/* =========================================================================
   MATH 151 Exam I Trainer - stylesheet
   Graph-paper / study-desk aesthetic: deep navy, mint accent, amber rewards.
   ========================================================================= */

:root {
  --bg:        #0b1220;
  --bg-2:      #0e1729;
  --panel:     #121e33;
  --panel-2:   #16243c;
  --line:      #22334f;
  --line-soft: #1b2a44;
  --ink:       #e8eef7;
  --ink-dim:   #9fb0c7;
  --ink-faint: #6b7f99;
  --mint:      #4fd1a5;
  --mint-dim:  #2c8f72;
  --amber:     #f5b954;
  --rose:      #ef6b7a;
  --blue:      #6aa9ff;
  --violet:    #a78bfa;
  --radius:    16px;
  --radius-sm: 10px;
  --shadow:    0 10px 30px rgba(0, 0, 0, .35);
  --font:      'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --mono:      'JetBrains Mono', 'SFMono-Regular', Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
  font-family: var(--font);
  color: var(--ink);
  background-color: var(--bg);
  background-image:
    linear-gradient(rgba(255, 255, 255, .022) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, .022) 1px, transparent 1px),
    radial-gradient(1100px 600px at 12% -8%, rgba(79, 209, 165, .10), transparent 60%),
    radial-gradient(900px 500px at 92% 0%, rgba(106, 169, 255, .10), transparent 55%);
  background-size: 26px 26px, 26px 26px, auto, auto;
  min-height: 100vh;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

/* ------------------------------- top bar -------------------------------- */
.topbar {
  position: sticky; top: 0; z-index: 40;
  background: rgba(11, 18, 32, .82);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line-soft);
}
.topbar-inner {
  max-width: 1180px; margin: 0 auto;
  padding: 12px 22px;
  display: flex; align-items: center; gap: 22px;
}
.brand {
  display: flex; align-items: center; gap: 12px;
  background: none; border: 0; color: inherit; cursor: pointer;
  padding: 4px 6px; border-radius: var(--radius-sm);
}
.brand:hover { background: rgba(255, 255, 255, .05); }
.brand-mark {
  width: 40px; height: 40px; flex: 0 0 40px;
  display: grid; place-items: center;
  font-size: 24px; font-weight: 700;
  color: var(--bg);
  background: linear-gradient(140deg, var(--mint), #7ee7c4);
  border-radius: 12px;
}
.brand-text { display: flex; flex-direction: column; text-align: left; }
.brand-text strong { font-size: 15px; letter-spacing: -.01em; }
.brand-text small { font-size: 11.5px; color: var(--ink-faint); }

.hud { margin-left: auto; display: flex; align-items: center; gap: 26px; flex-wrap: wrap; }
.hud-item { display: flex; flex-direction: column; line-height: 1.25; }
.hud-key { font-size: 12px; color: var(--ink-dim); }
.hud-key b { color: var(--ink); font-size: 14px; }
.hud-sub { font-size: 11px; color: var(--ink-faint); }
.hud-sub b { color: var(--mint); }
.hud-xp { display: flex; flex-direction: column; gap: 4px; min-width: 130px; }
.hud-xp-track {
  height: 7px; border-radius: 99px;
  background: #1a2a44; overflow: hidden;
}
.hud-xp-track i {
  display: block; height: 100%; width: 0%;
  background: linear-gradient(90deg, var(--mint), var(--blue));
  transition: width .45s cubic-bezier(.2, .8, .2, 1);
}
.hud-xp span { font-size: 11px; color: var(--ink-dim); }

/* -------------------------------- layout -------------------------------- */
main { max-width: 1180px; margin: 0 auto; padding: 34px 22px 80px; }

.screen { display: none; animation: rise .35s ease both; }
.screen.active { display: block; }

@keyframes rise {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: none; }
}

/* --------------------------------- hero --------------------------------- */
.hero { text-align: center; padding: 26px 0 34px; }
.eyebrow {
  display: inline-block; margin: 0 0 14px;
  font-size: 12px; letter-spacing: .14em; text-transform: uppercase;
  color: var(--mint); border: 1px solid rgba(79, 209, 165, .35);
  background: rgba(79, 209, 165, .08);
  padding: 6px 14px; border-radius: 99px;
}
.hero h1 {
  margin: 0 0 14px;
  font-size: clamp(34px, 5.4vw, 58px);
  line-height: 1.05; letter-spacing: -.03em;
  background: linear-gradient(120deg, #ffffff 20%, var(--mint) 90%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.lede {
  max-width: 640px; margin: 0 auto;
  color: var(--ink-dim); font-size: 16.5px;
}
.hero-actions {
  margin-top: 26px; display: flex; gap: 14px;
  justify-content: center; flex-wrap: wrap;
}

