* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, Roboto, sans-serif;
}

html, body {
    width: 100%;
    overflow-x: hidden;
    background: linear-gradient(135deg, #0f0c29 0%, #302b63 50%, #24243e 100%);
    background-attachment: fixed;
    color: #e0e0e0;
    scroll-behavior: smooth;
    -ms-overflow-style: none;
    scrollbar-width: none;
    font-size: 16px;
    line-height: 1.6;
}

html::-webkit-scrollbar {
    width: 0;
    height: 0;
    display: none;
}

a {
    text-decoration: none;
    color: inherit;
}

.loading {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #0f0c29 0%, #302b63 50%, #24243e 100%);
    z-index: 1000;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: opacity 0.8s ease, visibility 0.8s ease;
}

.loading.hidden {
    opacity: 0;
    visibility: hidden;
}

.loading-content {
    text-align: center;
    position: relative;
}

.loading-spinner {
    width: 120px;
    height: 120px;
    position: relative;
    margin: 0 auto 30px;
}

.spinner-ring {
    position: absolute;
    width: 100%;
    height: 100%;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: #00d4ff;
    animation: spin 1.5s linear infinite;
}

.spinner-ring:nth-child(1) {
    border-top-color: #00d4ff;
    animation-delay: 0s;
}

.spinner-ring:nth-child(2) {
    width: 80%;
    height: 80%;
    top: 10%;
    left: 10%;
    border-top-color: #7b2cbf;
    animation-delay: 0.2s;
    animation-direction: reverse;
}

.spinner-ring:nth-child(3) {
    width: 60%;
    height: 60%;
    top: 20%;
    left: 20%;
    border-top-color: #f72585;
    animation-delay: 0.4s;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loading-content h2 {
    color: #fff;
    font-size: 1.5rem;
    font-weight: 300;
    letter-spacing: 3px;
    text-transform: uppercase;
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 0.6; }
    50% { opacity: 1; }
}

#menu-box {
    position: fixed;
    width: 100%;
    height: 80px;
    background: rgba(15, 12, 41, 0.6);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    z-index: 100;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    justify-content: center;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

#menu-box.scrolled {
    background: rgba(15, 12, 41, 0.9);
    backdrop-filter: blur(40px);
    -webkit-backdrop-filter: blur(40px);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
    border-bottom: 1px solid rgba(0, 212, 255, 0.2);
}

.menu {
    width: 100%;
    max-width: 1400px;
    padding: 0 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.logo h2 {
    color: #fff;
    font-size: 28px;
    transition: all 0.3s ease;
    font-weight: 600;
    letter-spacing: 1px;
    text-shadow: 0 0 20px rgba(0, 212, 255, 0.5);
}

.logo h2:hover {
    color: #00d4ff;
    text-shadow: 0 0 30px rgba(0, 212, 255, 0.8);
}

.nav-links {
    display: flex;
    gap: 8px;
}

.nav-links a {
    color: rgba(255, 255, 255, 0.85);
    padding: 12px 24px;
    transition: all 0.3s ease;
    font-size: 15px;
    font-weight: 500;
    position: relative;
    overflow: hidden;
    border: 1px solid transparent;
}

.nav-links a::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(0, 212, 255, 0.15), rgba(123, 44, 191, 0.15));
    opacity: 0;
    transition: opacity 0.3s ease;
    z-index: -1;
}

.nav-links a:hover {
    color: #00d4ff;
    border-color: rgba(0, 212, 255, 0.3);
    background: rgba(0, 212, 255, 0.05);
}

.nav-links a:hover::before {
    opacity: 1;
}

#menu-box.scrolled .logo h2 {
    color: #fff;
}

#menu-box.scrolled .nav-links a {
    color: rgba(255, 255, 255, 0.85);
}

#content {
    padding: 120px 0 80px;
    position: relative;
    min-height: 100vh;
}

#content::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 30% 30%, rgba(0, 212, 255, 0.05) 0%, transparent 50%),
                radial-gradient(circle at 70% 70%, rgba(123, 44, 191, 0.05) 0%, transparent 50%);
    pointer-events: none;
}

.content-box {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 40px;
    position: relative;
    z-index: 1;
}

.content-box h2 {
    font-size: 2.8rem;
    color: #fff;
    margin-bottom: 50px;
    position: relative;
    padding-bottom: 20px;
    font-weight: 700;
    letter-spacing: -0.5px;
    text-align: center;
}

.content-box h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 120px;
    height: 3px;
    background: linear-gradient(90deg, #00d4ff 0%, #7b2cbf 50%, #f72585 100%);
    border-radius: 2px;
}

.search-container {
    margin: 40px 0;
    text-align: center;
}

#search {
    width: 100%;
    max-width: 600px;
    padding: 18px 30px;
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 50px;
    font-size: 1.1rem;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(20px);
    color: #fff;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}

#search::placeholder {
    color: rgba(255, 255, 255, 0.5);
}

#search:focus {
    outline: none;
    border-color: rgba(0, 212, 255, 0.5);
    box-shadow: 0 8px 32px rgba(0, 212, 255, 0.3);
    background: rgba(255, 255, 255, 0.08);
    transform: translateY(-2px);
}

