:root {
    --ms-crop-top: 370px;
    --form-view-height: calc(100vh - 310px);
    --form-view-min-height: 620px;
    --card-width: 1180px;
    --iframe-width: 1180px;
    --pvn-blue: #364185;
    --pvn-green: #009d48;
}

* { box-sizing: border-box; }

html { min-height: 100%; overflow-x: hidden; background: #173273; }

body {
    min-height: 100vh;
    margin: 0;
    overflow-x: hidden;
    background:
        radial-gradient(circle at 14% 10%, rgba(43, 57, 139, .07) 0, rgba(43, 57, 139, 0) 34%),
        radial-gradient(circle at 88% 14%, rgba(0, 157, 72, .055) 0, rgba(0, 157, 72, 0) 30%),
        linear-gradient(180deg, #eef4f8 0%, #f6f9fb 52%, #edf5f7 100%);
    background-attachment: fixed;
    color: #172033;
    font-family: "Barlow", "Segoe UI", Arial, sans-serif;
}

body::before {
    position: fixed;
    z-index: 0;
    inset: 0;
    background:
        linear-gradient(rgba(43, 57, 139, .018) 1px, transparent 1px),
        linear-gradient(90deg, rgba(43, 57, 139, .018) 1px, transparent 1px);
    background-size: 64px 64px;
    content: "";
    mask-image: linear-gradient(to bottom, rgba(0, 0, 0, .3), transparent 72%);
    pointer-events: none;
    -webkit-mask-image: linear-gradient(to bottom, rgba(0, 0, 0, .3), transparent 72%);
}

.contest-entry-page { position: relative; z-index: 1; width: 100%; padding: 38px 20px 72px; }

.contest-form-card {
    width: min(var(--card-width), calc(100vw - 32px));
    margin: 0 auto;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, .78);
    border-radius: 18px;
    background: rgba(255, 255, 255, .97);
    box-shadow: 0 22px 60px rgba(38, 66, 105, .16), 0 4px 16px rgba(38, 66, 105, .08);
}

.contest-form-banner { position: relative; width: 100%; overflow: hidden; background: #d9f3ff; }
.contest-form-banner::after { position: absolute; z-index: 2; right: 0; bottom: 0; left: 0; height: 4px; background: linear-gradient(90deg, #2b398b 0%, #2b398b 55%, var(--pvn-green) 100%); content: ""; pointer-events: none; }
.contest-form-banner a, .contest-form-banner img { display: block; width: 100%; }
.contest-form-banner img { height: auto; object-fit: contain; }

.contest-form-body { position: relative; width: 100%; height: max(var(--form-view-min-height), var(--form-view-height)); overflow: hidden; background: #f3f8fa; overscroll-behavior: contain; -webkit-overflow-scrolling: touch; }
.contest-form-body::before { position: absolute; z-index: 3; top: 0; right: 0; left: 0; height: 2px; background: #f3f8fa; content: ""; pointer-events: none; }
.contest-form-body iframe { position: absolute; top: calc(-1 * var(--ms-crop-top)); left: 50%; display: block; width: calc(var(--iframe-width) + 28px); height: calc(100% + var(--ms-crop-top)); border: 0; transform: translateX(-50%); }
.contest-form-fallback { padding: 10px 16px; background: #f7fafc; color: #5e687b; font-size: 13px; line-height: 1.45; text-align: center; }
.contest-form-fallback a { color: var(--pvn-blue); font-weight: 700; }
.contest-form-brand-line { height: 5px; background: linear-gradient(90deg, var(--pvn-blue), #238ac3 50%, var(--pvn-green)); }

