:root {
    --mau-xanh: #1568d9;
    --mau-xanh-dam: #003190;
    --mau-cam: #fd6802;
    --mau-nen: #f5f7fb;
    --mau-vien: #e5e8ef;
    --font: "Be Vietnam Pro", "Segoe UI", system-ui, sans-serif;
}
*, *::before, *::after { box-sizing: border-box; }
body.cong-hoc {
    margin: 0;
    font-family: var(--font);
    background: var(--mau-nen);
    color: #1a1a1a;
}
body.cong-hoc--dang-nhap {
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 1rem;
    background: linear-gradient(160deg, rgba(0,49,144,.1), transparent 48%), var(--mau-nen);
}
.ch-dau { background: var(--mau-xanh-dam); color: #fff; }
.ch-dau__noi {
    width: 100%;
    max-width: 100%;
    margin: 0 auto;
    padding: .9rem var(--le-ngang-trang, 1rem);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
}
.ch-dau a { color: #fff; text-decoration: none; font-weight: 600; margin-right: .75rem; }
.ch-nhan { font-weight: 800; }
.ch-khung { width: 100%; max-width: 100%; margin: 0 auto; padding: 1.25rem var(--le-ngang-trang, 1rem) 2rem; box-sizing: border-box; }
.ch-the {
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,49,144,.08);
    padding: 1.1rem 1.25rem;
    margin-bottom: 1rem;
}
.ch-dang-nhap { max-width: 420px; width: 100%; margin-top: 8vh; }
.ch-nhan-hieu { margin: 0 0 .75rem; font-weight: 800; color: var(--mau-cam); }
.ch-dang-nhap h1 { margin: 0 0 .35rem; color: var(--mau-xanh-dam); font-size: 1.5rem; }
.ch-o {
    display: block;
    width: 100%;
    min-height: 42px;
    margin-top: .35rem;
    padding: .5rem .75rem;
    border: 1px solid var(--mau-vien);
    border-radius: 8px;
    font: inherit;
}
.ch-nut {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 40px;
    padding: .45rem 1rem;
    border: 0;
    border-radius: 8px;
    background: var(--mau-xanh);
    color: #fff;
    font-weight: 700;
    text-decoration: none;
    cursor: pointer;
}
.ch-nut--cam { background: var(--mau-cam); }
.ch-dang-nhap .ch-nut { width: 100%; margin-top: .5rem; }
.ch-loi { color: #dc2626; }
.ch-ok { border-left: 4px solid #1f9d55; }
.ch-goi-y { font-size: .9rem; color: #5a5a5a; }
.ch-object { margin: .75rem 0; padding: .75rem 0; border-top: 1px solid var(--mau-vien); }
.ch-nd { white-space: pre-wrap; }
label { font-weight: 600; }