/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    background-color: #f5f5f5;
    color: #333;
}

header {
    text-align: center;
    padding: 2rem;
    background-color: #fff;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

h1 {
    color: #2c3e50;
    margin-bottom: 0.5rem;
}

/* 单位卡片网格布局 */
.unit-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    padding: 2rem;
    max-width: 1400px;
    margin: 0 auto;
}

.unit-card {
    background-color: #fff;
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
}

.unit-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.unit-card h2 {
    color: #1a73e8;
    margin-bottom: 0.5rem;
    font-size: 1.5rem;
    font-weight: 700;
}

.unit-description {
    color: #5f6368;
    margin-bottom: 1rem;
    font-size: 0.9rem;
}

.conversion-options {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
    margin-top: 1rem;
}

.conversion-option {
    background: #f8f9fa;
    border: 1px solid #e8eaed;
    border-radius: 6px;
    padding: 0.75rem;
    transition: all 0.2s ease;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    text-decoration: none;
    color: inherit;
    cursor: pointer;
}

.conversion-option:hover {
    background: #f1f3f4;
    border-color: #dadce0;
    transform: translateY(-2px);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.option-label {
    color: #3c4043;
    font-weight: 500;
    font-size: 0.9rem;
}

.option-example {
    color: #5f6368;
    font-size: 0.8rem;
    font-style: italic;
}

/* 响应式设计调整 */
@media (max-width: 600px) {
    .conversion-options {
        grid-template-columns: 1fr;
    }
}

footer {
    text-align: center;
    padding: 2rem;
    background-color: #f8f9fa;
    margin-top: 2rem;
}

/* About页面样式 */
.about-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

.about-container section {
    background: #fff;
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.about-container h2 {
    color: #1a73e8;
    margin-bottom: 1rem;
    font-size: 1.5rem;
    font-weight: 700;
}

.about-container ul {
    list-style-type: none;
    padding-left: 1.5rem;
}

.about-container li {
    margin-bottom: 0.75rem;
    position: relative;
    color: #5f6368;
}

.about-container li::before {
    content: "•";
    color: #1a73e8;
    position: absolute;
    left: -1rem;
}

.about-container strong {
    color: #3c4043;
}

.contact ul li,
.privacy ul li {
    color: #5f6368;
}

/* 响应式调整 */
@media (max-width: 600px) {
    .about-container {
        padding: 1rem;
    }
    
    .about-container section {
        padding: 1rem;
        margin-bottom: 1rem;
    }
}

/* 导航栏样式 */
.nav-container {
    background-color: #ffffff;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    color: #2196F3;
    font-size: 1.5rem;
    font-weight: bold;
    text-decoration: none;
    transition: color 0.3s ease;
}

.nav-logo:hover {
    color: #1976D2;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: #333;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-links a:hover {
    color: #2196F3;
}

/* 页面容器样式 */
.page-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-content {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-links {
        gap: 1rem;
    }
}