:root {
  --ink: #17202b; --muted: #5d6b7a; --line: #dfe5ec; --bg: #f4f6f9; --card: #ffffff;
  /* Prime Robotics logo colours: orange wordmark, blue "robotics" */
  --orange: #f7942d; --blue: #168dc6;
  --brand: #163a5f; --brand-ink: #ffffff; --accent: #168dc6; --ok: #1f8f4e; --warn: #b7791f; --bad: #c0392b; --soft: #eef3f9;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body { font-family: var(--sans); color: var(--ink); background: var(--bg); font-size: 15px; line-height: 1.5; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
h1 { font-size: 1.6rem; margin: 0 0 .5rem; letter-spacing: -.01em; }
h2 { font-size: 1.2rem; margin: 1.4rem 0 .5rem; }
h3 { font-size: 1.02rem; margin: 1rem 0 .4rem; }
p { margin: .4rem 0 .8rem; }
code { font-family: var(--mono); font-size: .92em; background: var(--soft); padding: .1em .35em; border-radius: 4px; }
pre { background: #0f1720; color: #e6edf3; padding: .9rem 1rem; border-radius: 8px; overflow: auto; font-size: .86rem; line-height: 1.45; }
pre code { background: none; padding: 0; color: inherit; }
.muted { color: var(--muted); }
.small { font-size: .86rem; }
.pad { padding: 1rem; }
.wrap { max-width: 1180px; margin: 0 auto; padding: 1.4rem 1.2rem 3rem; }
.wrap.narrow { max-width: 820px; }
.row { display: flex; gap: .6rem; align-items: center; flex-wrap: wrap; }
.spacer { flex: 1; }
.right { margin-left: auto; }

/* nav: white, with the Prime Robotics logo */
.topnav { background: #fff; color: var(--ink); border-bottom: 1px solid var(--line); box-shadow: 0 1px 6px rgba(0,0,0,.04); }
.topnav .wrap { display: flex; align-items: center; gap: 1.1rem; padding: .55rem 1.2rem; }
.topnav a { color: #33414f; font-weight: 500; padding: .45rem 0; border-bottom: 2px solid transparent; }
.topnav a:hover { text-decoration: none; color: var(--ink); }
.topnav a.active { color: var(--ink); border-bottom-color: var(--orange); }
.topnav .who { color: var(--muted); font-size: .9rem; }
.brand { display: inline-flex; align-items: center; gap: .6rem; margin-right: .6rem; border-bottom: 0 !important; }
.brand img { height: 34px; width: auto; display: block; }
.brand span { font-weight: 600; color: var(--brand); font-size: 1.05rem; letter-spacing: .01em; padding-left: .6rem; border-left: 1px solid var(--line); }
.logo { display: block; height: 56px; width: auto; margin: 0 0 1rem; }
.logo-sm { height: 22px; width: auto; display: block; }

/* cards & tables */
.card { background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 1.1rem 1.2rem; margin: 0 0 1rem; }
.card.table-card { padding: 0; overflow: hidden; }
.card h2:first-child, .card h3:first-child { margin-top: 0; }
table { width: 100%; border-collapse: collapse; font-size: .93rem; }
th, td { text-align: left; padding: .6rem .8rem; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font-size: .78rem; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); background: #fafbfd; }
tr.clickable { cursor: pointer; }
tr.clickable:hover { background: #f7f9fc; }
td.num { text-align: right; font-variant-numeric: tabular-nums; }
.page-head { display: flex; align-items: center; justify-content: space-between; gap: 1rem; flex-wrap: wrap; margin-bottom: 1rem; }
.tabs { display: flex; gap: .3rem; flex-wrap: wrap; margin-bottom: .8rem; }
.tabs button { background: #fff; border: 1px solid var(--line); border-radius: 999px; padding: .35rem .9rem; cursor: pointer; font: inherit; color: var(--ink); }
.tabs button.active { background: var(--brand); color: #fff; border-color: var(--brand); }
.tabs button .n { opacity: .7; margin-left: .3rem; font-size: .85em; }

