/* Bố cục: thanh bên cố định + vùng làm việc dạng bảng điều khiển; trên điện thoại thanh bên chuyển xuống đáy. */
:root {
  --bg: #f4f5f8; --panel: #ffffff; --panel-2: #f8f9fc; --line: #e2e5ee; --line-2: #eef0f5;
  --fg: #1a2033; --fg-2: #4d566d; --fg-3: #8a92a7;
  --side: #16213a; --side-fg: #c9d1e6; --side-active: #24335a;
  --accent: #2449c7; --accent-2: #e8edfc; --accent-fg: #ffffff;
  --ok: #18794e; --ok-bg: #e3f4ea; --warn: #9a5b00; --warn-bg: #fdf1dc; --bad: #c0362c; --bad-bg: #fde8e6; --info: #3b5bb5; --info-bg: #e8edfc;
  --muted-bg: #eef0f4;
  --shadow: 0 1px 2px rgba(22, 33, 58, .06), 0 4px 16px rgba(22, 33, 58, .05);
  --f-display: "Lexend", "Be Vietnam Pro", system-ui, sans-serif;
  --f-body: "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", sans-serif;
  --r: 10px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1422; --panel: #171e30; --panel-2: #1b2337; --line: #2a3450; --line-2: #222b42;
    --fg: #e6eaf5; --fg-2: #aab3ca; --fg-3: #737d97;
    --side: #0b101c; --side-fg: #a9b3cc; --side-active: #1d2846;
    --accent: #7d9cff; --accent-2: #23304f; --accent-fg: #0f1422;
    --ok: #5fd39a; --ok-bg: #173628; --warn: #f3b552; --warn-bg: #3a2d14; --bad: #ff8a80; --bad-bg: #3d1f1d; --info: #9db3ff; --info-bg: #23304f;
    --muted-bg: #222a3f; --shadow: 0 1px 2px rgba(0, 0, 0, .3); color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0f1422; --panel: #171e30; --panel-2: #1b2337; --line: #2a3450; --line-2: #222b42;
  --fg: #e6eaf5; --fg-2: #aab3ca; --fg-3: #737d97;
  --side: #0b101c; --side-fg: #a9b3cc; --side-active: #1d2846;
  --accent: #7d9cff; --accent-2: #23304f; --accent-fg: #0f1422;
  --ok: #5fd39a; --ok-bg: #173628; --warn: #f3b552; --warn-bg: #3a2d14; --bad: #ff8a80; --bad-bg: #3d1f1d; --info: #9db3ff; --info-bg: #23304f;
  --muted-bg: #222a3f; --shadow: 0 1px 2px rgba(0, 0, 0, .3); color-scheme: dark;
}

* { box-sizing: border-box; }
html, body, #root { height: 100%; }
body { margin: 0; background: var(--bg); color: var(--fg); font: 14px/1.5 var(--f-body); font-variant-numeric: tabular-nums; }
h1, h2, h3, h4 { font-family: var(--f-display); font-weight: 600; margin: 0; text-wrap: balance; letter-spacing: -.01em; }
h1 { font-size: 22px; } h2 { font-size: 18px; } h3 { font-size: 15px; } h4 { font-size: 14px; }
a { color: var(--accent); }
button, input, select, textarea { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.muted { color: var(--fg-3); } .small { font-size: 12.5px; } .nowrap { white-space: nowrap; }
.label { font-size: 11px; text-transform: uppercase; letter-spacing: .07em; color: var(--fg-3); font-weight: 600; }
[hidden] { display: none !important; }

