:root {
  --ink: #1b2a4a;
  --paper: #f7f5f2;
  --card: #ffffff;
  --accent: #c8532b;
  --accent-dark: #9c3f20;
  --muted-ink: #4a5468;
  --line: #ddd6cf;
  --ok-bg: #e2efdf;
  --ok-ink: #24502a;
  --warn-bg: #fbe9dd;
  --warn-ink: #8a3a1b;
  --late-bg: #f9e0e0;
  --late-ink: #7a1f24;
  --focus: #2b6cb0;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  background: var(--paper);
  color: var(--ink);
  line-height: 1.55;
}

.topbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  align-items: baseline;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  background: var(--ink);
  color: var(--paper);
}

.topbar h1 { font-size: 1.25rem; margin: 0; }
.session-box { display: flex; align-items: center; gap: 0.75rem; font-size: 0.95rem; }

main { max-width: 60rem; margin: 0 auto; padding: 1.5rem 1.25rem 3rem; }

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}
.narrow { max-width: 26rem; }
.section-head { display: flex; flex-wrap: wrap; gap: 0.5rem 1rem; align-items: baseline; }
h2 { font-size: 1.35rem; margin: 0 0 0.5rem; }
h3 { font-size: 1.1rem; margin-top: 0; }

label { display: block; margin: 0.75rem 0 0.25rem; font-weight: bold; font-size: 0.95rem; }
input, select {
  width: 100%;
  padding: 0.55rem 0.6rem;
  font: inherit;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: var(--card);
  color: var(--ink);
}

.btn {
  display: inline-block;
  margin-top: 1rem;
  padding: 0.5rem 1.1rem;
  font: inherit;
  border-radius: 5px;
  border: 1px solid transparent;
  cursor: pointer;
}
.btn.primary { background: var(--accent); color: #fff; }
.btn.primary:hover { background: var(--accent-dark); }
.btn.ghost { background: transparent; color: var(--paper); border-color: var(--paper); margin-top: 0; padding: 0.3rem 0.8rem; }
.btn.small { margin-top: 0; padding: 0.25rem 0.6rem; font-size: 0.85rem; background: var(--ink); color: #fff; }

:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }

table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 0.55rem 0.6rem; border-bottom: 1px solid var(--line); }
th { font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.04em; color: var(--muted-ink); }
.table-wrap { overflow-x: auto; }

.badge { display: inline-block; padding: 0.1rem 0.6rem; border-radius: 999px; font-size: 0.85rem; font-family: Verdana, sans-serif; }
.badge.paid { background: var(--ok-bg); color: var(--ok-ink); }
.badge.open { background: var(--warn-bg); color: var(--warn-ink); }
.badge.overdue { background: var(--late-bg); color: var(--late-ink); }

.muted { color: var(--muted-ink); }
.error { color: var(--accent-dark); font-weight: bold; }
.footer { font-size: 0.8rem; text-align: center; padding: 1rem; border-top: 1px solid var(--line); }
.visually-hidden {
  position: absolute; width: 1px; height: 1px; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap;
}
.hidden { display: none; }

@media (max-width: 480px) {
  .card { padding: 1rem; }
  .btn.ghost { margin-top: 0.4rem; }
}