/* =====================================================================
   TutorSim – giao diện theo Figma "TutorSim UI v1" (Material 3, Roboto)
   Màu lấy từ biến Figma: light/* và dark/*. Đổi theme: data-theme trên <html>.
   ===================================================================== */
:root {
  --font: "Roboto", system-ui, -apple-system, "Segoe UI", sans-serif;
  --bg-grad: linear-gradient(120deg, #c9e5fa 7.3%, #e8f3fd 43%, #f3f8fc 88.6%);
  --surface: #ffffff;
  --surface-2: #f6fafe;
  --surface-3: #f3f8fd;
  --surface-4: #fbfdff;
  --border: rgba(220, 231, 240, 0.9);
  --border-2: #dce7f0;
  --border-opt: #c9d3dd;
  --radio: #79808a;
  --on-surface: #171c20;
  --on-surface-var: #41474d;
  --muted: #52606d;
  --muted-2: #6c7a96;
  --primary: #70beff;
  --on-primary: #00344f;
  --primary-container: #c1e6fd;
  --on-primary-container: #00344f;
  --strong: #2b6597;
  --on-strong: #ffffff;
  --error: #ba1a1a;
  --error-bg: #fff8f7;
  --error-border: #f3c7c3;
  --error-line: #fde3e0;
  --good: #2dbe73; --good-bg: #e8f8ef; --good-border: #b7e7cc; --good-text: #175f45;
  --bad: #f04a5a; --bad-bg: #ffe9ec; --bad-border: #f7c3cb;
  --blank: #3896ff; --blank-bg: #e9f4ff; --blank-border: #cfe2ff;
  --warn: #f2b33d; --warn-bg: #fff1d6; --warn-text: #7a4b00;
  --violet: #7e59e5; --violet-2: #8360ea; --violet-bg: #efe9ff; --violet-bg-2: #f1eaff; --violet-text: #7151b6; --violet-soft: #f0e8fd;
  --ink: #152042; --ink-2: #142044;
  --card-row: #faf9fe; --card-row-border: #e4e5f2;
  --m3-card: #f7f2fa; --m3-avatar: #eaddff; --m3-avatar-text: #4f378a; --m3-ph: #e6dfec; --m3-ph-shape: #cdc6d4;
  --nav-bg: #ffffff;
  --avatar-bg: #e4f3fb;
  --bubble: #eef1f5;
  --bar-track: #e3eaf1;
  --shadow: 0 4px 16px rgba(33, 61, 92, 0.11);
  --shadow-nav: 2px 0 7px rgba(0, 0, 0, 0.25);
  --overlay: rgba(23, 35, 60, 0.45);
  --wave-1: url("img/wave-1.svg");
  --wave-2: url("img/wave-2.svg");
  --toggle: url("img/mode-toggle-light.svg");
  --radius: 16px;
  color-scheme: light;
}
:root[data-theme="dark"] {
  --bg-grad: linear-gradient(120deg, #2e4f86 7.3%, #203a6b 43%, #13254a 88.6%);
  --surface: #1e2b45;
  --surface-2: #26354f;
  --surface-3: #26354f;
  --surface-4: #223150;
  --border: rgba(52, 68, 106, 0.9);
  --border-2: #34446a;
  --border-opt: #44557a;
  --radio: #8b939c;
  --on-surface: #dee3e8;
  --on-surface-var: #c1c7ce;
  --muted: #a9b4c2;
  --muted-2: #a9b4c2;
  --primary: #70beff;
  --on-primary: #00344f;
  --primary-container: #004c74;
  --on-primary-container: #c1e6fd;
  --strong: #70beff;
  --on-strong: #00344f;
  --error: #ffb4ab;
  --error-bg: #3a2530;
  --error-border: #6b3b44;
  --error-line: #5a2d36;
  --good: #5fd99a; --good-bg: #1d3b35; --good-border: #2f6a55; --good-text: #a6f0c8;
  --bad: #ff8a95; --bad-bg: #44283a; --bad-border: #7a3a4a;
  --blank: #79b8ff; --blank-bg: #23395e; --blank-border: #35557f;
  --warn: #f2b33d; --warn-bg: #4a3b1c; --warn-text: #ffd89a;
  --violet: #8f6cf0; --violet-2: #b49cff; --violet-bg: #2f2a55; --violet-bg-2: #2f2a55; --violet-text: #cbbcff; --violet-soft: #2c2a52;
  --ink: #dee3e8; --ink-2: #dee3e8;
  --card-row: #26354f; --card-row-border: #34446a;
  --m3-card: #26354f; --m3-avatar: #3b3570; --m3-avatar-text: #d9ccff; --m3-ph: #2e3f5c; --m3-ph-shape: #4a5d80;
  --nav-bg: #1e2b45;
  --avatar-bg: #c1e6fd;
  --bubble: #26354f;
  --bar-track: #34446a;
  --shadow: 0 4px 16px rgba(5, 12, 30, 0.35);
  --overlay: rgba(5, 10, 25, 0.6);
  --wave-1: url("img/wave-1-dark.svg");
  --wave-2: url("img/wave-2-dark.svg");
  --toggle: url("img/mode-toggle-dark.svg");
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; }
html { background: var(--bg-grad); min-height: 100%; }
body {
  font: 400 16px/24px var(--font);
  color: var(--on-surface);
  background: var(--bg-grad) fixed;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}
:root[data-theme="dark"] body::before {
  /* bầu trời sao + trăng khuyết như bản Dark trong Figma */
  content: ""; position: fixed; inset: 0; pointer-events: none; z-index: 0;
  background:
    url("img/moon.svg") no-repeat right 220px top 36px / 46px auto,
    radial-gradient(1.6px 1.6px at 12% 18%, #fff9 50%, transparent 51%),
    radial-gradient(1.2px 1.2px at 28% 64%, #fff8 50%, transparent 51%),
    radial-gradient(2px 2px at 46% 12%, #fffb 50%, transparent 51%),
    radial-gradient(1.4px 1.4px at 63% 82%, #fff7 50%, transparent 51%),
    radial-gradient(1.8px 1.8px at 78% 30%, #fffa 50%, transparent 51%),
    radial-gradient(1.2px 1.2px at 90% 70%, #fff8 50%, transparent 51%),
    radial-gradient(1.5px 1.5px at 8% 88%, #fff8 50%, transparent 51%),
    radial-gradient(1.3px 1.3px at 55% 45%, #fff6 50%, transparent 51%);
}
#app { position: relative; z-index: 1; }
img { display: block; max-width: 100%; }
button, input, textarea, select { font: inherit; color: inherit; }
a { color: inherit; }
:focus-visible { outline: 3px solid var(--primary); outline-offset: 2px; border-radius: 6px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.muted { color: var(--on-surface-var); }
.small { font-size: 12px; line-height: 16px; }
.center { text-align: center; }
.row { display: flex; gap: 12px; align-items: center; flex-wrap: wrap; }
.grow { flex: 1 1 0; min-width: 0; }
.stack { display: flex; flex-direction: column; gap: 12px; }
.hidden { display: none !important; }

