/* 福到了 - 简约大气风格 */

:root {
    /* 配色 */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-card: #ffffff;

    --text-primary: #1a1a1a;
    --text-secondary: #4a4a4a;
    --text-muted: #6b7280;

    --accent-blue: #2563eb;
    --accent-blue-light: #3b82f6;
    --accent-blue-dark: #1d4ed8;

    --border-color: #e5e7eb;
    --border-light: #f3f4f6;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);

    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.7;
    color: var(--text-primary);
    background: var(--bg-primary);
    overflow-x: hidden;
}

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

/* ==================== Header ==================== */

.header {
    padding: 1.2rem 0 1rem;
    text-align: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.logo {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    letter-spacing: 0.05em;
    color: white;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.cursor {
    display: inline-block;
    width: 3px;
    height: 1em;
    background: white;
    margin-left: 0.1em;
    animation: blink 1s infinite;
    vertical-align: middle;
}

@keyframes blink {
    0%, 50% { opacity: 1; }
    51%, 100% { opacity: 0; }
}

.tagline {
    font-size: 0.95rem;
    font-weight: 300;
    opacity: 0.95;
    letter-spacing: 0.05em;
}

/* ==================== Net Age Predictor ==================== */

.net-age-predictor {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    margin-top: 1rem;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.net-age-input {
    flex: 1;
    padding: 0.75rem 1rem;
    font-size: 0.95rem;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 25px;
    background: rgba(255, 255, 255, 0.15);
    color: white;
    outline: none;
    transition: all var(--transition-normal);
}

.net-age-input::placeholder {
    color: rgba(255, 255, 255, 0.7);
}

.net-age-input:focus {
    border-color: rgba(255, 255, 255, 0.6);
    background: rgba(255, 255, 255, 0.25);
    box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.1);
}

.net-age-btn {
    width: 44px;
    height: 44px;
    border: none;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.25);
    color: white;
    font-size: 1rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    justify-content: center;
}

.net-age-btn:hover {
    background: rgba(255, 255, 255, 0.35);
    transform: scale(1.05);
}

.net-age-btn:active {
    transform: scale(0.95);
}

.net-age-result {
    margin-top: 1rem;
    min-height: 60px;
    opacity: 0;
    transition: opacity var(--transition-normal);
    position: relative;
}

.net-age-result.show {
    opacity: 1;
}

.net-age-loading {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    color: rgba(255, 255, 255, 0.9);
    font-size: 0.9rem;
    padding: 0.75rem 1.5rem;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    max-width: 500px;
    margin: 0 auto;
}

.net-age-success {
    color: rgba(255, 255, 255, 0.95);
    font-size: 0.95rem;
    line-height: 1.6;
    padding: 1rem 1.5rem 1rem 1.5rem;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 12px;
    max-width: 500px;
    margin: 0 auto;
    backdrop-filter: blur(10px);
    white-space: pre-line;
    position: relative;
}

.net-age-error {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    color: rgba(255, 200, 200, 0.95);
    font-size: 0.9rem;
    padding: 0.75rem 1.5rem 0.75rem 1.5rem;
    background: rgba(255, 100, 100, 0.15);
    border-radius: 12px;
    max-width: 500px;
    margin: 0 auto;
    position: relative;
}

.net-age-close {
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
    width: 28px;
    height: 28px;
    border: none;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    color: rgba(255, 255, 255, 0.9);
    font-size: 0.9rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.net-age-close:hover {
    background: rgba(255, 255, 255, 0.25);
    color: rgba(255, 255, 255, 1);
    transform: scale(1.1);
}

.net-age-close:active {
    transform: scale(0.95);
}

.net-age-disclaimer {
    font-size: 0.75em;
    opacity: 0.8;
}

/* ==================== Content ==================== */

.content {
    padding: 1rem 0;
}

.content-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.topic-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    transition: all var(--transition-normal);
    opacity: 0;
    transform: translateY(20px);
    display: flex;
    flex-direction: column;
}

