/* 新增下划线效果 */
a.active {
    color: #4a6bff; /* 选中状态文字颜色 */
}

a.active::after {
    content: '';
    position: absolute;
    bottom: -5px; /* 调整下划线位置 */
    left: 0;
    width: 100%;
    height: 3px;
    background-color: #4a6bff;
    border-radius: 3px;
    animation: underline 0.3s ease-out;
}

@keyframes underline {
    from {
        transform: scaleX(0);
    }
    to {
        transform: scaleX(1);
    }
}

.fdl-container {
    position: fixed;
    top: 10rem;
    left: 40rem;
    perspective: 1000px;
    z-index: 999;
}

.fdl-main {
    position: relative;
    display: inline-block;
    padding: 15px 25px;
    font-family: 'Segoe UI', system-ui, sans-serif;
    font-size: clamp(14px, 2vw, 18px);
    font-weight: 600;
    color: #333;
    text-decoration: none;
    border-radius: 8px;
    background: linear-gradient(145deg, #87CEEB, #1046d0);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    transform-style: preserve-3d;
    transition: all 0.3s cubic-bezier(0.23, 1, 0.32, 1);
    overflow: hidden;
    z-index: 1;
    border: 1px solid rgba(0, 0, 0, 0.1);
}

.fdl-main::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.7), transparent);
    transition: all 0.6s ease;
    z-index: -1;
}

.fdl-main:hover {
    transform: translateY(-3px) rotateX(8deg);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
    color: #222;
}

.fdl-main:hover::before {
    left: 100%;
}

.fdl-wave {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    background: url('data:image/svg+xml;utf8,<svg viewBox="0 0 1200 120" xmlns="http://www.w3.org/2000/svg" preserveAspectRatio="none"><path d="M0,0V46.29c47.79,22.2,103.59,32.17,158,28,70.36-5.37,136.33-33.31,206.8-37.5C438.64,32.43,512.34,53.67,583,72.05c69.27,18,138.3,24.88,209.4,13.08,36.15-6,69.85-17.84,104.45-29.34C989.49,25,1113-14.29,1200,52.47V0Z" fill="rgba(100,100,100,0.2)"/></svg>');
    background-repeat: repeat-x;
    background-size: 1200px 80px;
    animation: fdl-wave-anim 8s linear infinite;
    opacity: 0.7;
    z-index: -1;
}

@keyframes fdl-wave-anim {
    0% { background-position-x: 0; }
    100% { background-position-x: 1200px; }
}

.fdl-particles {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
}

.fdl-particle {
    position: absolute;
    background: rgba(80, 80, 80, 0.6);
    border-radius: 50%;
    pointer-events: none;
    animation: fdl-float 4s infinite ease-in-out;
    box-shadow: 0 0 3px rgba(255,255,255,0.8);
}

@keyframes fdl-float {
    0%, 100% { transform: translateY(0) rotate(0deg); opacity: 0.6; }
    50% { transform: translateY(-10px) rotate(180deg); opacity: 1; }
}

.fdl-highlight {
    color: #fafafa;
    font-weight: 700;
}

.fdl-arrow {
    margin-left: 6px;
    transition: all 0.3s ease;
    display: inline-block;
    color: #fafafa;
}

@media (max-width: 768px) {
    .fdl-container {
        top: 9rem;
        left: 15rem;
    }
    
    .fdl-main {
        padding: 12px 20px;
        font-size: 14px;
    }
}

@media (max-width: 480px) {
    .fdl-container {
        top: 9rem;
        left: 7rem;
    }
    
    .fdl-main {
        padding: 10px 16px;
        font-size: 13px;
    }
}