/* ---------------- Typography (Figma text styles) ---------------- */
.headline-l { font: 700 40px/40px var(--font); margin: 0; }
.headline-s { font: 400 24px/32px var(--font); margin: 0; }
.title-l { font: 400 22px/28px var(--font); margin: 0; }
.title-m { font: 500 16px/24px var(--font); margin: 0; }
.label-l { font: 500 14px/20px var(--font); }
.label-m { font: 500 12px/16px var(--font); letter-spacing: .1px; }
.body-l { font: 400 16px/24px var(--font); }
.body-s { font: 400 13px/18px var(--font); }
.overline { font: 500 14px/20px var(--font); color: var(--on-surface-var); text-transform: uppercase; }

/* ---------------- Khung: thanh điều hướng + nội dung ---------------- */
.shell { display: flex; gap: 9px; padding: 20px 20px 20px 15px; min-height: 100vh; }
.nav {
  position: sticky; top: 20px; flex: 0 0 91px; height: calc(100vh - 40px); min-height: 560px;
  background: var(--nav-bg); border: 1px solid rgba(0, 0, 0, .1); border-radius: 12px; box-shadow: var(--shadow-nav);
  display: flex; flex-direction: column; align-items: center; padding: 27px 0 20px; z-index: 5;
}
.nav-logo {
  width: 56px; height: 56px; border-radius: 28px; border: 3px solid #fff; background: var(--primary-container);
  box-shadow: 0 2px 6px rgba(33, 61, 92, .18); overflow: hidden; display: grid; place-items: center; cursor: pointer; padding: 0;
}
.nav-logo img { width: 58px; height: 58px; margin-top: 2px; }
.nav-items { margin-top: auto; margin-bottom: auto; width: 100%; display: flex; flex-direction: column; gap: 4px; border-top: 1px solid rgba(0,0,0,.08); border-bottom: 1px solid rgba(0,0,0,.08); padding: 4px 0; }
.nav-item {
  display: flex; flex-direction: column; align-items: center; gap: 4px; padding: 4px 0 8px; text-decoration: none;
  color: var(--on-surface-var); font: 500 12px/16px var(--font); letter-spacing: .5px; background: none; border: 0; cursor: pointer; width: 100%;
}
.nav-item .ic-wrap { width: 44px; height: 44px; border-radius: 16px; display: grid; place-items: center; transition: background .15s; }
.nav-item:hover .ic-wrap { background: color-mix(in srgb, var(--primary-container) 55%, transparent); }
.nav-item[aria-current="page"] { color: var(--on-primary-container); }
.nav-item[aria-current="page"] .ic-wrap { background: var(--primary-container); }
.ic { width: 24px; height: 24px; display: inline-block; background: currentColor; -webkit-mask: var(--m) center / contain no-repeat; mask: var(--m) center / contain no-repeat; }
.nav-item .ic { color: var(--on-surface); }
.ic-home { --m: url("img/ic-home.svg"); } .ic-book { --m: url("img/ic-book.svg"); } .ic-chart { --m: url("img/ic-chart.svg"); }
.ic-check { --m: url("img/ic-check.svg"); } .ic-bar { --m: url("img/ic-bar.svg"); } .ic-pie { --m: url("img/ic-pie.svg"); }
.ic-bookc { --m: url("img/ic-bookc.svg"); }
.nav-avatar {
  width: 47px; height: 47px; border-radius: 50%; border: 1px solid rgba(31, 69, 102, .15); background: var(--avatar-bg);
  overflow: hidden; cursor: pointer; padding: 0; display: grid; place-items: center;
}
.nav-avatar img { width: 48px; height: 48px; margin-top: 2px; }
.main { flex: 1 1 0; min-width: 0; display: flex; flex-direction: column; gap: 16px; padding-bottom: 72px; }

