:root {
  --bg: #f4f6f7; --card: #ffffff; --ink: #1c2b30; --muted: #5f7076; --line: #dde4e6;
  --brand: #0f5c63; --brand-ink: #ffffff; --brand-soft: #e3f0f1;
  --warn: #b42318; --warn-soft: #fdecea; --ok: #1a7f4b; --ok-soft: #e4f5ec; --amber: #a15c00; --amber-soft: #fff3de;
  --radius: 10px;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #11181a; --card: #1a2427; --ink: #e8eef0; --muted: #9bb0b6; --line: #2c3a3e;
    --brand: #4fb3bd; --brand-ink: #062a2e; --brand-soft: #1c3438;
    --warn: #ff8a80; --warn-soft: #3a1f1d; --ok: #6fd69f; --ok-soft: #173326; --amber: #f2b45a; --amber-soft: #38290f; }
}
* { box-sizing: border-box; }
html { font-size: 16px; }
body { margin: 0; background: var(--bg); color: var(--ink); font-family: system-ui, "Segoe UI", Roboto, Arial, sans-serif; line-height: 1.45; }
button, input, select, textarea { font: inherit; color: inherit; }
.boot { padding: 2rem; color: var(--muted); }
a { color: var(--brand); }
h1 { font-size: 1.35rem; margin: 0 0 .75rem; }
h2 { font-size: 1.05rem; margin: 1.25rem 0 .5rem; }
.muted { color: var(--muted); }
.small { font-size: .85rem; }

/* Khung */
.shell { display: grid; grid-template-columns: 230px 1fr; min-height: 100vh; }
.side { background: var(--card); border-right: 1px solid var(--line); padding: 1rem .75rem; position: sticky; top: 0; height: 100vh; overflow-y: auto; }
.brand { font-weight: 700; font-size: 1.2rem; color: var(--brand); padding: .25rem .5rem 1rem; }
.nav a { display: block; padding: .6rem .75rem; border-radius: 8px; color: var(--ink); text-decoration: none; margin-bottom: 2px; }
.nav a:hover { background: var(--brand-soft); }
.nav a.on { background: var(--brand); color: var(--brand-ink); font-weight: 600; }
.nav .group { margin: 1rem .75rem .25rem; font-size: .75rem; letter-spacing: .04em; text-transform: uppercase; color: var(--muted); }
.nav a.soon { color: var(--muted); }
.main { padding: 1.25rem; max-width: 1000px; width: 100%; }
.top { display: none; }
.who { margin-top: 1.25rem; padding: .75rem; border-top: 1px solid var(--line); font-size: .9rem; }

@media (max-width: 820px) {
  .shell { display: block; }
  .top { display: flex; align-items: center; justify-content: space-between; background: var(--card); border-bottom: 1px solid var(--line); padding: .6rem 1rem; position: sticky; top: 0; z-index: 5; }
  .side { display: none; position: fixed; inset: 0 25% 0 0; z-index: 10; height: 100vh; box-shadow: 0 0 40px rgba(0,0,0,.25); }
  .side.open { display: block; }
  .main { padding: 1rem; }
}

/* Thành phần */
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 1rem; margin-bottom: 1rem; }
.grid { display: grid; gap: .75rem; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); }
.stat { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: .8rem 1rem; }
.stat b { display: block; font-size: 1.6rem; }
.stat.bad b { color: var(--warn); }
.btn { border: 1px solid var(--brand); background: var(--brand); color: var(--brand-ink); padding: .55rem 1rem; border-radius: 8px; cursor: pointer; min-height: 40px; }
.btn.ghost { background: transparent; color: var(--brand); }
.btn.danger { border-color: var(--warn); background: transparent; color: var(--warn); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn.sm { padding: .3rem .7rem; min-height: 32px; font-size: .9rem; }
.row { display: flex; gap: .5rem; flex-wrap: wrap; align-items: center; }
.row.between { justify-content: space-between; }
.stack > * + * { margin-top: .75rem; }
label { display: block; font-size: .9rem; color: var(--muted); margin-bottom: .2rem; }
input, select, textarea { width: 100%; padding: .55rem .65rem; border: 1px solid var(--line); border-radius: 8px; background: var(--card); min-height: 40px; }
textarea { min-height: 90px; resize: vertical; }
.filters { display: grid; gap: .5rem; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); margin-bottom: .75rem; }
.item { display: block; width: 100%; text-align: left; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: .75rem 1rem; margin-bottom: .5rem; cursor: pointer; text-decoration: none; color: inherit; }
.item:hover { border-color: var(--brand); }
.item .t { font-weight: 600; }
.badge { display: inline-block; font-size: .78rem; padding: .1rem .55rem; border-radius: 999px; background: var(--brand-soft); color: var(--brand); margin-right: .3rem; }
.badge.NEW { background: var(--line); color: var(--ink); }
.badge.DOING { background: var(--brand-soft); color: var(--brand); }
.badge.REVIEW { background: var(--amber-soft); color: var(--amber); }
.badge.DONE { background: var(--ok-soft); color: var(--ok); }
.badge.RETURNED { background: var(--warn-soft); color: var(--warn); }
.badge.URGENT, .badge.late { background: var(--warn-soft); color: var(--warn); }
.badge.HIGH { background: var(--amber-soft); color: var(--amber); }
table { width: 100%; border-collapse: collapse; font-size: .92rem; }
th, td { text-align: left; padding: .45rem .5rem; border-bottom: 1px solid var(--line); vertical-align: top; }
th { color: var(--muted); font-weight: 600; }
.note { border-left: 3px solid var(--line); padding: .25rem .75rem; margin: .5rem 0; }
.note.STATUS { border-color: var(--brand); }
.note.SYSTEM { color: var(--muted); }
.empty { color: var(--muted); padding: 1rem 0; }
.err { color: var(--warn); background: var(--warn-soft); padding: .5rem .75rem; border-radius: 8px; }
.login { max-width: 380px; margin: 8vh auto; padding: 0 1rem; }
.login .card { padding: 1.5rem; }
.overlay { position: fixed; inset: 0; background: rgba(0,0,0,.45); display: flex; align-items: flex-start; justify-content: center; padding: 4vh 1rem; overflow-y: auto; z-index: 20; }
.modal { background: var(--card); border-radius: var(--radius); padding: 1.25rem; width: 100%; max-width: 520px; }
#toast { position: fixed; left: 50%; bottom: 1.25rem; transform: translateX(-50%); z-index: 30; max-width: 90vw; }
#toast div { background: var(--ink); color: var(--bg); padding: .6rem 1rem; border-radius: 8px; margin-top: .4rem; }
#toast div.bad { background: var(--warn); color: #fff; }
.soon-box { text-align: center; padding: 3rem 1rem; }