/* -------------------------------- buttons ------------------------------- */
.btn {
  font: inherit; font-weight: 600; cursor: pointer;
  border-radius: 12px; border: 1px solid transparent;
  padding: 11px 20px; transition: transform .12s ease, background .2s, border-color .2s, box-shadow .2s;
}
.btn:active { transform: translateY(1px); }
.btn-primary {
  background: linear-gradient(140deg, var(--mint), #6fe0bb);
  color: #062018;
  box-shadow: 0 6px 20px rgba(79, 209, 165, .22);
}
.btn-primary:hover { box-shadow: 0 8px 26px rgba(79, 209, 165, .34); }
.btn-primary:disabled {
  background: #1c2c45; color: var(--ink-faint);
  box-shadow: none; cursor: not-allowed;
}
.btn-ghost {
  background: rgba(255, 255, 255, .04);
  border-color: var(--line); color: var(--ink);
}
.btn-ghost:hover { background: rgba(255, 255, 255, .09); }
.btn-lg { padding: 14px 26px; font-size: 16px; }
.btn-sm { padding: 7px 13px; font-size: 13px; }
.link-btn {
  background: none; border: 0; color: var(--ink-faint);
  font: inherit; text-decoration: underline; cursor: pointer;
}
.link-btn:hover { color: var(--rose); }

/* ------------------------------ mode cards ------------------------------ */
.mode-grid {
  display: grid; gap: 16px; margin: 8px 0 30px;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}
.mode-card {
  position: relative; overflow: hidden;
  display: flex; flex-direction: column; gap: 8px;
  text-align: left; cursor: pointer; font: inherit; color: inherit;
  background: linear-gradient(165deg, var(--panel), var(--bg-2));
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
  transition: transform .18s ease, border-color .2s, box-shadow .2s;
}
.mode-card:hover {
  transform: translateY(-3px);
  border-color: rgba(79, 209, 165, .45);
  box-shadow: var(--shadow);
}
.mode-card.accent { border-color: rgba(245, 185, 84, .4); }
.mode-card.accent:hover { border-color: rgba(245, 185, 84, .8); }
.mode-icon { font-size: 26px; }
.mode-name { font-size: 18px; font-weight: 700; letter-spacing: -.01em; }
.mode-desc { font-size: 13.5px; color: var(--ink-dim); }
.mode-meta {
  margin-top: auto; padding-top: 10px;
  font-size: 11px; letter-spacing: .1em; text-transform: uppercase;
  color: var(--ink-faint);
}

/* ------------------------------- home cols ------------------------------ */
.home-cols {
  display: grid; gap: 18px;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
}
.panel {
  background: linear-gradient(170deg, var(--panel), var(--bg-2));
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
}
.panel h2 { margin: 0 0 4px; font-size: 17px; }
.panel-sub { margin: 0 0 16px; font-size: 13px; color: var(--ink-faint); }

.weak-list { display: flex; flex-direction: column; gap: 8px; }
.weak-row {
  display: grid; grid-template-columns: 42px 1fr 90px 42px;
  align-items: center; gap: 10px;
  background: rgba(255, 255, 255, .03);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-sm);
  padding: 10px 12px; cursor: pointer;
  font: inherit; color: inherit; text-align: left;
}
.weak-row:hover { border-color: rgba(79, 209, 165, .5); background: rgba(79, 209, 165, .06); }
.weak-id { font-family: var(--mono); font-size: 12px; color: var(--mint); }
.weak-name { font-size: 13.5px; }
.weak-bar { height: 6px; background: #1a2a44; border-radius: 99px; overflow: hidden; }
.weak-bar i { display: block; height: 100%; background: linear-gradient(90deg, var(--rose), var(--amber)); }
.weak-pct { font-size: 12px; color: var(--ink-dim); text-align: right; }