/* ---------- khung ứng dụng ---------- */
.app { display: grid; grid-template-columns: 92px 1fr; grid-template-rows: 56px 1fr; height: 100%; }
.top { grid-column: 1 / -1; display: flex; align-items: center; gap: 12px; background: var(--panel); border-bottom: 1px solid var(--line); padding: 0 max(16px, env(safe-area-inset-right, 0px)) 0 max(16px, env(safe-area-inset-left, 0px)); position: sticky; top: 0; z-index: 20; }
.brand { display: flex; align-items: center; gap: 10px; font-family: var(--f-display); font-weight: 700; font-size: 16px; min-width: 0; }
.brand .mark { width: 30px; height: 30px; border-radius: 8px; background: var(--accent); color: var(--accent-fg); display: grid; place-items: center; font-size: 13px; letter-spacing: -.02em; flex: none; }
.brand .name { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.chip { display: inline-flex; align-items: center; gap: 4px; padding: 3px 10px; border: 1px solid var(--line); border-radius: 999px; font-size: 12.5px; color: var(--fg-2); white-space: nowrap; }
.top .sp { flex: 1; }
.side { background: var(--side); color: var(--side-fg); display: flex; flex-direction: column; padding: 8px 0; overflow-y: auto; }
.side a { display: flex; flex-direction: column; align-items: center; gap: 3px; padding: 10px 4px; color: var(--side-fg); text-decoration: none; font-size: 11.5px; text-align: center; position: relative; line-height: 1.25; }
.side a svg { width: 21px; height: 21px; stroke: currentColor; fill: none; stroke-width: 1.7; }
.side a:hover { background: var(--side-active); color: #fff; }
.side a.on { background: var(--side-active); color: #fff; box-shadow: inset 3px 0 0 var(--accent); }
.side .badge { position: absolute; top: 4px; right: 14px; background: #e5484d; color: #fff; border-radius: 999px; font-size: 10px; padding: 0 5px; min-width: 16px; line-height: 16px; font-weight: 700; }
.main { overflow-y: auto; padding-block: 20px 40px; padding-left: max(16px, env(safe-area-inset-left, 0px)); padding-right: max(16px, env(safe-area-inset-right, 0px)); min-width: 0; }
.wrap { max-width: 1280px; margin: 0 auto; display: grid; gap: 16px; }
@media (max-width: 760px) {
  .app { grid-template-columns: 1fr; grid-template-rows: 52px 1fr 62px; }
  .side { grid-row: 3; flex-direction: row; padding: 0 0 env(safe-area-inset-bottom, 0px); overflow-x: auto; overflow-y: hidden; }
  .side a { flex: 1 0 64px; padding: 7px 2px; font-size: 10.5px; }
  .side a.on { box-shadow: inset 0 3px 0 var(--accent); }
  .side .badge { right: 8px; }
  .main { grid-row: 2; padding-block: 14px 24px; }
  .hide-m { display: none !important; }
}

/* ---------- thành phần ---------- */
.card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--r); box-shadow: var(--shadow); min-width: 0; }
.card > .hd { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; padding: 14px 16px; border-bottom: 1px solid var(--line-2); }
.card > .hd .sub { color: var(--fg-3); font-size: 12.5px; }
.card > .bd { padding: 16px; }
.row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.row.end { justify-content: flex-end; }
.grow { flex: 1; min-width: 0; }
.hd .in.grow, .hd input.in:not([type=date]) { flex: 1 1 200px; }
.grid { display: grid; gap: 12px; }
.g2 { grid-template-columns: repeat(2, minmax(0, 1fr)); } .g3 { grid-template-columns: repeat(3, minmax(0, 1fr)); } .g4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.stats { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); }
@media (max-width: 760px) { .g2, .g3, .g4 { grid-template-columns: 1fr; } .stats { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.stat { background: var(--panel); border: 1px solid var(--line); border-radius: var(--r); padding: 12px 14px; display: grid; gap: 2px; text-align: left; cursor: default; }
button.stat { cursor: pointer; } button.stat:hover { border-color: var(--accent); }
.stat .v { font-family: var(--f-display); font-size: 24px; font-weight: 600; line-height: 1.2; }
.stat .v small { font-size: 13px; color: var(--fg-3); font-weight: 500; }
.stat .bar { margin-top: 6px; }
.stat.alert .v { color: var(--bad); } .stat.warn .v { color: var(--warn); } .stat.good .v { color: var(--ok); }
.stat.sel { border-color: var(--accent); box-shadow: inset 0 0 0 1px var(--accent); }
.bar { height: 6px; background: var(--muted-bg); border-radius: 99px; overflow: hidden; min-width: 60px; }
.bar > i { display: block; height: 100%; background: var(--accent); border-radius: 99px; }
.bar.ok > i { background: var(--ok); }

.btn { display: inline-flex; align-items: center; justify-content: center; gap: 6px; border: 1px solid var(--line); background: var(--panel); color: var(--fg); border-radius: 8px; padding: 7px 13px; cursor: pointer; font-weight: 500; white-space: nowrap; text-decoration: none; line-height: 1.3; }
.btn:hover { border-color: var(--fg-3); }
.btn.pri { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }
.btn.pri:hover { filter: brightness(1.08); }
.btn.danger { color: var(--bad); }
.btn.sm { padding: 4px 9px; font-size: 12.5px; }
.btn.ghost { border-color: transparent; background: transparent; }
.btn[disabled] { opacity: .55; cursor: progress; }
.tabs { display: flex; gap: 6px; flex-wrap: wrap; }
.tab { border: 1px solid var(--line); background: var(--panel); border-radius: 8px; padding: 7px 13px; cursor: pointer; font-weight: 500; color: var(--fg-2); }
.tab.on { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }

