:root {
  --bg: #f6f7f9;
  --card: #ffffff;
  --ink: #1f2937;
  --sub: #6b7280;
  --line: #e5e7eb;
  --brand: #e8a33d;
  --brand-dark: #c9822a;
  --ok: #16a34a;
  --no: #dc2626;
  --accent: #2563eb;
  --radius: 14px;
}
* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font-family: "Pretendard", -apple-system, "Segoe UI", "Malgun Gothic", sans-serif;
  line-height: 1.6;
}
a { color: inherit; text-decoration: none; }

/* nav */
.topnav {
  display: flex; align-items: center; gap: 18px;
  background: var(--card); border-bottom: 1px solid var(--line);
  padding: 12px 22px; position: sticky; top: 0; z-index: 10;
  box-shadow: 0 1px 4px rgba(0,0,0,.03);
}
.brand { font-weight: 800; font-size: 19px; }
.brand span { color: var(--brand-dark); }
.topnav .links { display: flex; gap: 6px; flex: 1; flex-wrap: wrap; }
.topnav .links a {
  padding: 7px 13px; border-radius: 999px; color: var(--sub); font-weight: 600; font-size: 15px;
}
.topnav .links a:hover { background: #f3f4f6; color: var(--ink); }
.topnav .links a.on { background: var(--brand); color: #fff; }
.dday {
  background: #fff3e0; color: var(--brand-dark); font-weight: 800;
  padding: 6px 14px; border-radius: 999px; font-size: 15px; white-space: nowrap;
}
.userbox { font-size: 14px; color: var(--sub); white-space: nowrap; display: flex; align-items: center; gap: 8px; }
.userbox strong { color: var(--ink); }
.logout { border: 1px solid var(--line); background: #fff; color: var(--sub); font-size: 13px;
  padding: 5px 11px; border-radius: 999px; cursor: pointer; }
.logout:hover { border-color: var(--no); color: var(--no); }

/* 모바일 햄버거 토글 (데스크톱에선 숨김) */
.navtoggle { display: none; font-size: 24px; line-height: 1; padding: 4px 10px; cursor: pointer;
  border: 1px solid var(--line); border-radius: 10px; color: var(--ink); background: #fff; }

.container { max-width: 860px; margin: 26px auto; padding: 0 18px; }
h1 { font-size: 24px; margin: 0 0 4px; }
.muted { color: var(--sub); }

/* cards */
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 20px; margin-bottom: 16px;
}
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px,1fr)); gap: 12px; }
.stat { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; }
.stat .n { font-size: 28px; font-weight: 800; color: var(--brand-dark); }
.stat .l { color: var(--sub); font-size: 14px; }

/* subject chips */
.chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0; }
.chip {
  padding: 8px 14px; border-radius: 999px; border: 1px solid var(--line);
  background: #fff; font-weight: 600; font-size: 14px; cursor: pointer;
}
.chip.on { background: var(--accent); color: #fff; border-color: var(--accent); }

/* list */
.list-item {
  display: flex; align-items: center; gap: 10px; padding: 13px 16px;
  border: 1px solid var(--line); border-radius: 12px; background: #fff; margin-bottom: 8px;
}
.list-item:hover { border-color: var(--brand); }
.tag { font-size: 12px; padding: 2px 9px; border-radius: 999px; background: #eef2ff; color: var(--accent); font-weight: 700; }
.tag-exam { background: #fef3c7; color: #b45309; }
.tag-multi { background: #fde68a; color: #92400e; font-weight: 800; }
.tag-self { background: #f1f5f9; color: #64748b; }
.tag-type { background: #dcfce7; color: #15803d; }
.tag-scope { background: #ede9fe; color: #6d28d9; }

