/* =========================================================================
   Tema Amourette — panggung teater kertas, taman mawar di baliknya.

   Titik tolaknya video pembuka bergaya kertas potong (papercraft): panggung
   teater krem berukir emas dengan tirai merah muda; tirai tersibak, kamera
   masuk ke taman kertas berlapis dengan lengkung mawar, lalu tiba di kartu
   krem berbingkai OVAL mawar berpita.

   Gagasan utama: KERTAS BERLAPIS. Isi = kartu kertas krem yang tepi atasnya
   bergelombang seperti mahkota panggung, dengan selembar kertas merah muda
   tersusun di belakangnya (bayangan tegas bergeser, seperti lapisan
   papercraft di video); kepala bagian = panggung kecil bertirai; foto
   mempelai lonjong seperti bingkai oval di video.
   Warna: merah muda tirai (utama), krem kertas, hijau daun, emas ukiran.
   Huruf: Corinthia (nama & judul), Bodoni Moda (sub judul), Figtree (teks).
   ========================================================================= */

:root {
    --c-paper: #FAF3E8;
    --c-ink: #3C3431;
    --c-accent: #A85A5F;

    --c-muted: color-mix(in srgb, var(--c-ink) 72%, #fff);
    --c-rule: color-mix(in srgb, var(--amt-gold) 45%, #fff);
    --c-sunk: color-mix(in srgb, var(--amt-rose) 14%, #fff);
    --c-action: var(--c-accent);

    --f-names: 'Corinthia', cursive;
    --f-display: 'Bodoni Moda', 'Cormorant Garamond', Georgia, serif;
    --f-body: 'Figtree', system-ui, sans-serif;
    --f-script: var(--f-names);

    --amt-gold: #BC9558;   /* ukiran emas panggung */
    --amt-gold-hi: #E2C892;
    --amt-rose: #E6B9B3;   /* lapisan kertas merah muda */
    --amt-leaf: #8C9E86;   /* daun kertas */
    --amt-sheet: #FBF6EE;  /* kertas krem */
    --amt-ivory: #FFFDF8;
    /* Video 720 × 1280. Ponsel: menutupi layar. Layar lebar: utuh setinggi layar. */
    --amt-w: max(100vw, 100dvh * 9 / 16);
}
@media (min-aspect-ratio: 3 / 4) {
    :root { --amt-w: calc(100dvh * 9 / 16); }
}

body.inv.amt {
    background: #E9E1D6; color: var(--c-ink);
    font-family: var(--f-body); font-size: .92rem; line-height: 1.75;
}
.amt-amp { font-family: var(--f-names); color: var(--amt-gold); }

/* ---------------------------------------------------------- latar isi */

/* Taman kertas berlapis dengan lengkung mawar (tengah video), dilembutkan. */
.amt-backdrop {
    position: fixed; inset: 0; z-index: 0; pointer-events: none;
    background: linear-gradient(rgb(250 243 232 / .35), rgb(250 243 232 / .5)), var(--amt-latar) center 40% / cover no-repeat, #E9E1D6;
}

/* ---------------------------------------------------------------- sampul */

.amt .inv-cover.amt-cover { padding: 0; display: block; overflow: hidden; background: #E9E1D6; }
.amt-stage {
    position: absolute; left: 50%; top: 50%;
    width: var(--amt-w); aspect-ratio: 9 / 16; transform: translate(-50%, -50%);
    container-type: inline-size; overflow: hidden;
}
.amt-stage__poster, .amt-stage__start, .amt-stage__video { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }

/* --- Sampul dua langkah (kelas dari theme.js) -------------------------
   diam       : bingkai pertama video + sapaan + tombol "Buka undangan"
   .is-playing: video berjalan, sapaan memudar
   .is-ready  : nama, tanggal & jadwal masuk bingkai lengkung; tombol "Lihat undangan" */
.amt-stage__video { opacity: 0; }
.amt-stage.is-playing .amt-stage__video { opacity: 1; }
.amt-stage__start { transition: opacity .3s ease .25s; }
.amt-stage.is-playing .amt-stage__start, .amt-stage.is-ready .amt-stage__start { opacity: 0; }

