/* 更新全局样式 */
body {
    font-family: 'Orbitron', 'Microsoft YaHei', sans-serif;
    color: #e0f7ff;
    margin: 0;
    padding: 20px;
    line-height: 1.6;
    overflow-x: hidden;
    position: relative;
}

/* 粒子背景样式 */
#particles-js {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -2;
    background: radial-gradient(circle at center, #0c1445 0%, #020617 70%);
}

/* 动态星空背景 */
.stars-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
}

.stars {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: transparent;
    pointer-events: none;
}

.stars:after {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: radial-gradient(white 1px, transparent 1px);
    background-size: 100px 100px;
    background-position: 0 0;
    animation: starsMove 200s linear infinite;
}

.stars2:after {
    background-size: 150px 150px;
    animation-duration: 150s;
    opacity: 0.7;
}

.stars3:after {
    background-size: 200px 200px;
    animation-duration: 100s;
    opacity: 0.4;
}

@keyframes starsMove {
    from { background-position: 0 0; }
    to { background-position: 1000px 1000px; }
}

/* 全息投影标题效果 */
header {
    text-align: center;
    margin: 40px auto 60px;
    max-width: 800px;
    position: relative;
    padding: 30px 20px;
    border-radius: 16px;
    background: rgba(10, 20, 50, 0.4);
    box-shadow: 0 0 30px rgba(0, 100, 255, 0.3);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(64, 156, 255, 0.3);
    overflow: hidden;
}

header:before {
    content: "";
    position: absolute;
    top: 0;
    left: -100%;
    width: 200%;
    height: 100%;
    background: linear-gradient(90deg, 
        transparent, 
        rgba(64, 156, 255, 0.2), 
        transparent);
    animation: shine 3s infinite linear;
}

@keyframes shine {
    0% { left: -100%; }
    100% { left: 100%; }
}

.holographic-text {
    font-size: 2.8em;
    background: linear-gradient(90deg, #00f2ff, #5d7fff, #ff4dff);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    text-shadow: 0 0 15px rgba(93, 127, 255, 0.7);
    position: relative;
    z-index: 2;
    margin: 20px 0;
    letter-spacing: 2px;
    animation: hologramPulse 3s infinite alternate;
}

@keyframes hologramPulse {
    0% { text-shadow: 0 0 10px rgba(93, 127, 255, 0.5); }
    100% { text-shadow: 0 0 25px rgba(93, 127, 255, 0.9), 
                        0 0 40px rgba(93, 127, 255, 0.6); }
}

.scan-line {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, 
        transparent, 
        rgba(0, 247, 255, 0.8), 
        transparent);
    animation: scan 4s infinite linear;
    box-shadow: 0 0 10px rgba(0, 247, 255, 0.5);
    z-index: 1;
}

@keyframes scan {
    0% { top: 0; }
    50% { top: 100%; }
    100% { top: 100%; }
}

.tech-grid {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        linear-gradient(rgba(64, 156, 255, 0.1) 1px, transparent 1px),
        linear-gradient(90deg, rgba(64, 156, 255, 0.1) 1px, transparent 1px);
    background-size: 40px 40px;
    z-index: 0;
    pointer-events: none;
}

/* 更新主内容区样式 */
main {
    max-width: 1200px;
    margin: 0 auto 50px;
    background: rgba(10, 25, 60, 0.6);
    padding: 40px;
    border-radius: 20px;
    box-shadow: 0 10px 40px rgba(0, 60, 255, 0.2);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(64, 156, 255, 0.3);
    position: relative;
    overflow: hidden;
}

main:before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 5px;
    background: linear-gradient(90deg, #00f2ff, #5d7fff, #ff4dff);
    box-shadow: 0 0 15px rgba(93, 127, 255, 0.5);
}

h2 {
    color: #5d7fff;
    border-bottom: 2px solid rgba(93, 127, 255, 0.5);
    padding-bottom: 15px;
    margin-bottom: 30px;
    text-shadow: 0 0 10px rgba(93, 127, 255, 0.3);
    font-size: 1.8em;
}

h3 {
    color: #00f2ff;
    font-size: 1.4em;
}

/* 更新课程介绍卡片样式 */
.course-intro .intro-columns {
    display: flex;
    justify-content: space-between;
    gap: 40px;
}

.course-intro .column {
    flex: 1;
    background: rgba(15, 35, 80, 0.5);
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 8px 25px rgba(0, 30, 100, 0.4);
    border: 1px solid rgba(64, 156, 255, 0.2);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.course-intro .column:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 30px rgba(0, 100, 255, 0.5);
}

details {
    margin-bottom: 15px;
    border: 1px solid rgba(64, 156, 255, 0.3);
    border-radius: 10px;
    padding: 15px;
    background: rgba(20, 45, 100, 0.3);
    transition: all 0.3s ease;
}

details:hover {
    border-color: rgba(0, 242, 255, 0.5);
    box-shadow: 0 0 15px rgba(0, 242, 255, 0.2);
}

summary {
    cursor: pointer;
    font-weight: bold;
    color: #5d7fff;
    outline: none;
    font-size: 1.1em;
    padding: 8px 0;
    position: relative;
}

summary:after {
    content: "+";
    position: absolute;
    right: 0;
    transition: transform 0.3s ease;
    font-size: 1.2em;
    color: #00f2ff;
}

details[open] summary:after {
    transform: rotate(45deg);
}

summary:hover {
    color: #00f2ff;
}

details[open] {
    background: rgba(10, 30, 70, 0.5);
    border-color: rgba(0, 242, 255, 0.5);
}

details p {
    margin-top: 15px;
    color: #cce6ff;
    padding-left: 10px;
    border-left: 2px solid rgba(0, 242, 255, 0.5);
}

