:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --border: #e3e6ea;
  --text: #16202c;
  --muted: #667180;
  --accent: #1d4ed8;
  --accent-soft: #eef3ff;
  --ok: #0f7b48;
  --ok-soft: #e7f6ee;
  --zalo: #0068ff;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(16,32,44,.06), 0 4px 12px rgba(16,32,44,.05);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1419; --surface: #171d24; --border: #262f3a; --text: #e8ecf1;
    --muted: #93a0b0; --accent: #6b9cff; --accent-soft: #1a2436;
    --ok: #4ade80; --ok-soft: #14291f;
    --shadow: 0 1px 2px rgba(0,0,0,.3), 0 4px 12px rgba(0,0,0,.25);
  }
}

* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font: 16px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  -webkit-text-size-adjust: 100%;
}

.hero { padding: 28px 16px 14px; max-width: 760px; margin: 0 auto; }
.hero h1 { margin: 0; font-size: 1.6rem; letter-spacing: -.02em; }
.sub { margin: 6px 0 0; color: var(--muted); font-size: .875rem; }

.searchbar {
  position: sticky; top: 0; z-index: 10; background: var(--bg);
  padding: 10px 16px 12px; border-bottom: 1px solid var(--border);
}
.search-wrap { position: relative; max-width: 760px; margin: 0 auto; }
.search-icon {
  position: absolute; left: 13px; top: 50%; transform: translateY(-50%);
  width: 19px; height: 19px; fill: none; stroke: var(--muted); stroke-width: 2;
  stroke-linecap: round; pointer-events: none;
}
#q {
  width: 100%; padding: 13px 40px 13px 40px; font-size: 16px; color: var(--text);
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); outline: none; -webkit-appearance: none;
}
#q:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
#q::-webkit-search-cancel-button { display: none; }
.clear {
  position: absolute; right: 8px; top: 50%; transform: translateY(-50%);
  width: 28px; height: 28px; border: 0; border-radius: 50%; cursor: pointer;
  background: transparent; color: var(--muted); font-size: 22px; line-height: 1;
}
.hint { max-width: 760px; margin: 9px auto 0; font-size: .8rem; color: var(--muted); }
.chip {
  border: 1px solid var(--border); background: var(--surface); color: var(--muted);
  border-radius: 999px; padding: 3px 10px; font-size: .78rem; cursor: pointer; margin-right: 4px;
}
.chip:hover { border-color: var(--accent); color: var(--accent); }

main { max-width: 760px; margin: 0 auto; padding: 16px 16px 40px; }

.course {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow); margin-bottom: 12px; overflow: hidden;
}
.course-head { padding: 13px 15px 11px; border-bottom: 1px solid var(--border); }
.course-name { font-weight: 640; letter-spacing: -.01em; }
.code {
  display: inline-block; font: 600 .72rem/1.5 ui-monospace, SFMono-Regular, Menlo, monospace;
  background: var(--accent-soft); color: var(--accent);
  padding: 1px 7px; border-radius: 5px; margin-bottom: 5px; letter-spacing: .02em;
}
.tc { color: var(--muted); font-weight: 400; font-size: .85rem; }

.slot {
  display: flex; align-items: center; gap: 12px; width: 100%; text-align: left;
  padding: 12px 14px; background: none; border: 0; border-top: 1px solid var(--border);
  color: var(--text); font: inherit; cursor: pointer;
}
.slot:first-of-type { border-top: 0; }
.slot:hover { background: var(--accent-soft); }

/* Ca thi: viên nhãn đậm, là thứ phân biệt chính giữa các dòng */
.slot-ca {
  flex-shrink: 0; display: grid; place-items: center;
  min-width: 46px; padding: 6px 9px;
  font-size: .8rem; font-weight: 700; letter-spacing: .01em;
  color: var(--accent); background: var(--accent-soft);
  border-radius: 8px;
}
.slot[aria-expanded="true"] .slot-ca { color: #fff; background: var(--accent); }

.slot-when { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 1px; }

/* Giờ thi: thông tin sinh viên cần nhất -> to nhất, tương phản đầy đủ */
.slot-time {
  font-size: 1.04rem; font-weight: 700; color: var(--text);
  letter-spacing: -.01em; font-variant-numeric: tabular-nums;
}
.slot-time .dash { margin: 0 4px; font-weight: 500; opacity: .5; }

/* Ngày thi: rõ ràng, không còn mờ như trước */
.slot-date { font-size: .84rem; font-weight: 600; color: var(--muted); }
.badge {
  flex-shrink: 0; font-size: .74rem; font-weight: 600; padding: 4px 9px; border-radius: 999px;
  background: var(--bg); color: var(--muted); border: 1px solid var(--border);
}
.badge.has { background: var(--ok-soft); color: var(--ok); border-color: transparent; }

