.study-main { min-height: 640px; }
.study-section[hidden] { display: none; }
.study-layout { display: grid; grid-template-columns: minmax(0, 1fr) 310px; gap: 20px; align-items: stretch; }
.flashcard-wrap { min-width: 0; }
.aviation-flashcard {
  position: relative;
  display: flex;
  min-height: 430px;
  flex-direction: column;
  justify-content: space-between;
  border: 1px solid var(--line);
  border-radius: 28px;
  background: var(--learning-neutral);
  box-shadow: var(--shadow);
  padding: clamp(24px, 4vw, 42px);
  cursor: pointer;
  outline: none;
  touch-action: pan-y;
  user-select: none;
  transition: border-color .2s ease, background .2s ease, box-shadow .2s ease, transform .2s ease;
}
.aviation-flashcard.is-swiping { transition: none; }
.aviation-flashcard.is-throwing { pointer-events: none; opacity: .15; transition: transform .24s cubic-bezier(.18,.75,.32,1), opacity .22s ease; }
.aviation-flashcard::after { position: absolute; top: 50%; z-index: 3; border: 2px solid currentColor; border-radius: 999px; padding: 10px 16px; font-size: .9rem; font-weight: 950; opacity: 0; pointer-events: none; transform: translateY(-50%) scale(.9); transition: opacity .12s ease, transform .12s ease; }
.aviation-flashcard.swipe-left::after { right: 22px; content: "✕ Again"; background: var(--learning-incorrect-bg); color: var(--learning-incorrect); opacity: 1; transform: translateY(-50%) scale(1); }
.aviation-flashcard.swipe-right::after { left: 22px; content: "✓ Know"; background: var(--learning-correct-bg); color: var(--learning-correct); opacity: 1; transform: translateY(-50%) scale(1); }
.aviation-flashcard:hover,
.aviation-flashcard:focus-visible { border-color: var(--mint-strong); transform: translateY(-2px); }
.aviation-flashcard.is-correct,
.aviation-flashcard.is-complete { border: 2px solid var(--learning-correct); background: var(--learning-correct-bg); color: var(--learning-correct); box-shadow: 0 18px 42px color-mix(in srgb, var(--learning-correct) 24%, transparent); }
.aviation-flashcard.is-incorrect { border: 2px solid var(--learning-incorrect); background: var(--learning-incorrect-bg); color: var(--learning-incorrect); box-shadow: 0 14px 34px color-mix(in srgb, var(--learning-incorrect) 19%, transparent); }
.aviation-flashcard.is-resolving { cursor: default; }
.flashcard-topline { display: flex; align-items: center; justify-content: space-between; gap: 14px; color: var(--muted); font-size: .75rem; font-weight: 800; letter-spacing: .07em; text-transform: uppercase; }
.flashcard-meta { display: inline-flex; flex-wrap: wrap; align-items: center; justify-content: flex-end; gap: 9px; }
.learning-status { display: inline-flex; min-height: 26px; align-items: center; border: 1px solid currentColor; border-radius: 999px; padding: 3px 9px; font-size: .64rem; font-weight: 900; }
.learning-status[data-state="new"] { background: var(--learning-new-bg); color: var(--learning-new); }
.learning-status[data-state="correct"] { background: var(--learning-correct-bg); color: var(--learning-correct); }
.learning-status[data-state="incorrect"] { background: var(--learning-incorrect-bg); color: var(--learning-incorrect); }
.aviation-flashcard-center { max-width: 760px; margin: auto; text-align: center; }
.aviation-flashcard-center h2 { margin: 0; font: 600 clamp(2.1rem, 6vw, 4.8rem)/1.06 Georgia, serif; }
.aviation-flashcard.definition-first .aviation-flashcard-center h2 { font-size: clamp(1.35rem, 3vw, 2.35rem); line-height: 1.35; }
.aviation-flashcard.definition-first .aviation-flash-definition { font: 600 clamp(2rem, 5vw, 3.8rem)/1.08 Georgia, serif; }
.aviation-flashcard-center > p { margin: 24px 0 0; }
#flash-prompt { color: var(--muted); font-weight: 750; }
.aviation-flash-definition { max-width: 680px; color: var(--ink); font-size: clamp(1rem, 2vw, 1.28rem); line-height: 1.65; opacity: 0; transform: translateY(8px); transition: opacity .2s ease, transform .2s ease; }
.aviation-flashcard.revealed .aviation-flash-definition { opacity: 1; transform: translateY(0); }
.aviation-flashcard.revealed #flash-prompt { display: none; }
.aviation-flashcard > small { color: var(--muted); }
.flash-actions { display: flex; justify-content: center; gap: 10px; margin-top: 14px; }
.flash-actions .button { min-width: 140px; }