.amt-cover__text, .amt-cover__foot { transition: opacity 1.1s ease, transform 1.1s var(--ease), visibility 0s linear 0s; }
.amt-stage:not(.is-ready) .amt-cover__text { opacity: 0; visibility: hidden; transform: translateY(12px); transition-duration: .3s, .3s, 0s; transition-delay: 0s, 0s, .3s; }
.amt-stage.is-playing:not(.is-ready) .amt-cover__foot { opacity: 0; visibility: hidden; transform: translateY(10px); transition-duration: .5s, .5s, 0s; transition-delay: 0s, 0s, .5s; }
.amt-stage.is-ready .amt-cover__foot { transition-delay: .7s, .7s, 0s; }
.amt-stage:not(.is-ready) #inv-open, .amt-stage.is-ready .amt-play, .amt-cover__foot [hidden] { display: none; }

/* Sebelum tirai tersibak (diam & selama video): sapaan di depan tirai yang
   masih tertutup. Baru pindah ke bawah oval saat .is-ready — ketika sapaan
   sudah tak terlihat — jadi tidak ada lompatan. */
.amt-stage:not(.is-ready) .amt-cover__foot { top: 80cqw; bottom: auto; }

/* Oval di akhir video: dalam x 15–85% (tengah 50%), y 7–137cqw (tengah
   72cqw); mawar hanya di garis oval, pita di bawahnya mulai ±139cqw. Kotak
   teks dijaga di dalam oval (setengah lebar oval di tepi kotak ±27cqw). */
.amt-cover__text {
    position: absolute; left: 23cqw; width: 54cqw; top: 32cqw; height: 78cqw;
    display: flex; flex-direction: column; align-items: center; justify-content: safe center; gap: 1.2cqw;
    text-align: center;
}
.amt-cover__label { margin: 0; font: italic 400 3.3cqw/1.3 var(--f-display); letter-spacing: .02em; white-space: nowrap; color: #8E7246; }
.amt-cover__names {
    display: grid; justify-items: center; width: 100%; margin: 0;
    font: 700 16cqw/1 var(--f-names); color: #94494F; text-wrap: balance;
}
.amt-cover__names .amt-amp { font-size: .36em; font-weight: 400; line-height: 1.3; color: #9A7A44; }
.amt-cover__date {
    margin: .6cqw 0 0; padding-top: 1.6cqw; border-top: 1px solid var(--amt-gold);
    font: 500 3.3cqw/1.2 var(--f-display); letter-spacing: .03em; white-space: nowrap; color: var(--c-ink);
}
/* Halaman lapang: jadwal boleh dua kolom. */
.amt-cover__sched { display: flex; flex-wrap: wrap; justify-content: center; gap: .8cqw 3.5cqw; max-width: 44cqw; margin: .2cqw 0 0; }
.amt-cover__sched p { display: grid; justify-items: center; margin: 0; font: 400 2.3cqw/1.35 var(--f-body); color: var(--c-muted); text-align: center; }
.amt-cover__sched-title { font: 600 2.1cqw/1.4 var(--f-body); letter-spacing: .1em; text-transform: uppercase; color: #94494F; }

.amt-cover__foot {
    /* Langkah akhir: menempel di bawah layar (di meja, di bawah kartu).
       Diukur dari bawah karena tinggi tombol dalam rem. Bila panggung 9:16
       lebih tinggi dari layar (tablet potret), bagian bawahnya terpotong —
       geser naik sebesar potongan itu supaya tombol tetap terlihat. */
    position: absolute; left: 19cqw; width: 62cqw;
    bottom: calc(max(0px, (var(--amt-w) * 16 / 9 - 100dvh) / 2) + 1.6cqw);
    display: grid; justify-items: center; padding: 2.8cqw 4cqw 3.4cqw; border-radius: 1.4cqw; text-align: center;
    background: rgb(251 244 234 / .82); -webkit-backdrop-filter: blur(8px); backdrop-filter: blur(8px);
    border-radius: 1.6cqw; box-shadow: 0 0 0 1px rgb(188 149 88 / .6), 1.6cqw 2cqw 0 var(--amt-rose), 0 16px 30px -18px rgb(80 55 45 / .5);
}
.amt-cover__to { margin: 0; font-size: max(.72rem, 2.8cqw); color: var(--c-muted); }
.amt-cover__guest { max-width: 100%; margin: .1rem 0 0; font: 400 max(1.15rem, 5.2cqw)/1.25 var(--f-display); color: var(--c-ink); overflow-wrap: anywhere; }

