.error404 {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    background:
        radial-gradient(circle at top, rgba(0, 174, 204, 0.08), transparent 35%),
        var(--bg);
}

.error404_content {
    max-width: 620px;
    text-align: center;
    animation: fadeInUp .5s ease;
}

.error404_code {
    display: block;
    font-size: clamp(6rem, 18vw, 12rem);
    font-weight: 800;
    line-height: 1;
    color: var(--navy);
    opacity: .15;
    letter-spacing: -6px;
    margin-bottom: 1rem;
}

.error404_title {
    font-size: clamp(2rem, 4vw, 3rem);
    color: var(--text);
    margin-bottom: 1rem;
}

.error404_text {
    color: var(--text-mid);
    font-size: 1.05rem;
    line-height: 1.8;
    margin-bottom: 2rem;
}

.error404_tips {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.4rem;
    text-align: left;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.error404_tips p {
    font-weight: 600;
    color: var(--text);
    margin-bottom: .8rem;
}

.error404_tips ul {
    padding-left: 1.2rem;
}

.error404_tips li {
    color: var(--text-mid);
    margin-bottom: .6rem;
    line-height: 1.6;
}