/* UD Blockchain Design System 
   Theme: Professional, Financial, Tech-Forward (Deep Blue)
*/

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

:root {
    /* 核心品牌色 */
    --ud-blue-900: #111827; /* 深夜藍 - 用於導航、Footer */
    --ud-blue-800: #1e3a8a; /* 企業藍 - 用於主區塊背景 */
    --ud-blue-600: #2563eb; /* 亮藍色 - 用於按鈕、強調 */
    --ud-blue-500: #3b82f6; /* 天藍色 - 用於圖標、Hover */
    --ud-blue-50:  #eff6ff; /* 淺藍底 - 用於裝飾背景 */
    
    /* 文字與中性色 */
    --ud-gray-900: #111827; /* 主標題 */
    --ud-gray-600: #4b5563; /* 正文 */
    --ud-gray-50:  #f9fafb; /* 頁面背景 */
    --ud-white:    #ffffff;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--ud-gray-50);
    color: var(--ud-gray-600);
    line-height: 1.6;
    margin: 0;
    padding: 0;
}

/* --- 通用組件 (Components) --- */

/* 1. 按鈕 (Buttons) */
.ud-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 2rem;
    border-radius: 0.75rem;
    font-weight: 600;
    transition: all 0.3s ease;
    text-decoration: none;
    cursor: pointer;
}

.ud-btn-primary {
    background-color: var(--ud-blue-600);
    color: var(--ud-white);
    box-shadow: 0 4px 6px -1px rgba(37, 99, 235, 0.2);
}

.ud-btn-primary:hover {
    background-color: var(--ud-blue-500);
    transform: translateY(-2px);
    box-shadow: 0 10px 15px -3px rgba(37, 99, 235, 0.3);
}

.ud-btn-outline {
    background-color: transparent;
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: var(--ud-white);
}

.ud-btn-outline:hover {
    background-color: var(--ud-white);
    color: var(--ud-gray-900);
}

/* 2. 卡片 (Cards) */
.ud-card {
    background-color: var(--ud-white);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    border: 1px solid rgba(229, 231, 235, 0.5); /* 淡淡的邊框 */
    transition: all 0.3s ease;
}

.ud-card:hover {
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    transform: translateY(-4px);
}

/* 特殊卡片：頂部有彩色邊框 */
.ud-card-accent-blue { border-top: 4px solid var(--ud-blue-600); }
.ud-card-accent-indigo { border-top: 4px solid #4f46e5; }
.ud-card-accent-purple { border-top: 4px solid #9333ea; }

/* 3. 標題與文字 (Typography) */
.ud-heading-section {
    font-size: 2.25rem;
    font-weight: 700;
    color: var(--ud-gray-900);
    line-height: 1.2;
    margin-bottom: 1rem;
}

.ud-subheading {
    color: var(--ud-blue-600);
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    font-size: 0.875rem;
    margin-bottom: 0.5rem;
    display: block;
}

.ud-text-lead {
    font-size: 1.25rem;
    color: var(--ud-gray-600);
    max-width: 42rem;
    margin-left: auto;
    margin-right: auto;
}

/* 4. Hero Section 背景 */
.ud-hero-bg {
    background: linear-gradient(rgba(17, 24, 39, 0.85), rgba(17, 24, 39, 0.95)), url('https://images.unsplash.com/photo-1494412574643-35d32468817e?ixlib=rb-1.2.1&auto=format&fit=crop&w=1950&q=80');
    background-size: cover;
    background-position: center;
    background-attachment: fixed; /* 視差滾動效果 */
}

/* 5. 導航欄 (Navbar) */
.ud-nav-link {
    color: var(--ud-gray-600);
    font-weight: 500;
    padding: 0.5rem 1rem;
    transition: color 0.2s;
}
.ud-nav-link:hover {
    color: var(--ud-blue-600);
}

/* Helper Classes (類似 Tailwind 的常用工具，方便微調) */
.text-center { text-align: center; }
.mb-16 { margin-bottom: 4rem; }
.py-20 { padding-top: 5rem; padding-bottom: 5rem; }