.flash-reader-controls { display: flex; align-items: center; justify-content: center; gap: 12px; margin-top: 10px; }
.flash-reader-controls .button { min-width: 150px; }
.flash-reader-controls span { color: var(--muted); font-size: .78rem; font-weight: 750; }
.button.learning-correct { border-color: var(--learning-correct); background: var(--learning-correct-bg); color: var(--learning-correct); }
.button.learning-incorrect { border-color: var(--learning-incorrect); background: var(--learning-incorrect-bg); color: var(--learning-incorrect); }
.study-side-panel { display: flex; flex-direction: column; border: 1px solid var(--line); border-radius: 28px; background: var(--surface); box-shadow: var(--shadow); padding: 24px; }
.study-field { display: grid; gap: 7px; }
.study-field > span { margin: 0; }
.flash-direction-field { margin-top: 14px; }
.flash-pool-field { margin-top: auto; padding-top: 15px; }
.flash-session-list { display: grid; gap: 7px; margin: 20px 0; padding: 0; list-style: none; }
.flash-session-list[hidden] { display: none !important; }
.flash-session-list li { display: grid; grid-template-columns: 27px minmax(0, 1fr); align-items: center; gap: 9px; min-height: 36px; color: var(--muted); font-size: .8rem; }
.flash-session-list li::before { content: attr(data-number); display: grid; width: 27px; height: 27px; place-items: center; border: 1px solid var(--line); border-radius: 50%; color: var(--ink); font-size: .68rem; font-weight: 850; }
.flash-session-list li.active { color: var(--ink); font-weight: 800; }
.flash-session-list li.active::before { background: var(--ink); color: var(--bg); }
.flash-session-list li.known::before { content: "✓"; background: var(--learning-correct-bg); color: var(--learning-correct); }
.study-toggle { display: flex; align-items: center; gap: 9px; margin-top: auto; padding: 15px 0; color: var(--ink); font-size: .82rem; font-weight: 750; }
.study-toggle input { width: 18px; min-height: 18px; margin: 0; accent-color: var(--mint-strong); }
.hide-card-list-toggle { margin: 14px 0 0; padding: 0; }
.known-cards-panel { margin-top: 20px; border: 1px solid var(--line); border-radius: 24px; background: var(--surface); padding: clamp(20px, 4vw, 30px); }
.known-cards-heading { display: flex; align-items: center; justify-content: space-between; gap: 16px; margin-bottom: 16px; }
.known-cards-heading h2 { margin: 0; font-size: 1.4rem; }
.known-cards-heading strong { display: grid; min-width: 42px; height: 42px; place-items: center; border-radius: 50%; background: var(--peach); color: var(--ink); }
.known-card-list { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 9px; }
.known-card-list details { min-width: 0; border: 1px solid color-mix(in srgb, var(--learning-correct) 28%, var(--line)); border-radius: 12px; background: var(--learning-correct-bg); color: var(--learning-correct); padding: 12px 14px; }
.known-card-list summary { overflow: hidden; cursor: pointer; font-weight: 850; text-overflow: ellipsis; white-space: nowrap; }
.known-card-list p { margin: 10px 0 0; color: var(--ink); font-size: .8rem; line-height: 1.48; }
.practice-view { display: none; }
.practice-view.active { display: block; }
.practice-grid { display: grid; grid-template-columns: minmax(0, 1.08fr) minmax(300px, .92fr); gap: 20px; }
.study-setup-panel,
.study-history-panel { padding: clamp(22px, 4vw, 36px); }
.topic-picker { margin: 20px 0; border: 1px solid var(--line); border-radius: 16px; background: var(--surface-strong); padding: 14px; }
.topic-picker legend { padding: 0 6px; color: var(--muted); font-size: .76rem; font-weight: 800; }
.topic-options { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 6px; }
.topic-option { display: grid; grid-template-columns: 18px minmax(0, 1fr); align-items: center; gap: 8px; border-radius: 9px; padding: 8px; cursor: pointer; }
.topic-option:hover { background: var(--mint); }
.topic-option input { width: 17px; min-height: 17px; margin: 0; accent-color: var(--mint-strong); }
.topic-option span { margin: 0; color: var(--ink); }
.study-setup-panel > .study-field { margin: 18px 0; }
.study-setup-panel > .button { margin: 4px 7px 0 0; }
.study-history-panel .history-list { max-height: 420px; }
.jeopardy-toolbar { display: flex; align-items: stretch; gap: 10px; margin-bottom: 15px; }