/* 更新学生风采展示样式 */
.student-showcase {
    margin-top: 60px;
    text-align: center;
    position: relative;
    padding-top: 40px;
}

.student-showcase:before {
    content: "";
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80%;
    height: 2px;
    background: linear-gradient(90deg, transparent, #00f2ff, #5d7fff, transparent);
    box-shadow: 0 0 10px rgba(0, 242, 255, 0.5);
}

.student-showcase .tip {
    color: #8ab3ff;
    font-style: italic;
    margin-bottom: 30px;
    text-shadow: 0 0 5px rgba(138, 179, 255, 0.3);
}

.avatar-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: 30px;
    margin-top: 30px;
}

.avatar {
    cursor: pointer;
    text-align: center;
    transition: transform 0.4s ease;
    position: relative;
    perspective: 1000px;
}

.avatar .avatar-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    transition: transform 0.6s;
}

.avatar:hover .avatar-inner {
    transform: rotateY(180deg);
}

.avatar img {
    width: 100px;
    height: 100px;
    border-radius: 50%;
    border: 2px solid #5d7fff;
    box-shadow: 0 0 20px rgba(93, 127, 255, 0.4);
    object-fit: cover;
    background: linear-gradient(45deg, #1a2a6c, #b21f1f, #2575fc);
    backface-visibility: hidden;
}

.avatar .avatar-back {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100px;
    border-radius: 50%;
    background: linear-gradient(45deg, #00f2ff, #5d7fff);
    backface-visibility: hidden;
    transform: rotateY(180deg);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 0 25px rgba(93, 127, 255, 0.6);
}

.avatar .avatar-back span {
    color: white;
    font-weight: bold;
    font-size: 0.9em;
    text-shadow: 0 0 5px rgba(0,0,0,0.5);
    padding: 5px;
}

.avatar span {
    display: block;
    margin-top: 15px;
    font-weight: bold;
    color: #cce6ff;
    transition: color 0.3s ease;
    text-shadow: 0 0 5px rgba(0,0,0,0.3);
}

.avatar:hover span {
    color: #00f2ff;
    text-shadow: 0 0 10px rgba(0, 242, 255, 0.5);
}

/* 更新信封弹窗样式 */
.envelope-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.4s ease, visibility 0.4s ease;
}

.envelope-modal.visible {
    opacity: 1;
    visibility: visible;
}

.envelope {
    position: relative;
    width: 90%;
    max-width: 600px;
    height: 80vh;
    max-height: 800px;
    background: linear-gradient(135deg, #1a2a6c, #3a7bd5);
    border-radius: 15px;
    box-shadow: 0 15px 50px rgba(0, 100, 255, 0.6);
    /* 移除transform动画属性 */
}

/* 添加信封打开动画 */
@keyframes envelopeOpen {
    0% {
        transform: scale(0.5) rotateX(-90deg);
        opacity: 0;
    }
    100% {
        transform: scale(1) rotateX(0deg);
        opacity: 1;
    }
}

.envelope-modal.visible .envelope {
    animation: envelopeOpen 0.6s cubic-bezier(0.68, -0.55, 0.27, 1.55) forwards;
}

/* 确保信封内容可见 */
.letter {
    position: relative;
    background: linear-gradient(to bottom, #0c1e4a, #162b5b);
    margin: 0 auto;
    width: 95%;
    height: 90%;
    top: 5%;
    border-radius: 10px;
    padding: 20px;
    box-shadow: 0 0 20px rgba(0, 100, 255, 0.3) inset;
    overflow-y: auto;
    z-index: 2; /* 确保在最上层 */
    scrollbar-width: thin;
    scrollbar-color: #5d7fff #162b5b;
}

.letter::-webkit-scrollbar {
    width: 8px;
}

.letter::-webkit-scrollbar-track {
    background: #162b5b;
    border-radius: 4px;
}

.letter::-webkit-scrollbar-thumb {
    background: #5d7fff;
    border-radius: 4px;
    border: 2px solid #162b5b;
}

.letter::-webkit-scrollbar-thumb:hover {
    background: #00f2ff;
}

#student-name {
    color: #00f2ff;
    text-shadow: 0 0 10px rgba(0, 242, 255, 0.5);
    font-size: 1.8em;
    text-align: center;
    margin-bottom: 20px;
}

#student-comment {
    color: #cce6ff;
    line-height: 1.8;
    font-size: 1.1em;
    text-shadow: 0 0 5px rgba(0,0,0,0.3);
}

.student-image-placeholder {
    background: linear-gradient(45deg, #0f2027, #203a43, #2c5364);
    border: 1px solid rgba(64, 156, 255, 0.5);
    box-shadow: 0 0 15px rgba(64, 156, 255, 0.3);
}

.close-btn {
    color: #00f2ff;
    font-size: 32px;
    text-shadow: 0 0 10px rgba(0, 242, 255, 0.5);
}

.close-btn:hover {
    color: #ff4dff;
    text-shadow: 0 0 15px rgba(255, 77, 255, 0.8);
}

/* 添加高科技加载动画 */
@keyframes float {
    0% { transform: translateY(0px); }
    50% { transform: translateY(-15px); }
    100% { transform: translateY(0px); }
}

/* 响应式设计 */
@media (max-width: 768px) {
    .course-intro .intro-columns {
        flex-direction: column;
        gap: 30px;
    }
    
    .avatar-grid {
        grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
        gap: 20px;
    }
    
    .holographic-text {
        font-size: 2em;
    }
}