/* 수업도우미 — 모바일 우선 스타일 */
:root {
  --bg: #f5f7fa;
  --surface: #ffffff;
  --border: #d8dde3;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --danger: #dc2626;
  --danger-hover: #b91c1c;
  --success: #16a34a;
  --warning: #f59e0b;
  --warn-bg: #fef3c7;
  --absent: #fee2e2;
  --present: #dcfce7;
  --header-bg: #1e293b;
  --link: #2563eb;
}

* { box-sizing: border-box; }
html, body {
  margin: 0; padding: 0;
  font-family: -apple-system, "Segoe UI", "Apple SD Gothic Neo", "Malgun Gothic",
    "Noto Sans KR", sans-serif;
  font-size: 16px;
  line-height: 1.5;
  color: var(--text);
  background: var(--bg);
  -webkit-text-size-adjust: 100%;
}

a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ---- 상단 헤더 ---- */
header.app-header {
  background: var(--header-bg);
  color: #fff;
  padding: 0.6rem 0.9rem;
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; justify-content: space-between;
  box-shadow: 0 2px 4px rgba(0,0,0,0.08);
}
header.app-header h1 {
  font-size: 1.05rem; margin: 0; font-weight: 600;
}
header.app-header h1 a { color: #fff; }
header.app-header .meta {
  font-size: 0.78rem; color: #cbd5e1;
}

/* ---- 네비게이션 ---- */
nav.tabs {
  background: #fff; border-bottom: 1px solid var(--border);
  display: flex; overflow-x: auto;
  position: sticky; top: 48px; z-index: 9;
}
nav.tabs a {
  flex: 0 0 auto;
  padding: 0.75rem 0.9rem;
  color: var(--muted);
  font-size: 0.9rem; white-space: nowrap;
  border-bottom: 3px solid transparent;
}
nav.tabs a.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  font-weight: 600;
}

/* ---- 메인 레이아웃 ---- */
main {
  padding: 0.8rem;
  max-width: 1100px;
  margin: 0 auto;
}

h2 { font-size: 1.15rem; margin: 0.4rem 0 0.7rem; }
h3 { font-size: 1.0rem; margin: 0.6rem 0 0.4rem; }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.9rem;
  margin-bottom: 0.8rem;
}
.card h2:first-child, .card h3:first-child { margin-top: 0; }

.muted { color: var(--muted); font-size: 0.85rem; }
.warn { color: var(--danger); font-weight: 500; }

/* ---- 알림(flash) ---- */
.flash {
  padding: 0.6rem 0.9rem; border-radius: 6px;
  margin-bottom: 0.7rem;
  background: #e0f2fe; border: 1px solid #7dd3fc; color: #075985;
}
.flash.error { background: #fee2e2; border-color: #fca5a5; color: #991b1b; }
.flash.success { background: #dcfce7; border-color: #86efac; color: #166534; }

/* ---- 폼 ---- */
form { margin: 0; }
label { display: block; font-size: 0.85rem; color: var(--muted); margin: 0.4rem 0 0.2rem; }
input[type=text], input[type=date], input[type=email], input[type=number],
input[type=password], input[type=file], select, textarea {
  width: 100%; padding: 0.55rem 0.65rem;
  border: 1px solid var(--border); border-radius: 6px;
  font-size: 1rem; background: #fff; color: var(--text);
  font-family: inherit;
}
input:focus, select:focus, textarea:focus {
  outline: none; border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37,99,235,0.15);
}
textarea { resize: vertical; min-height: 4rem; }

.row { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.row > * { flex: 1 1 auto; }

