:root {
  --ink: #10243f;
  --ink-soft: #3a4f6a;
  --paper: #f3efe6;
  --paper-2: #ebe4d6;
  --line: #d5cbb6;
  --accent: #b42318;
  --accent-deep: #8c1a12;
  --sea: #1f6f6a;
  --ok: #1f6f4a;
  --bad: #9b1c1c;
  --shadow: 0 18px 50px rgba(16, 36, 63, 0.12);
  --radius: 18px;
  --font-display: "Fraunces", Georgia, serif;
  --font-body: "Outfit", system-ui, sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  font-family: var(--font-body);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.5;
}

.atmosphere {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(ellipse 80% 50% at 10% -10%, rgba(31, 111, 106, 0.18), transparent 55%),
    radial-gradient(ellipse 60% 40% at 100% 0%, rgba(180, 35, 24, 0.12), transparent 50%),
    linear-gradient(180deg, #f7f3ea 0%, #ebe4d6 100%);
  background-image:
    radial-gradient(ellipse 80% 50% at 10% -10%, rgba(31, 111, 106, 0.18), transparent 55%),
    radial-gradient(ellipse 60% 40% at 100% 0%, rgba(180, 35, 24, 0.12), transparent 50%),
    repeating-linear-gradient(
      -18deg,
      transparent,
      transparent 22px,
      rgba(16, 36, 63, 0.015) 22px,
      rgba(16, 36, 63, 0.015) 23px
    ),
    linear-gradient(180deg, #f7f3ea 0%, #ebe4d6 100%);
}

#app {
  width: min(920px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 1.5rem 0 3rem;
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 1rem;
  margin-bottom: 1.75rem;
}

.brand {
  display: flex;
  gap: 0.85rem;
  align-items: center;
}

.brand-mark {
  width: 2.6rem;
  height: 2.6rem;
  border-radius: 0.7rem;
  background:
    linear-gradient(145deg, var(--accent) 0 38%, transparent 38% 42%, var(--ink) 42% 58%, transparent 58% 62%, var(--sea) 62%);
  box-shadow: inset 0 0 0 2px rgba(16, 36, 63, 0.08);
}

.brand-name {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.7rem, 4vw, 2.25rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.05;
}

.brand-sub,
.source-note {
  margin: 0.15rem 0 0;
  color: var(--ink-soft);
  font-size: 0.92rem;
}

.source-note {
  text-align: right;
}

.panel {
  background: rgba(255, 252, 246, 0.88);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(1.25rem, 3vw, 2rem);
  box-shadow: var(--shadow);
  backdrop-filter: blur(6px);
}

.home-panel h1 {
  margin: 0 0 0.65rem;
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4.5vw, 2.6rem);
  line-height: 1.15;
  letter-spacing: -0.02em;
  max-width: 14ch;
}

.lede {
  margin: 0 0 1.5rem;
  color: var(--ink-soft);
  font-size: 1.05rem;
  max-width: 42ch;
}

.mode-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.85rem;
}

.mode-card {
  text-align: left;
  border: 1px solid var(--line);
  background: #fffdf8;
  border-radius: 14px;
  padding: 1rem 1.1rem;
  cursor: pointer;
  transition: transform 160ms ease, border-color 160ms ease, box-shadow 160ms ease;
}

.mode-card:hover,
.mode-card:focus-visible {
  transform: translateY(-2px);
  border-color: #b9ad93;
  box-shadow: 0 10px 24px rgba(16, 36, 63, 0.08);
  outline: none;
}

.mode-card.primary {
  background: linear-gradient(160deg, #163257 0%, #10243f 100%);
  color: #f7f3ea;
  border-color: transparent;
}

.mode-card.primary .mode-desc {
  color: rgba(243, 239, 230, 0.78);
}

.mode-label {
  display: block;
  font-weight: 650;
  font-size: 1.05rem;
  margin-bottom: 0.2rem;
}

.mode-desc {
  display: block;
  color: var(--ink-soft);
  font-size: 0.92rem;
}

.filters {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 1.5rem;
  margin-top: 1.35rem;
  align-items: end;
}

.filters label {
  display: grid;
  gap: 0.35rem;
  font-size: 0.88rem;
  color: var(--ink-soft);
}

.filters select {
  font: inherit;
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 0.55rem 0.75rem;
  background: #fffdf8;
  min-width: 16rem;
}

.check {
  display: flex !important;
  align-items: center;
  gap: 0.5rem;
  padding-bottom: 0.45rem;
}

.quiz-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.linkish {
  border: 0;
  background: transparent;
  color: var(--sea);
  font: inherit;
  font-weight: 600;
  cursor: pointer;
  padding: 0;
}

#progress {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.92rem;
}

.section-tag {
  margin: 0 0 0.5rem;
  color: var(--accent-deep);
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