.badge-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(120px, 1fr)); gap: 10px; }
.badge {
  display: flex; flex-direction: column; align-items: center; gap: 6px;
  padding: 14px 8px; border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, .025);
  border: 1px solid var(--line-soft);
  filter: grayscale(1); opacity: .42;
}
.badge.owned {
  filter: none; opacity: 1;
  border-color: rgba(245, 185, 84, .45);
  background: rgba(245, 185, 84, .08);
}
.badge-icon { font-size: 22px; }
.badge-name { font-size: 11px; text-align: center; color: var(--ink-dim); }

.foot-note {
  margin-top: 28px; display: flex; gap: 14px;
  justify-content: center; align-items: center;
  font-size: 12px; color: var(--ink-faint);
}

/* ------------------------------ screen head ----------------------------- */
.screen-head { margin-bottom: 24px; }
.screen-head h2 { margin: 14px 0 6px; font-size: 26px; letter-spacing: -.02em; }
.screen-head p { margin: 0; color: var(--ink-dim); font-size: 14.5px; max-width: 720px; }

/* ------------------------------ topic grid ------------------------------ */
.topic-grid {
  display: grid; gap: 14px;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}
.topic-card {
  text-align: left; font: inherit; color: inherit; cursor: pointer;
  background: linear-gradient(168deg, var(--panel), var(--bg-2));
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
  display: flex; flex-direction: column; gap: 10px;
  transition: transform .16s ease, border-color .2s, box-shadow .2s;
}
.topic-card:hover {
  transform: translateY(-3px);
  border-color: rgba(79, 209, 165, .45);
  box-shadow: var(--shadow);
}
.topic-top { display: flex; align-items: center; gap: 10px; }
.topic-icon {
  width: 34px; height: 34px; flex: 0 0 34px;
  display: grid; place-items: center;
  font-size: 13px; font-weight: 700; font-family: var(--mono);
  color: var(--mint);
  background: rgba(79, 209, 165, .1);
  border: 1px solid rgba(79, 209, 165, .28);
  border-radius: 9px;
}
.topic-id { font-family: var(--mono); font-size: 13px; color: var(--ink-dim); }
.topic-tag {
  margin-left: auto; font-size: 10px; letter-spacing: .09em;
  text-transform: uppercase; color: var(--ink-faint);
  border: 1px solid var(--line); border-radius: 99px; padding: 3px 9px;
}
.topic-name { font-size: 15.5px; font-weight: 650; letter-spacing: -.01em; }
.topic-blurb { font-size: 13px; color: var(--ink-faint); min-height: 34px; }
.topic-meter { height: 6px; border-radius: 99px; background: #1a2a44; overflow: hidden; }
.topic-meter i { display: block; height: 100%; background: linear-gradient(90deg, var(--mint), var(--blue)); }
.topic-foot {
  display: flex; justify-content: space-between;
  font-size: 11.5px; color: var(--ink-faint);
}

/* --------------------------------- quiz --------------------------------- */
.quiz-head {
  display: flex; justify-content: space-between; align-items: center;
  gap: 16px; flex-wrap: wrap; margin-bottom: 12px;
}
.quiz-head-left { display: flex; flex-direction: column; }
.quiz-label { font-size: 13px; color: var(--mint); font-weight: 600; }
.quiz-progress { font-size: 12px; color: var(--ink-faint); }
.quiz-head-right { display: flex; align-items: center; gap: 10px; }
.pill {
  font-size: 12.5px; color: var(--ink-dim);
  background: rgba(255, 255, 255, .05);
  border: 1px solid var(--line); border-radius: 99px;
  padding: 5px 12px;
}
.pill b { color: var(--ink); }
.timer {
  display: none; font-family: var(--mono); font-size: 13px;
  color: var(--amber); border: 1px solid rgba(245, 185, 84, .4);
  background: rgba(245, 185, 84, .1);
  border-radius: 99px; padding: 5px 12px;
}
.timer.show { display: inline-block; }
.timer.urgent { color: var(--rose); border-color: rgba(239, 107, 122, .5); background: rgba(239, 107, 122, .12); }

.quiz-bar { height: 5px; border-radius: 99px; background: #16233b; overflow: hidden; margin-bottom: 20px; }
.quiz-bar i { display: block; height: 100%; background: linear-gradient(90deg, var(--mint), var(--blue)); transition: width .35s ease; }

.quiz-card {
  background: linear-gradient(172deg, var(--panel), var(--bg-2));
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 26px;
}
.q-prompt { font-size: 18px; margin-bottom: 18px; }
.q-prompt .tex-block { margin: 6px 0; }