/* 버튼 */
button, .btn {
  display: inline-block;
  padding: 0.55rem 0.95rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: #fff;
  color: var(--text);
  font-size: 0.95rem;
  font-family: inherit;
  cursor: pointer;
  transition: background-color 120ms;
}
button:hover, .btn:hover { background: #f3f4f6; }
button.primary, .btn.primary {
  background: var(--primary); color: #fff; border-color: var(--primary);
}
button.primary:hover, .btn.primary:hover {
  background: var(--primary-hover); border-color: var(--primary-hover);
}
button.danger, .btn.danger {
  background: var(--danger); color: #fff; border-color: var(--danger);
}
button.danger:hover, .btn.danger:hover {
  background: var(--danger-hover); border-color: var(--danger-hover);
}
button.warn, .btn.warn {
  background: var(--warning); color: #fff; border-color: var(--warning);
}
.btn-row { display: flex; flex-wrap: wrap; gap: 0.4rem; margin-top: 0.5rem; }

/* 테이블 */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: 0.92rem; }
th, td {
  border: 1px solid var(--border);
  padding: 0.45rem 0.55rem; text-align: left; vertical-align: middle;
}
th { background: #f1f5f9; font-weight: 600; }
tbody tr:nth-child(even) td { background: #f9fafb; }

/* 시간표 그리드 */
.timetable {
  display: grid;
  grid-template-columns: 56px repeat(5, 1fr);
  gap: 4px;
}
.timetable .cell {
  min-height: 64px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.4rem 0.5rem;
  font-size: 0.82rem;
  text-align: center;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  cursor: pointer;
}
.timetable .cell.has-class { background: #fffbeb; }
.timetable .cell strong { font-weight: 600; color: var(--text); }
.timetable .cell .sub { color: var(--muted); font-size: 0.75rem; }
.timetable .head {
  background: #1e293b; color: #fff;
  font-weight: 600; font-size: 0.85rem;
  border-radius: 6px; padding: 0.4rem;
  display: flex; align-items: center; justify-content: center;
}
.timetable .row-head {
  background: #475569; color: #fff;
  font-size: 0.8rem;
  border-radius: 6px; padding: 0.4rem;
  display: flex; align-items: center; justify-content: center;
}

/* 학생 카드 (출결/참여도) */
.student-card {
  display: flex; gap: 0.7rem; align-items: center;
  background: var(--surface);
  border: 1px solid var(--border); border-radius: 8px;
  padding: 0.55rem 0.7rem; margin-bottom: 0.45rem;
}
.student-card .num {
  width: 2rem; text-align: center; font-weight: 600; color: var(--muted);
  font-size: 0.85rem;
}
.student-card .name { flex: 1 1 auto; font-weight: 500; }
.student-card .toggle {
  padding: 0.4rem 0.7rem; border-radius: 6px; min-width: 56px;
  text-align: center; font-weight: 600; font-size: 0.9rem; cursor: pointer;
  border: 1px solid var(--border); background: var(--present);
}
.student-card.absent .toggle { background: var(--absent); }
.student-card .memo {
  flex: 2 1 12rem;
}
.student-card .photo {
  width: 40px; height: 50px; object-fit: cover;
  border-radius: 4px; border: 1px solid var(--border);
}

/* 학생 상세 */
.student-detail {
  display: flex; gap: 1rem; flex-wrap: wrap;
}
.student-detail .photo-box img {
  width: 200px; max-width: 50vw; border-radius: 8px; border: 1px solid var(--border);
}
.kv { display: grid; grid-template-columns: 6rem 1fr; gap: 0.4rem 0.7rem; font-size: 0.95rem; }
.kv dt { color: var(--muted); }
.kv dd { margin: 0; }

/* 모바일 최적화 */
@media (max-width: 600px) {
  main { padding: 0.5rem; }
  .timetable {
    grid-template-columns: 36px repeat(5, 1fr);
    font-size: 0.75rem;
  }
  .timetable .cell { padding: 0.3rem; min-height: 54px; }
  .student-card { flex-wrap: wrap; }
  .student-card .memo { flex-basis: 100%; }
  table { font-size: 0.85rem; }
  th, td { padding: 0.35rem 0.4rem; }
  nav.tabs a { padding: 0.6rem 0.7rem; font-size: 0.85rem; }
}

/* 인쇄 */
@media print {
  header.app-header, nav.tabs, .btn-row, button { display: none; }
}