/* ---------------- Thẻ, hộp, trang trí ---------------- */
.card {
  position: relative; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 24px; overflow: hidden;
}
.card.pad-sm { padding: 20px 24px; }
.card-head { display: flex; align-items: center; gap: 10px; margin-bottom: 12px; }
.card-head .title-l { flex: 1; }
.waves { position: absolute; left: -1px; right: -1px; bottom: -1px; height: 90px; pointer-events: none; z-index: 0; }
.waves::before, .waves::after { content: ""; position: absolute; left: 0; right: 0; bottom: 0; background-repeat: no-repeat; background-size: 100% 100%; }
.waves::before { top: 19%; background-image: var(--wave-1); }
.waves::after { top: 44%; background-image: var(--wave-2); }
.waves.sm { height: 70px; }
.card > *:not(.waves):not(.deco) { position: relative; z-index: 1; }
.deco { position: absolute; pointer-events: none; z-index: 0; }
.deco-row { display: flex; justify-content: space-around; align-items: flex-end; gap: 12px; margin-top: auto; padding-top: 24px; pointer-events: none; }
.deco-row img { height: auto; }
.chip {
  display: inline-flex; align-items: center; gap: 6px; padding: 6px 12px; border-radius: 8px; border: 1px solid var(--border-opt);
  background: var(--surface); font: 500 12px/16px var(--font); color: var(--on-surface-var); white-space: nowrap;
}
.pill { display: inline-flex; align-items: center; padding: 4px 12px; border-radius: 999px; background: var(--primary-container); color: var(--on-primary-container); font: 500 14px/20px var(--font); white-space: nowrap; }
.pill.sm { padding: 2px 10px; }
.pill.warn { background: var(--warn-bg); color: var(--warn-text); }
.pill.good { background: var(--good-bg); color: var(--good); }
.pill.bad { background: var(--bad-bg); color: var(--bad); }
.pill.blank { background: var(--blank-bg); color: var(--blank); }
.stat { background: var(--surface-3); border: 1px solid var(--border-2); border-radius: 12px; padding: 12px 16px; min-width: 140px; }
.stat b { display: block; font: 400 22px/28px var(--font); color: var(--on-surface); }
.stat span { font: 500 12px/16px var(--font); color: var(--on-surface-var); }
.avatar { flex: 0 0 auto; border-radius: 50%; background: var(--avatar-bg); border: 1px solid rgba(31, 69, 102, .15); overflow: hidden; display: grid; place-items: center; }
.avatar img { width: 104%; height: 104%; margin-top: 4%; }
.empty { display: flex; flex-direction: column; align-items: center; text-align: center; gap: 6px; padding: 24px 16px; background: var(--surface-2); border: 1px solid var(--border-2); border-radius: 12px; }
.empty b { font: 500 17px/24px var(--font); color: var(--ink); }
.empty span { font-size: 13px; line-height: 18px; color: var(--muted-2); }
.empty .pics { display: flex; align-items: center; justify-content: center; gap: 24px; margin-bottom: 6px; }
.spinner { width: 28px; height: 28px; border-radius: 50%; border: 3px solid var(--primary-container); border-top-color: var(--primary); animation: spin 0.9s linear infinite; margin: 32px auto; }
@keyframes spin { to { transform: rotate(360deg); } }
.loading { padding: 40px; text-align: center; color: var(--on-surface-var); }

/* ---------------- Nút (Material 3) ---------------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 40px; padding: 10px 24px; border-radius: 100px;
  border: 1px solid transparent; font: 500 14px/20px var(--font); letter-spacing: .1px; cursor: pointer; text-decoration: none;
  background: var(--primary); color: var(--on-primary); transition: filter .15s, box-shadow .15s, background .15s; white-space: nowrap;
}
.btn:hover:not(:disabled) { filter: brightness(1.04); box-shadow: 0 1px 3px rgba(0,0,0,.18); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn.lg { min-height: 56px; padding: 16px 32px; font-size: 16px; }
.btn.strong { background: var(--strong); color: var(--on-strong); }
.btn.tonal { background: var(--primary-container); color: var(--on-primary-container); }
.btn.outline { background: transparent; border-color: var(--radio); color: var(--on-surface-var); }
.btn.outline.danger { background: transparent; border-color: var(--error); color: var(--error); }
.btn.text { background: transparent; color: var(--strong); padding: 10px 12px; }
.btn.violet { background: var(--violet); color: #fff; border-radius: 10px; }
.btn.danger:not(.outline) { background: var(--error); color: #fff; }
.btn.block { width: 100%; }
.link { background: none; border: 0; padding: 0; color: var(--strong); cursor: pointer; text-decoration: none; font: inherit; }
.link:hover { text-decoration: underline; }

/* ---------------- Ô nhập (M3 outlined text field) ---------------- */
.tf { position: relative; display: block; }
.tf input, .tf textarea, .tf select {
  width: 100%; min-height: 48px; padding: 12px 16px; border: 1px solid var(--radio); border-radius: 4px; background: var(--surface);
  color: var(--on-surface); font: 400 16px/24px var(--font); outline: none; resize: none;
}
.tf input::placeholder, .tf textarea::placeholder { color: var(--on-surface-var); opacity: .8; }
.tf input:focus, .tf textarea:focus, .tf select:focus { border: 2px solid var(--strong); padding: 11px 15px; }
.tf > span {
  position: absolute; left: 12px; top: -8px; padding: 0 4px; background: var(--surface); font: 400 12px/16px var(--font);
  color: var(--on-surface-var); pointer-events: none;
}
.tf.invalid input { border: 2px solid var(--error); padding: 11px 15px; }
.tf.invalid > span { color: var(--error); }
.tf-error { display: block; margin-top: 4px; font: 400 12px/16px var(--font); color: var(--error); }
.form-error { color: var(--error); font-size: 14px; line-height: 20px; }
.notice { display: flex; gap: 10px; align-items: flex-start; padding: 12px 16px; border-radius: 11px; font: 500 13px/18px var(--font); }
.notice.violet { background: var(--violet-soft); color: var(--violet-text); }
.notice.error { background: var(--error-bg); color: var(--error); border: 1px solid var(--error-border); }
.notice.info { background: var(--surface-3); color: var(--on-surface-var); border: 1px solid var(--border-2); }
.notice .i { flex: 0 0 22px; height: 22px; border-radius: 50%; display: grid; place-items: center; font: 700 13px/1 var(--font); color: #fff; background: var(--violet); }
.notice.error .i { background: var(--error); }

/* ---------------- Công tắc sáng/tối (Mode Toggle) ---------------- */
.mode-toggle {
  position: fixed; right: 39px; bottom: 30px; width: 128px; height: 52px; border: 0; padding: 0; cursor: pointer; z-index: 40;
  background: none; border-radius: 26px;
}
.mode-toggle::before { content: ""; position: absolute; left: -12px; top: -8px; width: 152px; height: 76px; background: var(--toggle) no-repeat center / contain; }