.choices { display: grid; gap: 11px; }
.choices.compact { gap: 8px; }
.choice {
  display: flex; align-items: center; gap: 13px;
  text-align: left; font: inherit; color: inherit; cursor: pointer;
  background: rgba(255, 255, 255, .035);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 13px 16px;
  transition: border-color .16s, background .16s, transform .1s;
}
.choice:hover:not(:disabled) {
  border-color: rgba(106, 169, 255, .55);
  background: rgba(106, 169, 255, .07);
}
.choice:disabled { cursor: default; }
.choice-key {
  flex: 0 0 26px; height: 26px;
  display: grid; place-items: center;
  font-size: 12px; font-weight: 700; font-family: var(--mono);
  color: var(--ink-dim);
  background: rgba(255, 255, 255, .06);
  border-radius: 7px;
}
.choice-tex { font-size: 16px; }
.choice.is-correct {
  border-color: rgba(79, 209, 165, .75);
  background: rgba(79, 209, 165, .12);
}
.choice.is-correct .choice-key { background: var(--mint); color: #062018; }
.choice.is-wrong {
  border-color: rgba(239, 107, 122, .75);
  background: rgba(239, 107, 122, .12);
}
.choice.is-wrong .choice-key { background: var(--rose); color: #2a0a0f; }
.choice.picked { border-color: rgba(106, 169, 255, .8); background: rgba(106, 169, 255, .12); }

.numeric { display: flex; gap: 12px; flex-wrap: wrap; }
.num-input {
  flex: 1 1 200px; font: inherit; font-size: 16px; font-family: var(--mono);
  color: var(--ink); background: rgba(0, 0, 0, .28);
  border: 1px solid var(--line); border-radius: 12px;
  padding: 12px 15px; outline: none;
}
.num-input:focus { border-color: var(--mint); box-shadow: 0 0 0 3px rgba(79, 209, 165, .16); }
.num-input.is-correct { border-color: var(--mint); }
.num-input.is-wrong { border-color: var(--rose); }

.feedback { display: none; margin-top: 20px; }
.feedback.show {
  display: block; padding: 18px;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: rgba(0, 0, 0, .22);
}
.feedback.good { border-color: rgba(79, 209, 165, .45); background: rgba(79, 209, 165, .06); }
.feedback.bad  { border-color: rgba(239, 107, 122, .45); background: rgba(239, 107, 122, .06); }
.fb-head { font-size: 16px; font-weight: 700; margin-bottom: 10px; }
.feedback.good .fb-head { color: var(--mint); }
.feedback.bad .fb-head { color: var(--rose); }
.fb-answer { font-size: 15px; margin-bottom: 10px; color: var(--ink); }
.fb-sub {
  font-size: 11px; letter-spacing: .11em; text-transform: uppercase;
  color: var(--ink-faint); margin: 8px 0 6px;
}
.fb-line { font-size: 15px; color: var(--ink-dim); padding: 3px 0; }
.fb-line .tex-block { margin: 2px 0; }

.quiz-actions { margin-top: 20px; display: flex; justify-content: flex-end; }

/* --------------------------------- boss --------------------------------- */
.boss-score {
  font-size: 17px; margin-bottom: 18px; padding: 0 4px;
}
.boss-timerbar {
  display: flex; align-items: center; gap: 12px; margin-bottom: 16px;
}
.boss-timer-hint { font-size: 12px; color: var(--ink-faint); }
.boss-score b { color: var(--amber); font-size: 21px; }
.boss-body { display: flex; flex-direction: column; gap: 22px; }
.boss-problem {
  background: linear-gradient(172deg, var(--panel), var(--bg-2));
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px;
}
.boss-head { display: flex; align-items: baseline; gap: 12px; }
.boss-label { font-size: 16px; font-weight: 700; color: var(--mint); }
.boss-points { font-size: 12px; color: var(--ink-faint); }
.boss-title { font-size: 13.5px; color: var(--ink-dim); margin: 4px 0 16px; }
.boss-part {
  border-top: 1px solid var(--line-soft);
  padding: 18px 0 6px;
}
.boss-part-label {
  font-size: 11px; letter-spacing: .1em; text-transform: uppercase;
  color: var(--ink-faint); margin-bottom: 10px;
}
.boss-part.graded-correct { border-left: 3px solid var(--mint); padding-left: 14px; margin-left: -17px; }
.boss-part.graded-wrong   { border-left: 3px solid var(--rose); padding-left: 14px; margin-left: -17px; }
.boss-solution { margin-top: 14px; }
.boss-footer { margin-top: 26px; display: flex; justify-content: center; }