.pill { display: inline-block; padding: 1px 9px; border-radius: 999px; font-size: 12px; font-weight: 500; white-space: nowrap; background: var(--muted-bg); color: var(--fg-2); }
.pill.ok { background: var(--ok-bg); color: var(--ok); } .pill.warn { background: var(--warn-bg); color: var(--warn); }
.pill.bad { background: var(--bad-bg); color: var(--bad); } .pill.info { background: var(--info-bg); color: var(--info); }
.kind { display: inline-block; font-size: 10.5px; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; padding: 0 6px; border-radius: 4px; margin-right: 6px; vertical-align: 1px; }
.kind.test { background: var(--warn-bg); color: var(--warn); } .kind.review { background: var(--bad-bg); color: var(--bad); } .kind.sup { background: var(--ok-bg); color: var(--ok); }

.tbl-wrap { overflow-x: auto; }
table.tbl { width: 100%; border-collapse: collapse; font-size: 13.5px; }
.tbl th { text-align: left; font-weight: 600; color: var(--fg-2); font-size: 12.5px; padding: 9px 10px; border-bottom: 1px solid var(--line); white-space: nowrap; background: var(--panel-2); position: sticky; top: 0; }
.tbl td { padding: 10px; border-bottom: 1px solid var(--line-2); vertical-align: top; }
.tbl tr.click { cursor: pointer; } .tbl tr.click:hover td { background: var(--panel-2); }
.tbl tr.now td { background: var(--accent-2); }
.tbl td.c, .tbl th.c { text-align: center; }
.tbl .b { font-weight: 600; }
.empty { padding: 28px 16px; text-align: center; color: var(--fg-3); }

.field { display: grid; gap: 4px; }
.field > span { font-size: 12.5px; color: var(--fg-2); font-weight: 500; }
.in, select.in, textarea.in { width: 100%; border: 1px solid var(--line); border-radius: 8px; padding: 8px 10px; background: var(--panel); min-width: 0; }
textarea.in { resize: vertical; min-height: 80px; line-height: 1.55; }
.in:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 0 3px var(--accent-2); }
.form { display: grid; gap: 12px; }
.checks { display: flex; flex-wrap: wrap; gap: 6px; }
.checks label { display: inline-flex; align-items: center; gap: 5px; border: 1px solid var(--line); border-radius: 8px; padding: 5px 10px; cursor: pointer; }
.checks input:checked + span { font-weight: 600; color: var(--accent); }

/* ---------- hộp thoại ---------- */
.modal-bg { position: fixed; inset: 0; background: rgba(10, 14, 26, .45); z-index: 70; display: flex; align-items: center; justify-content: center; padding: 3vh max(12px, env(safe-area-inset-right, 0px)) 4vh max(12px, env(safe-area-inset-left, 0px)); overflow: hidden; }
.modal { background: var(--panel); border-radius: 14px; width: min(760px, 100%); max-height: calc(100% - 0px); box-shadow: 0 20px 60px rgba(0, 0, 0, .25); display: flex; flex-direction: column; margin: auto 0; }
.modal.wide { width: min(1100px, 100%); }
.modal.narrow { width: min(440px, 100%); }
.modal .mh { display: flex; align-items: flex-start; gap: 10px; padding: 16px 18px; border-bottom: 1px solid var(--line-2); }
.modal .mb { padding: 18px; display: grid; gap: 14px; overflow-y: auto; min-height: 0; flex: 1 1 auto; }
.modal .mf { padding: 12px 18px; border-top: 1px solid var(--line-2); display: flex; gap: 8px; justify-content: flex-end; flex-wrap: wrap; background: var(--panel); border-radius: 0 0 14px 14px; flex: none; }
.x { border: 0; background: transparent; font-size: 22px; line-height: 1; cursor: pointer; color: var(--fg-3); padding: 2px 6px; margin-left: auto; }
.toast { position: fixed; left: 50%; bottom: calc(24px + env(safe-area-inset-bottom, 0px)); transform: translateX(-50%); background: var(--fg); color: var(--bg); padding: 10px 16px; border-radius: 10px; z-index: 80; box-shadow: var(--shadow); max-width: calc(100% - 32px); }
.toast.bad { background: var(--bad); color: #fff; }
.loading { position: fixed; inset: 0; display: grid; place-items: center; background: color-mix(in srgb, var(--bg) 70%, transparent); z-index: 90; }
.spin { width: 34px; height: 34px; border: 3px solid var(--line); border-top-color: var(--accent); border-radius: 50%; animation: sp 0.8s linear infinite; }
@keyframes sp { to { transform: rotate(360deg); } }
@media (prefers-reduced-motion: reduce) { .spin { animation-duration: 3s; } }

