* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", Arial, sans-serif;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: url('../background.png') no-repeat center bottom / cover;
    position: relative;
    overflow: hidden;
}
/* 浮动装饰球 */
.floating-bg {
    position: absolute;
    border-radius: 50%;
    opacity: 0.3;
    filter: blur(40px);
    animation: float 6s ease-in-out infinite;
}
.bg-1 {
    width: 15vw;
    height: 15vw;
    background: rgba(255, 255, 255, 0.3);
    top: 10%;
    left: 10%;
    animation-delay: 0s;
}
.bg-2 {
    width: 13vw;
    height: 13vw;
    background: rgba(251, 191, 36, 0.4);
    bottom: 10%;
    right: 10%;
    animation-delay: -3s;
}
.bg-3 {
    width: 10vw;
    height: 10vw;
    background: rgba(168, 85, 247, 0.3);
    top: 50%;
    right: 30%;
    animation-delay: -1.5s;
}
@keyframes float {
    0%, 100% { transform: translateY(0) rotate(0deg); }
    50% { transform: translateY(-1.2vw) rotate(5deg); }
}
/* 打字机光标效果 */
.typing-cursor {
    display: inline-block;
    width: 0.1rem;
    height: 1.2em;
    background-color: #3a6b4c;
    margin-left: 0.1rem;
    animation: blink 0.7s step-end infinite;
    vertical-align: middle;
}
@keyframes blink {
    50% { opacity: 0; }
}
.flip-card {
    background-color: transparent;
    perspective: 1000px;
    cursor: pointer;
    height: 5.5vw;
    min-height: 50px;
    min-width: 18vw;
    width: 100%;
    display: block;
}
.flip-card-inner {
    position: relative;
    width: 100%;
    height: 5.5vw;
    min-height: 50px;
    text-align: center;
    transition: transform 0.8s;
    transform-style: preserve-3d;
}
.flip-card:hover .flip-card-inner {
    transform: rotateX(180deg);
}
.flip-card-front, .flip-card-back {
    position: absolute;
    top: 0;
    left: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    padding: 1.1vw 2.5vw;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    border-radius: 1vw;
    font-size: 1.5rem;
    font-weight: 600;
    border: 2px solid rgba(74, 140, 97, 0.2);
    box-sizing: border-box;
}
.flip-card-front {
    background: rgba(255, 255, 255, 0.6);
    backdrop-filter: blur(8px);
    color: #2c5a2c;
    box-shadow: 0 0.3vw 1vw rgba(74, 140, 97, 0.08);
}
.flip-card-back {
    background: linear-gradient(135deg, rgba(74, 140, 97, 0.9), rgba(100, 180, 120, 0.9));
    color: white;
    transform: rotateX(180deg);
    box-shadow: 0 0.8vw 2.5vw rgba(74, 140, 97, 0.35);
    border-color: rgba(74, 140, 97, 0.5);
}
.login-wrapper {
    display: flex;
    gap: 2.5vw;
    margin-top: 7vw;
    z-index: 10;
    position: relative;
}
.login-container {
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(24px);
    padding: 1.7vw 3.5vw 2vw 3.5vw;
    border-radius: 1.8vw;
    box-shadow:
        0 1.2vw 3.5vw -1.2vw rgba(0, 0, 0, 0.08),
        0 0 0 0.05vw rgba(255, 255, 255, 0.4) inset;
    text-align: left;
    width: 28vw;
    max-width: 480px;
    animation: slideUp 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
    transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    border: 1px solid rgba(74, 140, 97, 0.12);
}
.login-container:hover {
    transform: translateY(-0.4vw) scale(1.01);
    box-shadow:
        0 2.5vw 5vw -1.5vw rgba(74, 140, 97, 0.22),
        0 0 0 0.05vw rgba(255, 255, 255, 0.4) inset;
    border-color: rgba(74, 140, 97, 0.28);
}
.login-container:nth-child(2) {
    animation-delay: 0.1s;
}
@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(2.5vw) scale(0.95);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}
.login-container h2 {
    font-size: 1.6rem;
    color: #dbb22c;
    margin-bottom: 1vw;
    font-weight: 700;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5vw;
    letter-spacing: -0.5px;
}
.login-container h2 span {
    font-size: 1.6vw;
    animation: leafWave 3s ease-in-out infinite;
}
@keyframes leafWave {
    0%, 100% { transform: rotate(-5deg); }
    50% { transform: rotate(5deg); }
}
.login-container p {
    color: #5a6b7a;
    font-size: 0.9rem;
    line-height: 1.85;
    margin-bottom: 0;
    letter-spacing: 0.1px;
    text-align: justify;
    word-break: break-word;
    hyphens: auto;
}
.lang-btn-en {
    font-family: 'Playfair Display', 'Georgia', serif;
}
.lang-btn-zh {
    font-family: 'KaiTi', 'STKaiti', '楷体', serif;
}
/* 英文模式样式 */
.lang-en .login-container p {
    font-family: 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    font-size: 0.82rem;
    line-height: 1.75;
    word-break: break-all;
    word-wrap: break-word;
}
.lang-en .login-container h2 {
    font-family: 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    font-size: 1.45rem;
}
.lang-en .model-tag {
    font-size: 0.78rem;
    font-family: 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
}
.lang-en .feature-desc {
    font-size: 0.82rem;
    font-family: 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.7;
    overflow-wrap: anywhere;
}
/* 英文模式卡片宽度调整 */
.lang-en .login-container {
    width: 32vw;
    max-width: 580px;
}
.lang-en .login-wrapper {
    gap: 3vw;
}
.lang-en [onclick*="about_us.html"] {
    width: 88vw !important;
}

.footer {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    padding: 0.6vw 0;
    background-color: #1e293b;
    color: rgba(255,255,255,0.6);
    font-size: 0.85rem;
    text-align: center;
    letter-spacing: 0.5px;
    z-index: 100;
}
.footer a {
    color: rgba(255,255,255,0.75);
    text-decoration: none;
}
.footer a:hover {
    color: rgba(255,255,255,1);
    text-decoration: underline;
}
/* 手机端隐藏左侧叶片图片 */
@media (max-width: 768px) {
    .left-leaf {
        display: none !important;
    }
}
/* 响应式布局 */
@media (max-width: 1400px) {
    .login-container {
        width: 26vw;
    }
}
@media (max-width: 1200px) {
    .login-wrapper {
        flex-direction: column;
        align-items: center;
        gap: 3vw;
    }
    .login-container {
        width: 55vw;
        min-width: 320px;
        padding: 4.5vw 4vw;
    }
}
@media (max-width: 768px) {
    .login-container {
        width: 90vw;
        min-width: 280px;
        padding: 6vw 5vw;
    }
    .login-container h2 {
        font-size: 1.5rem;
    }
    .login-container p {
        font-size: 0.9rem;
    }
}