:root {
    --primary-blue: #2A6DFF;
    --secondary-purple: #7C4DFF;
    --text-primary: #2D3748;
    --text-secondary: #4A5568;
    --background: #FFFFFF;
    --border: #E2E8F0;
    --shadow: 0 1px 3px rgba(0,0,0,0.1);
}
.container {
  width: 50%;
  height: 300px;
  overflow: hidden; /* ·ÀֹͼƬÒç³öÈÝÆ÷ */
}

.container img {
  max-width: 100%;
  max-height: 100%;
}
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', 'Microsoft Yahei', sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

nav {
    background: var(--background);
    padding: 1rem;
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
    display: flex;
    justify-content: center;
}

nav a {
    color: var(--text-primary);
    text-decoration: none;
    margin: 0 1rem;
    padding: 0.6rem 1.2rem;
    border-radius: 8px;
    transition: all 0.2s ease;
    font-weight: 500;
}

nav a:hover {
    background: rgba(42,109,255,0.05);
    color: var(--primary-blue);
}

.container {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1.5rem;
}

.section {
    margin: 2rem 0;
    padding: 2rem;
    background: var(--background);
    border-radius: 12px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
}

h2 {
    color: var(--primary-blue);
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
}

.category-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin: 1.5rem 0;
}

.category-btn {
    padding: 1rem;
    background: rgba(42,109,255,0.05);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--primary-blue);
    cursor: pointer;
    transition: all 0.2s ease;
    font-weight: 500;
}

.category-btn:hover {
    background: rgba(42,109,255,0.1);
    transform: translateY(-2px);
}

.download-btn {
    display: inline-flex;
    align-items: center;
    padding: 0.6rem 1.2rem;
    background: var(--primary-blue);
    border-radius: 6px;
    color: white;
    text-decoration: none;
    margin: 0.5rem 0;
    font-size: 0.9rem;
    transition: opacity 0.2s ease;
}

.download-btn:hover {
    opacity: 0.9;
}

.tool-list li {
    background: rgba(249,250,251,1);
    padding: 1.2rem;
    margin: 1rem 0;
    border-radius: 8px;
    border: 1px solid var(--border);
}

.calculator-form {
    padding: 1.5rem;
    border-radius: 8px;
    background: rgba(249,250,251,1);
}

input[type="text"] {
    width: 200px;
    padding: 0.8rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    margin: 0.5rem 0;
}

.warning {
    background: rgba(255,235,238,1);
    border: 1px solid #FF5252;
    padding: 1rem;
    border-radius: 8px;
    margin: 1rem 0;
    color: #FF1744;
}

@media (max-width: 768px) {
    .container {
        padding: 0 1rem;
    }
    
    nav {
        flex-wrap: wrap;
    }
    
    nav a {
        margin: 0.3rem;
        padding: 0.5rem 1rem;
    }
}