/* ---------------- Màn đăng nhập ---------------- */
.auth { display: grid; grid-template-columns: 560px 1fr; min-height: 100vh; background: var(--surface-2); }
.auth-intro { position: relative; background: linear-gradient(90deg, #d6edfe, #edf6fd 55%, #f7fbfe); padding: 160px 72px 40px; overflow: hidden; }
:root[data-theme="dark"] .auth-intro { background: linear-gradient(90deg, #284776, #1f3866 55%, #18305c); }
:root[data-theme="dark"] .auth { background: transparent; }
.auth-intro .brand { font: 700 40px/40px var(--font); margin: 0 0 90px; }
.auth-intro .tag1 { font: 700 40px/40px var(--font); margin: 0 0 12px; }
.auth-intro .tag2 { font: 400 24px/32px var(--font); margin: 0 0 58px; }
.auth-intro .tag3 { font: 400 16px/24px var(--font); color: var(--muted); margin: 0; max-width: 300px; }
.auth-intro .mascot { width: 220px; margin-top: 80px; }
.auth-intro .deco-a { position: absolute; right: 120px; top: 110px; width: 60px; }
.auth-intro .deco-b { position: absolute; right: 116px; top: 230px; width: 54px; }
.auth-intro .deco-c { position: absolute; right: 108px; top: 330px; width: 60px; }
.auth-side { position: relative; display: grid; place-items: center; padding: 48px 24px; }
.auth-card {
  position: relative; width: min(659px, 100%); background: var(--surface); border-radius: 50px; padding: 46px 54px 40px;
  box-shadow: 0 0 2.5px rgba(0, 0, 0, .1), 0 8px 30px rgba(33,61,92,.06); overflow: hidden;
}
.auth-card h1 { font: 700 40px/40px var(--font); margin: 0 0 20px; }
.auth-card .sub { font: 400 13px/18px var(--font); color: var(--muted); margin: 0 0 12px; }
.auth-card .sub2 { font: 400 20px/24px var(--font); color: var(--muted); margin: 0 0 28px; }
.auth-form { display: flex; flex-direction: column; gap: 24px; }
.auth-actions { display: flex; justify-content: flex-end; align-items: center; gap: 8px; margin-top: -8px; }
.auth-foot { margin-top: 56px; display: flex; flex-direction: column; gap: 12px; font: 400 20px/24px var(--font); color: var(--muted); padding-right: 100px; }
.auth-foot button { font-size: 20px; color: var(--muted); text-align: left; align-self: flex-start; }
.auth-card .crab { position: absolute; right: 44px; bottom: 26px; width: 84px; transform: rotate(-5deg); }
.role-pick { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }
.role-pick b { font: 500 14px/20px var(--font); }
.role-btn { padding: 6px 14px; border-radius: 8px; border: 1px solid transparent; background: #e8def8; color: #4a4458; font: 500 14px/20px var(--font); cursor: pointer; }
.role-btn[aria-checked="true"] { background: var(--strong); color: var(--on-strong); }
:root[data-theme="dark"] .role-btn:not([aria-checked="true"]) { background: #3b3570; color: #e8def8; }

/* ---------------- Gia sư: trang chủ ---------------- */
.page-head { display: flex; align-items: center; gap: 20px; padding: 24px 28px; flex-wrap: wrap; }
.page-head .who { flex: 1 1 280px; min-width: 0; }
.page-head .who p { margin: 0; }
.stats { display: flex; gap: 12px; flex-wrap: wrap; }
.cols { display: grid; grid-template-columns: minmax(0, 731fr) minmax(0, 556fr); gap: 16px; align-items: stretch; flex: 1; }
.cols > .card { display: flex; flex-direction: column; }
.opt-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.opt {
  display: flex; gap: 12px; align-items: flex-start; padding: 16px; border-radius: 12px; border: 1px solid var(--border-opt);
  background: var(--surface); cursor: pointer; text-align: left; width: 100%;
}
.opt.persona { align-items: center; }
.opt[aria-checked="true"] { background: var(--primary-container); border: 2px solid var(--primary); padding: 15px; }
.opt .radio { flex: 0 0 20px; width: 20px; height: 20px; border-radius: 50%; border: 2px solid var(--radio); margin-top: 2px; position: relative; }
.opt.persona .radio { margin-top: 0; }
.opt[aria-checked="true"] .radio { border-color: var(--strong); }
.opt[aria-checked="true"] .radio::after { content: ""; position: absolute; inset: 3px; border-radius: 50%; background: var(--strong); }
.opt .t { font: 500 16px/24px var(--font); color: var(--on-surface); }
.opt .d { font: 400 13px/18px var(--font); color: var(--on-surface-var); }
.opt[aria-checked="true"] .t, .opt[aria-checked="true"] .d { color: var(--on-primary-container); }
.opt .pic { flex: 0 0 56px; width: 56px; height: 56px; border-radius: 28px; background: var(--avatar-bg); border: 1px solid rgba(31,69,102,.15); overflow: hidden; position: relative; }
.opt .pic img { position: absolute; left: -4px; top: -9px; width: 68px; height: 68px; max-width: none; }
.step-title { font: 500 16px/24px var(--font); margin: 6px 0 0; }
.summary-bar { display: flex; align-items: center; gap: 16px; padding-top: 16px; margin-top: auto; flex-wrap: wrap; }
.summary-bar .grow .label-m { color: var(--on-surface-var); }
.hist { display: flex; flex-direction: column; gap: 12px; }
.hist-item {
  display: flex; gap: 12px; align-items: center; padding: 12px 16px; border-radius: 12px; background: var(--surface-2);
  border: 1px solid var(--border-2); text-decoration: none; color: inherit; cursor: pointer; width: 100%; text-align: left;
}
.hist-item:hover { border-color: var(--primary); }
.hist-item .a { flex: 1; min-width: 0; }
.hist-item .a b { display: block; font: 500 16px/24px var(--font); }
.hist-item .a span, .hist-item .c span { font: 500 12px/16px var(--font); color: var(--on-surface-var); }
.hist-item .c { text-align: right; flex: 0 0 auto; }
.hist-item .c b { display: block; font: 400 13px/18px var(--font); }