.topic-card.visible {
    opacity: 1;
    transform: translateY(0);
}

.topic-card:hover {
    border-color: var(--accent-blue);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.topic-icon {
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-blue-light));
    border-radius: 12px;
    color: white;
    font-size: 1.5rem;
    margin-bottom: 1rem;
    flex-shrink: 0;
}

.topic-title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.title-text {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text-primary);
}

.title-line {
    flex: 1;
    height: 2px;
    background: linear-gradient(90deg, var(--accent-blue), transparent);
    opacity: 0.3;
}

.topic-content p {
    font-size: 0.9rem;
    line-height: 1.7;
    color: var(--text-secondary);
    text-align: justify;
    flex: 1;
}

.learn-more-link {
    color: var(--accent-blue);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition-normal);
}

.learn-more-link:hover {
    color: var(--accent-blue-dark);
    text-decoration: underline;
}

/* ==================== Navigation ==================== */

.navigation {
    padding: 4rem 0;
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-light);
}

.nav-title {
    text-align: center;
    margin-bottom: 2.5rem;
}

.nav-title-text {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
}

.nav-title-underline {
    width: 60px;
    height: 3px;
    background: var(--accent-blue);
    margin: 0.5rem auto 0;
    border-radius: 2px;
}

.nav-links {
    display: flex;
    justify-content: center;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    padding: 2rem 2.5rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    text-decoration: none;
    color: var(--text-primary);
    transition: all var(--transition-normal);
    min-width: 350px;
}

.nav-link:hover {
    border-color: var(--accent-blue);
    box-shadow: var(--shadow-md);
    transform: translateY(-3px);
}

.nav-icon-wrapper {
    font-size: 2rem;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-blue-light));
    border-radius: 12px;
    color: white;
}

.nav-content h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
    color: var(--text-primary);
}

.nav-content p {
    font-size: 0.875rem;
    color: var(--text-muted);
}

.nav-arrow {
    margin-left: auto;
    font-size: 1.25rem;
    color: var(--accent-blue);
}

/* ==================== Footer ==================== */

.footer {
    padding: 3rem 0;
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-light);
}

.footer-content {
    margin-bottom: 1.5rem;
}

.footer-info {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    align-items: center;
}

.contact, .icp {
    font-size: 1rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.contact i, .icp i {
    color: var(--accent-blue);
}

.icp a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color var(--transition-normal);
}

.icp a:hover {
    color: var(--accent-blue);
    text-decoration: underline;
}

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.copyright {
    font-size: 0.875rem;
    color: var(--text-muted);
}

.social-links {
    display: flex;
    gap: 0.75rem;
}

.tech-badge {
    padding: 0.4rem 0.8rem;
    font-size: 0.75rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    color: var(--accent-blue);
    font-weight: 500;
}

/* ==================== 响应式设计 ==================== */

@media (max-width: 768px) {
    .logo {
        font-size: 2rem;
    }

    .content-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .topic-card {
        padding: 1.5rem;
    }

    .nav-links {
        flex-direction: column;
    }

    .nav-link {
        width: 100%;
        max-width: 350px;
    }

    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }

    .header {
        padding: 2rem 0 1.5rem;
    }

    .logo {
        font-size: 1.75rem;
    }

    .tagline {
        font-size: 0.85rem;
    }

    .net-age-predictor {
        flex-direction: column;
        gap: 0.75rem;
    }

    .net-age-input {
        width: 100%;
    }

    .net-age-btn {
        width: 100%;
        border-radius: 25px;
        height: 44px;
    }

    .net-age-result {
        font-size: 0.85rem;
    }

    .content {
        padding: 2rem 0;
    }

    .topic-icon {
        width: 48px;
        height: 48px;
        font-size: 1.3rem;
    }

    .title-text {
        font-size: 1.2rem;
    }

    .topic-content p {
        font-size: 0.85rem;
    }
}

/* ==================== 滚动条样式 ==================== */

::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--accent-blue);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-blue-dark);
}

/* 选择文字样式 */
::selection {
    background: rgba(37, 99, 235, 0.2);
    color: var(--text-primary);
}

::-moz-selection {
    background: rgba(37, 99, 235, 0.2);
    color: var(--text-primary);
}