* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Arial', sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    overflow-y: auto;
    padding: 20px 0;
    position: relative;
}

/* 遮罩层样式 */
.mask {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: #000;
    z-index: 100;
    animation: maskFadeOut 3s ease-in-out forwards;
}

/* 遮罩层动画 */
@keyframes maskFadeOut {
    0% {
        opacity: 1;
        transform: scale(1);
    }
    50% {
        opacity: 0.5;
        transform: scale(1.1);
    }
    70% {
        opacity: 0.3;
        transform: scale(1.3);
    }
    100% {
        opacity: 0;
        transform: scale(2);
        visibility: hidden;
    }
}

.container {
    position: relative;
    text-align: center;
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 20px 0;
}

.envelope {
    position: relative;
    width: 380px;
    height: 260px;
    cursor: pointer;
    transform-style: preserve-3d;
    transition: all 0.3s ease;
    opacity: 0;
    z-index: 5;
    filter: drop-shadow(0 10px 30px rgba(0, 0, 0, 0.15));
}

.envelope:hover {
    transform: scale(1.03) translateY(-5px);
    transition: all 0.3s ease;
    filter: drop-shadow(0 15px 40px rgba(0, 0, 0, 0.2));
}

.envelope.clicked {
    transform: scale(0.97);
    transition: all 0.1s ease;
}

.letter {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%) translateY(0) scale(0.4);
    width: 800px;
    height: auto;
    min-height: 800px;
    background: linear-gradient(135deg, #ffffff 0%, #f8f8f8 100%);
    padding: 40px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    z-index: 2;
    transition: all 1.8s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    overflow: hidden;
    opacity: 0.95;
    border-radius: 6px;
    visibility: hidden;
    max-width: 90%;
}

.envelope-front {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #e8e8e8 0%, #d4d4d4 100%);
    clip-path: polygon(0 0, 100% 0, 100% 100%, 50% 70%, 0 100%);
    z-index: 3;
    transition: all 1.2s ease;
    border-radius: 8px;
}

.envelope-front::before {
    content: '';
    position: absolute;
    top: 10px;
    left: 10px;
    right: 10px;
    bottom: 10px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 4px;
    pointer-events: none;
}

.envelope-front::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 80px;
    height: 80px;
    border: 3px solid rgba(255, 255, 255, 0.4);
    border-radius: 50%;
    pointer-events: none;
}

.envelope-flower {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 60px;
    height: 60px;
    z-index: 6;
    pointer-events: none;
}

.envelope-flower::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 20px;
    height: 20px;
    background: radial-gradient(circle, #ff6b6b 0%, #ee5a5a 100%);
    border-radius: 50%;
    box-shadow: 0 2px 8px rgba(238, 90, 90, 0.4);
}

.envelope-flower .petal {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 18px;
    height: 40px;
    background: linear-gradient(135deg, #ff8a8a 0%, #ff6b6b 100%);
    border-radius: 50% 50% 50% 50%;
    box-shadow: 0 1px 4px rgba(238, 90, 90, 0.3);
}

.envelope-flower .petal:nth-child(1) {
    transform: translate(-50%, -50%) rotate(0deg);
}

.envelope-flower .petal:nth-child(2) {
    transform: translate(-50%, -50%) rotate(72deg);
}

.envelope-flower .petal:nth-child(3) {
    transform: translate(-50%, -50%) rotate(144deg);
}

.envelope-flower .petal:nth-child(4) {
    transform: translate(-50%, -50%) rotate(216deg);
}

.envelope-flower .petal:nth-child(5) {
    transform: translate(-50%, -50%) rotate(288deg);
}

.envelope-back {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #f0f0f0 0%, #e0e0e0 100%);
    z-index: 1;
    transition: all 1.5s ease;
    border-radius: 8px;
}

.envelope-flap {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 50%;
    background: linear-gradient(135deg, #dcdcdc 0%, #c8c8c8 100%);
    clip-path: polygon(0 0, 50% 100%, 100% 0);
    z-index: 4;
    transition: all 1s ease;
    border-radius: 8px 8px 0 0;
}

.letter-content {
    text-align: left;
    line-height: 1.5;
    color: #333;
    transition: all 1.5s ease;
    font-family: 'Noto Serif SC', serif;
    letter-spacing: 0.3px;
}

.letter-content h1 {
    margin-bottom: 25px;
    color: #2c3e50;
    font-weight: 500;
    font-style: normal;
    /* text-align: center; */
    font-size: 22px;
    letter-spacing: 2px;
}

.letter-content p {
    margin-bottom: 16px;
    text-indent: 2em;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    padding-bottom: 8px;
    color: #555;
    font-size: 15px;
}

/* 动画效果 */
.envelope.open {
    opacity: 0;
    visibility: hidden;
    height: 0;
    width: 0;
    transition: all 1.5s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.envelope.open .envelope-flap {
    transform: rotateX(-180deg) translateY(-50%);
    opacity: 0;
    transition: all 1s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.envelope.open .envelope-front {
    transform: rotateX(-180deg) scale(0.8);
    opacity: 0;
    transition: all 1.2s cubic-bezier(0.25, 0.46, 0.45, 0.94) 0.2s;
}

.envelope.open .envelope-back {
    opacity: 0;
    transform: scale(0.8);
    transition: all 1.5s cubic-bezier(0.25, 0.46, 0.45, 0.94) 0.3s;
}

.letter.show {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translateX(-50%) translateY(-50%) scale(1);
    height: auto;
    min-height: 800px;
    width: 800px;
    max-width: 90%;
    padding: 40px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
    z-index: 10;
    opacity: 1;
    visibility: visible;
    transition: all 1.8s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    overflow-y: auto;
    max-height: 90vh;
}

.letter.show .letter-content {
    transform: translateY(0);
    opacity: 1;
    transition: all 1.5s ease-in-out 0.3s;
}

/* 不给看内容样式 */
.no-content {
    text-align: center;
    padding: 100px 20px;
    font-size: 24px;
    color: #666;
    font-weight: 500;
    display: none;
    transition: all 1.5s ease-in-out 0.3s;
}

.letter.show .no-content {
    transform: translateY(0);
    opacity: 1;
    transition: all 1.5s ease-in-out 0.3s;
}





/* 响应式设计 */
@media (max-width: 480px) {
    .envelope {
        width: 320px;
        height: 210px;
    }
    
    .letter {
        width: 290px;
        height: 190px;
        padding: 15px;
    }
    
    .letter.show {
        width: 360px;
        padding: 14px;
        transform: translateX(-50%) translateY(-50%);
    }
    
    .letter-content h1 {
        font-size: 18px;
        margin-bottom: 15px;
    }
    
    .letter-content p {
        font-size: 14px;
        margin-bottom: 10px;
    }
}

/* iPhone 15 Pro 适配 */
@media (max-width: 393px) {
    .envelope {
        width: 300px;
        height: 200px;
    }
    
    .letter {
        width: 270px;
        height: 175px;
        padding: 12px;
    }
    
    .letter.show {
        width: 290px;
        padding: 18px;
        transform: translateX(-50%) translateY(-50%);
    }
    
    .letter-content h1 {
        font-size: 16px;
        margin-bottom: 12px;
    }
    
    .letter-content p {
        font-size: 13px;
        margin-bottom: 8px;
    }
}

/* 备案号样式 */
.footer {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    text-align: center;
    padding: 15px 0;
    z-index: 1000;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
}

.footer p {
    margin: 0;
    font-size: 12px;
    color: #666;
}

.footer a {
    color: #666;
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer a:hover {
    color: #333;
    text-decoration: underline;
}