:root{--bg:#f5f6f8;--fg:#1d2330;--mut:#667085;--card:#fff;--bd:#d9dde4;--err:#b42318;--pri:#1d4ed8}
@media (prefers-color-scheme:dark){:root{--bg:#12151c;--fg:#e8ebf2;--mut:#9aa3b5;--card:#1b2030;--bd:#2e3548;--err:#ff8b80;--pri:#7aa2ff}}
*{box-sizing:border-box}
body{margin:0;font:18px/1.5 system-ui,"Segoe UI",sans-serif;background:var(--bg);color:var(--fg)}
main{max-width:480px;margin:0 auto;padding:16px}
.card{background:var(--card);border:1px solid var(--bd);border-radius:12px;padding:18px;margin:24px 0}
h1{font-size:1.4rem;margin:0 0 .6em}
label{display:block;margin:14px 0}
input{display:block;width:100%;margin-top:6px;padding:14px;border:1px solid var(--bd);border-radius:10px;background:var(--bg);color:var(--fg);font:inherit}
.btn{width:100%;padding:14px;border:0;border-radius:10px;background:var(--pri);color:#fff;font:inherit;font-weight:600;cursor:pointer}
.btn.sec{background:transparent;color:var(--fg);border:1px solid var(--bd)}
.muted{color:var(--mut)}.small{font-size:.85rem}.err{color:var(--err)}
.ma{font-size:1.8rem;font-weight:700;margin:.1em 0;word-break:break-all}
.thongbao{font-size:1.15rem;line-height:1.45;padding:12px 14px;margin:0 0 14px;border-radius:10px;border-left:6px solid var(--err);background:rgba(180,35,24,.08);color:var(--fg)}
.thongbao.cuoi{color:var(--err);font-weight:800;font-size:1.25rem;background:rgba(180,35,24,.14)}
.thongbao.khoa{border-left-width:10px;font-weight:600;background:rgba(180,35,24,.14)}
:root{--ok:#0a7d3c;--okbg:#e3f6ea}
@media (prefers-color-scheme:dark){:root{--ok:#4cc97f;--okbg:#14301f}}
a.btn{display:block;text-align:center;text-decoration:none}
.btn.lon{padding:18px;font-size:1.2rem;margin-top:8px}
.kq{font-size:2.4rem;font-weight:800;text-align:center;margin:.2em 0}
.kq.dat{color:var(--ok)}.kq.khong{color:var(--err)}
.trangthai{font-size:1.2rem;font-weight:600}
fieldset.hang{border:0;margin:0 0 8px;padding:0}fieldset.hang legend{padding:0;margin-bottom:8px}
label.opt{display:flex;align-items:center;gap:12px;padding:16px;margin:8px 0;border:2px solid var(--bd);border-radius:12px;font-size:1.2rem;cursor:pointer}
label.opt input{width:24px;height:24px;margin:0;flex:none}
label.opt:has(input:checked){border-color:var(--pri);background:rgba(29,78,216,.1);font-weight:700}
.nhacnho{margin:12px 0;padding:12px 14px;border-radius:10px;border-left:6px solid #e0a800;background:rgba(224,168,0,.12);font-size:1.05rem;line-height:1.45}
.nhacnho p{margin:.2em 0}.nhacnho ul{margin:.3em 0 .5em;padding-left:1.2em}
/* GĐ7b: đăng nhập ba bước + xếp hàng đếm ngược */
.chao{font-size:1.25rem;margin:.3em 0}
.dem{font-size:3.4rem;font-weight:800;text-align:center;margin:.3em 0;font-variant-numeric:tabular-nums}
.dem .don-vi{font-size:1.2rem;font-weight:600;color:var(--mut)}
#dn .btn+.btn{margin-top:10px}
#dn [hidden],.card[hidden]{display:none}
@media (max-width:380px){main{padding:12px}.card{padding:14px}.dem{font-size:2.8rem}}

/* GĐ5: chân trang nhỏ, không chiếm chỗ của nội dung */
.chan{max-width:480px;margin:0 auto;padding:0 16px 16px;text-align:center;font-size:.8rem;color:var(--mut);overflow-wrap:anywhere}

/* GĐ5: nút Hiện/Ẩn mật khẩu (vùng bấm >= 44 px, không làm tràn ngang ở 360 px) */
.mk-boc{display:flex;gap:8px;align-items:stretch;margin-top:6px}
.mk-boc input,.mk-boc input:not([type=file]){flex:1;min-width:0;margin-top:0;width:auto}
.mk-nut{flex:none;min-width:64px;min-height:44px;padding:0 12px;border:1px solid var(--bd);border-radius:10px;background:transparent;color:var(--fg);font:inherit;font-size:.95rem;cursor:pointer}