/* ---------------- Gia sư: luyện tập ---------------- */
.problem-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.problem { position: relative; overflow: hidden; background: var(--surface-2); border: 1px solid var(--border-2); border-radius: 12px; padding: 16px 16px 40px; }
.problem p { margin: 0; }
.solution { background: var(--error-bg); border: 1px solid var(--error-border); border-radius: 12px; padding: 16px; display: flex; flex-direction: column; gap: 6px; }
.solution .overline { color: var(--error); }
.solution .line { white-space: pre-wrap; margin: 0; }
.solution .wrong { background: var(--error-line); color: var(--error); border-radius: 6px; padding: 4px 8px; }
.practice-cols { display: grid; grid-template-columns: minmax(0, 731fr) minmax(0, 556fr); gap: 16px; flex: 1; min-height: 560px; }
.practice-cols.collapsed { grid-template-columns: minmax(0, 1fr) 260px; }
.chat { display: flex; flex-direction: column; padding: 0; }
.chat-head { display: flex; align-items: center; gap: 12px; padding: 14px 24px; border-bottom: 1px solid var(--border-2); }
.legend { display: flex; gap: 12px; font: 500 12px/16px var(--font); color: var(--on-surface-var); }
.legend i { display: inline-block; width: 10px; height: 10px; border-radius: 50%; margin-right: 6px; vertical-align: -1px; }
.chat-log { flex: 1 1 0; min-height: 280px; max-height: 62vh; overflow-y: auto; padding: 20px 24px; display: flex; flex-direction: column; gap: 16px; }
.msg { display: flex; gap: 10px; align-items: flex-start; }
.msg.me { justify-content: flex-end; }
.msg .body { display: flex; flex-direction: column; gap: 4px; max-width: min(460px, 78%); }
.msg.me .body { align-items: flex-end; }
.msg .who { font: 500 12px/16px var(--font); color: var(--on-surface-var); }
.bubble { padding: 10px 14px; font: 400 14px/20px var(--font); white-space: pre-wrap; word-break: break-word; background: var(--bubble); border-radius: 4px 16px 16px 16px; }
.msg.me .bubble { background: var(--primary); color: var(--on-primary); border-radius: 16px 4px 16px 16px; }
.msg.me.failed .bubble { opacity: .55; }
.msg .fail { font: 500 12px/16px var(--font); color: var(--error); }
.msg .warn { font: 400 12px/16px var(--font); color: var(--warn-text); background: var(--warn-bg); border-radius: 8px; padding: 6px 10px; }
.typing { display: flex; align-items: center; gap: 10px; font: 500 12px/16px var(--font); color: var(--on-surface-var); }
.typing img { width: 64px; height: 32px; }
.chat-banner { display: flex; gap: 12px; align-items: center; padding: 14px 24px; }
.chat-banner.error { background: var(--error-bg); color: var(--error); }
.chat-banner.ok { background: var(--good-bg); color: var(--good-text); }
.chat-banner p { margin: 0; flex: 1; font: 400 13px/18px var(--font); }
.chat-banner b { display: block; font: 500 14px/20px var(--font); }
.composer { display: flex; gap: 12px; align-items: center; padding: 12px 24px 16px; border-top: 1px solid var(--border-2); }
.composer .tf { flex: 1; }
.geo-card { display: flex; flex-direction: column; gap: 12px; padding: 16px 20px 90px; }
.geo-box { flex: 1; min-height: 320px; border: 1px solid var(--border-2); border-radius: 12px; background: #fff; display: grid; place-items: center; overflow: hidden; }
.geo-empty { color: var(--on-surface-var); font-size: 13px; text-align: center; padding: 20px; }

/* ---------------- Báo cáo ---------------- */
.score-box { display: flex; align-items: center; gap: 16px; background: var(--primary-container); color: var(--on-primary-container); border-radius: 16px; padding: 14px 24px; }
.score-box img { width: 64px; height: 64px; }
.score-box .num { font: 700 40px/40px var(--font); }
.score-box .of { font: 400 22px/28px var(--font); }
.crit { background: var(--surface-4); border: 1px solid var(--border-2); border-radius: 12px; padding: 12px 16px; display: flex; flex-direction: column; gap: 6px; }
.crit-head { display: flex; align-items: center; gap: 10px; }
.crit-head .n { width: 24px; height: 24px; border-radius: 12px; background: var(--primary-container); color: var(--on-primary-container); display: grid; place-items: center; font: 500 12px/16px var(--font); }
.crit-head .t { flex: 1; font: 500 16px/24px var(--font); }
.bar { height: 6px; border-radius: 3px; background: var(--bar-track); overflow: hidden; }
.bar > i { display: block; height: 100%; border-radius: 3px; background: var(--primary); }
.bar.warn > i { background: var(--warn); }
.crit p { margin: 0; font: 400 13px/18px var(--font); }
.crit p b { font-weight: 500; }
.crit p.ev { color: var(--on-surface-var); }
.next-box { background: var(--surface-3); border: 1px solid var(--primary-container); border-radius: 12px; padding: 16px; display: flex; flex-direction: column; gap: 10px; }
.next-box .k { flex: 0 0 130px; font: 500 12px/16px var(--font); color: var(--on-surface-var); }
.next-box .v { flex: 1; font: 500 14px/20px var(--font); }
.next-box .r { display: flex; gap: 12px; }
.center-col { display: flex; flex-direction: column; align-items: center; gap: 12px; }
.transcript { margin-top: 8px; }
.transcript summary { cursor: pointer; font: 500 14px/20px var(--font); color: var(--strong); }

