/* ================================================================
   MathTutor — Student UI  |  Bright & playful · Teal + Green
   ================================================================ */

/* ── Tokens ─────────────────────────────────────────────────────── */
:root {
  --mt-teal:        #0ea5a0;
  --mt-teal-dk:     #0c8a86;
  --mt-teal-lt:     #e0f7f6;
  --mt-teal-mid:    #5dcdc9;
  --mt-green:       #22c55e;
  --mt-green-lt:    #dcfce7;
  --mt-green-dk:    #16a34a;
  --mt-amber:       #f59e0b;
  --mt-amber-lt:    #fef9c3;
  --mt-coral:       #f87171;
  --mt-coral-lt:    #fef2f2;
  --mt-purple-lt:   #f3e8ff;
  --mt-purple:      #9333ea;
  --mt-text:        #0f172a;
  --mt-muted:       #64748b;
  --mt-border:      #cdf0ee;
  --mt-bg:          #f0faf9;
  --mt-card:        #ffffff;
  --mt-radius-sm:   10px;
  --mt-radius-md:   16px;
  --mt-radius-lg:   24px;
  --mt-radius-pill: 100px;
  --mt-font:        -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

/* ── Reset ──────────────────────────────────────────────────────── */
.mt-wrap *, .mt-wrap *::before, .mt-wrap *::after { box-sizing: border-box; }
.mt-wrap { font-family: var(--mt-font); color: var(--mt-text); background: var(--mt-bg); border-radius: var(--mt-radius-lg); padding: 20px; max-width: 860px; margin: 0 auto; }

/* ── Screens ────────────────────────────────────────────────────── */
.mt-screen { display: none; }
.mt-screen.mt-active { display: block; }

/* ── Top bar ────────────────────────────────────────────────────── */
.mt-topbar {
  display: flex; justify-content: space-between; align-items: center;
  margin-bottom: 18px;
}
.mt-topbar-left { display: flex; align-items: center; gap: 8px; }
.mt-logo-mark { font-size: 20px; color: var(--mt-teal); font-weight: 900; }
.mt-greeting { font-size: 18px; font-weight: 700; color: var(--mt-text); }
.mt-topbar-right { display: flex; gap: 8px; }

.mt-streak-badge, .mt-xp-badge {
  background: var(--mt-card); border: 1.5px solid var(--mt-border);
  border-radius: var(--mt-radius-pill); padding: 5px 14px;
  font-size: 13px; font-weight: 700; color: var(--mt-teal);
}

/* ── Stat strip ─────────────────────────────────────────────────── */
.mt-stat-strip {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px;
  margin-bottom: 20px;
}
.mt-stat-card {
  background: var(--mt-card); border-radius: var(--mt-radius-md);
  border: 1.5px solid var(--mt-border); padding: 14px 12px;
  text-align: center; display: flex; flex-direction: column; align-items: center; gap: 3px;
}
.mt-stat-icon { font-size: 22px; line-height: 1; }
.mt-stat-val { font-size: 24px; font-weight: 900; color: var(--mt-teal); line-height: 1.1; }
.mt-stat-val.mt-green  { color: var(--mt-green-dk); }
.mt-stat-val.mt-amber  { color: var(--mt-amber); }
.mt-stat-label { font-size: 11px; font-weight: 600; color: var(--mt-muted); text-transform: uppercase; letter-spacing: .05em; }

/* ── Start screen ───────────────────────────────────────────────── */
.mt-start-card {
  background: var(--mt-card); border-radius: var(--mt-radius-lg);
  border: 1.5px solid var(--mt-border); padding: 40px 32px;
  text-align: center; max-width: 520px; margin: 0 auto;
}
.mt-start-hero { margin-bottom: 28px; }
.mt-start-emoji { font-size: 56px; line-height: 1; margin-bottom: 12px; }
.mt-start-title { font-size: 26px; font-weight: 800; color: var(--mt-text); margin: 0 0 6px; }
.mt-start-sub   { font-size: 15px; color: var(--mt-muted); margin: 0; }