/* Tombol sampul: merah muda tirai, berlis emas. */
.amt-open {
    margin-top: max(.6rem, 2.4cqw); padding: .8rem 1.8rem; border: 0; border-radius: 999px;
    background: var(--c-accent); color: var(--amt-ivory);
    font: 600 .88rem/1 var(--f-body); letter-spacing: .03em; white-space: nowrap; cursor: pointer;
    box-shadow: inset 0 0 0 1px rgb(255 255 255 / .2), 0 0 0 3px rgb(251 244 234 / .9), 0 0 0 4px var(--amt-gold), 0 10px 22px -12px rgb(80 55 45 / .5);
    transition: background .25s ease;
}
.amt-open:hover { background: var(--c-ink); }
.amt-open:focus-visible { outline: 2px solid var(--c-ink); outline-offset: 6px; }

/* ---------------------------------------------------------------- isi */

body.amt:not(.is-open) .amt-main { visibility: hidden; opacity: 0; }
body.amt.is-open .amt-main { animation: amt-fade 1s ease both .3s; }
@keyframes amt-fade { from { opacity: 0; } }

.amt .inv__main.amt-main {
    position: relative; z-index: 1;
    width: min(100% - 2rem, 30rem); max-width: none; margin: 0 auto; padding: 24vh 0 0;
}

/* Kartu kertas berlapis: kertas krem bertekstur (kertas.jpg dari kartu di
   akhir video, dicerahkan); tepi atas bergelombang seperti mahkota panggung
   (::before); selembar kertas merah muda tersusun di belakangnya lewat
   bayangan tegas yang bergeser; garis emas tipis di dalam tepi (::after). */
.amt .inv-section {
    position: relative; margin: 1.2rem 0 13vh; padding: 3.4rem 1.9rem 3rem;
    border: 0; border-radius: 4px; text-align: center;
    background:
        linear-gradient(rgb(253 249 242 / .84), rgb(253 249 242 / .84)),
        url('kertas.jpg') center / cover,
        var(--amt-sheet);
    box-shadow: 9px 11px 0 var(--amt-rose), 9px 11px 0 1px rgb(168 90 95 / .25), 0 26px 40px -24px rgb(80 55 45 / .55);
}
.amt .inv-section::before,
.amt .inv-section::after { content: ''; position: absolute; pointer-events: none; }
.amt .inv-section::before {
    left: 0; right: 0; top: -11px; height: 12px;
    background: radial-gradient(circle at 50% 100%, #F8F3EA 10.5px, transparent 11px) center top / 26px 12px repeat-x;
}
.amt .inv-section::after { inset: 12px; border: 1px solid color-mix(in srgb, var(--amt-gold) 55%, transparent); border-radius: 2px; }

/* Kepala bagian: panggung kecil bertirai */
.amt-head { margin-bottom: 1.2rem; text-align: center; }
.amt-head__stage { display: block; width: 5.2rem; height: auto; margin: 0 auto .3rem; overflow: visible; fill: none; stroke-linecap: round; stroke-linejoin: round; }
.amt-head__line, .amt-head__floor { stroke: var(--amt-gold); stroke-width: 1; }
.amt-head__arch { fill: color-mix(in srgb, var(--amt-gold-hi) 25%, transparent); stroke: var(--amt-gold); stroke-width: 1.5; }
.amt-head__crown { stroke: var(--amt-gold); stroke-width: 1.5; }
.amt-head__curtain { fill: var(--c-accent); }
.amt-head__title { margin: 0; font: 700 clamp(2.5rem, 10.5vw, 2.95rem)/1.05 var(--f-names); word-spacing: .22em; color: var(--c-accent); }
.amt-head__lead { max-width: 24rem; margin: .5rem auto 0; color: var(--c-muted); }

/* Pembuka */
.amt .inv-bismillah { color: var(--c-accent); }
.amt-verse { margin: 0 0 1.5rem; }
.amt-verse__text { margin: 0; font: 400 1.18rem/1.7 var(--f-display); color: var(--c-ink); }
.amt-verse__source { margin-top: .6rem; font: 400 .95rem/1.3 var(--f-display); letter-spacing: .12em; color: var(--c-accent); }
.amt-lede { max-width: 25rem; margin: 0 auto; color: var(--c-muted); }

