* { box-sizing: border-box; }
body { font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif; margin: 0; background: #fafafa; color: #222; }
header { display:flex; align-items:center; justify-content: space-between; padding: 12px 16px; background: #0e7a57; color: white; }
#auth button { margin-left: 8px; }
.hidden { display: none; }
h1 { margin: 0; font-size: 20px; }
main { padding: 16px; max-width: 900px; margin: 0 auto; }
.card { background: white; border-radius: 14px; padding: 16px; margin: 12px 0; box-shadow: 0 2px 8px rgba(0,0,0,.08); }
.row { display: flex; gap: 8px; margin: 8px 0; flex-wrap: wrap; }
input, select { padding: 10px; border: 1px solid #ddd; border-radius: 8px; min-width: 180px; }
button { padding: 10px 14px; border: 0; border-radius: 10px; background: #eee; cursor: pointer; }
button.primary { background: #0e7a57; color: white; }
button[disabled] { opacity: .5; cursor: not-allowed; }
table { width: 100%; border-collapse: collapse; margin-top: 8px; }
th, td { border-bottom: 1px solid #eee; padding: 8px; text-align: left; }
#assignmentList li { padding: 6px 0; }
.error { color: #b00020; min-height: 1.2em; }
.hidden {
    display: none !important;
  }