.mt-subject-toggle { display: flex; gap: 8px; justify-content: center; flex-wrap: wrap; margin-bottom: 28px; }
.mt-toggle-option input[type="radio"] { display: none; }
.mt-toggle-pill {
  display: block; padding: 9px 20px; border-radius: var(--mt-radius-pill);
  border: 2px solid var(--mt-border); background: var(--mt-card);
  font-size: 14px; font-weight: 600; cursor: pointer; color: var(--mt-muted);
  transition: all .15s;
}
.mt-toggle-option input:checked + .mt-toggle-pill {
  background: var(--mt-teal); border-color: var(--mt-teal); color: #fff;
}
.mt-toggle-option:hover .mt-toggle-pill { border-color: var(--mt-teal); color: var(--mt-teal); }

/* ── Buttons ────────────────────────────────────────────────────── */
.mt-btn {
  display: inline-flex; align-items: center; justify-content: center;
  gap: 6px; padding: 10px 22px; border-radius: var(--mt-radius-pill);
  border: none; font-size: 14px; font-weight: 700; cursor: pointer;
  transition: transform .12s, background .15s, box-shadow .15s;
  font-family: var(--mt-font);
}
.mt-btn:active:not(:disabled) { transform: scale(.96); }
.mt-btn:disabled { opacity: .45; cursor: not-allowed; }

.mt-btn-primary { background: var(--mt-teal); color: #fff; }
.mt-btn-primary:hover:not(:disabled) { background: var(--mt-teal-dk); }

.mt-btn-hint {
  background: var(--mt-amber-lt); color: #92400e;
  border: 2px solid #fde68a;
}
.mt-btn-hint:hover:not(:disabled) { background: #fde68a; }

.mt-btn-lg { font-size: 16px; padding: 14px 32px; }

/* ── Practice layout ────────────────────────────────────────────── */
.mt-practice-layout {
  display: grid; grid-template-columns: 1fr 260px; gap: 16px; align-items: start;
}

/* ── Problem card ───────────────────────────────────────────────── */
.mt-problem-card {
  background: var(--mt-card); border-radius: var(--mt-radius-lg);
  border: 1.5px solid var(--mt-border); overflow: hidden;
}
.mt-card-header {
  background: var(--mt-teal); padding: 13px 20px;
  display: flex; justify-content: space-between; align-items: center;
}
.mt-topic-tag {
  color: #fff; font-size: 12px; font-weight: 700;
  text-transform: uppercase; letter-spacing: .07em; opacity: .95;
}
.mt-diff-dots { display: flex; gap: 4px; align-items: center; }
.mt-diff-dot {
  width: 8px; height: 8px; border-radius: 50%;
  background: rgba(255,255,255,.3); transition: background .2s;
}
.mt-diff-dot.mt-filled { background: #fff; }

.mt-progress-row {
  display: flex; align-items: center; gap: 10px;
  padding: 14px 20px 0; 
}
.mt-progress-track {
  flex: 1; height: 7px; background: var(--mt-teal-lt);
  border-radius: 4px; overflow: hidden;
}
.mt-progress-fill {
  height: 100%; background: var(--mt-teal);
  border-radius: 4px; transition: width .4s cubic-bezier(.4,0,.2,1);
  width: 0%;
}
.mt-prog-label { font-size: 12px; font-weight: 700; color: var(--mt-muted); white-space: nowrap; }

.mt-problem-body { padding: 22px 20px 20px; }
.mt-question {
  font-size: 19px; font-weight: 600; line-height: 1.55;
  color: var(--mt-text); margin-bottom: 22px; min-height: 52px;
}

