/**
 * Global CSS - Design System & Common Styles for VIF Marine Propellers
 * Purpose: Design Tokens + Base Styles + Universal Components
 */

/* ========== 1. CSS Reset ========== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: #333;
    background: #fff;
    overflow-x: hidden;
}

/* ========== 2. Design Tokens - Color System ========== */
:root {
    --brand-primary: #1EB7E6;
    --brand-secondary: #0c5273;
    --text-primary: #333333;
    --text-secondary: #666666;
    --text-light: #999999;
    --bg-white: #ffffff;
    --bg-light: #f8f9fa;
    --bg-dark: #2c3e50;
    --border-color: #e0e0e0;
    --success: #28a745;
    --error: #dc3545;
    --accent: #ffc107;
}

/* ========== 3. Typography System ========== */
h1 { font-size: 2.5rem; font-weight: 700; line-height: 1.2; margin-bottom: 1.5rem; color: var(--text-primary); }
h2 { font-size: 2rem; font-weight: 700; line-height: 1.3; margin-bottom: 1.25rem; color: var(--text-primary); }
h3 { font-size: 1.75rem; font-weight: 600; line-height: 1.3; margin-bottom: 1rem; color: var(--text-primary); }
h4 { font-size: 1.5rem; font-weight: 600; line-height: 1.4; margin-bottom: 0.875rem; color: var(--text-primary); }
h5 { font-size: 1.25rem; font-weight: 600; line-height: 1.4; margin-bottom: 0.75rem; color: var(--text-primary); }
h6 { font-size: 1.125rem; font-weight: 600; line-height: 1.4; margin-bottom: 0.5rem; color: var(--text-primary); }
p { font-size: 1rem; line-height: 1.6; margin-bottom: 1rem; color: var(--text-primary); }
.lead { font-size: 1.125rem; font-weight: 300; line-height: 1.7; color: var(--text-secondary); }

/* ========== 4. Spacing Utilities ========== */
.container {
    width: 100%;
    padding-right: 15px;
    padding-left: 15px;
    margin-right: auto;
    margin-left: auto;
}
.section-padding { padding: 4rem 0; }
.mb-0 { margin-bottom: 0 !important; }
.mb-1 { margin-bottom: 0.5rem !important; }
.mb-2 { margin-bottom: 1rem !important; }
.mb-3 { margin-bottom: 1.5rem !important; }
.mb-4 { margin-bottom: 2rem !important; }
.mb-5 { margin-bottom: 3rem !important; }
.mt-0 { margin-top: 0 !important; }
.mt-1 { margin-top: 0.5rem !important; }
.mt-2 { margin-top: 1rem !important; }
.mt-3 { margin-top: 1.5rem !important; }
.mt-4 { margin-top: 2rem !important; }
.mt-5 { margin-top: 3rem !important; }

/* ========== 5. Layout Utilities ========== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }
.d-flex { display: flex; }
.justify-content-center { justify-content: center; }
.justify-content-between { justify-content: space-between; }
.align-items-center { align-items: center; }

/* ========== 6. Common Components ========== */
/* Buttons - 全站通用按钮 */
.btn {
    display: inline-block;
    padding: 12px 30px;
    font-size: 1rem;
    font-weight: 500;
    text-align: center;
    text-decoration: none;
    border-radius: 4px;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
    min-width: 48px;
    min-height: 48px;
}
.btn-primary {
    background-color: var(--brand-primary);
    color: #fff;
}
.btn-primary:hover {
    background-color: var(--brand-secondary);
    color: #fff;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(30, 183, 230, 0.3);
}
.btn-secondary {
    background-color: transparent;
    color: #fff;
    border: 2px solid #fff;
}
.btn-secondary:hover {
    background-color: #fff;
    color: var(--brand-primary);
}

/* Cards - 基础卡片样式 */
.card {
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    transition: all 0.3s ease;
}
.card:hover {
    box-shadow: 0 8px 16px rgba(0,0,0,0.1);
    transform: translateY(-4px);
}

/* ========== 7. Responsive Container ========== */
@media (min-width: 576px) { .container { max-width: 540px; } }
@media (min-width: 768px) { .container { max-width: 720px; } }
@media (min-width: 992px) { .container { max-width: 960px; } }
@media (min-width: 1200px) { .container { max-width: 1140px; } }

/* ========== 8. Accessibility ========== */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: #000;
    color: #fff;
    padding: 8px 12px;
    text-decoration: none;
    z-index: 10000;
}
.skip-link:focus { top: 0; }

/* ========== 9. Images ========== */
img, .img-fluid {
    max-width: 100%;
    height: auto;
    display: block;
}

/* ========== 10. Section Backgrounds ========== */
.bg-light {
    background-color: var(--bg-light) !important;
}
.bg-dark {
    background-color: var(--bg-dark) !important;
    color: #fff;
}
.bg-primary {
    background-color: var(--brand-primary) !important;
    color: #fff;
}