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

body {
    font-family: 'PingFang SC', 'Helvetica Neue', Arial, sans-serif;
    overflow: hidden;
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    color: #333;
    position: relative;
    background-color: #f8f9fa;
}

.dynamic-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    background: linear-gradient(135deg, #e0f7fa 0%, #80deea 50%, #4fc3f7 100%);
    background-size: 200% 200%;
    animation: gradientBG 12s ease infinite;
    opacity: 0.9;
}

@keyframes gradientBG {
    0% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
    100% {
        background-position: 0% 50%;
    }
}

.bubbles {
    position: absolute;
    width: 100%;
    height: 100%;
    z-index: 1;
    overflow: hidden;
}

.bubble {
    position: absolute;
    bottom: -100px;
    background: rgba(255, 255, 255, 0.7);
    border-radius: 50%;
    animation: rise 10s infinite ease-in;
    box-shadow: 0 2px 10px rgba(255, 255, 255, 0.3);
}

.bubble:nth-child(1) {
    width: 40px;
    height: 40px;
    left: 10%;
    animation-duration: 8s;
}

.bubble:nth-child(2) {
    width: 20px;
    height: 20px;
    left: 20%;
    animation-duration: 5s;
    animation-delay: 1s;
}

.bubble:nth-child(3) {
    width: 50px;
    height: 50px;
    left: 35%;
    animation-duration: 7s;
    animation-delay: 2s;
}

.bubble:nth-child(4) {
    width: 80px;
    height: 80px;
    left: 50%;
    animation-duration: 11s;
    animation-delay: 0s;
}

.bubble:nth-child(5) {
    width: 35px;
    height: 35px;
    left: 55%;
    animation-duration: 6s;
    animation-delay: 1s;
}

.bubble:nth-child(6) {
    width: 45px;
    height: 45px;
    left: 65%;
    animation-duration: 8s;
    animation-delay: 3s;
}

.bubble:nth-child(7) {
    width: 25px;
    height: 25px;
    left: 75%;
    animation-duration: 7s;
    animation-delay: 2s;
}

.bubble:nth-child(8) {
    width: 80px;
    height: 80px;
    left: 80%;
    animation-duration: 6s;
    animation-delay: 1s;
}

@keyframes rise {
    0% {
        bottom: -100px;
        transform: translateX(0);
        opacity: 0.7;
    }
    50% {
        transform: translateX(100px);
        opacity: 1;
    }
    100% {
        bottom: 1080px;
        transform: translateX(-200px);
        opacity: 0;
    }
}

.content-container {
    position: relative;
    z-index: 2;
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 90%;
    max-width: 500px;
    padding: 20px 0;
}

.content {
    text-align: center;
    padding: 30px;
    width: 100%;
    background: rgba(255, 255, 255, 0.92);
    border-radius: 20px;
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(8px);
    animation: fadeIn 1s ease;
    margin-bottom: 15px;
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.teacher-name {
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    background: linear-gradient(45deg, #0077b6, #00b4d8);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    animation: fadeIn 0.8s ease;
    letter-spacing: 1px;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.course-title {
    font-size: 1.6rem;
    margin-bottom: 1.8rem;
    color: #0077b6;
    font-weight: 500;
    animation: fadeIn 1s ease;
    letter-spacing: 0.5px;
}

.motto {
    font-size: 1.15rem;
    line-height: 1.8;
    margin-bottom: 1.8rem;
    color: #5a6a7a;
    animation: fadeIn 1.2s ease;
    font-weight: 400;
}

.date {
    font-size: 0.95rem;
    margin-bottom: 2rem;
    color: #6c757d;
    animation: fadeIn 1.4s ease;
    font-weight: 300;
}

.stats-container {
    display: flex;
    justify-content: space-between;
    width: 100%;
    margin-bottom: 1.5rem;
    gap: 15px;
}

.stat-box {
    flex: 1;
    padding: 15px;
    background: rgba(255, 255, 255, 0.85);
    border-radius: 12px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    border: 1px solid rgba(0, 0, 0, 0.05);
    animation: fadeIn 1.5s ease;
}

.stat-box h3 {
    font-size: 1rem;
    margin-bottom: 10px;
    color: #0077b6;
}

.stat-box p {
    font-size: 0.9rem;
    margin-bottom: 5px;
    color: #5a6a7a;
}

.enter-btn {
    display: inline-block;
    padding: 15px 40px;
    background: linear-gradient(45deg, #0077b6, #00b4d8);
    color: white;
    border: none;
    border-radius: 50px;
    font-size: 1.15rem;
    font-weight: 500;
    cursor: pointer;
    box-shadow: 0 5px 20px rgba(0, 119, 182, 0.3);
    transition: all 0.4s cubic-bezier(0.25, 0.8, 0.25, 1);
    position: relative;
    overflow: hidden;
    animation: fadeIn 1.6s ease;
    letter-spacing: 0.5px;
    z-index: 1;
}

.enter-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 25px rgba(0, 119, 182, 0.4);
}

.enter-btn:active {
    transform: translateY(1px);
    box-shadow: 0 3px 15px rgba(0, 119, 182, 0.3);
}

.enter-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(45deg, #00b4d8, #0077b6);
    opacity: 0;
    transition: opacity 0.4s ease;
    z-index: -1;
}

.enter-btn:hover::before {
    opacity: 1;
}

.copyright {
    text-align: center;
    color: #6c757d;
    font-size: 0.85rem;
    width: 100%;
    animation: fadeIn 2s ease;
    padding: 12px;
    background: rgba(255, 255, 255, 0.85);
    border-radius: 10px;
    backdrop-filter: blur(3px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    font-weight: 300;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}