padding: 4px 12px;
  border-radius: 99px;
  border: 1.5px solid var(--cbt-border);
  background: none;
  font-family: var(--cbt-font-body);
  font-size: 11px;
  font-weight: 700;
  color: var(--cbt-muted);
  cursor: pointer;
  transition: all 0.2s;
}
.cbt-filter-btn.active { background: var(--cbt-ink); border-color: var(--cbt-ink); color: #fff; }
.cbt-filter-btn:hover:not(.active) { border-color: var(--cbt-ink); color: var(--cbt-ink); }

.cbt-review-list { max-height: 460px; overflow-y: auto; }
.cbt-review-item {
  padding: 14px 18px;
  border-bottom: 1px solid var(--cbt-surface2);
  display: flex;
  gap: 12px;
  align-items: flex-start;
}
.cbt-review-item:last-child { border-bottom: none; }
.cbt-review-status {
  width: 22px; height: 22px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 11px; flex-shrink: 0; margin-top: 1px;
}
.cbt-review-status.correct { background: var(--cbt-green-lt); color: var(--cbt-green); }
.cbt-review-status.wrong   { background: var(--cbt-red-lt);   color: var(--cbt-red); }
.cbt-review-status.skipped { background: var(--cbt-surface2); color: var(--cbt-muted); }
.cbt-review-content { flex: 1; }
.cbt-review-q { font-size: 13px; font-weight: 600; line-height: 1.5; margin-bottom: 6px; }
.cbt-review-answer-row {
  font-size: 12px; color: var(--cbt-muted);
  display: flex; gap: 6px; margin-bottom: 2px;
}
.cbt-review-answer-row .cbt-tag-correct { color: var(--cbt-green); font-weight: 700; }
.cbt-review-answer-row .cbt-tag-wrong   { color: var(--cbt-red);   font-weight: 700; }

/* ════════════════════════════════════════════════════════════
   RESPONSIVE
════════════════════════════════════════════════════════════ */
@media (max-width: 600px) {
  .cbt-subject-grid   { grid-template-columns: repeat(2, 1fr); }
  .cbt-options-row    { grid-template-columns: 1fr 1fr; }
  .cbt-year-grid      { grid-template-columns: repeat(4, 1fr); }
  .cbt-question-card  { padding: 20px 16px; }
  .cbt-q-text         { font-size: 15px; }
  .cbt-result-actions { grid-template-columns: 1fr; }
  .cbt-calc-modal     { right: 10px; width: calc(100vw - 20px); bottom: 14px; }
  .cbt-quiz-topbar    { padding: 0 12px; gap: 8px; }
  .cbt-setup-header   { padding: 16px 16px 0; }
  .cbt-setup-body     { padding: 16px 16px 60px; }
}
@media (max-width: 380px) {
  .cbt-exam-tabs    { flex-wrap: wrap; }
  .cbt-options-row  { grid-template-columns: 1fr; }
}