:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --surface-2: #f0f2f5;
  --border: #dfe3e8;
  --border-strong: #c5ccd4;
  --text: #14181d;
  --muted: #626b76;
  --faint: #8b95a1;
  --accent: #0d6b63;
  --accent-soft: #e3f2f0;
  --accent-text: #095049;
  --danger: #b3261e;
  --danger-soft: #fdeceb;
  --warn: #8a5a00;
  --warn-soft: #fdf3e0;
  --ok: #1c6b35;
  --ok-soft: #e6f4ea;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(16, 24, 40, .05), 0 4px 14px rgba(16, 24, 40, .05);
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1215;
    --surface: #171b20;
    --surface-2: #1f242a;
    --border: #2b3138;
    --border-strong: #3b434c;
    --text: #e8ebee;
    --muted: #9aa4b0;
    --faint: #737e8a;
    --accent: #3fb0a4;
    --accent-soft: #14322f;
    --accent-text: #7fd8cd;
    --danger: #f2837a;
    --danger-soft: #3a1e1c;
    --warn: #e0b36a;
    --warn-soft: #382c17;
    --ok: #6fcf8c;
    --ok-soft: #16301f;
    --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 6px 18px rgba(0, 0, 0, .3);
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 { margin: 0 0 .4em; line-height: 1.25; font-weight: 650; letter-spacing: -.01em; }
h1 { font-size: 1.5rem; }
h2 { font-size: 1.12rem; }
h3 { font-size: .95rem; }
p { margin: 0 0 .8em; }
a { color: var(--accent-text); }

/* ---------- layout ---------- */
.topbar {
  position: sticky; top: 0; z-index: 30;
  display: flex; align-items: center; gap: 14px; flex-wrap: wrap;
  padding: 12px 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.brand { display: flex; align-items: center; gap: 10px; margin-right: auto; min-width: 0; }
.brand .mark {
  width: 32px; height: 32px; flex: none; border-radius: 8px;
  background: var(--accent); color: #fff;
  display: grid; place-items: center; font-weight: 700; font-size: 14px;
}
.brand b { display: block; font-size: .95rem; line-height: 1.2; }
.brand span { display: block; font-size: .78rem; color: var(--muted); }

nav.tabs { display: flex; gap: 2px; flex-wrap: wrap; }
nav.tabs button {
  border: 0; background: none; color: var(--muted);
  padding: 7px 13px; border-radius: 7px; font: inherit; font-size: .88rem; cursor: pointer;
}
nav.tabs button:hover { background: var(--surface-2); color: var(--text); }
nav.tabs button[aria-current="true"] { background: var(--accent-soft); color: var(--accent-text); font-weight: 600; }

main { max-width: 1120px; margin: 0 auto; padding: 22px 20px 80px; }
.page { display: none; }
.page.active { display: block; }
.page-head { display: flex; align-items: flex-end; gap: 14px; flex-wrap: wrap; margin-bottom: 16px; }
.page-head .grow { flex: 1 1 240px; }
.page-head p { color: var(--muted); font-size: .9rem; margin: 0; }

/* ---------- cards ---------- */
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow);
  padding: 18px; margin-bottom: 16px;
}
.card.tight { padding: 14px; }
.card > h2 { display: flex; align-items: center; gap: 8px; }
.grid { display: grid; gap: 14px; }
.grid.cols2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.grid.cols3 { grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); }
.grid.cols4 { grid-template-columns: repeat(auto-fit, minmax(165px, 1fr)); }

.stat { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px 16px; }
.stat .n { font-size: 1.7rem; font-weight: 660; letter-spacing: -.02em; line-height: 1.1; }
.stat .k { font-size: .78rem; color: var(--muted); text-transform: uppercase; letter-spacing: .05em; margin-top: 3px; }

/* ---------- forms ---------- */
label { display: block; font-size: .82rem; font-weight: 600; color: var(--muted); margin-bottom: 5px; }
input, select, textarea {
  width: 100%; padding: 9px 11px; font: inherit; color: var(--text);
  background: var(--surface); border: 1px solid var(--border-strong);
  border-radius: 8px; outline: none;
}
input:focus, select:focus, textarea:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
input[type="checkbox"] { width: auto; }
.field { margin-bottom: 13px; }
.field .hint { font-size: .78rem; color: var(--faint); margin-top: 4px; font-weight: 400; }
.row { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); }
fieldset { border: 1px solid var(--border); border-radius: 8px; padding: 13px 14px; margin: 0 0 14px; }
legend { font-size: .8rem; font-weight: 650; color: var(--muted); padding: 0 5px; }

