/* 基础样式 - 大地色系+森林绿 */
        :root {
            --earth-brown: #8B7355;
            --earth-light: #C4BBAF;
            --forest-dark: #2C5E1A;
            --forest-mid: #4A7856;
            --forest-light: #7D9F6F;
            --accent-color: #E6C229;
        }
        
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            margin: 0;
            padding: 0;
            background-color: #F5F1E8;
            color: #333;
            line-height: 1.6;
            background-image: url('data:image/svg+xml;utf8,<svg width="100" height="100" viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg"><path d="M0,0 L100,0 L100,100 L0,100 Z" fill="none" stroke="%23C4BBAF" stroke-width="0.5" stroke-dasharray="5,5"/></svg>');
        }
        
        /* 手绘风格元素 */
        .hand-drawn {
            position: relative;
        }
        
        .hand-drawn:after {
            content: "";
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            border: 2px solid var(--earth-brown);
            border-radius: 255px 15px 225px 15px/15px 225px 15px 255px;
            pointer-events: none;
        }
        
        /* 树叶形状导航栏 */
        .leaf-nav {
            background-color: var(--forest-dark);
            padding: 1rem 0;
            position: relative;
            clip-path: polygon(0 0, 100% 0, 100% 80%, 50% 100%, 0 80%);
            margin-bottom: 2rem;
        }
        
        .leaf-nav ul {
            display: flex;
            justify-content: center;
            list-style: none;
            padding: 0;
            margin: 0;
            flex-wrap: wrap;
        }
        
        .leaf-nav li {
            margin: 0 1.5rem;
            position: relative;
        }
        
        .leaf-nav a {
            color: white;
            text-decoration: none;
            font-weight: bold;
            padding: 0.5rem 1rem;
            display: block;
            transition: all 0.3s ease;
            background-color: var(--forest-mid);
            border-radius: 50% 20% / 10% 40%;
            box-shadow: 3px 3px 5px rgba(0,0,0,0.2);
        }
        
        .leaf-nav a:hover {
            background-color: var(--forest-light);
            transform: translateY(-3px);
        }
        
        /* 页眉 */
        header {
            text-align: center;
            padding: 2rem 0;
            background: linear-gradient(to bottom, var(--forest-dark), var(--forest-mid));
            color: white;
            position: relative;
        }
        
        header h1 {
            font-size: 3rem;
            margin: 0;
            text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
            font-family: 'Brush Script MT', cursive;
        }
        
        header p {
            font-size: 1.2rem;
            max-width: 800px;
            margin: 1rem auto;
        }
        
        /* 主要内容区 */
        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 1rem;
        }
        
        /* 卡片样式 */
        .card {
            background-color: white;
            border-radius: 10px;
            padding: 1.5rem;
            margin-bottom: 2rem;
            box-shadow: 0 4px 8px rgba(0,0,0,0.1);
            position: relative;
            overflow: hidden;
        }
        
        .card-title {
            color: var(--forest-dark);
            border-bottom: 2px dashed var(--earth-light);
            padding-bottom: 0.5rem;
            margin-top: 0;
        }
        
        /* 碳排放计算器 */
        .carbon-calculator {
            background-color: #F9F7F0;
            border: 2px solid var(--earth-light);
        }
        
        .calculator-form {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 1rem;
        }
        
        .calculator-form label {
            display: block;
            margin-bottom: 0.5rem;
            color: var(--earth-brown);
            font-weight: bold;
        }
        
        .calculator-form input, 
        .calculator-form select {
            width: 100%;
            padding: 0.5rem;
            border: 1px solid var(--earth-light);
            border-radius: 4px;
            background-color: white;
        }
        
        .calculator-form button {
            grid-column: span 2;
            background-color: var(--forest-mid);
            color: white;
            border: none;
            padding: 0.75rem;
            border-radius: 4px;
            cursor: pointer;
            font-weight: bold;
            transition: background-color 0.3s;
        }
        
        .calculator-form button:hover {
            background-color: var(--forest-dark);
        }
        
        .calculator-result {
            margin-top: 1rem;
            padding: 1rem;
            background-color: var(--forest-light);
            color: white;
            border-radius: 4px;
            display: none;
        }
        
        /* 树木生长可视化 */
        .tree-visualization {
            height: 300px;
            background-color: #F0EDE4;
            position: relative;
            overflow: hidden;
        }
        
        .tree {
            position: absolute;
            bottom: 0;
            left: 50%;
            transform: translateX(-50%);
            transition: all 2s ease;
        }
        
        .tree-trunk {
            width: 30px;
            height: 0;
            background-color: var(--earth-brown);
            margin: 0 auto;
            position: relative;
        }
        
        .tree-canopy {
            width: 0;
            height: 0;
            border-left: 50px solid transparent;
            border-right: 50px solid transparent;
            border-bottom: 100px solid var(--forest-mid);
            position: absolute;
            bottom: 100%;
            left: 50%;
            transform: translateX(-50%);
            opacity: 0.8;
        }
        
        .tree-controls {
            display: flex;
            justify-content: center;
            margin-top: 1rem;
            gap: 1rem;
        }
        
