/* 학습자료 수학 연산: 웹에서는 직접 풀고 채점, 시험지는 A4 로 따로 출력 */

/* ---------- 시험지 (A4) ---------- */

.a4 {
  width: 210mm;
  height: 297mm;
  padding: 14mm 14mm 12mm;
  overflow: hidden;
  background: #fff;
  color: #171717;
  font-size: 16px;
  line-height: 1.5;
  break-after: page;
}
.a4:last-child { break-after: auto; }

.arith-key__title { margin: 0 0 10px; padding-bottom: 8px; border-bottom: 1.5px solid #171717; font-size: 16px; font-weight: 700; }
.arith-key { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 6px 20px; margin: 0; padding: 0; list-style: none; font-size: 14px; }
.arith-key li { display: flex; align-items: baseline; gap: 8px; padding: 6px 0; border-bottom: 1px solid var(--color-divider); }

.arith-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 16px;
  padding-bottom: 10px;
  border-bottom: 1.5px solid #171717;
}

.arith-head__title { font-size: 18px; font-weight: 700; color: #171717; }
.arith-head__grade { margin-right: 8px; color: var(--color-primary); }
.arith-head__sep { margin: 0 2px; font-weight: 400; color: var(--color-text-disabled); }

.arith-head__fields { display: flex; flex-wrap: wrap; gap: 8px 18px; font-size: 12px; color: var(--color-text-muted); white-space: nowrap; }
.arith-head__fields span { display: inline-flex; align-items: flex-end; gap: 6px; }
.arith-head__fields span::after { content: ""; display: inline-block; width: 64px; border-bottom: 1px solid var(--color-border-strong); }
.arith-head__fields span:last-child::after { display: none; }
.arith-head__fields b { font-weight: 500; padding-left: 36px; border-bottom: 1px solid var(--color-border-strong); }

.arith-sec { margin-top: 18px; }

.arith-sec__prompt { margin-bottom: 4px; font-size: 14px; font-weight: 600; color: #171717; }
.arith-sec__name { margin-right: 8px; font-weight: 500; color: var(--color-text-muted); }

.arith-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); column-gap: 12mm; margin: 0; padding: 0; list-style: none; }

.prob {
  display: flex;
  align-items: baseline;
  gap: 8px;
  min-height: 46mm;
  padding: 5mm 0 4mm;
  border-bottom: 1px solid var(--color-divider);
  break-inside: avoid;
}

.prob__no { flex: none; min-width: 20px; font-size: 12px; color: var(--color-text-muted); font-variant-numeric: tabular-nums; }
.prob__q { flex: 1; min-width: 0; font-variant-numeric: tabular-nums; }
.prob--line .prob__q, .prob--arrow .prob__q { overflow-wrap: anywhere; }

/* 답: 자리는 남기고 글자만 숨긴다 */
.ans { display: inline-block; min-width: 2.5em; visibility: hidden; }

.blank {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 1.9em;
  height: 1.6em;
  padding: 0 4px;
  border: 1px solid #8a8a8a;
  border-radius: 2px;
  vertical-align: middle;
}
.blank .ans { min-width: 0; }

.arrow { margin: 0 8px; color: var(--color-text-muted); }

.ans-line { display: block; min-height: 1.6em; margin-top: 8px; }

/* ---------- 수식 ---------- */

.v { font-family: "Times New Roman", "Noto Serif KR", serif; font-size: 1.08em; font-style: italic; padding-right: 0.04em; }

.prob sup, .arith-sec sup { font-size: 0.68em; line-height: 0; }

.fr {
  display: inline-flex;
  flex-direction: column;
  align-items: stretch;
  margin: 0 2px;
  font-size: 0.92em;
  line-height: 1.15;
  text-align: center;
  vertical-align: middle;
}
.fr__n { padding: 0 3px 1px; border-bottom: 1px solid currentColor; }
.fr__d { padding: 1px 3px 0; }

.mx { display: inline-flex; align-items: center; white-space: nowrap; }
.mx .fr { margin-left: 1px; }

.rt { white-space: nowrap; }
.rt__in { padding: 0 1px 0 1px; border-top: 1px solid currentColor; }

.rep { position: relative; display: inline-block; }
.rep::before {
  content: "";
  position: absolute;
  top: 0.02em;
  left: 50%;
  width: 3px;
  height: 3px;
  margin-left: -1.5px;
  border-radius: 50%;
  background: currentColor;
}

.sys { display: inline-flex; align-items: center; gap: 4px; vertical-align: middle; }
.sys__brace { font-size: 2.6em; font-weight: 200; line-height: 1; transform: scaleX(0.7); }
.sys__rows { display: flex; flex-direction: column; gap: 2px; }