/* badges */
.badge { display: inline-block; padding: .15rem .55rem; border-radius: 999px; font-size: .78rem; font-weight: 600; white-space: nowrap; background: #e5e9ef; color: #33414f; }
.badge.PENDING { background: #eef1f5; color: #4d5a68; }
.badge.IN_PROGRESS { background: #e3f0ff; color: #1a4f8a; }
.badge.GRADING_PENDING { background: #fff3d6; color: #7a5200; }
.badge.GRADING_IN_PROGRESS { background: #ffe9c7; color: #8a4b00; }
.badge.GRADING_COMPLETED { background: #dff5e7; color: #14603a; }
.badge.warn { background: #fdecea; color: #8a1f14; }
.badge.ok { background: #dff5e7; color: #14603a; }
.badge.tier { background: #eef3f9; color: #163a5f; }

/* buttons & forms */
.btn { display: inline-block; border: 1px solid var(--line); background: #fff; color: var(--ink); border-radius: 8px; padding: .5rem .95rem; font: inherit; font-weight: 500; cursor: pointer; line-height: 1.2; }
.btn:hover { background: #f6f8fb; text-decoration: none; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.primary:hover { background: #1868c2; }
.btn.danger { color: var(--bad); border-color: #f0c9c4; }
.btn.danger:hover { background: #fdf2f0; }
.btn.small { padding: .3rem .6rem; font-size: .85rem; }
.btn:disabled { opacity: .55; cursor: not-allowed; }
label { display: block; font-weight: 600; font-size: .88rem; margin: .8rem 0 .3rem; }
label .hint { font-weight: 400; color: var(--muted); }
input[type=text], input[type=email], input[type=number], input[type=password], input:not([type]), select, textarea {
  width: 100%; font: inherit; padding: .5rem .65rem; border: 1px solid var(--line); border-radius: 8px; background: #fff; color: var(--ink);
}
input:focus, select:focus, textarea:focus { outline: 2px solid #bcd6f7; border-color: var(--accent); }
textarea { min-height: 6rem; resize: vertical; }
textarea.code { font-family: var(--mono); font-size: .86rem; min-height: 16rem; line-height: 1.45; tab-size: 2; white-space: pre; }
textarea.tall { min-height: 22rem; }
.search { width: 20rem; max-width: 100%; }
.check { display: flex; gap: .6rem; align-items: flex-start; font-weight: 500; margin: .5rem 0; }
.check input { margin-top: .3rem; }
.radio-list { display: grid; gap: .4rem; }
.radio-list label { display: flex; gap: .6rem; align-items: center; font-weight: 500; margin: 0; padding: .55rem .7rem; border: 1px solid var(--line); border-radius: 8px; cursor: pointer; }
.radio-list label.on { border-color: var(--accent); background: #f2f8ff; }
.radio-list .mins { margin-left: auto; color: var(--muted); font-size: .85rem; }
.field-error { color: var(--bad); font-size: .86rem; }
.actions { display: flex; gap: .6rem; align-items: center; flex-wrap: wrap; margin-top: 1rem; }
.kv { display: grid; grid-template-columns: max-content 1fr; gap: .25rem 1rem; font-size: .93rem; }
.kv dt { color: var(--muted); }
.kv dd { margin: 0; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
@media (max-width: 800px) { .grid2 { grid-template-columns: 1fr; } }

/* toast */
.toast { position: fixed; left: 50%; bottom: 1.5rem; transform: translateX(-50%); background: #17202b; color: #fff; padding: .6rem 1rem; border-radius: 8px; font-size: .92rem; z-index: 50; box-shadow: 0 6px 24px rgba(0,0,0,.25); }
.toast.bad { background: var(--bad); }
.toast.ok { background: var(--ok); }

/* modal */
.modal-back { position: fixed; inset: 0; background: rgba(15,23,32,.45); display: flex; align-items: center; justify-content: center; z-index: 40; padding: 1rem; }
.modal { background: #fff; border-radius: 12px; width: min(900px, 100%); max-height: 90vh; display: flex; flex-direction: column; box-shadow: 0 20px 60px rgba(0,0,0,.3); }
.modal header { padding: .9rem 1.2rem; border-bottom: 1px solid var(--line); display: flex; align-items: center; gap: 1rem; }
.modal header h2 { margin: 0; font-size: 1.1rem; }
.modal .body { padding: 1rem 1.2rem; overflow: auto; }
.modal footer { padding: .8rem 1.2rem; border-top: 1px solid var(--line); display: flex; gap: .6rem; justify-content: flex-end; }
.pick { display: flex; gap: .7rem; padding: .5rem .3rem; border-bottom: 1px solid var(--line); align-items: flex-start; font-weight: 400; margin: 0; }
.pick input { margin-top: .3rem; }
.pick .q { white-space: pre-wrap; }