.jeopardy-toolbar > div { display: grid; min-width: 130px; gap: 2px; border: 1px solid var(--line); border-radius: 15px; background: var(--surface); padding: 11px 15px; }
.jeopardy-toolbar small { color: var(--muted); font-size: .7rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.jeopardy-toolbar strong { font-size: 1.35rem; }
.jeopardy-toolbar .button { margin-left: auto; }
.jeopardy-board-wrap { overflow-x: auto; border-radius: 22px; box-shadow: var(--shadow); }
.jeopardy-board { display: grid; grid-template-columns: repeat(6, minmax(150px, 1fr)); min-width: 930px; gap: 4px; background: #102f63; padding: 4px; }
.jeopardy-category { display: grid; min-height: 90px; place-items: center; background: #173d7d; color: #fff; padding: 14px 9px; font-size: .77rem; font-weight: 900; letter-spacing: .05em; text-align: center; text-transform: uppercase; }
.jeopardy-cell { min-height: 88px; border: 1px solid rgba(255,255,255,.13) !important; border-radius: 0; background: #154b9a; color: #f5c95c; cursor: pointer; font-size: 1.42rem; font-weight: 950; text-shadow: 0 2px 0 rgba(0,0,0,.22); }
.jeopardy-cell:hover,
.jeopardy-cell:focus-visible { background: #1d62c6; outline: 3px solid #f5c95c; outline-offset: -4px; }
.jeopardy-cell.used { background: #102f63; color: transparent; cursor: default; }
.jeopardy-clue { width: min(760px, calc(100% - 28px)); border: 1px solid rgba(255,255,255,.2); border-radius: 24px; background: #123d7b; color: white; box-shadow: 0 28px 90px rgba(0,0,0,.44); padding: clamp(22px, 5vw, 42px); }
.jeopardy-clue::backdrop { background: rgba(4, 14, 30, .74); backdrop-filter: blur(6px); }
.jeopardy-close { position: absolute; top: 14px; right: 14px; display: grid; width: 38px; height: 38px; place-items: center; border-color: rgba(255,255,255,.35); border-radius: 50%; background: transparent; color: white; cursor: pointer; font-size: 1.2rem; }
.jeopardy-clue > span { color: #f5c95c; font-size: .75rem; font-weight: 850; letter-spacing: .08em; text-transform: uppercase; }
.jeopardy-clue h2 { margin: 22px 0; font: 600 clamp(1.35rem, 4vw, 2.15rem)/1.42 Georgia, serif; }
.jeopardy-options { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 9px; }
.jeopardy-options button { min-height: 58px; border-color: rgba(255,255,255,.28); border-radius: 13px; background: rgba(255,255,255,.08); color: white; padding: 10px 14px; cursor: pointer; font-weight: 800; }
.jeopardy-options button:hover:not(:disabled),
.jeopardy-options button:focus-visible { background: rgba(255,255,255,.17); outline: 2px solid #f5c95c; }
.jeopardy-options button.correct { border-color: #72e59f; background: #185f3b; color: #dfffe9; }
.jeopardy-options button.incorrect { border-color: #ff9fa6; background: #751f2b; color: #ffe6e8; text-decoration: line-through; }
#jeopardy-feedback { min-height: 24px; margin: 16px 0 0; color: #f5c95c; font-weight: 850; }
:root[data-theme="dark"] .study-side-panel,
:root[data-theme="dark"] .known-cards-panel,
:root[data-theme="dark"] .study-history-panel,
:root[data-theme="dark"] .study-setup-panel { background: var(--surface); }

@media (max-width: 820px) {
  .study-layout,
  .practice-grid { grid-template-columns: 1fr; }
  .study-side-panel { min-height: auto; }
  .flash-session-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .study-toggle { margin-top: 0; }
  .flash-pool-field { margin-top: 0; }
  .known-card-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 520px) {
  .study-app-header h1 { font-size: 2rem; }
  .aviation-flashcard { min-height: 370px; border-radius: 22px; }
  .aviation-flashcard-center h2 { font-size: 2.35rem; }
  .flash-actions .button { min-width: 0; flex: 1; }
  .flash-reader-controls { align-items: stretch; flex-direction: column; text-align: center; }
  .flash-reader-controls .button { width: 100%; }
  .flash-session-list,
  .known-card-list,
  .topic-options,
  .jeopardy-options { grid-template-columns: 1fr; }
  .jeopardy-toolbar { flex-wrap: wrap; }
  .jeopardy-toolbar > div { flex: 1; min-width: 120px; }
  .jeopardy-toolbar .button { width: 100%; margin-left: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .aviation-flashcard,
  .aviation-flash-definition { transition: none; }
  .aviation-flashcard.is-throwing { opacity: 0; }
}