html,
body {
        margin: 0;
        padding: 0;
        background: #000;
}

body {
        padding-bottom: calc(var(--btn-height, 120px) + 32px + env(safe-area-inset-bottom));
}

.layout {
        position: relative;
        max-width: 750px;
        margin: 0 auto;
}

.bg {
        display: block;
        width: 100%;
        height: auto;
}

.button-spacer {
        height: calc(var(--btn-height, 64px) + 32px + env(safe-area-inset-bottom));
}

.button-container {
        position: fixed;
        bottom: calc(16px + env(safe-area-inset-bottom));
        left: 50%;
        transform: translateX(-50%);
        width: 100%;
        max-width: 512px;
        display: flex;
        flex-direction: column;
        align-items: center;
        gap: 18px;
        padding: 0 12px;
        z-index: 1000;
}

.button-container a {
        display: block;
        border: none;
        outline: none;
        box-shadow: none;
        -webkit-tap-highlight-color: transparent;
}

.button-container a:focus,
.button-container a:active,
.button-container a:focus-visible {
        border: none;
        outline: none;
        box-shadow: none;
}

.button-container img {
        width: min(512px, calc(100vw - 64px));
        max-width: none;
        cursor: pointer;
        animation: button-breathe 3.2s cubic-bezier(0.4, 0, 0.2, 1) infinite;
        transition: transform 0.2s ease, filter 0.2s ease;
        transform-origin: center;
        will-change: transform, filter;
}

@keyframes button-breathe {
        0%,
        100% {
                transform: scale(1);
                filter: brightness(1) drop-shadow(0 0 0 rgba(255, 180, 0, 0));
        }

        50% {
                transform: scale(1.06);
                filter: brightness(1.08) drop-shadow(0 10px 24px rgba(255, 180, 0, 0.35));
        }
}

@media (prefers-reduced-motion: reduce) {
        .button-container img {
                animation: none;
        }
}