/* shared_css: General styles for the entire application */
:root {
    --primary-color: #007bff; /* Blue */
    --secondary-color: #6c757d; /* Gray */
    --accent-color: #28a745; /* Green */
    --danger-color: #dc3545; /* Red */
    --warning-color: #ffc107; /* Yellow */
    --info-color: #17a2b8; /* Cyan */
    --light-color: #f8f9fa; /* Light Gray */
    --dark-color: #343a40; /* Dark Gray */
    --text-color: #333; /* Darker text */
    --bg-color: #fff; /* White background */
    --border-color: #dee2e6; /* Light border */
    --font-family-sans-serif: 'Roboto', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Helvetica Neue', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';
    --font-size-base: 16px;
    --line-height-base: 1.6;
    --container-max-width: 1200px;
    --spacing-unit: 1rem;
}

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family-sans-serif);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--text-color);
    background-color: var(--bg-color);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s ease, text-decoration 0.3s ease;
}

a:hover {
    color: var(--dark-color);
    text-decoration: underline;
}

h1, h2, h3, h4, h5, h6 {
    margin-top: 0;
    margin-bottom: var(--spacing-unit);
    font-weight: 700;
    line-height: 1.2;
    color: var(--dark-color);
}

p {
    margin-bottom: var(--spacing-unit);
}

ul, ol {
    list-style: none;
    margin-bottom: var(--spacing-unit);
}

img {
    max-width: 100%;
    height: auto;
    vertical-align: middle;
}

.container {
    max-width: var(--container-max-width);
    margin-left: auto;
    margin-right: auto;
    padding-left: calc(var(--spacing-unit) * 1.5);
    padding-right: calc(var(--spacing-unit) * 1.5);
    width: 100%;
}

/* Buttons */
.btn {
    display: inline-block;
    font-weight: 500;
    color: var(--bg-color);
    text-align: center;
    vertical-align: middle;
    user-select: none;
    background-color: transparent;
    border: 1px solid transparent;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    line-height: 1.5;
    border-radius: 0.3rem;
    transition: all 0.2s ease-in-out;
    cursor: pointer;
}

.btn-primary {
    color: var(--bg-color);
    background-color: var(--primary-color);
    border-color: var(--primary-color);
}

.btn-primary:hover {
    background-color: #0056b3;
    border-color: #0056b3;
}

.btn-secondary {
    color: var(--dark-color);
    background-color: var(--light-color);
    border-color: var(--secondary-color);
}

.btn-secondary:hover {
    color: var(--bg-color);
    background-color: var(--secondary-color);
    border-color: var(--secondary-color);
}

/* Header styles */
.main-header {
    background-color: var(--bg-color);
    padding: var(--spacing-unit) 0;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

.main-header.scrolled {
    background-color: rgba(255, 255, 255, 0.98);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.main-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.main-header .logo img {
    height: 40px;
    width: auto;
}

.main-nav ul {
    display: flex;
    gap: calc(var(--spacing-unit) * 1.5);
}

.main-nav .nav-link {
    color: var(--dark-color);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
}

.main-nav .nav-link::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width 0.3s ease;
}

.main-nav .nav-link:hover::after,
.main-nav .nav-link.active::after {
    width: 100%;
}

.auth-buttons {
    display: flex;
    gap: var(--spacing-unit);
}

.menu-toggle {
    display: none; /* Hidden on desktop */
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    position: relative;
    z-index: 1001;
}

.menu-toggle span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--dark-color);
    margin: 5px 0;
    transition: all 0.3s ease;
}

/* Footer styles */
.main-footer {
    background-color: var(--dark-color);
    color: var(--light-color);
    padding: calc(var(--spacing-unit) * 3) 0;
    margin-top: auto; /* Pushes footer to the bottom */
}

.main-footer a {
    color: var(--light-color);
    opacity: 0.8;
}

.main-footer a:hover {
    color: var(--primary-color);
    opacity: 1;
    text-decoration: underline;
}

.main-footer .footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: calc(var(--spacing-unit) * 2);
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.main-footer .footer-col h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-unit);
    font-size: 1.2rem;
}

.main-footer .footer-col ul {
    padding: 0;
}

.main-footer .footer-col ul li {
    margin-bottom: 0.75rem;
}

.main-footer .footer-col p {
    font-size: 0.9rem;
    line-height: 1.8;
    margin-bottom: var(--spacing-unit);
    opacity: 0.9;
}

.main-footer .social-links {
    display: flex;
    gap: var(--spacing-unit);
    margin-top: calc(var(--spacing-unit) * 1.5);
}

.main-footer .social-links img {
    width: 24px;
    height: 24px;
    filter: invert(100%) saturate(0%) brightness(100%); /* Make icons white */
    transition: filter 0.3s ease;
}

.main-footer .social-links a:hover img {
    filter: invert(50%) sepia(80%) saturate(2000%) hue-rotate(190deg) brightness(100%); /* Primary color on hover */
}

.main-footer .footer-bottom {
    text-align: center;
    padding-top: calc(var(--spacing-unit) * 1.5);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    font-size: 0.85rem;
    opacity: 0.7;
}

/* Back to Top Button */
.back-to-top-btn {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: var(--primary-color);
    color: var(--light-color);
    width: 45px;
    height: 45px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
    z-index: 999;
}

.back-to-top-btn.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top-btn svg {
    width: 24px;
    height: 24px;
}

/* Cookie Consent Banner */
.cookie-consent-banner {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background-color: var(--dark-color);
    color: var(--light-color);
    padding: var(--spacing-unit) calc(var(--spacing-unit) * 1.5);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-unit);
    z-index: 10000;
    box-shadow: 0 -2px 10px rgba(0,0,0,0.1);
    opacity: 0;
    transition: opacity 0.5s ease-in-out;
}

.cookie-consent-banner p {
    margin: 0;
    flex-grow: 1;
    font-size: 0.9rem;
}

.cookie-consent-banner p a {
    color: var(--primary-color);
    text-decoration: underline;
}

.cookie-consent-banner .btn {
    flex-shrink: 0;
    white-space: nowrap;
}

/* Responsive adjustments */
@media (max-width: 992px) {
    .main-nav {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: var(--bg-color);
        box-shadow: 0 8px 16px rgba(0,0,0,0.1);
        padding: var(--spacing-unit) 0;
        border-top: 1px solid var(--border-color);
    }

    .main-nav.active {
        display: flex;
    }

    .main-nav ul {
        flex-direction: column;
        align-items: center;
        gap: var(--spacing-unit);
    }

    .menu-toggle {
        display: block;
    }

    .auth-buttons {
        display: none; /* Hide on smaller screens by default when menu is toggled */
    }

    .auth-buttons.hidden-on-mobile-nav-active {
        display: none;
    }

    .menu-toggle.active span:nth-child(1) {
        transform: rotate(-45deg) translate(-5px, 6px);
    }

    .menu-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .menu-toggle.active span:nth-child(3) {
        transform: rotate(45deg) translate(-5px, -6px);
    }
}

@media (max-width: 768px) {
    .main-footer .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .main-footer .social-links {
        justify-content: center;
    }

    .cookie-consent-banner {
        flex-direction: column;
        text-align: center;
    }

    .cookie-consent-banner .btn {
        width: 100%;
    }
}
/* 移动端内容区防溢出（系统追加，请勿删除） */
@media (max-width: 768px) {
  .page-content img {
    max-width: 100% !important;
    height: auto !important;
    display: block;
  }
  .page-content {
    overflow-x: hidden;
    max-width: 100%;
  }
  body {
    overflow-x: hidden;
  }
}