.box { border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px; background: var(--panel-2); }
.box.note { background: var(--warn-bg); border-color: transparent; color: var(--fg); }
.kv { display: grid; grid-template-columns: max-content 1fr; gap: 6px 14px; font-size: 13.5px; }
.kv dt { color: var(--fg-3); } .kv dd { margin: 0; min-width: 0; }
.prose { line-height: 1.65; white-space: pre-wrap; overflow-wrap: anywhere; }
.bands { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 8px; }
.band { border: 1px solid var(--line); border-radius: 10px; padding: 10px; text-align: center; background: var(--panel); }
.band .v { font-family: var(--f-display); font-size: 24px; font-weight: 600; }
.band.all { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }
.band.all .label { color: inherit; opacity: .85; }
@media (max-width: 560px) { .bands { grid-template-columns: repeat(3, minmax(0, 1fr)); } }
.anskey { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 4px 12px; font-size: 13px; }
.anskey div { padding: 3px 0; border-bottom: 1px dashed var(--line-2); overflow-wrap: anywhere; }
.right { color: var(--ok); } .wrong { color: var(--bad); }
.avatar { width: 30px; height: 30px; border-radius: 50%; background: var(--accent-2); color: var(--accent); display: grid; place-items: center; font-weight: 700; font-size: 12px; flex: none; }
.cell { display: inline-block; width: 22px; height: 22px; border-radius: 5px; text-align: center; line-height: 22px; font-size: 11px; font-weight: 700; cursor: pointer; }
.cell.g { background: var(--ok-bg); color: var(--ok); } .cell.s { background: var(--info-bg); color: var(--info); } .cell.m { background: var(--bad-bg); color: var(--bad); } .cell.n { background: var(--muted-bg); color: var(--fg-3); cursor: default; }
.demo-flag { background: var(--warn-bg); color: var(--warn); font-weight: 600; font-size: 12px; padding: 3px 9px; border-radius: 6px; white-space: nowrap; }

/* ---------- đăng nhập ---------- */
.login { min-height: 100%; display: grid; place-items: center; padding-block: 24px; padding-left: max(16px, env(safe-area-inset-left, 0px)); padding-right: max(16px, env(safe-area-inset-right, 0px)); }
.login .card { width: min(400px, 100%); padding: 28px; display: grid; gap: 14px; }
.login .brand { justify-content: center; font-size: 19px; }
.login .brand .mark { width: 38px; height: 38px; font-size: 15px; border-radius: 10px; }
.login .tag { text-align: center; color: var(--fg-2); margin-top: -6px; }
.demo-accts { font-size: 12.5px; color: var(--fg-2); display: grid; gap: 4px; }
.demo-accts button { border: 1px dashed var(--line); background: var(--panel-2); border-radius: 8px; padding: 6px 8px; text-align: left; cursor: pointer; }