/* 문제 번호 + 풀이 이력 */
.qno { display: inline-flex; align-items: center; justify-content: center; width: 26px; height: 26px;
  border-radius: 50%; background: var(--brand); color: #fff; font-weight: 800; font-size: 14px; }
.qtext { font-size: 16px; font-weight: 600; margin: 12px 0 14px; white-space: pre-line; }
.hist { margin: 10px 0 4px; font-size: 13px; display: flex; align-items: center; gap: 5px; flex-wrap: wrap; }
.hb { display: inline-block; padding: 2px 8px; border-radius: 999px; font-size: 12px; font-weight: 700; }
.hb.o { background: #f0fdf4; color: var(--ok); }
.hb.x { background: #fef2f2; color: var(--no); }
.hb.more { background: #f1f5f9; color: #64748b; }
.mk { display: inline-block; width: 19px; height: 19px; line-height: 19px; text-align: center;
  border-radius: 5px; font-weight: 800; font-size: 13px; }
.mk.o { color: var(--ok); background: #dcfce7; }
.mk.x { color: var(--no); background: #fee2e2; }
.choices .choice { margin: 7px 0; }
.chip.small { padding: 5px 11px; font-size: 13px; }
/* 저장 버튼/배지 */
.savebtn { border: 1px solid var(--line); background: #fff; color: var(--sub); font-weight: 700;
  font-size: 13px; padding: 5px 12px; border-radius: 999px; cursor: pointer; }
.savebtn:hover { border-color: var(--brand); color: var(--brand-d); }
.savebtn.on { background: #fff3e0; color: var(--brand-d); border-color: var(--brand); }
.tag-saved { background: #fff3e0; color: var(--brand-d); }
/* 해설 문단 */
.explain p { margin: 0 0 8px; }
.explain .expl-body p:last-child { margin-bottom: 0; }
/* 해설 편집 */
.expl-foot { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; margin-top: 10px; }
.expl-btn { border: 1px solid var(--line); background: #fff; color: var(--sub); font-weight: 700;
  font-size: 13px; padding: 5px 12px; border-radius: 999px; cursor: pointer; }
.expl-btn:hover { border-color: var(--brand); color: var(--brand-d); }
.expl-btn.on { background: var(--brand); color: #fff; border-color: var(--brand); }
.expl-btn.on:hover { background: var(--brand-dark); color: #fff; }
.tag-mine { background: #ede9fe; color: #6d28d9; }
.expl-ta { width: 100%; min-height: 120px; padding: 12px; border: 1px solid var(--line);
  border-radius: 10px; font-size: 14px; font-family: inherit; line-height: 1.6; resize: vertical; }
.done-badge { color: var(--ok); font-weight: 700; margin-left: auto; }

/* buttons */
.btn {
  display: inline-block; padding: 11px 20px; border-radius: 10px; border: none;
  background: var(--brand); color: #fff; font-weight: 700; font-size: 15px; cursor: pointer;
}
.btn:hover { background: var(--brand-dark); }
.btn.ghost { background: #fff; color: var(--ink); border: 1px solid var(--line); }
.btn.blue { background: var(--accent); }
.btn.block { display: block; width: 100%; text-align: center; }

/* quiz */
.choice {
  display: block; width: 100%; text-align: left; padding: 14px 16px; margin: 8px 0;
  border: 1.5px solid var(--line); border-radius: 12px; background: #fff; font-size: 15px; cursor: pointer;
}
.choice:hover { border-color: var(--accent); }
.choice.correct { border-color: var(--ok); background: #f0fdf4; }
.choice.wrong { border-color: var(--no); background: #fef2f2; }
.explain { background: #f9fafb; border-left: 4px solid var(--brand); padding: 14px 16px; border-radius: 8px; margin-top: 14px; }
.badge-ok { color: var(--ok); font-weight: 800; }
.badge-no { color: var(--no); font-weight: 800; }