.panel { padding: 0 15px 15px; border-top: 1px solid var(--border); }
.panel[hidden] { display: none; }

.btn {
  display: flex; align-items: center; justify-content: center; gap: 8px; width: 100%;
  padding: 12px; margin-top: 12px; border: 0; border-radius: 10px; cursor: pointer;
  font: 600 .95rem/1 inherit; text-decoration: none;
}
.btn-zalo { background: var(--zalo); color: #fff; }
.btn-main { background: var(--accent); color: #fff; }
.btn-main:disabled { opacity: .55; cursor: default; }
.btn-ghost { background: transparent; color: var(--muted); border: 1px solid var(--border); }

label { display: block; margin-top: 12px; font-size: .84rem; font-weight: 600; }
input[type=url], input[type=text] {
  width: 100%; margin-top: 5px; padding: 11px; font-size: 16px; color: var(--text);
  background: var(--bg); border: 1px solid var(--border); border-radius: 9px; outline: none;
}
input[type=url]:focus, input[type=text]:focus { border-color: var(--accent); }
.field-hint { font-size: .78rem; color: var(--muted); font-weight: 400; margin-top: 4px; }
.err { color: #d7263d; font-size: .82rem; margin-top: 8px; }
.note-box { background: var(--bg); border-radius: 9px; padding: 10px 12px; margin-top: 12px; font-size: .88rem; }
.note-box strong { display: block; font-size: .76rem; color: var(--muted); margin-bottom: 2px; font-weight: 600; }

.empty { text-align: center; color: var(--muted); padding: 44px 16px; }
.empty strong { display: block; color: var(--text); margin-bottom: 4px; }
.count { color: var(--muted); font-size: .82rem; margin: 0 0 12px; }

footer { max-width: 760px; margin: 0 auto; padding: 22px 16px 40px; border-top: 1px solid var(--border); }
footer p { margin: 0 0 6px; font-size: .8rem; color: var(--muted); }
.muted { opacity: .8; }

.toast {
  position: fixed; left: 50%; bottom: 24px; transform: translate(-50%, 80px);
  background: var(--text); color: var(--bg); padding: 11px 18px; border-radius: 999px;
  font-size: .88rem; font-weight: 500; opacity: 0; transition: .25s; pointer-events: none; z-index: 50;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

/* danh sách nhóm theo phòng thi */
.grps { display: grid; gap: 8px; margin-top: 12px; }
.grp {
  display: flex; align-items: center; gap: 10px; padding: 11px 13px;
  background: var(--bg); border: 1px solid var(--border); border-radius: 10px;
  text-decoration: none; color: var(--text);
}
.grp:hover { border-color: var(--zalo); background: var(--accent-soft); }
.grp-room {
  flex-shrink: 0; font: 600 .82rem/1 ui-monospace, SFMono-Regular, Menlo, monospace;
  background: var(--surface); border: 1px solid var(--border);
  padding: 5px 8px; border-radius: 6px;
}
.grp-note { flex: 1; min-width: 0; font-size: .84rem; color: var(--muted);
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.grp-go { flex-shrink: 0; margin-left: auto; font-size: .82rem; font-weight: 600; color: var(--zalo); }
.grp-bad { opacity: .6; }
.grp-bad .grp-note { color: #d7263d; }
.mo-form { margin-top: 12px; }
.grp-wrap { display: flex; align-items: stretch; gap: 6px; }
.grp-wrap .grp { flex: 1; min-width: 0; }
.bao-hong {
  flex-shrink: 0; padding: 0 10px; font-size: .72rem; font-weight: 600; cursor: pointer;
  color: var(--muted); background: transparent;
  border: 1px solid var(--border); border-radius: 10px;
}
.bao-hong:hover:not(:disabled) { border-color: #d7263d; color: #d7263d; }
.bao-hong:disabled { opacity: .6; cursor: default; }

/* thanh lọc theo ngày thi */
.ngaybar {
  display: flex; gap: 6px; max-width: 760px; margin: 10px auto 0;
  overflow-x: auto; scrollbar-width: none; -webkit-overflow-scrolling: touch;
}
.ngaybar::-webkit-scrollbar { display: none; }
.dchip {
  flex-shrink: 0; cursor: pointer; white-space: nowrap;
  padding: 7px 13px; font: 600 .82rem/1 inherit;
  color: var(--muted); background: var(--surface);
  border: 1px solid var(--border); border-radius: 999px;
}
.dchip:hover { border-color: var(--accent); color: var(--accent); }
.dchip.on { background: var(--accent); border-color: transparent; color: #fff; }
.dchip .n { opacity: .7; font-weight: 500; margin-left: 5px; }