/* ---------------- Học sinh ---------------- */
.student .card { border-color: #e4ebf6; }
:root[data-theme="dark"] .student .card { border-color: var(--border); }
.hero { position: relative; background: #eef2ff; border-radius: 14px; min-height: 223px; overflow: hidden; display: flex; align-items: center; padding: 32px 42px; }
:root[data-theme="dark"] .hero { background: #26355a; }
.hero h1 { font: 700 50px/1.2 var(--font); color: #151e49; margin: 0 0 6px; }
.hero p { font: 400 20px/1.4 var(--font); color: #64728e; margin: 0; }
:root[data-theme="dark"] .hero h1 { color: #e6ebff; }
:root[data-theme="dark"] .hero p { color: #b8c3dc; }
.hero .pastel { position: absolute; border-radius: 50%; background: #dfe7ff; }
:root[data-theme="dark"] .hero .pastel { background: #2f4170; }
.hero .art { position: absolute; right: 10px; bottom: 6px; width: min(477px, 42%); }
.hero-wrap { padding: 8px; }
.sec-title { display: flex; align-items: center; gap: 15px; margin: 4px 0 12px; }
.sec-title h2 { font: 500 24px/1.6 var(--font); color: var(--ink-2); margin: 0; }
.sec-ic { flex: 0 0 45px; width: 45px; height: 45px; border-radius: 13px; background: var(--violet-bg); display: grid; place-items: center; color: var(--violet); }
.sec-ic svg { width: 26px; height: 26px; }
.exam-row { display: flex; align-items: center; gap: 12px; padding: 16px 12px; background: var(--card-row); border: 1px solid var(--card-row-border); border-radius: 12px; }
.exam-row .doc { flex: 0 0 50px; height: 50px; border-radius: 13px; background: var(--violet-bg); display: grid; place-items: center; color: #7356de; }
.exam-row .doc svg { width: 26px; height: 30px; }
.exam-row .info { flex: 1; min-width: 0; }
.exam-row .info b { display: block; font: 500 17px/1.6 var(--font); color: var(--ink); }
.exam-row .info span { font: 400 14px/1.6 var(--font); color: var(--muted-2); }
.exam-row .btn { min-width: 121px; min-height: 45px; }
.predict { text-align: center; padding: 22px; }
.predict .big { font: 700 44px/1.1 var(--font); color: var(--violet-2); margin: 6px 0; }
.mis-row { display: flex; gap: 12px; align-items: center; padding: 12px; background: var(--card-row); border: 1px solid var(--card-row-border); border-radius: 12px; }
.mis-row .ex { flex: 0 0 42px; height: 42px; border-radius: 12.6px; background: var(--violet-bg-2); display: grid; place-items: center; }
.mis-row .ex i { width: 24px; height: 24px; border-radius: 50%; background: var(--violet-2); color: #fff; display: grid; place-items: center; font: 700 12px/1 var(--font); font-style: normal; }
.mis-row .tx { flex: 1; min-width: 0; }
.mis-row .tx b { display: block; font: 500 16px/1.4 var(--font); color: var(--ink); }
.mis-row .tx span { font: 400 13px/18px var(--font); color: var(--muted-2); }
.mis-row .cnt { font: 500 13px/18px var(--font); color: var(--muted-2); white-space: nowrap; }

/* làm bài */
.exam-head { display: grid; grid-template-columns: auto 1fr auto auto; gap: 24px; align-items: center; padding: 20px; }
.exam-head .docbig { width: 64px; height: 64px; border-radius: 19px; background: #e9f4ff; display: grid; place-items: center; color: #3896ff; }
:root[data-theme="dark"] .exam-head .docbig { background: #23395e; }
.exam-head h1 { font: 700 28px/1.3 var(--font); color: var(--ink); margin: 0; }
.exam-head .meta { font: 400 16px/1.6 var(--font); color: var(--muted-2); }
.progress { min-width: 240px; padding-left: 28px; border-left: 2px solid #e5edf6; }
:root[data-theme="dark"] .progress { border-color: var(--border-2); }
.progress b { font: 500 17px/1.6 var(--font); color: var(--ink); }
.progress .track { display: flex; align-items: center; gap: 16px; margin-top: 8px; }
.progress .track .bar { flex: 1; height: 14px; border-radius: 7px; background: #e6eef8; }
:root[data-theme="dark"] .progress .track .bar { background: var(--bar-track); }
.progress .track .bar > i { background: #3896ff; border-radius: 7px; }
.progress .track span { font: 500 18px/1 var(--font); color: var(--muted-2); }
.timer { display: flex; align-items: center; gap: 10px; background: #e9f4ff; border: 1px solid #cfe2ff; border-radius: 16px; padding: 12px 18px; }
:root[data-theme="dark"] .timer { background: #23395e; border-color: #35557f; }
.timer img { width: 44px; height: 44px; }
.timer b { display: block; font: 700 32px/1.1 var(--font); color: #3896ff; font-variant-numeric: tabular-nums; }
.timer span { font: 400 14px/1.4 var(--font); color: var(--muted-2); }
.timer.low { background: var(--bad-bg); border-color: var(--bad-border); }
.timer.low b { color: var(--bad); }
.exam-cols { display: grid; grid-template-columns: minmax(0, 473fr) minmax(0, 806fr); gap: 12px; }
.qgrid { display: grid; grid-template-columns: repeat(5, minmax(0, 74px)); gap: 12px; }
.qbtn { position: relative; aspect-ratio: 1; border-radius: 10px; background: #f4f7fb; border: 1px solid #e2eaf3; font: 500 18px/1 var(--font); color: var(--ink); cursor: pointer; }
:root[data-theme="dark"] .qbtn { background: var(--surface-2); border-color: var(--border-2); }
.qbtn.done { background: var(--good-bg); border-color: var(--good-border); color: var(--good-text); }
.qbtn.done::after { content: "✓"; position: absolute; right: 7px; bottom: 5px; font: 700 15px/1 var(--font); color: var(--good); }
.qbtn.current { background: var(--surface); border: 2px solid #3896ff; }
.qbtn.flag::before { content: "🔖"; position: absolute; left: 4px; top: 2px; font-size: 12px; }
.qlegend { display: flex; gap: 18px; font: 400 15px/1.6 var(--font); color: var(--muted-2); margin: 6px 0 16px; flex-wrap: wrap; }
.qlegend i { display: inline-block; width: 14px; height: 14px; border-radius: 50%; margin-right: 8px; vertical-align: -2px; }
.geo-panel { background: #f7fafe; border: 1px solid #d8e5f1; border-radius: 14px; padding: 13px 14px; margin-top: 18px; }
:root[data-theme="dark"] .geo-panel { background: var(--surface-2); border-color: var(--border-2); }
.geo-panel h3 { margin: 0; font: 700 18px/1.4 var(--font); color: #253b53; }
:root[data-theme="dark"] .geo-panel h3 { color: var(--on-surface); }
.geo-panel .geo-box { min-height: 290px; margin: 10px 0; }
.qbadge { display: inline-block; background: #e9f4ff; color: #3896ff; font: 700 16px/1 var(--font); border-radius: 14px; padding: 13px 22px; }
:root[data-theme="dark"] .qbadge { background: #23395e; }
.qtext { font: 500 26px/1.45 var(--font); color: var(--ink); margin: 28px 0 24px; }
.answer { display: flex; align-items: center; gap: 16px; width: 100%; min-height: 68px; padding: 14px 20px; border-radius: 12px; border: 1px solid #e2eaf3; background: var(--surface); text-align: left; cursor: pointer; margin-bottom: 16px; font: 500 17px/1.5 var(--font); color: var(--ink); }
:root[data-theme="dark"] .answer { border-color: var(--border-2); }
.answer .rd { flex: 0 0 20px; height: 20px; border-radius: 50%; border: 2px solid #49454f; position: relative; }
:root[data-theme="dark"] .answer .rd { border-color: var(--radio); }
.answer b { font-weight: 700; }
.answer[aria-checked="true"] { border: 2px solid #3896ff; background: #f0f7ff; padding: 13px 19px; }
:root[data-theme="dark"] .answer[aria-checked="true"] { background: #23395e; }
.answer[aria-checked="true"] .rd { border-color: #3896ff; }
.answer[aria-checked="true"] .rd::after { content: ""; position: absolute; inset: 3px; border-radius: 50%; background: #3896ff; }
.flag-btn { background: none; border: 0; cursor: pointer; font: 400 15px/1.6 var(--font); color: var(--muted-2); }
.flag-btn[aria-pressed="true"] { color: #3896ff; font-weight: 500; }
.exam-foot { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; margin-top: 12px; }

