:root {
  --bg: #f4f6fb;
  --card: #ffffff;
  --ink: #1f2430;
  --muted: #6b7280;
  --accent: #4f46e5;
  --accent-dark: #4338ca;
  --border: #e5e7eb;
  --success: #16a34a;
  --warning: #d97706;
  --danger: #dc2626;
  --radius: 10px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.5;
}

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

.container { max-width: 1000px; margin: 0 auto; padding: 20px; }

/* Top bar */
.topbar {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  padding: 12px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.brand { font-weight: 700; font-size: 1.15rem; color: var(--ink); }
.brand span { color: var(--accent); }
.nav { display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }
.nav .who { color: var(--muted); font-size: 0.9rem; }

/* Cards */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
}
.card h2, .card h3 { margin-top: 0; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 16px; }

.muted { color: var(--muted); font-size: 0.9rem; }
.small { font-size: 0.85rem; }

/* Buttons */
.btn {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  border: none;
  padding: 9px 16px;
  border-radius: 7px;
  font-size: 0.95rem;
  cursor: pointer;
  text-decoration: none;
}
.btn:hover { background: var(--accent-dark); text-decoration: none; color: #fff; }
.btn.secondary { background: #eef0f7; color: var(--ink); }
.btn.secondary:hover { background: #e2e5f0; }
.btn.danger { background: var(--danger); }
.btn.small { padding: 5px 10px; font-size: 0.85rem; }
.btn.link { background: none; color: var(--accent); padding: 4px 8px; }

/* Forms */
label { display: block; font-weight: 600; margin: 12px 0 4px; font-size: 0.92rem; }
input[type=text], input[type=password], input[type=email], input[type=number],
input[type=datetime-local], select, textarea {
  width: 100%;
  padding: 9px 11px;
  border: 1px solid var(--border);
  border-radius: 7px;
  font-size: 0.95rem;
  font-family: inherit;
  background: #fff;
}
textarea { min-height: 90px; resize: vertical; }
.form-narrow { max-width: 480px; }
.help { color: var(--muted); font-size: 0.85rem; margin-top: 4px; }
.checkbox-row { display: flex; align-items: center; gap: 8px; margin-top: 14px; }
.checkbox-row input { width: auto; }
.checkbox-row label { margin: 0; font-weight: 500; }

/* Flash messages */
.flash { padding: 11px 14px; border-radius: 7px; margin-bottom: 14px; font-size: 0.95rem; }
.flash.success { background: #dcfce7; color: #14532d; border: 1px solid #bbf7d0; }
.flash.danger { background: #fee2e2; color: #7f1d1d; border: 1px solid #fecaca; }
.flash.warning { background: #fef3c7; color: #78350f; border: 1px solid #fde68a; }
.flash.info { background: #dbeafe; color: #1e3a8a; border: 1px solid #bfdbfe; }

/* Tables */
table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.03em; color: var(--muted); }
tr:last-child td { border-bottom: none; }

/* Badges */
.badge {
  display: inline-block;
  padding: 3px 9px;
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 600;
}
.badge.submitted { background: #dbeafe; color: #1e40af; }
.badge.graded { background: #dcfce7; color: #14532d; }
.badge.missing { background: #f3f4f6; color: #6b7280; }
.badge.late { background: #fef3c7; color: #92400e; }
.badge.final { background: #ede9fe; color: #5b21b6; }

.mono { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 0.85rem; }

.row-between { display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; }
.divider { border: none; border-top: 1px solid var(--border); margin: 16px 0; }
.inline-form { display: inline; }