.contest-gate { display: flex; min-height: 560px; align-items: center; flex-direction: column; justify-content: center; padding: 54px 24px 64px; background: radial-gradient(circle at 50% 15%, rgba(0, 157, 72, .08), transparent 34%), #f7fafc; text-align: center; }
.contest-gate__icon { display: grid; width: 72px; height: 72px; place-items: center; margin-bottom: 18px; border-radius: 50%; background: linear-gradient(145deg, var(--pvn-blue), #238ac3); color: #fff; font-size: 32px; box-shadow: 0 12px 28px rgba(54, 65, 133, .2); }
.contest-gate__eyebrow { margin: 0 0 8px; color: var(--pvn-green); font-size: 13px; font-weight: 800; letter-spacing: .16em; text-transform: uppercase; }
.contest-gate h1 { margin: 0; color: var(--pvn-blue); font-size: clamp(28px, 4vw, 44px); line-height: 1.15; }
.contest-gate__message { max-width: 680px; margin: 16px auto 28px; color: #566279; font-size: 17px; line-height: 1.6; }
.contest-countdown { display: grid; width: min(600px, 100%); grid-template-columns: repeat(4, 1fr); gap: 12px; }
.contest-countdown > div { padding: 18px 10px 15px; border: 1px solid rgba(54, 65, 133, .12); border-radius: 14px; background: #fff; box-shadow: 0 8px 24px rgba(38, 66, 105, .08); }
.contest-countdown strong, .contest-countdown span { display: block; }
.contest-countdown strong { color: var(--pvn-blue); font-size: clamp(26px, 5vw, 42px); line-height: 1; }
.contest-countdown span { margin-top: 8px; color: #69758a; font-size: 12px; font-weight: 700; text-transform: uppercase; }
.contest-gate__time { margin: 24px 0 0; color: #39465e; font-size: 14px; font-weight: 700; }
.contest-gate__back { display: inline-flex; min-height: 44px; align-items: center; justify-content: center; border-radius: 9px; background: var(--pvn-blue); padding: 10px 20px; color: #fff; font-weight: 700; text-decoration: none; }
.contest-gate--closed .contest-gate__icon { background: linear-gradient(145deg, #6b7485, #3f495c); }

@media (min-width: 1200px) {
    .contest-form-banner img { max-height: 300px; object-fit: cover; object-position: center; }
}

@media (max-width: 760px) {
    :root {
        --card-width: 100%;
        --iframe-width: 100%;
        /* Header Microsoft Forms trên mobile thấp hơn desktop; 370px làm mất phần đầu Câu 1. */
        --ms-crop-top: 310px;
        --form-view-height: calc(100dvh - 155px);
        --form-view-min-height: 560px;
    }
    html { background: #eef7fb; }
    body { background: linear-gradient(180deg, #eef4f8 0%, #f7fafc 55%, #edf5f7 100%); background-attachment: scroll; }
    body::before { display: none; }
    .contest-entry-page { padding: env(safe-area-inset-top, 0) env(safe-area-inset-right, 0) env(safe-area-inset-bottom, 0) env(safe-area-inset-left, 0); }
    .contest-form-card { width: 100%; border: 0; border-radius: 0; box-shadow: none; }
    .contest-form-banner img { max-height: none; object-fit: contain; }
    .contest-form-body iframe { left: 0; width: calc(100% + 28px); transform: none; }
    .contest-form-fallback { padding-right: max(14px, env(safe-area-inset-right)); padding-left: max(14px, env(safe-area-inset-left)); font-size: 12px; }
    .contest-gate { min-height: calc(100dvh - 70px); padding: 38px 16px 48px; }
    .contest-gate__icon { width: 58px; height: 58px; font-size: 25px; }
    .contest-gate__message { margin-bottom: 22px; font-size: 15px; }
    .contest-countdown { gap: 7px; }
    .contest-countdown > div { padding: 14px 4px 12px; border-radius: 10px; }
    .contest-countdown strong { font-size: clamp(24px, 8vw, 34px); }
    .contest-countdown span { font-size: 10px; }
}

/* Giữ mức crop mobile khi điện thoại xoay ngang hoặc trên tablet có viewport rộng. */
@media (hover: none) and (pointer: coarse) {
    :root { --ms-crop-top: 310px; }
}