/* ── Multiple choice ────────────────────────────────────────────── */
.mt-choices { display: grid; grid-template-columns: 1fr 1fr; gap: 9px; margin-bottom: 18px; }
.mt-choice {
  padding: 12px 16px; border-radius: var(--mt-radius-sm);
  border: 2px solid var(--mt-border); background: var(--mt-card);
  font-size: 14px; font-weight: 500; cursor: pointer;
  text-align: left; color: var(--mt-text);
  transition: border-color .15s, background .15s, color .15s;
  font-family: var(--mt-font); line-height: 1.4;
}
.mt-choice:hover:not(:disabled) { border-color: var(--mt-teal); background: var(--mt-teal-lt); }
.mt-choice.selected  { border-color: var(--mt-teal); background: var(--mt-teal-lt); color: var(--mt-teal-dk); font-weight: 700; }
.mt-choice.correct   { border-color: var(--mt-green); background: var(--mt-green-lt); color: var(--mt-green-dk); font-weight: 700; }
.mt-choice.wrong     { border-color: var(--mt-coral); background: var(--mt-coral-lt); color: #dc2626; font-weight: 700; }

/* ── Numeric input ──────────────────────────────────────────────── */
.mt-input-wrap { margin-bottom: 18px; }
.mt-answer-input {
  width: 100%; padding: 13px 18px; font-size: 18px; font-weight: 600;
  border: 2px solid var(--mt-border); border-radius: var(--mt-radius-sm);
  outline: none; color: var(--mt-text); background: #fff;
  transition: border-color .15s; font-family: var(--mt-font);
}
.mt-answer-input:focus { border-color: var(--mt-teal); background: var(--mt-teal-lt); }
.mt-answer-input::placeholder { color: #94a3b8; font-weight: 400; }

.mt-action-row { display: flex; gap: 10px; justify-content: space-between; align-items: center; }

/* ── Hint drawer ────────────────────────────────────────────────── */
.mt-hint-drawer {
  background: var(--mt-amber-lt); border: 1.5px solid #fde68a;
  border-radius: var(--mt-radius-md); padding: 16px 18px; margin-top: 12px;
}
.mt-hint-tabs { display: flex; gap: 6px; margin-bottom: 12px; }
.mt-hint-tab {
  padding: 5px 14px; border-radius: var(--mt-radius-pill);
  border: 1.5px solid #fcd34d; background: transparent;
  font-size: 12px; font-weight: 700; cursor: pointer; color: #92400e;
  font-family: var(--mt-font); transition: all .15s;
}
.mt-hint-tab.mt-active { background: var(--mt-amber); border-color: var(--mt-amber); color: #fff; }
.mt-hint-text { font-size: 14px; line-height: 1.7; color: #78350f; }

/* ── Feedback ───────────────────────────────────────────────────── */
.mt-feedback { margin-top: 12px; }
.mt-feedback-inner {
  display: flex; gap: 14px; align-items: flex-start;
  border-radius: var(--mt-radius-md); padding: 16px 18px; margin-bottom: 12px;
}
.mt-feedback-inner.mt-correct { background: var(--mt-green-lt); border: 1.5px solid #86efac; }
.mt-feedback-inner.mt-wrong   { background: var(--mt-coral-lt);  border: 1.5px solid #fca5a5; }
.mt-feedback-icon { font-size: 24px; line-height: 1; flex-shrink: 0; margin-top: 1px; }
.mt-feedback-message { font-size: 15px; font-weight: 700; color: var(--mt-text); margin-bottom: 4px; }
.mt-solution-steps { font-size: 13px; color: var(--mt-muted); line-height: 1.7; }
.mt-solution-steps ol { margin: 6px 0 0 18px; padding: 0; }
.mt-solution-steps li { margin-bottom: 3px; }
.mt-steps-head { font-weight: 700; color: var(--mt-text); margin-bottom: 4px; }

/* ── Sidebar ────────────────────────────────────────────────────── */
.mt-sidebar { display: flex; flex-direction: column; gap: 12px; }

.mt-xp-card {
  background: var(--mt-teal); border-radius: var(--mt-radius-lg);
  padding: 18px 18px 16px; color: #fff;
}
.mt-xp-top { display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px; }
.mt-xp-label { font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: .07em; opacity: .8; }
.mt-streak-mini {
  background: rgba(255,255,255,.2); border-radius: var(--mt-radius-pill);
  padding: 3px 10px; font-size: 12px; font-weight: 700;
}
.mt-xp-val { font-size: 34px; font-weight: 900; letter-spacing: -1px; line-height: 1; margin-bottom: 10px; }
.mt-xp-bar-track { height: 5px; background: rgba(255,255,255,.25); border-radius: 3px; overflow: hidden; }
.mt-xp-bar-fill  { height: 100%; background: #fff; border-radius: 3px; width: 0%; transition: width .6s ease; }