/* kết quả */
.res-head { display: grid; grid-template-columns: 1fr auto auto; gap: 24px; align-items: center; }
.res-head .scorebig { display: inline-block; background: var(--violet-bg-2); border-radius: 16px; padding: 10px 18px; margin-top: 12px; }
.res-head .scorebig b { display: block; font: 700 40px/1.1 var(--font); color: var(--violet-2); }
.res-head .scorebig span { font: 400 15px/1.6 var(--font); color: var(--muted-2); }
.metrics { display: flex; gap: 14px; flex-wrap: wrap; justify-content: flex-end; }
.metric { background: #f7f9fd; border: 1px solid #e2eaf3; border-radius: 14px; padding: 10px 16px; min-width: 114px; }
:root[data-theme="dark"] .metric { background: var(--surface-2); border-color: var(--border-2); }
.metric b { display: block; font: 700 26px/1.3 var(--font); color: var(--ink); }
.metric span { font: 400 13px/1.4 var(--font); color: var(--muted-2); }
.res-cols { display: grid; grid-template-columns: minmax(0, 435fr) minmax(0, 844fr); gap: 12px; }
.review { border: 1px solid var(--good-border); border-radius: 14px; padding: 15px; background: var(--surface); display: flex; flex-direction: column; gap: 8px; }
.review.bad { border-color: var(--bad-border); }
.review.blank { border-color: var(--blank-border); }
.review-head { display: flex; gap: 10px; align-items: flex-start; }
.review-head .q { flex: 1; font: 500 16px/1.6 var(--font); color: var(--ink); }
.st-ic { flex: 0 0 38px; height: 38px; border-radius: 11px; display: grid; place-items: center; }
.st-ic i { width: 22px; height: 22px; border-radius: 50%; display: grid; place-items: center; font: 700 12px/1 var(--font); font-style: normal; color: #fff; }
.st-ic.good { background: var(--good-bg); } .st-ic.good i { background: var(--good); }
.st-ic.bad { background: var(--bad-bg); } .st-ic.bad i { background: var(--bad); }
.st-ic.blank { background: var(--blank-bg); } .st-ic.blank i { background: transparent; border: 2px solid var(--blank); color: var(--blank); }
.ans-line { display: grid; grid-template-columns: 150px 1fr; font-size: 13px; line-height: 1.7; }
.ans-line b { font-weight: 700; }
.ans-line span { color: var(--muted-2); }
.explain { background: #f8fafe; border: 1px solid #e2eaf3; border-radius: 10px; padding: 9px 11px; font-size: 12px; line-height: 1.5; color: var(--muted-2); }
:root[data-theme="dark"] .explain { background: var(--surface-2); border-color: var(--border-2); }
.explain b { color: var(--violet-2); display: block; }
.filters { display: flex; gap: 10px; }
.filters button { border: 0; cursor: pointer; }
.filters button[aria-pressed="false"] { opacity: .45; }

/* ---------------- Quản lý ---------------- */
.mgr-title { display: flex; align-items: flex-start; gap: 16px; padding: 32px 32px 0; flex-wrap: wrap; }
.mgr-title > div { flex: 1; }
.mgr-title p { margin: 12px 0 0; color: var(--muted); }
.mgr-body { padding: 0 32px; display: flex; flex-direction: column; gap: 20px; }
.metric-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; }
.m3card {
  display: flex; align-items: stretch; min-height: 56px; border-radius: 12px; background: var(--m3-card); overflow: hidden; text-align: left; width: 100%;
  box-shadow: 0 1px 3px 1px rgba(0,0,0,.15), 0 1px 2px rgba(0,0,0,.3); border: 0; padding: 0; color: inherit; text-decoration: none;
}
button.m3card, a.m3card { cursor: pointer; }
button.m3card:hover, a.m3card:hover { filter: brightness(.98); }
.m3card[aria-current="true"] { outline: 2px solid var(--primary); }
.m3card .mono { flex: 0 0 40px; width: 40px; height: 40px; margin: 8px 0 8px 12px; align-self: center; border-radius: 50%; background: var(--m3-avatar); color: var(--m3-avatar-text); display: grid; place-items: center; font: 500 16px/1 var(--font); }
.m3card .txt { flex: 1; min-width: 0; padding: 8px 16px; display: flex; flex-direction: column; justify-content: center; }
.m3card .txt b { font: 500 16px/24px var(--font); color: var(--on-surface); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.m3card .txt span { font: 400 14px/20px var(--font); color: var(--on-surface-var); }
.m3card .ph { flex: 0 0 80px; background: var(--m3-ph); display: grid; place-items: center; }
.m3card .ph svg { width: 34px; height: 34px; color: var(--m3-ph-shape); }
.panel { background: var(--surface); border: 1px solid var(--border-2); border-radius: 18px; box-shadow: 0 4px 16px rgba(33,61,92,.1); padding: 22px 23px; position: relative; overflow: hidden; display: flex; flex-direction: column; gap: 16px; }
.panel h2 { font: 400 22px/28px var(--font); margin: 0; }
.panel .sub { font: 400 16px/20px var(--font); color: var(--muted); margin: 6px 0 0; }
.panel-head { display: flex; align-items: flex-start; gap: 12px; min-height: 72px; }
.panel-head > div:first-child { flex: 1; }
.panel-head img { height: auto; }
.two { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.hbar { display: flex; flex-direction: column; gap: 6px; }
.hbar span { font: 400 13px/18px var(--font); color: var(--on-surface-var); display: flex; justify-content: space-between; }
.hbar .bar { height: 8px; border-radius: 4px; }
.hbar .bar > i { background: #5b97cc; }
.search { display: flex; gap: 8px; }
.search .tf { flex: 1; }
.kv { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.table { width: 100%; border-collapse: collapse; font-size: 14px; }
.table th, .table td { text-align: left; padding: 10px 8px; border-bottom: 1px solid var(--border-2); }
.table th { font: 500 12px/16px var(--font); color: var(--on-surface-var); }

