:root {
  --bg: #f4f5f7;
  --surface: #ffffff;
  --border: #e2e5ea;
  --text: #1c2430;
  --muted: #66707d;
  --primary: #2f6fed;
  --primary-dark: #2559c7;
  --paid: #12805c;
  --paid-bg: #e3f5ee;
  --due: #9a6a00;
  --due-bg: #fdf2dc;
  --overdue: #c0362c;
  --overdue-bg: #fbe6e4;
  --inactive: #8a94a2;
  --inactive-bg: #eef0f3;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(20, 30, 45, 0.08), 0 1px 2px rgba(20, 30, 45, 0.04);
  color-scheme: light;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Inter", "Noto Sans Thai", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}
a { color: var(--primary); }
h1, h2, h3 { margin: 0 0 .5rem; font-weight: 650; }
button { font: inherit; cursor: pointer; }

/* ---------- layout ---------- */
header.topbar {
  display: flex; align-items: center; gap: 1rem;
  padding: .7rem 1.2rem;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.topbar .brand { font-weight: 700; font-size: 1.05rem; letter-spacing: -.01em; }
.topbar .brand span { color: var(--primary); }
.topbar nav { display: flex; gap: .25rem; flex-wrap: wrap; }
.topbar nav button {
  border: 0; background: transparent; padding: .45rem .8rem;
  border-radius: 8px; color: var(--muted); font-weight: 550;
}
.topbar nav button.active { background: #eef3fe; color: var(--primary-dark); }
.topbar .spacer { flex: 1; }
.topbar .who { color: var(--muted); font-size: .88rem; }
.topbar .who b { color: var(--text); }

main { max-width: 1120px; margin: 0 auto; padding: 1.4rem 1.2rem 4rem; }

.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow);
  padding: 1.2rem; margin-bottom: 1.2rem;
}

/* ---------- forms ---------- */
label { display: block; font-size: .84rem; font-weight: 600; color: var(--muted); margin-bottom: .3rem; }
input, select, textarea {
  width: 100%; padding: .55rem .65rem; border: 1px solid var(--border);
  border-radius: 8px; background: #fff; color: var(--text); font: inherit;
}
input:focus, select:focus, textarea:focus { outline: 2px solid #b9d0fb; border-color: var(--primary); }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: .9rem; }
.grid3 { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: .9rem; }
.field { margin-bottom: .9rem; }
@media (max-width: 640px) { .grid2, .grid3 { grid-template-columns: 1fr; } }

.btn {
  border: 0; background: var(--primary); color: #fff;
  padding: .58rem 1.1rem; border-radius: 8px; font-weight: 600;
}
.btn:hover { background: var(--primary-dark); }
.btn.ghost { background: transparent; color: var(--primary); border: 1px solid var(--border); }
.btn.danger { background: var(--overdue); }
.btn.sm { padding: .35rem .6rem; font-size: .84rem; }
.btn:disabled { opacity: .55; cursor: not-allowed; }

/* ---------- table ---------- */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: .92rem; }
th, td { text-align: left; padding: .6rem .7rem; border-bottom: 1px solid var(--border); vertical-align: middle; }
th { font-size: .78rem; text-transform: uppercase; letter-spacing: .03em; color: var(--muted); }
tbody tr:hover { background: #fafbfc; }

.pill {
  display: inline-flex; align-items: center; gap: .3rem;
  padding: .18rem .55rem; border-radius: 999px; font-size: .8rem; font-weight: 650;
}
.pill.paid { background: var(--paid-bg); color: var(--paid); }
.pill.due { background: var(--due-bg); color: var(--due); }
.pill.overdue { background: var(--overdue-bg); color: var(--overdue); }
.pill.inactive { background: var(--inactive-bg); color: var(--inactive); }
.pill.review { background: #ede7fb; color: #6b3fd4; }

.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: .8rem; margin-bottom: 1.2rem; }
.stat { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: .9rem 1rem; box-shadow: var(--shadow); }
.stat .n { font-size: 1.7rem; font-weight: 720; }
.stat .l { font-size: .82rem; color: var(--muted); font-weight: 600; }
.stat.paid .n { color: var(--paid); }
.stat.due .n { color: var(--due); }
.stat.overdue .n { color: var(--overdue); }
@media (max-width: 640px) { .stats { grid-template-columns: 1fr 1fr; } }

/* ---------- login ---------- */
.login-wrap { min-height: 82vh; display: flex; align-items: center; justify-content: center; }
.login-card { width: 100%; max-width: 380px; }

/* ---------- misc ---------- */
.muted { color: var(--muted); }
.row-actions { display: flex; gap: .4rem; flex-wrap: wrap; }
.toast {
  position: fixed; left: 50%; bottom: 1.5rem; transform: translateX(-50%);
  background: #1c2430; color: #fff; padding: .7rem 1.1rem; border-radius: 8px;
  box-shadow: var(--shadow); z-index: 50; max-width: 90vw; font-size: .92rem;
}
.toast.err { background: var(--overdue); }
.hidden { display: none !important; }
.inline-form { display: flex; gap: .5rem; align-items: flex-end; flex-wrap: wrap; }
dialog {
  border: 1px solid var(--border); border-radius: var(--radius); padding: 0;
  max-width: 560px; width: 92vw; box-shadow: 0 12px 40px rgba(20,30,45,.22);
}
dialog::backdrop { background: rgba(20, 30, 45, .35); }
.dialog-body { padding: 1.2rem; }
.dialog-head { padding: 1rem 1.2rem; border-bottom: 1px solid var(--border); font-weight: 650; }
.slip-preview img { max-height: 60vh; border-radius: 8px; border: 1px solid var(--border); }
small.hint { color: var(--muted); font-weight: 500; display: block; margin-top: .25rem; }