/* markdown */
.md table { border-collapse: collapse; width: 100%; margin: 12px 0; }
.md th, .md td { border: 1px solid var(--line); padding: 8px 10px; text-align: left; }
.md th { background: #f9fafb; }
.md code { background: #f3f4f6; padding: 2px 6px; border-radius: 5px; font-size: 90%; }
.md pre { background: #1e293b; color: #e2e8f0; padding: 14px; border-radius: 10px; overflow-x: auto; }
.md pre code { background: none; color: inherit; }
.md blockquote { border-left: 4px solid var(--brand); margin: 12px 0; padding: 6px 14px; color: var(--sub); background: #fffdf7; }
.md h2 { font-size: 19px; border-bottom: 2px solid var(--line); padding-bottom: 6px; }

/* flashcard */
.flashcard {
  border: 2px solid var(--brand); border-radius: 18px; padding: 34px 24px; text-align: center;
  background: linear-gradient(180deg,#fffdf8,#fff); min-height: 180px;
}
.flashcard .term { font-size: 26px; font-weight: 800; margin-bottom: 10px; }
.flashcard .def { display: none; color: var(--ink); font-size: 16px; text-align: left; }
.flashcard.flipped .def { display: block; }
.flashcard.flipped .hint { display: none; }
.box-badge { font-size: 13px; color: var(--sub); }

.row { display: flex; gap: 10px; flex-wrap: wrap; }
.progress { height: 10px; background: #eef0f3; border-radius: 999px; overflow: hidden; }
.progress > i { display: block; height: 100%; background: var(--brand); }
/* 학습 잔디 히트맵 */
.heatwrap { margin-top: 14px; overflow-x: auto; }
.heatgrid { display: flex; gap: 3px; min-width: max-content; }
.heatcol { display: flex; flex-direction: column; gap: 3px; }
.heatcell { width: 12px; height: 12px; border-radius: 3px; background: #ebedf0; display: inline-block; }
.heatcell.empty { background: transparent; }
.heatcell.l0 { background: #ebedf0; }
.heatcell.l1 { background: #ffe0b2; }
.heatcell.l2 { background: #ffb74d; }
.heatcell.l3 { background: #f57c00; }
.heatcell.l4 { background: #e65100; }
.heatlegend { display: flex; align-items: center; gap: 4px; margin-top: 10px; font-size: 12px; }
.heatlegend .heatcell { width: 11px; height: 11px; }

.foot { text-align: center; color: var(--sub); font-size: 13px; padding: 30px 0; }
textarea { width: 100%; padding: 12px; border: 1px solid var(--line); border-radius: 10px; font-size: 15px; font-family: inherit; }
.kw { display: inline-block; padding: 3px 10px; border-radius: 999px; font-size: 13px; font-weight: 700; margin: 3px; }
.kw.hit { background: #f0fdf4; color: var(--ok); }
.kw.miss { background: #fef2f2; color: var(--no); }

/* ===== 모바일 반응형 ===== */
@media (max-width: 720px) {
  .topnav { flex-wrap: wrap; gap: 10px 8px; padding: 10px 14px; }
  .brand { flex: 1; font-size: 17px; }
  .navtoggle { display: block; order: 3; }
  .dday { order: 2; font-size: 14px; padding: 5px 11px; }
  /* 링크: 기본 접힘 → 토글 시 세로 목록 */
  .topnav .links {
    order: 5; flex-basis: 100%; width: 100%;
    flex-direction: column; gap: 4px; display: none;
    padding-top: 8px; border-top: 1px solid var(--line); margin-top: 2px;
  }
  #navtog:checked ~ .links { display: flex; }
  .topnav .links a { padding: 12px 14px; border-radius: 10px; font-size: 16px; }
  .topnav .links a.on { background: var(--brand); color: #fff; }
  /* 유저박스: 토글 안으로, 접힘 */
  .userbox { order: 6; flex-basis: 100%; width: 100%; display: none;
    justify-content: space-between; padding-top: 6px; }
  #navtog:checked ~ .userbox { display: flex; }
  .container { margin: 18px auto; }
  h1 { font-size: 21px; }
}