/* Mempelai: foto lonjong seperti bingkai oval di video, berlapis kertas */
.amt-couple__grid { display: grid; gap: .5rem; }
.amt-couple__amp { margin: .3rem 0; font: 400 2.6rem/1 var(--f-names); color: var(--amt-gold); }
.amt-person { display: grid; justify-items: center; }
.amt-photo {
    width: 9rem; aspect-ratio: 3 / 4.1; margin: .4rem 0 1.4rem; padding: 5px; border-radius: 50%;
    background: var(--amt-ivory);
    border: 1px solid var(--amt-gold); outline: 1px solid color-mix(in srgb, var(--amt-gold) 45%, transparent); outline-offset: 5px;
    box-shadow: 6px 7px 0 var(--amt-rose), 0 12px 24px -16px rgb(80 55 45 / .5);
}
.amt-photo img, .amt-photo__initial { width: 100%; height: 100%; object-fit: cover; border-radius: 50%; }
.amt-photo__initial { display: grid; place-items: center; background: var(--c-sunk); font: 700 5rem/1 var(--f-names); color: var(--c-accent); }
.amt-person__text { min-width: 0; overflow-wrap: break-word; }
.amt-person__name { margin: 0; font: 700 2.6rem/1.05 var(--f-names); color: var(--c-accent); }
.amt-person__family { margin: .35rem 0 0; font-size: .88rem; color: var(--c-muted); }
.amt-person__bio { max-width: 22rem; margin: .6rem auto 0; font-size: .88rem; color: var(--c-muted); }
.amt-person__ig { display: inline-block; margin-top: .6rem; color: var(--c-accent); font-size: .84rem; font-weight: 600; text-decoration: none; }

/* Hitung mundur: potongan kertas krem bertumpuk di atas kertas merah muda */
.amt-countdown { display: flex; justify-content: center; gap: .7rem; margin: 0 auto 2.2rem; }
.amt .amt-countdown .inv-countdown__cell {
    display: grid; justify-items: center; gap: .15rem; min-width: 3.5rem; padding: .7rem .2rem .55rem;
    border: 1px solid color-mix(in srgb, var(--amt-gold) 55%, transparent); border-radius: 4px; background: var(--amt-ivory);
    box-shadow: 4px 5px 0 var(--amt-rose);
}
.amt .amt-countdown b { font: 500 1.6rem/1 var(--f-display); color: var(--c-accent); }
.amt .amt-countdown span { font-size: .66rem; text-transform: none; letter-spacing: .04em; color: var(--c-muted); }

/* Acara */
.amt-events__list { display: grid; gap: 0; }
.amt-event { padding: 1.35rem 0; }
.amt-event + .amt-event { border-top: 1px solid var(--c-rule); }
.amt-event.is-past { opacity: .55; }
.amt-event__title { margin: 0 0 .2rem; font: 700 2.6rem/1.05 var(--f-names); color: var(--c-accent); }
.amt-event__date { margin: 0; font: 400 1.12rem/1.4 var(--f-display); letter-spacing: .05em; }
.amt-event__time { margin: 0; color: var(--c-muted); }
.amt-event__venue { margin: .85rem 0 0; font-weight: 600; }
.amt-event__address { margin: .1rem 0 0; font-size: .88rem; color: var(--c-muted); }
.amt-event__meta { margin: .35rem 0 0; font-size: .84rem; color: var(--c-muted); }
.amt-event__actions { display: flex; flex-wrap: wrap; justify-content: center; gap: .5rem; margin-top: 1.1rem; }
.amt-event__actions .inv-btn { flex: 1 1 8.5rem; text-align: center; }

/* Tombol */
.amt .inv-btn { border-radius: 999px; padding: .72rem 1.2rem; font: 500 .82rem/1.2 var(--f-body); letter-spacing: .02em; text-transform: none; }
.amt .inv-btn--solid { background: var(--c-accent); border-color: var(--c-accent); color: var(--amt-ivory); box-shadow: none; }
.amt .inv-btn--ghost { background: rgb(255 255 255 / .55); border-color: var(--amt-gold); color: var(--c-ink); }
.amt .inv-btn:hover { filter: none; background: var(--c-ink); border-color: var(--c-ink); color: #fff; }