/* ---------- 웹: 문제 고르기 ---------- */

.ar-filter {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 14px;
  position: relative;
  margin-top: 16px;
  padding: 10px 12px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-panel);
}

.ar-grades { display: inline-flex; padding: 2px; border: 1px solid var(--color-border); border-radius: var(--radius-control); background: var(--color-surface-subtle); }
.ar-grades__group { display: flex; align-items: center; }
.ar-grades__group + .ar-grades__group { margin-left: 4px; padding-left: 4px; border-left: 1px solid var(--color-border); }
.ar-grades__cap { padding: 0 6px 0 4px; font-size: 11px; color: var(--color-text-disabled); }
.ar-grade {
  min-width: 28px; height: 28px; padding: 0 6px;
  border: none; border-radius: 3px; background: transparent;
  font: inherit; font-size: 13px; color: var(--color-text-muted); cursor: pointer;
}
.ar-grade:hover { color: var(--color-text-strong); }
.ar-grade[aria-pressed="true"] { background: var(--color-primary); color: #fff; font-weight: 600; }

.ar-unitpick { flex: 1 1 260px; min-width: 0; }
.ar-unitbtn {
  display: flex; align-items: center; gap: 8px;
  width: 100%; height: 34px; padding: 0 10px;
  border: 1px solid var(--color-border); border-radius: var(--radius-control);
  background: var(--color-surface); font: inherit; font-size: 13px; color: var(--color-text-strong);
  cursor: pointer; text-align: left;
}
.ar-unitbtn:hover, .ar-unitbtn[aria-expanded="true"] { border-color: var(--color-border-strong); }
.ar-unitbtn__k { flex: none; font-size: 12px; color: var(--color-text-muted); }
.ar-unitbtn__v { flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-weight: 600; }
.ar-unitbtn svg { flex: none; color: var(--color-text-muted); }

.ar-pop {
  position: absolute; left: -1px; right: -1px; top: calc(100% + 6px); z-index: 50;
  max-height: min(70vh, 560px); overflow-y: auto;
  padding: 8px 14px;
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-panel);
  box-shadow: var(--shadow-lg);
}
.ar-units { display: flex; flex-direction: column; }
.ar-unit { display: grid; grid-template-columns: 140px minmax(0, 1fr); gap: 10px; align-items: start; padding: 8px 0; }
.ar-unit + .ar-unit { border-top: 1px solid var(--color-divider); }
.ar-unit__name { padding-top: 5px; font-size: 12px; font-weight: 600; color: var(--color-text-muted); }
.ar-unit__chips { display: flex; flex-wrap: wrap; gap: 4px; }

.ar-chip {
  height: 28px; padding: 0 10px;
  border: 1px solid transparent; border-radius: var(--radius-control);
  background: transparent; font: inherit; font-size: 13px; color: var(--color-text);
  cursor: pointer;
}
.ar-chip:hover { background: var(--color-surface-subtle); border-color: var(--color-border); }
.ar-chip[aria-pressed="true"] { background: var(--color-primary-soft); border-color: var(--color-primary-light); color: var(--color-primary-dark); font-weight: 600; }
.ar-chip--all { color: var(--color-text-muted); }

#ar-counts .segment__btn { min-width: 36px; height: 28px; font-size: 13px; }
.ar-filter__actions { display: flex; gap: 8px; margin-left: auto; }

/* ---------- 웹: 풀이 ---------- */

.ar-layout { display: grid; grid-template-columns: minmax(0, 1fr) 272px; gap: 20px; align-items: start; margin-top: 20px; }

.ar-work__head { margin-bottom: 4px; }
.ar-work__crumb { margin: 0 0 2px; font-size: 13px; color: var(--color-text-muted); }
.ar-work__title { margin: 0; font-size: 22px; font-weight: 700; color: var(--color-text-strong); letter-spacing: -0.01em; }

.ar-sec { margin-top: 20px; }
.ar-sec__head { display: flex; align-items: baseline; gap: 10px; margin: 0 0 10px; font-size: 14px; font-weight: 600; color: var(--color-text-strong); }
.ar-sec__name { padding: 2px 8px; border-radius: 3px; background: var(--color-primary-soft); color: var(--color-primary-dark); font-size: 12px; }
.ar-sec__prompt { font-weight: 500; color: var(--color-text); }

.ar-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 12px; margin: 0; padding: 0; list-style: none; }