.mt-map-card {
  background: var(--mt-card); border-radius: var(--mt-radius-md);
  border: 1.5px solid var(--mt-border); padding: 14px 16px;
}
.mt-map-card-full { border-radius: var(--mt-radius-lg); padding: 18px 20px; }
.mt-map-title {
  font-size: 11px; font-weight: 800; text-transform: uppercase;
  letter-spacing: .07em; color: var(--mt-teal); margin-bottom: 10px;
}
.mt-map-grid { display: flex; flex-wrap: wrap; gap: 5px; }

/* ── Topic pills ────────────────────────────────────────────────── */
.mt-pill {
  display: inline-block; padding: 5px 11px;
  border-radius: var(--mt-radius-pill); font-size: 12px; font-weight: 600;
  text-transform: capitalize; line-height: 1.3;
}
.mt-locked      { background: #f1f5f9; color: #94a3b8; }
.mt-available   { background: var(--mt-teal-lt); color: var(--mt-teal-dk); }
.mt-in-progress { background: var(--mt-amber-lt); color: #92400e; }
.mt-mastered    { background: var(--mt-green-lt); color: var(--mt-green-dk); }

/* ── Dashboard ──────────────────────────────────────────────────── */
.mt-dash-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-bottom: 16px; }
.mt-legend-row { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 24px; }
.mt-dash-actions { text-align: center; }

/* ── Session complete ───────────────────────────────────────────── */
.mt-complete-card {
  position: relative; overflow: hidden;
  background: var(--mt-card); border-radius: var(--mt-radius-lg);
  border: 1.5px solid var(--mt-border); min-height: 360px;
  display: flex; align-items: center; justify-content: center;
}
.mt-complete-inner { text-align: center; padding: 40px 24px; position: relative; z-index: 2; }
.mt-complete-emoji { font-size: 64px; line-height: 1; margin-bottom: 10px; display: block; }
.mt-complete-title { font-size: 28px; font-weight: 900; color: var(--mt-text); margin: 0 0 6px; }
.mt-complete-sub   { font-size: 15px; color: var(--mt-muted); margin: 0 0 28px; }

.mt-complete-stats {
  display: flex; justify-content: center; align-items: center;
  gap: 0; margin-bottom: 28px;
  background: var(--mt-teal-lt); border-radius: var(--mt-radius-lg); padding: 18px 28px;
  display: inline-flex;
}
.mt-cstat { text-align: center; padding: 0 24px; }
.mt-cstat-val   { display: block; font-size: 32px; font-weight: 900; color: var(--mt-teal); line-height: 1; }
.mt-cstat-val.mt-green { color: var(--mt-green-dk); }
.mt-cstat-label { display: block; font-size: 11px; font-weight: 700; color: var(--mt-muted); text-transform: uppercase; letter-spacing: .05em; margin-top: 4px; }
.mt-cstat-divider { width: 1.5px; height: 40px; background: var(--mt-border); }

/* ── Responsive ─────────────────────────────────────────────────── */
@media (max-width: 620px) {
  .mt-wrap { padding: 14px; border-radius: var(--mt-radius-md); }
  .mt-practice-layout { grid-template-columns: 1fr; }
  .mt-sidebar { display: none; }
  .mt-stat-strip { grid-template-columns: repeat(2, 1fr); }
  .mt-choices { grid-template-columns: 1fr; }
  .mt-dash-grid { grid-template-columns: 1fr; }
  .mt-start-card { padding: 28px 20px; }
  .mt-topbar-right { display: none; }
  .mt-complete-stats { padding: 14px 16px; }
  .mt-cstat { padding: 0 14px; }
  .mt-cstat-val { font-size: 24px; }
}