/* ---------------- Hộp thoại, menu tài khoản, thông báo ---------------- */
.overlay { position: fixed; inset: 0; background: var(--overlay); display: grid; place-items: center; z-index: 60; padding: 16px; animation: fade .15s; }
@keyframes fade { from { opacity: 0; } }
.dialog { width: min(480px, 100%); background: var(--surface); border-radius: 28px; padding: 28px 24px 24px; box-shadow: 0 12px 40px rgba(0,0,0,.25); text-align: center; position: relative; }
.dialog .pic { width: 120px; margin: -4px auto 8px; }
.dialog h2 { font: 700 24px/32px var(--font); margin: 0 0 8px; }
.dialog p { margin: 0 0 20px; color: var(--on-surface-var); white-space: pre-line; }
.dialog .acts { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.dialog .acts .btn { min-width: 140px; }
.dialog .close { position: absolute; right: 16px; top: 14px; width: 32px; height: 32px; border-radius: 50%; border: 1px solid var(--border-2); background: var(--surface); cursor: pointer; font-size: 16px; }
.dialog form { text-align: left; display: flex; flex-direction: column; gap: 18px; margin-bottom: 20px; }
.menu {
  position: fixed; left: 78px; bottom: 34px; width: 248px; background: var(--surface); border-radius: 16px; z-index: 50;
  box-shadow: 0 8px 28px rgba(15,30,60,.22); padding: 16px; animation: fade .12s;
}
.menu .top { display: flex; gap: 12px; align-items: center; padding-bottom: 12px; border-bottom: 1px solid var(--border-2); margin-bottom: 10px; }
.menu .top b { display: block; font: 500 15px/20px var(--font); }
.menu .top span { font: 400 12px/16px var(--font); color: var(--on-surface-var); }
.menu dl { margin: 0 0 12px; display: grid; grid-template-columns: auto 1fr; gap: 8px 10px; font-size: 12px; line-height: 16px; }
.menu dt { color: var(--on-surface-var); }
.menu dd { margin: 0; text-align: right; font-weight: 500; overflow-wrap: anywhere; }
.menu .acts { display: flex; flex-direction: column; gap: 8px; }
.menu .btn { min-height: 36px; padding: 6px 16px; }
#toast { position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%); z-index: 70; pointer-events: none; }
#toast .t { background: #2d3138; color: #f1f0f4; border-radius: 4px; padding: 12px 16px; font: 400 14px/20px var(--font); box-shadow: 0 4px 12px rgba(0,0,0,.25); max-width: min(560px, 90vw); }

/* ---------------- Responsive ---------------- */
@media (max-width: 1180px) {
  .cols, .practice-cols, .practice-cols.collapsed, .exam-cols, .res-cols, .two { grid-template-columns: 1fr; }
  .metric-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .exam-head { grid-template-columns: auto 1fr; }
  .progress { border-left: 0; padding-left: 0; }
  .res-head { grid-template-columns: 1fr; }
  .metrics { justify-content: flex-start; }
  .auth { grid-template-columns: 1fr; }
  .auth-intro { padding: 32px 24px; }
  .auth-intro .brand { margin-bottom: 16px; }
  .auth-intro .tag2 { margin-bottom: 12px; }
  .auth-intro .mascot, .auth-intro .deco-a, .auth-intro .deco-b, .auth-intro .deco-c { display: none; }
}
@media (max-width: 760px) {
  .shell { padding: 12px 12px 96px; }
  .nav {
    position: fixed; left: 8px; right: 8px; bottom: 8px; top: auto; height: 72px; min-height: 0; flex-direction: row; padding: 0 10px;
    border-radius: 18px; justify-content: space-between;
  }
  .nav-items { flex-direction: row; margin: 0; border: 0; justify-content: center; width: auto; flex: 1; }
  .nav-item { width: 76px; padding: 4px 0; }
  .nav-logo { width: 44px; height: 44px; }
  .menu { left: auto; right: 12px; bottom: 92px; }
  .mode-toggle { right: 10px; top: 10px; bottom: auto; transform: scale(.6); transform-origin: right top; }
  .card { padding: 18px 16px; }
  .page-head { padding: 18px 16px; }
  .opt-grid, .problem-row, .metric-grid, .kv { grid-template-columns: 1fr; }
  .hero { padding: 24px; min-height: 160px; }
  .hero h1 { font-size: 34px; }
  .hero .art { display: none; }
  .qgrid { grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 8px; }
  .qtext { font-size: 20px; }
  .timer b { font-size: 24px; }
  .auth-card { padding: 32px 22px; border-radius: 28px; }
  .auth-card h1 { font-size: 30px; }
  .auth-foot { padding-right: 0; font-size: 16px; }
  .auth-card .crab { display: none; }
  .mgr-title, .mgr-body { padding-left: 4px; padding-right: 4px; }
  .headline-l { font-size: 30px; line-height: 36px; }
  .ans-line { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) { * { animation: none !important; transition: none !important; } }