/* Also applies to links that should look like buttons (a.btn). */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 9px 16px; font: inherit; font-weight: 600; font-size: .88rem;
  border-radius: 8px; border: 1px solid transparent; cursor: pointer;
  background: var(--accent); color: #fff; text-decoration: none;
}
.btn:hover { filter: brightness(1.08); }
.btn:disabled, .btn[aria-disabled="true"] { opacity: .5; cursor: not-allowed; filter: none; }
.btn.ghost { background: var(--surface); color: var(--text); border-color: var(--border-strong); }
.btn.ghost:hover { background: var(--surface-2); filter: none; }
.btn.danger { background: var(--danger); }
.btn.sm { padding: 5px 10px; font-size: .8rem; }
.btn-row { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
td .btn-row { flex-wrap: nowrap; }
td .btn-row .btn { white-space: nowrap; }

/* ---------- tables ---------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
table { width: 100%; border-collapse: collapse; font-size: .88rem; }
th, td { padding: 9px 12px; text-align: left; border-bottom: 1px solid var(--border); vertical-align: middle; }
th { font-size: .75rem; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); background: var(--surface-2); font-weight: 650; white-space: nowrap; }
tbody tr:last-child td { border-bottom: 0; }
tbody tr:hover { background: var(--surface-2); }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
.mono { font-family: var(--mono); font-size: .85em; }

/* ---------- pills ---------- */
.pill {
  display: inline-flex; align-items: center; gap: 5px;
  padding: 2px 9px; border-radius: 999px; font-size: .74rem; font-weight: 650;
  border: 1px solid transparent; white-space: nowrap;
}
.pill.ok { background: var(--ok-soft); color: var(--ok); }
.pill.warn { background: var(--warn-soft); color: var(--warn); }
.pill.bad { background: var(--danger-soft); color: var(--danger); }
.pill.info { background: var(--accent-soft); color: var(--accent-text); }
.pill.mute { background: var(--surface-2); color: var(--muted); border-color: var(--border); }

/* ---------- seats ---------- */
.seatline { display: flex; align-items: center; gap: 9px; margin: 10px 0 12px; flex-wrap: wrap; }
.seats { display: inline-flex; gap: 4px; }
.seats i {
  width: 11px; height: 11px; border-radius: 50%;
  border: 1.5px solid var(--accent); background: transparent;
}
.seats i.taken { background: var(--accent); }
.session-card.booked { border-color: var(--ok); }


/* ---------- day picker & schedule preview ---------- */
.daypick { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 4px; }
.daypick button {
  border: 1px solid var(--border-strong); background: var(--surface); color: var(--muted);
  border-radius: 7px; padding: 7px 12px; font: inherit; font-size: .82rem; font-weight: 600; cursor: pointer;
}
.daypick button[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: #fff; }

.breakrow { display: grid; grid-template-columns: 1.3fr 1fr 1fr auto; gap: 8px; align-items: end; margin-bottom: 8px; }
.breakrow label { margin-bottom: 3px; }
.breakrow .x {
  border: 1px solid var(--border-strong); background: var(--surface); color: var(--danger);
  border-radius: 7px; width: 36px; height: 38px; cursor: pointer; font-size: 1.1rem; line-height: 1;
}

.preview { border: 1px solid var(--border); border-radius: 8px; background: var(--surface-2); padding: 12px 14px; }
.preview h4 { margin: 0 0 6px; font-size: .85rem; }
.preview .daylist { max-height: 190px; overflow-y: auto; margin-top: 8px; }
.preview .dayrow { display: flex; gap: 8px; padding: 4px 0; border-top: 1px solid var(--border); font-size: .82rem; }
.preview .dayrow b { flex: 0 0 108px; font-weight: 600; }
.preview .times { color: var(--muted); font-family: var(--mono); font-size: .95em; }


/* ---------- help / tutorial ---------- */
/* Numbered (or bulleted) walkthrough steps, roomier than a plain list. */
.steps { margin: 0 0 14px; padding-left: 1.35em; }
.steps li { margin-bottom: 8px; line-height: 1.55; }
.steps li:last-child { margin-bottom: 0; }
.steps li b { font-weight: 650; }
:where([dir="rtl"]) .steps { padding-left: 0; padding-right: 1.35em; }