/* ---------- đề thi ---------- */
.paper { line-height: 1.65; font-size: 14.5px; }
.paper table { border-collapse: collapse; margin: 8px 0; width: 100%; }
.paper td, .paper th { border: 1px solid var(--line); padding: 6px 9px; vertical-align: top; text-align: left; }
.paper th { background: var(--panel-2); }
.paper h3 { margin: 18px 0 8px; } .paper p { margin: 8px 0; }
.paper .blank { display: inline-block; min-width: 70px; border-bottom: 1.5px solid var(--fg-2); margin: 0 3px; height: 1em; vertical-align: baseline; }
.paper .opts { display: grid; gap: 2px; margin: 0 0 10px 26px; }
.paper .qline { margin: 10px 0 4px; }
.paper .fig img { background: #fff; border-radius: 8px; border: 1px solid var(--line); }
.paper blockquote { margin: 10px 0; padding: 10px 14px; background: var(--warn-bg); border-radius: 8px; }
.exam { position: fixed; inset: 0; z-index: 60; background: var(--bg); display: grid; grid-template-rows: auto 1fr; }
.exam-top { background: var(--side); color: #fff; display: flex; align-items: center; gap: 12px; flex-wrap: wrap; padding: 10px max(16px, env(safe-area-inset-right, 0px)) 10px max(16px, env(safe-area-inset-left, 0px)); padding-top: max(10px, env(safe-area-inset-top, 0px)); }
.exam-top .steps { display: flex; gap: 4px; flex-wrap: wrap; }
.exam-top .steps span { padding: 3px 10px; border-radius: 6px; font-size: 12.5px; color: var(--side-fg); }
.exam-top .steps span.on { background: var(--accent); color: var(--accent-fg); }
.exam-top .steps span.done { color: #8fe0b5; }
.timer { font-family: var(--f-display); font-size: 18px; font-weight: 600; background: rgba(255, 255, 255, .08); padding: 3px 12px; border-radius: 8px; }
.timer.low { background: #c0362c; }
.exam-body { display: grid; grid-template-columns: minmax(0, 1fr) 340px; min-height: 0; }
.exam-body > div { overflow-y: auto; padding: 18px max(16px, env(safe-area-inset-left, 0px)) 40px; min-width: 0; }
.exam-body .sheet { background: var(--panel); border-left: 1px solid var(--line); padding-left: 16px; padding-right: max(16px, env(safe-area-inset-right, 0px)); }
.exam-body.one { grid-template-columns: minmax(0, 1fr); }
@media (max-width: 900px) { .exam-body { grid-template-columns: 1fr; overflow-y: auto; } .exam-body > div { overflow: visible; } .exam-body .sheet { border-left: 0; border-top: 1px solid var(--line); } }
.ans-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 6px 10px; }
.ans-grid label { display: flex; align-items: center; gap: 6px; }
.ans-grid label b { width: 24px; text-align: right; font-size: 12.5px; color: var(--fg-2); flex: none; }
.ans-grid input { width: 100%; border: 1px solid var(--line); border-radius: 6px; padding: 5px 7px; background: var(--panel); min-width: 0; }
.ans-grid input:not(:placeholder-shown) { border-color: var(--accent); background: var(--accent-2); }
.audio-box { display: grid; gap: 6px; padding: 12px; border: 1px solid var(--line); border-radius: 10px; background: var(--panel); margin-bottom: 14px; }
audio { width: 100%; height: 38px; }
.rec { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.rec .dot { width: 10px; height: 10px; border-radius: 50%; background: #e5484d; animation: pulse 1s infinite; }
@keyframes pulse { 50% { opacity: .3; } }
.wc { font-size: 12.5px; color: var(--fg-3); text-align: right; }
.wc.ok { color: var(--ok); }

.kind.extra { background: var(--info-bg); color: var(--info); }
/* ---------- bảng sửa giáo trình ---------- */
.ed td { padding: 6px; }
.ed textarea, .ed input, .ed select { width: 100%; border: 1px solid transparent; background: transparent; border-radius: 6px; padding: 5px 7px; font: inherit; font-size: 13.5px; line-height: 1.45; resize: vertical; min-width: 0; field-sizing: content; }
.ed textarea { min-height: 2.4em; }
.ed textarea:hover, .ed input:hover, .ed select:hover { border-color: var(--line); background: var(--panel); }
.ed textarea:focus, .ed input:focus, .ed select:focus { border-color: var(--accent); background: var(--panel); outline: none; box-shadow: 0 0 0 3px var(--accent-2); }
.ed[data-ro] textarea, .ed[data-ro] input, .ed[data-ro] select { pointer-events: none; }
.ed tr.dirty td { background: var(--warn-bg); }
.ed tr.done-row td:first-child { box-shadow: inset 3px 0 0 var(--ok); }
.savebar { position: sticky; bottom: 0; z-index: 5; display: flex; gap: 10px; align-items: center; flex-wrap: wrap; padding: 10px 16px; background: var(--panel); border-top: 1px solid var(--line); border-radius: 0 0 var(--r) var(--r); box-shadow: 0 -6px 16px rgba(22, 33, 58, .06); }
.mini { display: flex; gap: 4px; flex-wrap: wrap; }
.main .savebar { bottom: -40px; }
@media (max-width: 760px) { .main .savebar { bottom: -24px; } }