/* ------------------------------- formulas ------------------------------- */
.formula-body {
  display: grid; gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
}
.formula-card {
  background: linear-gradient(172deg, var(--panel), var(--bg-2));
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 20px;
}
.formula-card h3 { margin: 0 0 12px; font-size: 15px; color: var(--mint); }
.formula-row {
  padding: 9px 0; border-top: 1px solid var(--line-soft);
  font-size: 15px; overflow-x: auto;
}
.formula-row:first-of-type { border-top: 0; }

/* -------------------------------- report -------------------------------- */
.report-card {
  max-width: 620px; margin: 30px auto;
  background: linear-gradient(172deg, var(--panel), var(--bg-2));
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 30px; text-align: center;
}
.report-card h2 { margin: 0 0 20px; font-size: 22px; }
.report-main { display: flex; align-items: center; justify-content: center; gap: 30px; flex-wrap: wrap; }
.ring {
  --pct: 0;
  width: 132px; height: 132px; border-radius: 50%;
  display: grid; place-items: center;
  background: conic-gradient(var(--mint) calc(var(--pct) * 1%), #1a2a44 0);
  position: relative;
}
.ring::after {
  content: ''; position: absolute; inset: 11px;
  border-radius: 50%; background: var(--panel);
}
.ring span {
  position: relative; z-index: 1;
  font-size: 30px; font-weight: 700; letter-spacing: -.02em;
}
.report-stats { display: flex; gap: 22px; }
.stat { display: flex; flex-direction: column; }
.stat span { font-size: 21px; font-weight: 700; }
.stat small { font-size: 11px; color: var(--ink-faint); }
.verdict { margin: 24px 0; font-size: 15px; color: var(--ink-dim); }
.report-card h3 { font-size: 12px; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint); }
.chips { display: flex; gap: 9px; justify-content: center; flex-wrap: wrap; margin-bottom: 24px; }
.chip {
  font: inherit; font-size: 12.5px; cursor: pointer;
  color: var(--ink); background: rgba(255, 255, 255, .05);
  border: 1px solid var(--line); border-radius: 99px; padding: 8px 14px;
}
.chip:hover { border-color: rgba(79, 209, 165, .55); background: rgba(79, 209, 165, .08); }
.report-actions { display: flex; gap: 12px; justify-content: center; }

/* --------------------------------- graph -------------------------------- */
.graph-wrap {
  max-width: 300px; margin: 0 auto 18px;
  background: rgba(0, 0, 0, .25);
  border: 1px solid var(--line); border-radius: var(--radius-sm);
  padding: 10px;
}
.graph { width: 100%; height: auto; display: block; }

/* --------------------------------- toast -------------------------------- */
.toast {
  position: fixed; left: 50%; bottom: 28px; transform: translate(-50%, 30px);
  display: flex; align-items: center; gap: 11px;
  background: linear-gradient(140deg, #1d2f4c, #16243c);
  border: 1px solid rgba(245, 185, 84, .5);
  border-radius: 14px; padding: 14px 22px;
  box-shadow: var(--shadow);
  opacity: 0; pointer-events: none; transition: opacity .3s, transform .3s;
  z-index: 90; font-size: 14px;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }
.toast-icon { font-size: 20px; }
.toast b { color: var(--amber); }

/* -------------------------------- katex --------------------------------- */
.katex { font-size: 1.03em; }
.tex-fallback { font-family: var(--mono); font-size: .92em; color: var(--ink-dim); }

/* ------------------------------ responsive ------------------------------ */
@media (max-width: 760px) {
  .hud { gap: 16px; }
  .hud-item:nth-child(3) { display: none; }
  .brand-text small { display: none; }
  main { padding: 24px 15px 70px; }
  .quiz-card, .boss-problem, .panel, .report-card { padding: 18px; }
  .weak-row { grid-template-columns: 40px 1fr 60px; }
  .weak-pct { display: none; }
}
@media (max-width: 520px) {
  .hud-item:nth-child(4) { display: none; }
  .hud-xp { min-width: 90px; }
  .q-prompt { font-size: 16px; }
}