/* mũi tên cho biết dòng ca thi mở ra được */
.chev {
  flex-shrink: 0; width: 17px; height: 17px;
  fill: none; stroke: var(--muted); stroke-width: 2.2;
  stroke-linecap: round; stroke-linejoin: round;
  transition: transform .2s ease, stroke .2s ease;
}
.slot[aria-expanded="true"] { background: var(--accent-soft); }
.slot[aria-expanded="true"] .chev { transform: rotate(180deg); stroke: var(--accent); }
@media (prefers-reduced-motion: reduce) { .chev { transition: none; } }

/* màn hình hẹp: thu gọn để 1 dòng vẫn đủ chỗ */
@media (max-width: 380px) {
  .slot { gap: 9px; padding: 11px 12px; }
  .slot-ca { min-width: 40px; padding: 5px 7px; font-size: .74rem; }
  .slot-time { font-size: .97rem; }
  .slot-date { font-size: .78rem; }
  .badge { font-size: .68rem; padding: 3px 7px; }
}

/* nút dẫn sang trang tải ảnh lịch thi */
.cta-lich {
  display: flex; align-items: center; gap: 12px; margin-top: 14px; padding: 13px 15px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow); text-decoration: none; color: var(--text);
}
.cta-lich:hover { border-color: var(--accent); background: var(--accent-soft); }
.cta-ico { font-size: 1.4rem; flex-shrink: 0; }
.cta-txt { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 2px; }
.cta-txt b { font-size: .95rem; }
.cta-txt span { font-size: .8rem; color: var(--muted); }
.cta-mui { flex-shrink: 0; color: var(--accent); font-weight: 700; }

/* danh sách đang chờ nhóm */
.badge.cho { background: #fff6e0; color: #96690a; border-color: transparent; }
@media (prefers-color-scheme: dark) { .badge.cho { background: #3a2f11; color: #f0c35c; } }

.chos { margin-top: 12px; }
.chos-tit { margin: 0 0 7px; font-size: .82rem; font-weight: 600; color: var(--muted); }
.cho {
  display: flex; align-items: center; gap: 10px; padding: 10px 12px; margin-bottom: 7px;
  background: var(--bg); border: 1px dashed var(--border); border-radius: 10px;
}
.cho-n { flex: 1; min-width: 0; font-size: .84rem; font-weight: 600; }
.cho-tao {
  flex-shrink: 0; padding: 7px 12px; cursor: pointer;
  font: 600 .8rem/1 inherit; color: #fff; background: var(--accent);
  border: 0; border-radius: 8px;
}
.cho-tao:hover { opacity: .9; }

.hoac {
  margin-top: 14px; padding-top: 13px; border-top: 1px dashed var(--border);
}
.hoac > span { display: block; font-size: .82rem; color: var(--muted); margin-bottom: 2px; }
.hoac .btn { margin-top: 6px; }

/* lời mời bật thông báo */
.tb-moi {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin-top: 12px; padding: 11px 13px; font-size: .85rem;
  background: var(--accent-soft); border-radius: 10px;
}
.tb-moi > span { flex: 1; min-width: 160px; font-weight: 600; }
.tb-moi .btn { width: auto; margin: 0; padding: 8px 14px; flex-shrink: 0; }
.tb-on, .tb-off {
  margin-top: 12px; padding: 10px 13px; font-size: .83rem;
  background: var(--ok-soft); border-radius: 10px;
}
.tb-off { background: var(--bg); color: var(--muted); }

/* nút làm mới danh sách nhóm */
.count-row { display: flex; align-items: center; gap: 12px; margin-bottom: 12px; }
.count-row .count { margin: 0; flex: 1; min-width: 0; }
.lam-moi {
  display: inline-flex; align-items: center; gap: 6px; flex-shrink: 0;
  padding: 7px 12px; cursor: pointer; font: 600 .8rem/1 inherit;
  color: var(--muted); background: var(--surface);
  border: 1px solid var(--border); border-radius: 999px;
}
.lam-moi:hover:not(:disabled) { border-color: var(--accent); color: var(--accent); }
.lam-moi:disabled { opacity: .6; cursor: default; }
.lam-moi svg {
  width: 14px; height: 14px; fill: none; stroke: currentColor;
  stroke-width: 2.2; stroke-linecap: round; stroke-linejoin: round;
}
.lam-moi.quay svg { animation: quay 1s linear infinite; }
@keyframes quay { to { transform: rotate(360deg); } }
@media (prefers-reduced-motion: reduce) { .lam-moi.quay svg { animation: none; } }