/* Cerita: kuntum mawar kecil sebagai penanda */
.amt-story__list { display: grid; gap: 1.75rem; margin: 0; padding: 0; list-style: none; }
.amt-story__item { display: grid; justify-items: center; }
.amt-story__item::before {
    content: ''; width: .7rem; height: .7rem; margin-bottom: .6rem; border-radius: 50%;
    background: radial-gradient(circle at 40% 40%, #F4D2CC, var(--amt-rose) 60%);
    box-shadow: 0 0 0 3px var(--amt-sheet), 0 0 0 4px var(--amt-gold);
}
.amt-story__period { margin: 0; font: 400 .95rem/1.2 var(--f-display); letter-spacing: .14em; color: var(--c-muted); }
.amt-story__title { margin: .15rem 0 0; font: 400 1.35rem/1.3 var(--f-display); color: var(--c-ink); }
.amt-story__img { width: 100%; aspect-ratio: 4 / 3; margin-top: .75rem; object-fit: cover; border-radius: 3px; box-shadow: 0 0 0 1px var(--amt-gold), 0 0 0 5px var(--amt-ivory), 0 0 0 6px color-mix(in srgb, var(--amt-gold) 40%, transparent); }
.amt-story__text { max-width: 25rem; margin: .5rem 0 0; font-size: .9rem; color: var(--c-muted); }

/* Galeri (markup _base): foto pertama berpuncak lengkung seperti mulut panggung */
.amt .inv-gallery { display: grid; grid-template-columns: repeat(2, 1fr); gap: .45rem; }
.amt .inv-gallery__cell { padding: 0; border: 0; border-radius: 4px; aspect-ratio: 3 / 4; overflow: hidden; background: var(--c-sunk); cursor: zoom-in; }
.amt .inv-gallery__cell:first-child { grid-column: 1 / -1; width: 76%; margin: 0 auto 1.1rem; aspect-ratio: 3 / 4; border-radius: 999px 999px 4px 4px; box-shadow: 0 0 0 5px var(--amt-ivory), 0 0 0 6px color-mix(in srgb, var(--amt-gold) 60%, transparent), 9px 10px 0 4px var(--amt-rose); }
.amt .inv-gallery__cell img { width: 100%; height: 100%; object-fit: cover; }

/* Video & siaran langsung */
.amt .inv-video { padding: 0; border: 0; border-radius: 3px; overflow: hidden; background: #000; }
.amt .inv-video iframe { position: static; display: block; width: 100%; height: auto; aspect-ratio: 16 / 9; }

/* Form RSVP & ucapan (markup _base) */
.amt .inv-form { gap: 1.3rem; text-align: left; }
.amt .inv-label { font-size: .85rem; font-weight: 600; letter-spacing: 0; text-transform: none; color: var(--c-ink); }
.amt .inv-input { padding: .8rem 1rem; border: 1px solid var(--amt-gold); border-radius: .6rem; background: rgb(255 255 255 / .8); font-size: .95rem; }
.amt .inv-input:focus, .amt .inv-input:focus-visible { outline: none; border-color: var(--c-accent); box-shadow: 0 0 0 3px color-mix(in srgb, var(--c-accent) 16%, transparent); }
.amt .inv-choice { border-color: var(--amt-gold); border-radius: .6rem; background: rgb(255 255 255 / .8); }
.amt .inv-choice:has(:checked) { border-color: var(--c-accent); background: color-mix(in srgb, var(--c-accent) 7%, #fff); color: var(--c-accent); }
.amt .inv-choice input { accent-color: var(--c-accent); }
.amt .inv-form .inv-btn--solid { width: 100%; padding-block: .95rem; }
.amt .inv-tally div { border: 1px solid var(--amt-gold); border-radius: .6rem; background: rgb(255 255 255 / .75); }
.amt .inv-tally dd { font-family: var(--f-display); font-size: 1.9rem; color: var(--c-accent); }
.amt .inv-wish { padding: .95rem 1.1rem; border: 0; border-left: 2px solid var(--amt-gold); border-radius: 0 .6rem .6rem 0; background: rgb(255 255 255 / .7); text-align: left; }
.amt .inv-wish__name { font-weight: 600; color: var(--c-accent); }