        .tree-controls button {
            background-color: var(--earth-brown);
            color: white;
            border: none;
            padding: 0.5rem 1rem;
            border-radius: 4px;
            cursor: pointer;
        }
        
        /* 志愿者时间轴 */
        .timeline {
            position: relative;
            max-width: 800px;
            margin: 0 auto;
        }
        
        .timeline::after {
            content: '';
            position: absolute;
            width: 4px;
            background-color: var(--earth-brown);
            top: 0;
            bottom: 0;
            left: 50%;
            margin-left: -2px;
            border-radius: 2px;
        }
        
        .timeline-event {
            padding: 10px 40px;
            position: relative;
            background-color: inherit;
            width: 50%;
            box-sizing: border-box;
        }
        
        .timeline-event::after {
            content: '';
            position: absolute;
            width: 20px;
            height: 20px;
            background-color: white;
            border: 4px solid var(--forest-dark);
            border-radius: 50%;
            top: 15px;
            z-index: 1;
        }
        
        .left {
            left: 0;
        }
        
        .right {
            left: 50%;
        }
        
        .left::after {
            right: -12px;
        }
        
        .right::after {
            left: -12px;
        }
        
        .timeline-content {
            padding: 20px;
            background-color: white;
            border-radius: 6px;
            box-shadow: 0 2px 4px rgba(0,0,0,0.1);
            border: 1px solid var(--earth-light);
        }
        
        .timeline-content h3 {
            margin-top: 0;
            color: var(--forest-dark);
        }
        
        .timeline-content button {
            background-color: var(--forest-light);
            color: white;
            border: none;
            padding: 0.5rem 1rem;
            border-radius: 4px;
            cursor: pointer;
            margin-top: 0.5rem;
        }
        
        /* 生态摄影瀑布流 */
        .photo-gallery {
            columns: 3 250px;
            column-gap: 1rem;
        }
        
        .photo-item {
            break-inside: avoid;
            margin-bottom: 1rem;
            position: relative;
            border: 1px solid var(--earth-light);
            border-radius: 8px;
            overflow: hidden;
            box-shadow: 2px 2px 5px rgba(0,0,0,0.1);
            transition: transform 0.3s;
        }
        
        .photo-item:hover {
            transform: scale(1.02);
        }
        
        .photo-item img {
            width: 100%;
            height: auto;
            display: block;
        }
        
        .photo-caption {
            position: absolute;
            bottom: 0;
            left: 0;
            right: 0;
            background: rgba(43, 94, 26, 0.7);
            color: white;
            padding: 0.5rem;
            font-size: 0.9rem;
        }
        
        /* 新闻列表 */
        .news-list {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
            gap: 1.5rem;
        }
        
        .news-item {
            background-color: white;
            border-radius: 8px;
            overflow: hidden;
            box-shadow: 0 2px 4px rgba(0,0,0,0.1);
            transition: transform 0.3s;
            border: 1px solid var(--earth-light);
        }
        
        .news-item:hover {
            transform: translateY(-5px);
        }
        
        .news-image {
            height: 180px;
            overflow: hidden;
        }
        
        .news-image img {
            width: 100%;
            height: 100%;
            object-fit: cover;
            transition: transform 0.5s;
        }
        
        .news-item:hover .news-image img {
            transform: scale(1.1);
        }
        
        .news-content {
            padding: 1rem;
        }
        
        .news-date {
            color: var(--earth-brown);
            font-size: 0.8rem;
            margin-bottom: 0.5rem;
        }
        
        .news-title {
            color: var(--forest-dark);
            margin: 0 0 0.5rem 0;
            font-size: 1.1rem;
        }
        
        .news-excerpt {
            color: #666;
            font-size: 0.9rem;
            margin-bottom: 1rem;
        }
        
        .read-more {
            color: var(--forest-mid);
            text-decoration: none;
            font-weight: bold;
            font-size: 0.9rem;
        }
        
        /* 页脚 */
        footer {
            background-color: var(--earth-brown);
            color: white;
            text-align: center;
            padding: 2rem 0;
            margin-top: 2rem;
        }
        
        .footer-links {
            display: flex;
            justify-content: center;
            gap: 2rem;
            margin-bottom: 1rem;
            flex-wrap: wrap;
        }
        
        .footer-links a {
            color: white;
            text-decoration: none;
        }
        
        .footer-links a:hover {
            text-decoration: underline;
        }
        
        .social-icons {
            display: flex;
            justify-content: center;
            gap: 1rem;
            margin: 1rem 0;
        }
        
        .social-icons a {
            color: white;
            font-size: 1.5rem;
        }
        
        /* 响应式设计 */
        @media (max-width: 768px) {
            .calculator-form {
                grid-template-columns: 1fr;
            }
            
            .calculator-form button {
                grid-column: span 1;
            }
            
            .timeline::after {
                left: 31px;
            }
            
            .timeline-event {
                width: 100%;
                padding-left: 70px;
                padding-right: 25px;
            }
            
            .timeline-event::after {
                left: 21px;
            }
            
            .left::after, .right::after {
                left: 21px;
            }
            
            .right {
                left: 0;
            }
        }