.page-404 {
    padding: 60px 0;
    min-height: calc(100vh - var(--nav-h, 0px) - var(--footer-h, 0px));
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
    background:
        radial-gradient(ellipse at 0% 0%, color-mix(in srgb, var(--red-accent) 14%, transparent) 0%, transparent 50%),
        radial-gradient(ellipse at 100% 100%, color-mix(in srgb, var(--red-accent) 10%, transparent) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 50%, rgba(30, 30, 30, 0.5) 0%, transparent 70%),
        var(--bg-dark);
}

.page-404::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.03'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    pointer-events: none;
    z-index: 0;
}

.page-404::after {
    content: '';
    position: absolute;
    inset: -80px;
    background: url('../images/logo.png') center / 760px auto no-repeat;
    filter: blur(10px);
    opacity: 0.28;
    transform: translateZ(0);
    pointer-events: none;
    z-index: 0;
}

.page-404 > .container {
    position: relative;
    z-index: 1;
}

.page-404 .container,
.page-404 .row,
.page-404 [class^="col-"],
.page-404 [class*=" col-"] {
    background: transparent !important;
}

body.theme-forum .page-404 .card.card-404 {
    background: rgba(0, 0, 0, 0.08) !important;
    border: 1px solid rgba(255, 255, 255, 0.10) !important;
    box-shadow: 0 18px 50px rgba(0, 0, 0, 0.30);
    backdrop-filter: blur(2px);
    -webkit-backdrop-filter: blur(2px);
}

body.theme-forum .page-404 .card.card-404 .card-body {
    background: rgba(0, 0, 0, 0.04) !important;
    border: 1px solid rgba(255, 255, 255, 0.06) !important;
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
}
.card-body {
    padding: 36px 28px;
}

.error-code {
    font-size: clamp(4.5rem, 10vw, 7.5rem);
    line-height: 1;
    font-weight: 800;
    letter-spacing: 0.02em;
    margin-bottom: 12px;
    background: linear-gradient(135deg, var(--red-accent), var(--red-primary));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.error-title {
    color: var(--text-primary);
    font-weight: 700;
    margin-bottom: 8px;
}

.error-subtitle {
    color: var(--text-secondary);
    font-size: 1.05rem;
    margin-bottom: 22px;
}

.error-actions {
    display: flex;
    gap: 12px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 18px;
}

.error-actions .btn {
    min-width: 210px;
}

.error-meta {
    border-top: 1px solid rgba(255, 255, 255, 0.06);
    padding-top: 14px;
    margin-top: 16px;
}

.meta-item {
    display: flex;
    justify-content: center;
    gap: 8px;
    flex-wrap: wrap;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.meta-label {
    opacity: 0.85;
}

.meta-value {
    color: var(--text-primary);
    font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
    word-break: break-all;
}

.help-links {
    margin-top: 14px;
    display: flex;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
}

.help-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 14px;
    text-decoration: none;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.06);
    color: var(--text-secondary);
    transition: all 0.2s ease;
}

.help-link:hover {
    color: var(--text-primary);
    border-color: color-mix(in srgb, var(--red-accent) 35%, transparent);
    transform: translateY(-1px);
}

@media (max-width: 576px) {
    .page-404 {
        padding: 40px 0;
    }

    .page-404::after {
        background-size: 380px auto;
        opacity: 0.2;
    }

    .card-404 .card-body {
        padding: 28px 18px;
    }

    .error-actions .btn {
        width: 100%;
        min-width: 0;
    }
}