#question-text {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-size: clamp(1.35rem, 3.2vw, 1.85rem);
  line-height: 1.25;
}

.hint {
  margin: 0 0 1rem;
  color: var(--ink-soft);
  font-size: 0.95rem;
}

.choices {
  display: grid;
  gap: 0.65rem;
}

.choice {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  width: 100%;
  text-align: left;
  border: 1px solid var(--line);
  background: #fffdf8;
  border-radius: 12px;
  padding: 0.85rem 1rem;
  font: inherit;
  color: inherit;
  cursor: pointer;
  transition: border-color 140ms ease, background 140ms ease;
}

.choice:hover,
.choice:focus-visible {
  border-color: #a89a7c;
  outline: none;
}

.choice.selected {
  border-color: var(--sea);
  background: rgba(31, 111, 106, 0.08);
}

.choice.correct {
  border-color: var(--ok);
  background: rgba(31, 111, 74, 0.12);
}

.choice.incorrect {
  border-color: var(--bad);
  background: rgba(155, 28, 28, 0.08);
}

.choice input {
  margin-top: 0.2rem;
}

.choice-text {
  flex: 1;
}

.quiz-actions,
.row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 1.15rem;
}

.btn {
  font: inherit;
  font-weight: 600;
  border-radius: 999px;
  border: 1px solid transparent;
  padding: 0.7rem 1.2rem;
  cursor: pointer;
  background: var(--paper-2);
  color: var(--ink);
}

.btn.primary {
  background: var(--accent);
  color: #fff8f2;
}

.btn.primary:hover {
  background: var(--accent-deep);
}

.btn.ghost {
  background: transparent;
  border-color: var(--line);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.feedback {
  min-height: 1.4em;
  margin: 1rem 0 0;
  font-weight: 600;
}

.feedback.ok {
  color: var(--ok);
}

.feedback.bad {
  color: var(--bad);
}

.self-check ul,
.missed-list {
  margin: 0;
  padding-left: 1.15rem;
}

.self-check li,
.missed-list li {
  margin: 0.35rem 0;
}

.score {
  font-family: var(--font-display);
  font-size: clamp(2rem, 6vw, 3rem);
  margin: 0.4rem 0 0.6rem;
  letter-spacing: -0.03em;
}

.flashcard-view {
  display: grid;
  gap: 1rem;
}

.flashcard {
  display: block;
  width: 100%;
  min-height: 280px;
  padding: 0;
  border: 0;
  background: transparent;
  cursor: pointer;
  perspective: 1200px;
  text-align: left;
}

.flashcard-inner {
  position: relative;
  width: 100%;
  min-height: 280px;
  transform-style: preserve-3d;
  transition: transform 480ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.flashcard-inner.is-flipped {
  transform: rotateY(180deg);
}

.flashcard-face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 0.75rem;
  padding: 1.4rem 1.5rem;
  border-radius: 16px;
  border: 1px solid var(--line);
  backface-visibility: hidden;
  box-shadow: 0 14px 36px rgba(16, 36, 63, 0.1);
}

.flashcard-front {
  background:
    linear-gradient(160deg, rgba(31, 111, 106, 0.08), transparent 55%),
    #fffdf8;
}

.flashcard-back {
  background:
    linear-gradient(160deg, rgba(180, 35, 24, 0.08), transparent 50%),
    #10243f;
  color: #f7f3ea;
  transform: rotateY(180deg);
  overflow: auto;
}

.flash-eyebrow {
  margin: 0;
  font-size: 0.78rem;
  font-weight: 650;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-deep);
}

.flashcard-back .flash-eyebrow {
  color: rgba(247, 243, 234, 0.7);
}

.flash-text {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 3vw, 1.7rem);
  line-height: 1.3;
}

.flash-tap {
  margin: 0.4rem 0 0;
  color: var(--ink-soft);
  font-size: 0.9rem;
}

.flash-answers {
  margin: 0;
  padding-left: 1.1rem;
}

.flash-answers li {
  margin: 0.35rem 0;
}

.flash-actions {
  margin-top: 0.25rem;
}

.hidden {
  display: none !important;
}

footer {
  margin-top: 1.5rem;
  color: var(--ink-soft);
  font-size: 0.88rem;
}

footer a {
  color: var(--sea);
}

@media (max-width: 700px) {
  .mode-grid {
    grid-template-columns: 1fr;
  }

  .topbar {
    flex-direction: column;
    align-items: flex-start;
  }

  .source-note {
    text-align: left;
  }

  .filters select {
    min-width: 0;
    width: 100%;
  }

  .flashcard,
  .flashcard-inner {
    min-height: 320px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .mode-card,
  .choice,
  .flashcard-inner {
    transition: none;
  }
}