/* ==================== 
   全局基础样式 
   ==================== */
:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --text-dark: #333;
    --text-light: #666;
    --bg-light: #f8f9fa;
    --white: #fff;
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
    --transition: all 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-light);
    padding-top: 70px; /* 为固定导航栏留出空间 */
}

/* ==================== 
   固定导航栏样式 
   ==================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow);
    z-index: 1000;
    transition: var(--transition);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo a {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition);
    position: relative;
    padding: 0.5rem 0;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    transition: width 0.3s ease;
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

/* 移动端菜单按钮 */
.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.bar {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    border-radius: 3px;
    transition: var(--transition);
}

/* ==================== 
   响应式设计 
   ==================== */
@media (max-width: 968px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px rgba(0,0,0,0.05);
        padding: 2rem 0;
        gap: 1.5rem;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-toggle {
        display: flex;
    }

    /* 汉堡菜单动画 */
    .nav-toggle.active .bar:nth-child(1) {
        transform: rotate(-45deg) translate(-5px, 6px);
    }

    .nav-toggle.active .bar:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active .bar:nth-child(3) {
        transform: rotate(45deg) translate(-5px, -6px);
    }
}

@media (max-width: 480px) {
    body {
        padding-top: 60px;
    }
    
    .nav-container {
        height: 60px;
        padding: 0 1rem;
    }
    
    .nav-logo a {
        font-size: 1.2rem;
    }
}

/* ==================== 
   通用组件样式 
   ==================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.section-title {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: var(--text-dark);
    text-align: center;
}

.btn {
    display: inline-block;
    padding: 10px 25px;
    border-radius: 25px;
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.6);
}

.btn-secondary {
    background: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
    background: var(--primary-color);
    color: white;
}

/* 卡片基础样式 */
.card {
    background: white;
    border-radius: 10px;
    padding: 2rem;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(0,0,0,0.15);
}

/* 标签样式 */
.tag {
    display: inline-block;
    padding: 4px 12px;
    background: rgba(102, 126, 234, 0.1);
    color: var(--primary-color);
    border-radius: 20px;
    font-size: 0.85rem;
    margin-right: 0.5rem;
    margin-bottom: 0.5rem;
}

/* 模态框基础 */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    backdrop-filter: blur(4px);
}

.modal-content {
    background: white;
    margin: 10% auto;
    padding: 2rem;
    border-radius: 15px;
    width: 90%;
    max-width: 500px;
    position: relative;
    animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
    from {
        transform: translateY(-50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.close-btn {
    position: absolute;
    right: 1rem;
    top: 1rem;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-light);
}

.close-btn:hover {
    color: var(--text-dark);
}

/* 输入框样式 */
input[type="text"],
input[type="email"],
input[type="password"],
textarea,
select {
    width: 100%;
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 1rem;
    transition: var(--transition);
    font-family: inherit;
}

input:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
}
    
/* 页脚 */
.footer {
    background: var(--text-dark);
    color: white;
    text-align: center;
    padding: 2rem;
    margin-top: 4rem;
}

/* 滚动条美化 */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: #f1f1f1;
}

::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--secondary-color);
}

/* ==================== 
   工具类 
   ==================== */
.text-center { text-align: center; }
.mt-2 { margin-top: 2rem; }
.mb-2 { margin-bottom: 2rem; }
.hidden { display: none; }