/* Hadiah: kartu warna tirai, berlapis kertas krem di belakangnya */
.amt .inv-gifts { display: grid; gap: 1rem; }
.amt .inv-gift {
    position: relative; overflow: hidden; isolation: isolate; padding: 1.9rem 1.5rem; border: 0; border-radius: 4px; text-align: center; color: var(--amt-ivory);
    background: linear-gradient(160deg, color-mix(in srgb, var(--c-accent) 88%, #fff), color-mix(in srgb, var(--c-accent) 78%, #1a0c0c));
    box-shadow: inset 0 0 0 7px transparent, inset 0 0 0 8px rgb(255 240 225 / .4), inset 0 0 30px rgb(80 30 40 / .22), 7px 8px 0 #EEDFCB;
}
.amt .inv-gift::before {
    content: ''; position: absolute; z-index: -1; inset: 0;
    background:
        radial-gradient(55% 45% at 85% 10%, rgb(255 250 240 / .28), transparent 70%),
        radial-gradient(50% 40% at 10% 95%, rgb(142 165 132 / .35), transparent 70%);
}
.amt .inv-gift__logo { max-height: 1.6rem; margin-inline: auto; filter: brightness(0) invert(1); opacity: .9; }
.amt .inv-gift__label { font-size: .85rem; letter-spacing: .02em; text-transform: none; color: rgb(245 240 222 / .75); }
.amt .inv-gift__account { font: 400 1.75rem/1.3 var(--f-display); letter-spacing: .08em; color: #fff; }
.amt .inv-gift__holder, .amt .inv-gift__address { color: rgb(245 240 222 / .85); }
.amt .inv-gift .inv-btn--ghost { margin-top: 1rem; background: transparent; border-color: rgb(245 240 222 / .5); color: #fff; }
.amt .inv-gift__qr { display: block; max-width: 12rem; margin: .75rem auto 0; padding: .5rem; background: #fff; border-radius: .4rem; }

/* Penutup */
.amt .amt-closing { margin-bottom: 46vh; }
.amt-closing__text { max-width: 24rem; margin: 0 auto; color: var(--c-muted); }
.amt-closing__salutation { margin: 1.6rem 0 0; font: 400 1rem/1.3 var(--f-display); letter-spacing: .12em; color: var(--c-muted); }
.amt-closing__names { display: grid; margin: .2rem 0 0; font: 700 clamp(3.4rem, 15vw, 4rem)/1 var(--f-names); color: var(--c-accent); }
.amt-closing__names .amt-amp { font-size: .46em; line-height: 1.6; letter-spacing: .1em; }
.amt-closing__tag { margin: .8rem 0 0; font-size: .88rem; color: var(--c-muted); }

.amt .amt-footer {
    position: relative; margin: 0 -1rem; padding: 1rem; border-radius: 1rem 1rem 0 0;
    background: rgb(59 51 48 / .82); -webkit-backdrop-filter: blur(8px); backdrop-filter: blur(8px);
    color: rgb(251 244 234 / .85); font-size: .75rem; text-align: center;
}
.amt .amt-footer a { color: #fff; }

/* Musik, tombol QR, navigasi cepat */
.amt .inv-music { background: var(--c-accent); }
.amt .inv-checkin-btn { background: var(--c-accent); color: #fff; }
.amt { --qn-bg: rgb(251 244 234 / .94); --qn-fg: var(--c-muted); --qn-active: var(--c-accent); }

/* ------------------------------------------------------------ layar lebar */

@media (min-aspect-ratio: 3 / 4) {
    .amt .inv-cover.amt-cover { isolation: isolate; }
    .amt .inv-cover.amt-cover::before {
        content: ''; position: absolute; inset: -40px; z-index: -1;
        background: var(--amt-blur) center / cover; filter: blur(24px);
    }
    .amt-stage { box-shadow: 0 0 80px -10px rgb(0 0 0 / .45); }
}
@media (min-width: 900px) {
    .amt .inv-cover.amt-cover { left: 0; right: 0; width: auto; }
}

@media (prefers-reduced-motion: reduce) {
    body.amt.is-open .amt-main { animation: none; }
    .amt-cover__text, .amt-cover__foot, .amt-stage__start { transition: none; }
}

/* ------------------------------------------------- HP: bilah alamat menyusut
   Di HP, bilah alamat menutup sendiri saat digulir → tinggi layar berubah →
   latar fixed ikut berubah ukuran ("melompat"). Latar memakai tinggi layar
   TERBESAR (lvh) yang tetap, jadi tidak berubah saat bilah alamat muncul/hilang. */
.amt-backdrop { bottom: auto; height: 100vh; height: 100lvh; }