/* 16:9 frame that keeps its shape at every width, phone included. */
.videobox {
  position: relative;
  width: 100%;
  /* A full-width player on a wide screen is taller than the text beside it;
     capping it keeps the card readable without cropping the video. */
  max-width: 760px;
  aspect-ratio: 16 / 9;
  border-radius: 10px;
  overflow: hidden;
  background: #000;
  border: 1px solid var(--border);
}
.videobox iframe {
  position: absolute; inset: 0;
  width: 100%; height: 100%;
  border: 0;
  display: block;
}
/* Fallback for browsers without aspect-ratio (older Safari). */
@supports not (aspect-ratio: 16 / 9) {
  .videobox { height: 0; padding-bottom: 56.25%; }
}

/* The tutorial card, while it is still the thing the student has to do. */
.card.urgent { border-color: var(--warn); box-shadow: 0 0 0 3px var(--warn-soft), var(--shadow); }

/* The tutorial dialog gives the player more room than a normal dialog. */
#tutDlg { max-width: 700px; }
#tutDlg .videobox { max-width: none; }

button.pick-session { border: 1px solid var(--border); }
button.pick-session:hover { border-color: var(--border-strong); }
button.pick-session.chosen {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--accent-soft);
}

/* ---------- session day groups ---------- */
.daygroup { border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); margin-bottom: 12px; overflow: hidden; }
.daygroup > header {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  padding: 10px 14px; background: var(--surface-2); border-bottom: 1px solid var(--border);
}
.daygroup > header b { font-size: .92rem; }
.daygroup table { font-size: .86rem; }
.selbar {
  position: sticky; bottom: 0; z-index: 20;
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  background: var(--text); color: var(--bg); padding: 10px 16px;
  border-radius: 9px; margin-top: 12px; box-shadow: var(--shadow);
}
.selbar .btn.ghost { background: transparent; color: inherit; border-color: currentColor; }

/* ---------- misc ---------- */
.notice { padding: 11px 14px; border-radius: 8px; font-size: .88rem; margin-bottom: 14px; border: 1px solid transparent; }
.notice.error { background: var(--danger-soft); color: var(--danger); border-color: currentColor; }
.notice.ok { background: var(--ok-soft); color: var(--ok); border-color: currentColor; }
.notice.info { background: var(--accent-soft); color: var(--accent-text); }
.notice.warn { background: var(--warn-soft); color: var(--warn); }
.empty { text-align: center; padding: 36px 20px; color: var(--faint); font-size: .9rem; }
.muted { color: var(--muted); }
.small { font-size: .83rem; }
.bar { height: 6px; background: var(--surface-2); border-radius: 999px; overflow: hidden; min-width: 60px; }
.bar > i { display: block; height: 100%; background: var(--accent); border-radius: 999px; }

#toast {
  position: fixed; left: 50%; bottom: 26px; transform: translateX(-50%) translateY(20px);
  background: var(--text); color: var(--bg); padding: 11px 18px; border-radius: 9px;
  font-size: .88rem; font-weight: 550; box-shadow: var(--shadow); z-index: 100;
  opacity: 0; pointer-events: none; transition: opacity .18s, transform .18s; max-width: 90vw;
}
#toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
#toast.bad { background: var(--danger); color: #fff; }

dialog {
  border: 1px solid var(--border); border-radius: 12px; background: var(--surface); color: var(--text);
  padding: 0; max-width: 560px; width: calc(100% - 32px); box-shadow: 0 18px 50px rgba(0,0,0,.28);
}
dialog::backdrop { background: rgba(10, 14, 18, .55); }
dialog .dlg-head { padding: 16px 20px 0; }
dialog .dlg-body { padding: 12px 20px; max-height: 68vh; overflow-y: auto; }
dialog .dlg-foot { padding: 14px 20px; border-top: 1px solid var(--border); display: flex; gap: 8px; justify-content: flex-end; flex-wrap: wrap; }

/* ---------- auth screen ---------- */
.auth-wrap { min-height: 100vh; display: grid; place-items: center; padding: 24px 16px; }
.auth-card { width: 100%; max-width: 430px; }
.auth-card .card { padding: 26px; }
.auth-head { text-align: center; margin-bottom: 20px; }
.auth-head .mark { width: 46px; height: 46px; border-radius: 12px; margin: 0 auto 12px; background: var(--accent); color: #fff; display: grid; place-items: center; font-weight: 700; }
.switcher { display: flex; background: var(--surface-2); border-radius: 8px; padding: 3px; margin-bottom: 18px; }
.switcher button { flex: 1; border: 0; background: none; padding: 8px; border-radius: 6px; font: inherit; font-size: .88rem; font-weight: 600; color: var(--muted); cursor: pointer; }
.switcher button[aria-current="true"] { background: var(--surface); color: var(--text); box-shadow: 0 1px 2px rgba(0,0,0,.12); }