/* question editor */
.qcard { border: 1px solid var(--line); border-radius: 10px; padding: .9rem 1rem; margin: .7rem 0; background: #fbfcfe; }
.qcard .qhead { display: flex; align-items: center; gap: .6rem; }
.qcard .qhead .n { font-weight: 700; color: var(--muted); }
.opt { display: flex; gap: .5rem; align-items: center; margin: .35rem 0; }
.opt input[type=text] { flex: 1; }
.opt .tag { font-size: .78rem; color: var(--muted); white-space: nowrap; }

/* public / candidate */
body.public { background: linear-gradient(180deg, #eef2f7 0%, #f4f6f9 40%); }
.center { min-height: 100vh; display: flex; flex-direction: column; align-items: center; justify-content: center; padding: 2rem 1rem; }
.hero { width: min(560px, 100%); padding: 2rem; }
.hero h1 { font-size: 1.4rem; }
.foot { margin-top: 1rem; font-size: .88rem; }
.code-input { font-family: var(--mono); font-size: 1.2rem; letter-spacing: .12em; text-transform: uppercase; flex: 1; }
.take .wrap { max-width: 980px; }
.section-bar { position: sticky; top: 0; z-index: 10; background: #fff; border-bottom: 1px solid var(--line); box-shadow: 0 2px 10px rgba(0,0,0,.05); }
.section-bar .wrap { display: flex; align-items: center; gap: 1rem; padding: .6rem 1.2rem; flex-wrap: wrap; }
.section-bar .title { font-weight: 700; }
.timer { font-family: var(--mono); font-size: 1.35rem; font-weight: 700; padding: .15rem .6rem; border-radius: 8px; background: var(--soft); color: var(--brand); font-variant-numeric: tabular-nums; }
.timer.low { background: #fff3d6; color: #7a5200; }
.timer.critical { background: #fdecea; color: var(--bad); }
.savestate { font-size: .85rem; color: var(--muted); }
.savestate.bad { color: var(--bad); }
.qtext { white-space: pre-wrap; margin: .3rem 0 .6rem; font-size: 1rem; }
.choices { display: grid; gap: .4rem; }
.choices label { display: flex; gap: .6rem; align-items: flex-start; font-weight: 400; margin: 0; padding: .5rem .7rem; border: 1px solid var(--line); border-radius: 8px; cursor: pointer; background: #fff; }
.choices label:hover { border-color: #bcd6f7; }
.choices label.on { border-color: var(--accent); background: #f2f8ff; }
.choices .letter { font-weight: 700; color: var(--muted); min-width: 1.2rem; }
.scale { display: grid; grid-template-columns: 1fr repeat(5, 3rem) 1fr; align-items: center; gap: .3rem; padding: .6rem 0; border-bottom: 1px solid var(--line); }
.scale .stmt { grid-column: 1 / -1; margin-bottom: .2rem; }
.scale .end { font-size: .78rem; color: var(--muted); }
.scale .end.r { text-align: right; }
.bubble { display: flex; align-items: center; justify-content: center; }
.bubble input { appearance: none; width: 1.6rem; height: 1.6rem; border: 2px solid #b8c3cf; border-radius: 50%; cursor: pointer; margin: 0; }
.bubble input:checked { background: var(--accent); border-color: var(--accent); box-shadow: inset 0 0 0 3px #fff; }
.prompt-panel { background: #fff; border: 1px solid var(--line); border-radius: 10px; padding: .5rem 1.2rem 1rem; margin-bottom: 1rem; }
.prompt-panel h2 { font-size: 1.05rem; }
.prompt-panel h3 { font-size: 1rem; }
.prompt-panel h4 { font-size: .95rem; margin: .8rem 0 .3rem; }
.file { border: 1px solid var(--line); border-radius: 10px; padding: .7rem .9rem; margin: .6rem 0; background: #fbfcfe; }
.file .fhead { display: flex; gap: .6rem; align-items: center; margin-bottom: .4rem; }
.file .fhead input { font-family: var(--mono); flex: 1; }
.dropzone { border: 1px dashed #b8c3cf; border-radius: 10px; padding: 1rem; text-align: center; color: var(--muted); }
.done-mark { font-size: 3rem; color: var(--ok); }
.rules li { margin: .3rem 0; }
.section-list { display: grid; gap: .5rem; margin: .6rem 0 1rem; }
.section-list .s { display: flex; gap: .8rem; align-items: center; padding: .6rem .8rem; border: 1px solid var(--line); border-radius: 8px; background: #fff; }
.section-list .s .n { font-weight: 700; color: var(--muted); }
.section-list .s .m { margin-left: auto; color: var(--muted); }