.ar-card {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 14px 16px 16px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-panel);
  scroll-margin: 90px;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}
.ar-card:focus-within { border-color: var(--color-primary-light); box-shadow: 0 0 0 3px var(--color-primary-soft); }
.ar-card__top { display: flex; align-items: center; justify-content: space-between; }
.ar-no {
  display: inline-flex; align-items: center; justify-content: center;
  min-width: 26px; height: 26px; padding: 0 6px;
  border-radius: 13px; background: var(--color-neutral-bg);
  font-size: 12px; font-weight: 600; color: var(--color-neutral-text); font-variant-numeric: tabular-nums;
}
.ar-mark { font-size: 16px; font-weight: 700; }

.ar-q { font-size: 20px; line-height: 1.6; color: var(--color-text-strong); font-variant-numeric: tabular-nums; overflow-wrap: anywhere; }
.ar-q--inline { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 8px; }
.ar-op { color: var(--color-text-muted); }

.ar-in {
  flex: 1 1 120px;
  min-width: 0;
  height: 42px;
  padding: 0 12px;
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-control);
  background: var(--color-surface);
  font: inherit;
  font-size: 18px;
  color: var(--color-text-strong);
  outline: none;
}
.ar-in::placeholder { font-size: 14px; color: var(--color-text-disabled); }
.ar-in:focus { border-color: var(--color-primary); }
.ar-in--box { flex: none; width: 3.4em; height: 38px; padding: 0 6px; text-align: center; vertical-align: middle; }
.ar-a--line { display: flex; }
.ar-a--line .ar-in { width: 100%; }

.ar-sol { display: flex; align-items: baseline; gap: 8px; padding-top: 10px; border-top: 1px dashed var(--color-border); font-size: 13px; color: var(--color-text-muted); }
.ar-sol__v { font-size: 17px; font-weight: 600; color: var(--color-text-strong); }

.ar-card.is-right { border-color: #9fd0b2; background: #f6fbf8; }
.ar-card.is-right .ar-mark, .ar-card.is-right .ar-no { color: #217346; }
.ar-card.is-right .ar-no { background: #dcefe3; }
.ar-card.is-right .ar-in { border-color: #9fd0b2; background: #fff; }
.ar-card.is-wrong { border-color: #ecb8ad; background: var(--color-warning-bg); }
.ar-card.is-wrong .ar-mark { color: var(--color-warning-text); }
.ar-card.is-wrong .ar-no { background: #f7d9d2; color: var(--color-warning-text); }
.ar-card.is-wrong .ar-in { border-color: #ecb8ad; color: var(--color-warning-text); text-decoration: line-through; text-decoration-thickness: 1px; }
.ar-card.is-graded .ar-in::placeholder, .ar-card.is-wrong .ar-in::placeholder, .ar-card.is-right .ar-in::placeholder { color: transparent; }

/* ---------- 웹: 채점 패널 ---------- */

.ar-panel {
  position: sticky;
  top: calc(var(--topbar-height) + 20px);
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding: 18px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-panel);
}

.ar-nav { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 6px; max-height: 260px; overflow-y: auto; }
.ar-dot {
  height: 30px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-control);
  background: var(--color-surface);
  font: inherit; font-size: 12px; font-variant-numeric: tabular-nums;
  color: var(--color-text-muted);
  cursor: pointer;
}
.ar-dot:hover { border-color: var(--color-border-strong); color: var(--color-text-strong); }
.ar-dot.is-filled { background: var(--color-primary-soft); border-color: var(--color-primary-light); color: var(--color-primary-dark); font-weight: 600; }
.ar-dot.is-right { background: #dcefe3; border-color: #9fd0b2; color: #217346; font-weight: 600; }
.ar-dot.is-wrong { background: #f7d9d2; border-color: #ecb8ad; color: var(--color-warning-text); font-weight: 600; }

.ar-keys { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 4px; padding-top: 14px; border-top: 1px solid var(--color-divider); }
.ar-key {
  height: 32px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-control);
  background: var(--color-surface-subtle);
  font: inherit; font-size: 15px;
  color: var(--color-text-strong);
  cursor: pointer;
}
.ar-key:hover { background: var(--color-surface); border-color: var(--color-border-strong); }
.ar-panel.is-graded .ar-keys { display: none; }

.ar-panel__btn { width: 100%; height: 40px; font-size: 14px; }

/* ---------- 시험지 미리보기 ---------- */

.ar-preview { position: fixed; inset: 0; z-index: 200; display: flex; flex-direction: column; background: #e8e8e8; }
.ar-preview[hidden] { display: none; }
body.is-previewing { overflow: hidden; }
.ar-preview__bar {
  display: flex; align-items: center; gap: 12px;
  height: 56px; padding: 0 20px; flex: none;
  background: var(--color-surface); border-bottom: 1px solid var(--color-border);
}
.ar-preview__title { font-size: 15px; color: var(--color-text-strong); }
.ar-preview__pages { font-size: 13px; color: var(--color-text-muted); }
.ar-preview__actions { display: flex; gap: 8px; margin-left: auto; }

