:root {
  --bg: #f5f6f8;
  --surface: #ffffff;
  --border: #e0e3e8;
  --text: #1e2430;
  --muted: #6b7380;
  --brand: #2f6feb;
  --brand-dark: #1f52b8;
  --danger: #d0342c;
  --danger-bg: #fdecea;
  --success: #1c7c3f;
  --success-bg: #e9f7ee;
  --radius: 8px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}

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

.topbar {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.topbar-inner {
  max-width: 960px; margin: 0 auto; padding: 14px 20px;
  display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 10px;
}
.brand { font-weight: 700; font-size: 1.15rem; color: var(--text); }
.topnav { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }
.topnav .who { color: var(--muted); font-size: 0.9rem; }
.btn-nav { background: var(--brand); color: #fff; padding: 6px 14px; border-radius: 6px; }
.btn-nav:hover { background: var(--brand-dark); text-decoration: none; }

.container { max-width: 960px; margin: 0 auto; padding: 28px 20px 60px; }

.sitefooter { text-align: center; color: var(--muted); font-size: 0.85rem; padding: 30px 20px; }

h1 { font-size: 1.6rem; margin: 0 0 6px; }
h2 { font-size: 1.25rem; margin: 28px 0 12px; }
p.lead { color: var(--muted); margin-top: 0; }

.card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 20px 22px; margin-bottom: 18px;
}

.grid { display: grid; gap: 16px; }

.list-plain { list-style: none; margin: 0; padding: 0; }

.assignment-item, .submission-item, .admin-item {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 18px; margin-bottom: 12px; display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap;
}
.assignment-item h3, .submission-item h3, .admin-item h3 { margin: 0 0 4px; font-size: 1.05rem; }
.meta { color: var(--muted); font-size: 0.87rem; }

.badge { display: inline-block; padding: 2px 9px; border-radius: 999px; font-size: 0.75rem; font-weight: 600; }
.badge-open { background: var(--success-bg); color: var(--success); }
.badge-closed { background: var(--danger-bg); color: var(--danger); }
.badge-draft { background: #eef0f3; color: var(--muted); }
.badge-graded { background: var(--success-bg); color: var(--success); }
.badge-pending { background: #fff6e3; color: #9a6b00; }

form.stack { display: flex; flex-direction: column; gap: 16px; }

label { display: block; font-weight: 600; margin-bottom: 6px; font-size: 0.92rem; }
.hint { color: var(--muted); font-size: 0.82rem; margin-top: 4px; }

input[type=text], input[type=email], input[type=password], input[type=number], input[type=tel],
input[type=datetime-local], textarea, select {
  width: 100%; padding: 9px 11px; border: 1px solid var(--border); border-radius: 6px;
  font-size: 0.97rem; font-family: inherit; background: #fff; color: var(--text);
}
textarea { min-height: 110px; resize: vertical; }
input:focus, textarea:focus, select:focus { outline: 2px solid var(--brand); outline-offset: 1px; }

.field { margin-bottom: 2px; }
.checkbox-row, .radio-row { display: flex; align-items: center; gap: 8px; font-weight: 400; margin: 6px 0; }
.checkbox-row input, .radio-row input { width: auto; }
.checkbox-row label, .radio-row label { margin: 0; font-weight: 400; }

.btn {
  display: inline-block; background: var(--brand); color: #fff; border: none; padding: 10px 18px;
  border-radius: 6px; font-size: 0.95rem; font-weight: 600; cursor: pointer;
}
.btn:hover { background: var(--brand-dark); }
.btn-secondary { background: var(--surface); color: var(--text); border: 1px solid var(--border); }
.btn-secondary:hover { background: #f0f1f3; }
.btn-danger { background: var(--danger); }
.btn-danger:hover { background: #a92620; }
.btn-sm { padding: 5px 11px; font-size: 0.83rem; }
.link-btn { background: none; border: none; color: var(--brand); cursor: pointer; padding: 0; font-size: inherit; }
.link-btn:hover { text-decoration: underline; }

.actions { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.inline-form { display: inline; }

.alert { padding: 12px 16px; border-radius: 6px; margin-bottom: 16px; font-size: 0.92rem; }
.alert-error { background: var(--danger-bg); color: var(--danger); border: 1px solid #f3c6c2; }
.alert-success { background: var(--success-bg); color: var(--success); border: 1px solid #bfe6cc; }
.alert ul { margin: 4px 0 0; padding-left: 20px; }

table { width: 100%; border-collapse: collapse; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--border); font-size: 0.9rem; }
th { background: #fafbfc; color: var(--muted); font-weight: 600; }
tr:last-child td { border-bottom: none; }

.question-block { border: 1px solid var(--border); border-radius: var(--radius); padding: 18px 20px; margin-bottom: 16px; background: var(--surface); }
.question-block .qtitle { font-weight: 600; margin-bottom: 4px; }
.question-block .qdesc { color: var(--muted); font-size: 0.88rem; margin-bottom: 10px; }
.required-mark { color: var(--danger); }
.points-tag { color: var(--muted); font-size: 0.8rem; font-weight: 400; }

.section-header-block { border-left: 4px solid var(--brand); padding: 10px 16px; margin: 24px 0 16px; background: #eef4ff; border-radius: 0 6px 6px 0; }
.section-header-block h3 { margin: 0 0 4px; }
.section-header-block p { margin: 0; color: var(--muted); }

.option-row-edit { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; }
.option-row-edit input[type=text] { flex: 1; }

.token-box { background: #f0f4ff; border: 1px dashed var(--brand); border-radius: 6px; padding: 12px 14px; font-family: monospace; word-break: break-all; }

.type-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 10px; }
.type-card { display: block; border: 1px solid var(--border); border-radius: var(--radius); padding: 14px; background: var(--surface); }
.type-card:hover { border-color: var(--brand); text-decoration: none; }
.type-card strong { display: block; margin-bottom: 3px; }

.file-list { list-style: none; padding: 0; margin: 6px 0 0; }
.file-list li { margin-bottom: 4px; }

@media (max-width: 640px) {
  .assignment-item, .submission-item, .admin-item { flex-direction: column; align-items: flex-start; }
  table, thead, tbody, th, td, tr { display: block; }
  thead { display: none; }
  td { border: none; padding: 4px 0; }
  tr { border-bottom: 1px solid var(--border); padding: 8px 0; }
}