/* grading report */
.score-big { font-size: 2.6rem; font-weight: 800; line-height: 1; letter-spacing: -.02em; }
.score-big small { font-size: 1rem; font-weight: 500; color: var(--muted); }
.bar { height: 8px; background: var(--soft); border-radius: 4px; overflow: hidden; }
.bar i { display: block; height: 100%; background: var(--accent); }
.bar i.extra { background: var(--ok); }
.cat { display: grid; grid-template-columns: 9rem 1fr 4rem 5rem; gap: .7rem; align-items: center; padding: .45rem 0; border-bottom: 1px solid var(--line); }
.cat .name { font-weight: 600; }
.cat .name small { display: block; font-weight: 400; color: var(--muted); }
.cat .num { text-align: right; font-variant-numeric: tabular-nums; }
.rationale { color: #33414f; font-size: .92rem; margin: .15rem 0 .7rem; }
.timeline { display: flex; gap: .4rem; flex-wrap: wrap; font-size: .85rem; }
.timeline .step { padding: .3rem .6rem; border-radius: 6px; background: var(--soft); color: var(--muted); }
.timeline .step.done { background: #dff5e7; color: #14603a; }
.timeline .step.now { background: #e3f0ff; color: #1a4f8a; }
details { margin: .5rem 0; }
details summary { cursor: pointer; font-weight: 600; }
.verdict { font-weight: 700; text-transform: capitalize; }
.wg { display: grid; gap: .35rem; }
.wg .g { display: grid; grid-template-columns: 8rem 1fr 3rem 7rem; align-items: center; gap: .6rem; font-size: .92rem; }
.answer { white-space: pre-wrap; background: #fff; border: 1px solid var(--line); border-radius: 8px; padding: .6rem .8rem; margin: .3rem 0 .8rem; }
.copy { cursor: pointer; }
.code-big { font-family: var(--mono); font-size: 1.7rem; letter-spacing: .1em; font-weight: 700; color: var(--brand); }
.errbox { background: #fdecea; color: #8a1f14; border: 1px solid #f5c6c0; border-radius: 8px; padding: .7rem .9rem; }
.notice { background: #fff8e6; border: 1px solid #f3dfae; border-radius: 8px; padding: .7rem .9rem; }
@media (max-width: 700px) {
  .cat { grid-template-columns: 1fr 4rem; }
  .cat .bar { display: none; }
  .scale { grid-template-columns: repeat(5, 1fr); }
  .scale .end { grid-column: span 5; }
}

/* letter grades: A blue, B teal, C yellow-green, D orange, F red */
.grade-circle { display: inline-flex; align-items: center; justify-content: center; width: 4.6rem; height: 4.6rem; border-radius: 50%; color: #fff; font-weight: 800; font-size: 2.2rem; line-height: 1; flex: none; box-shadow: inset 0 -3px 0 rgba(0,0,0,.12); }
.grade-circle.small { width: 1.7rem; height: 1.7rem; font-size: .85rem; vertical-align: middle; margin-right: .25rem; }
.grade-A { background: #1f6fd6; }
.grade-B { background: #148f8a; }
.grade-C { background: #8f9a1b; }
.grade-D { background: #e07b1a; }
.grade-F { background: #c0392b; }