.ar-print { flex: 1; overflow: auto; padding: 24px; display: flex; flex-direction: column; align-items: center; gap: 24px; }
.ar-print .a4 { zoom: var(--zoom, 1); flex: none; box-shadow: 0 2px 10px rgba(40, 30, 15, 0.18); }

/* ---------- 좁은 화면 ---------- */

@media (max-width: 900px) {
  .ar-layout { grid-template-columns: minmax(0, 1fr); }

  /* 채점 단추는 화면 아래에 붙는다 */
  .ar-panel {
    position: sticky;
    top: auto;
    bottom: 0;
    z-index: 45;      /* 안에 든 기호 줄이 머리 위로 올라와야 한다 */
    order: 2;
    display: block;
    margin: 0 calc(-1 * var(--spacing-page));
    padding: 10px var(--spacing-page) calc(10px + env(safe-area-inset-bottom));
    border-width: 1px 0 0;
    border-radius: 0;
    box-shadow: 0 -6px 16px -8px rgba(0, 0, 0, 0.18);
  }
  .ar-nav { display: none; }
  .ar-panel__btn { width: 100%; height: 46px; font-size: 15.5px; }

  /* 기호 단추는 답을 적는 동안에만 화면 위쪽에 한 줄로 나온다 (자판에 가리지 않게) */
  .ar-keys {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 45;
    grid-template-columns: repeat(12, minmax(0, 1fr));
    gap: 0;
    padding: 4px 6px;
    border-top: none;
    border-bottom: 1px solid var(--color-border);
    background: var(--color-surface);
    box-shadow: 0 4px 12px -6px rgba(0, 0, 0, 0.2);
  }
  .ar-layout:has(.ar-in:focus) .ar-keys { display: grid; }
  .ar-panel.is-graded .ar-keys { display: none; }
  .ar-key { height: 40px; border: none; border-radius: 3px; background: transparent; font-size: 17px; }

  .ar-work__title { font-size: 20px; }
  .ar-work__crumb { font-size: 13.5px; }
  .ar-sec__head { flex-wrap: wrap; gap: 6px 10px; font-size: 15px; }
  .ar-sec__name { font-size: 13px; }
  .ar-no { font-size: 13px; }
  .ar-in { height: 46px; }
  .ar-in--box { height: 42px; width: 3.6em; }
  .ar-in::placeholder { font-size: 15px; }
  .ar-sol { font-size: 14px; }

  .ar-unitbtn { height: 44px; font-size: 15px; }
  .ar-unitbtn__k { font-size: 13px; }
  .ar-unit__name { font-size: 13px; }
  .ar-chip { height: 40px; padding: 0 12px; font-size: 14.5px; }
  .ar-grade { min-width: 38px; height: 38px; font-size: 15px; }
  .ar-grades__cap { font-size: 12.5px; }
  #ar-counts .segment__btn { min-width: 44px; height: 38px; font-size: 14.5px; }

  .ar-preview__bar { padding: 0 8px 0 16px; }
  .ar-print { padding: 12px; gap: 12px; }
}

@media (max-width: 720px) {
  .ar-filter { gap: 10px; }
  .ar-grades { display: flex; flex-wrap: wrap; row-gap: 2px; width: 100%; }
  .ar-grades__group { flex: none; }
  .ar-unitpick { flex-basis: 100%; }
  .ar-unit { grid-template-columns: minmax(0, 1fr); gap: 4px; }
  .ar-unit__name { padding-top: 0; }
  #ar-counts { display: flex; flex: 1 1 100%; }
  #ar-counts .segment__btn { flex: 1; }
  .ar-filter__actions { width: 100%; margin-left: 0; }
  .ar-filter__actions .btn { flex: 1; }
  .ar-cards { grid-template-columns: minmax(0, 1fr); }
  .ar-q { font-size: 21px; }
}

/* ---------- 출력 ---------- */

@media print {
  body.is-previewing > .topbar, body.is-previewing .sidebar, body.is-previewing .page-header,
  body.is-previewing .ar-filter, body.is-previewing .ar-layout, .ar-preview__bar { display: none !important; }
  body.is-previewing { background: #fff; overflow: visible; }
  body.is-previewing > .shell { display: block !important; min-height: 0; }
  body.is-previewing .main { padding: 0; }
  .ar-preview { position: static; display: block; background: #fff; }
  .ar-print { display: block; overflow: visible; padding: 0; }
  .ar-print .a4 { zoom: 1; box-shadow: none; }
  body:not(.is-previewing) .main { display: none; }
}

@page { size: A4; margin: 0; }