#problem-list {
    list-style: none;
    padding: 0;
}

#problem-list li {
    background: rgba(255, 255, 255, 0.03);
    backdrop-filter: blur(30px);
    border: 1px solid rgba(255, 255, 255, 0.08);
    margin: 20px 0;
    padding: 30px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

#problem-list li::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, #00d4ff 0%, #7b2cbf 50%, #f72585 100%);
}

#problem-list li:hover {
    transform: translateY(-8px);
    box-shadow: 0 16px 48px rgba(0, 212, 255, 0.2);
    border-color: rgba(0, 212, 255, 0.3);
    background: rgba(255, 255, 255, 0.05);
}

#problem-list .problem-title {
    color: #00d4ff;
    font-weight: 600;
    font-size: 1.4rem;
    display: block;
    margin-bottom: 15px;
    cursor: default;
    text-shadow: 0 0 20px rgba(0, 212, 255, 0.3);
}

#problem-list .problem-title:hover {
    color: #7b2cbf;
    text-shadow: 0 0 20px rgba(123, 44, 191, 0.5);
}

#problem-list small {
    color: rgba(255, 255, 255, 0.7);
    display: block;
    margin-bottom: 15px;
    font-size: 1rem;
    line-height: 1.7;
}

#problem-list mark {
    background: rgba(0, 212, 255, 0.15);
    color: #00d4ff;
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.85rem;
    margin-right: 8px;
    margin-bottom: 8px;
    display: inline-block;
    border: 1px solid rgba(0, 212, 255, 0.2);
    transition: all 0.3s ease;
}

#problem-list mark:hover {
    background: rgba(0, 212, 255, 0.25);
    border-color: rgba(0, 212, 255, 0.4);
    transform: translateY(-2px);
}

#footer {
    background: rgba(15, 12, 41, 0.9);
    backdrop-filter: blur(30px);
    color: #e0e0e0;
    padding: 80px 0 50px;
    position: relative;
    overflow: hidden;
}

#footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: linear-gradient(90deg, #00d4ff 0%, #7b2cbf 50%, #f72585 100%);
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 40px;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    position: relative;
    z-index: 1;
}

.footer-section {
    flex: 1;
    min-width: 300px;
    margin-bottom: 50px;
    padding: 0 25px;
}

.footer-section h3 {
    font-size: 1.4rem;
    margin-bottom: 30px;
    color: #fff;
    position: relative;
    padding-bottom: 15px;
    font-weight: 600;
}

.footer-section h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 70px;
    height: 3px;
    background: linear-gradient(90deg, #00d4ff 0%, #7b2cbf 100%);
    border-radius: 2px;
}

.footer-section p {
    line-height: 1.8;
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 25px;
}

.footer-links {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.footer-links a {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 0;
    transition: all 0.3s ease;
    color: rgba(255, 255, 255, 0.7);
    font-weight: 400;
}

.footer-links a:hover {
    color: #00d4ff;
    transform: translateX(10px);
}

.footer-links a i {
    font-size: 16px;
    transition: all 0.3s ease;
}

.footer-links a:hover i {
    color: #00d4ff;
    transform: scale(1.1);
}

.footer-bottom {
    text-align: center;
    padding-top: 40px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    margin-top: 40px;
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.5);
    position: relative;
    z-index: 1;
}

.footer-bottom a {
    color: #00d4ff;
    transition: all 0.3s ease;
    font-weight: 500;
}

.footer-bottom a:hover {
    text-shadow: 0 0 20px rgba(0, 212, 255, 0.5);
    color: #7b2cbf;
}

#musicControl {
    position: fixed;
    bottom: 30px;
    right: 30px;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.08);
    backdrop-filter: blur(20px);
    padding: 15px;
    cursor: pointer;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    transition: all 0.3s ease;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

#musicControl:hover {
    transform: scale(1.1);
    background: rgba(0, 212, 255, 0.2);
    border-color: rgba(0, 212, 255, 0.4);
    box-shadow: 0 12px 40px rgba(0, 212, 255, 0.4);
}

#musicControl:active {
    transform: scale(0.95);
}

#musicIcon {
    width: 32px;
    height: 32px;
    opacity: 0.9;
    display: block;
}

@media (max-width: 900px) {
    .content-box {
        padding: 0 20px;
    }
    
    .footer-content {
        padding: 0 20px;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .menu {
        justify-content: center;
    }
    
    .footer-section {
        min-width: 100%;
        padding: 0 15px;
    }
    
    .content-box h2 {
        font-size: 2.2rem;
    }
    
    #search {
        padding: 15px 25px;
        font-size: 1rem;
    }
    
    #problem-list li {
        padding: 25px 20px;
    }
    
    #problem-list .problem-title {
        font-size: 1.2rem;
    }
    
    #menu-box {
        height: 70px;
    }
    
    .menu {
        padding: 0 20px;
    }
}

@media (max-width: 480px) {
    .content-box h2 {
        font-size: 1.8rem;
    }
    
    #problem-list li {
        padding: 20px 15px;
    }
    
    #problem-list .problem-title {
        font-size: 1.1rem;
    }
    
    #problem-list small {
        font-size: 0.9rem;
    }
    
    .footer-content {
        padding: 0 15px;
    }
    
    .footer-section h3 {
        font-size: 1.2rem;
    }
    
    .logo h2 {
        font-size: 22px;
    }
    
    .content-box {
        padding: 0 15px;
    }
}