/* Checkboxes need a real tap target on a touch screen. */
input[type="checkbox"] {
  width: 18px; height: 18px; margin: 0; accent-color: var(--accent);
  flex: none; cursor: pointer;
}
@media (pointer: coarse) {
  input[type="checkbox"] { width: 24px; height: 24px; }
  td:has(> input[type="checkbox"]) { padding: 12px; }
}

/* Column widths belong in CSS, not inline, so the stacked layout can undo them. */
@media (min-width: 761px) {
  .daygroup td.pick  { width: 38px; }
  .daygroup td.when  { width: 150px; }
  .daygroup td.seats { width: 118px; }
  .daygroup td.state { width: 96px; }
  .daygroup td.acts  { width: 160px; }
}

/* The day group clips its corners; let the table inside scroll rather than
   hiding the action buttons at medium widths. */
.daygroup .rows { overflow-x: auto; }

/* ---------- tables that become cards on a narrow screen ---------- */
@media (max-width: 760px) {
  .stack thead { display: none; }
  .stack, .stack tbody, .stack tr, .stack td { display: block; width: auto; }
  .stack tr {
    padding: 12px 14px;
    border-bottom: 1px solid var(--border);
  }
  .stack tr:last-child { border-bottom: 0; }
  .stack tr:hover { background: none; }
  .stack td {
    border: 0; padding: 4px 0; text-align: left !important;
    display: flex; align-items: center; justify-content: space-between; gap: 14px;
  }
  .stack td::before {
    content: attr(data-label);
    flex: 0 0 auto;
    font-size: .72rem; font-weight: 650; letter-spacing: .04em;
    text-transform: uppercase; color: var(--muted);
  }
  .stack td:not([data-label])::before { content: none; }
  /* the first cell is the heading of the card */
  .stack td.lead { display: block; margin-bottom: 6px; }
  .stack td.lead::before { content: none; }
  /* a lead cell may restate a column; hide that column when it does */
  .stack tr:has(td.lead) td.dup { display: none; }
  .stack td.num { font-variant-numeric: tabular-nums; }
  .stack td .btn-row { flex-wrap: wrap; justify-content: flex-end; }
  .stack td.pick { justify-content: flex-start; gap: 10px; }
  .stack td.acts { justify-content: flex-end; margin-top: 6px; }
  .stack td input:not([type="checkbox"]), .stack td select { max-width: 62%; }
  .stack td.wide input, .stack td.wide select { max-width: none; flex: 1; }
  .stack td input[type="checkbox"] { max-width: none; }
  .table-wrap:has(.stack) { overflow-x: visible; }
  .daygroup .rows { overflow-x: visible; }

  /* A session is dense and repetitive, so it gets a compact card of its own
     rather than one labelled line per column. */
  .daygroup .stack tr {
    display: grid;
    grid-template-columns: auto 1fr auto;
    grid-template-areas:
      "pick when    state"
      "pick session session"
      "pick seats   acts";
    gap: 2px 10px;
    align-items: center;
    padding: 10px 12px;
  }
  .daygroup .stack td { display: block; padding: 0; text-align: left !important; }
  .daygroup .stack td::before { content: none; }
  .daygroup .stack td.pick    { grid-area: pick; align-self: start; padding-top: 2px; min-width: 26px; }
  .daygroup .stack td.when    { grid-area: when; font-weight: 650; }
  .daygroup .stack td.when .small { font-weight: 400; }
  .daygroup .stack td:nth-child(3) { grid-area: session; }
  .daygroup .stack td.seats   { grid-area: seats; }
  .daygroup .stack td.state   { grid-area: state; justify-self: end; }
  .daygroup .stack td.acts    { grid-area: acts; justify-self: end; margin-top: 4px; }
  .daygroup > header { padding: 12px 14px; }
}

@media (max-width: 560px) {
  main { padding: 16px 14px 70px; }
  .card { padding: 15px; }
  .topbar { padding: 10px 14px; gap: 8px; }
  .topbar .brand b { font-size: .9rem; }
  nav.tabs button { padding: 7px 10px; font-size: .85rem; }
  th, td { padding: 8px 9px; }
  h1 { font-size: 1.3rem; }
  .page-head p { font-size: .85rem; }
  dialog { width: calc(100% - 20px); }
  dialog .dlg-body { max-height: 62vh; }
  .breakrow { grid-template-columns: 1fr 1fr; gap: 8px 10px; }
  .breakrow > div:first-child { grid-column: 1 / -1; }
  .breakrow .x { grid-column: 2; justify-self: end; }
  .selbar { flex-direction: column; align-items: stretch; }
  .selbar .btn { width: 100%; }
}