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

:root {
    --primary: #ff6f00;
    --primary-light: #ff8c42;
    --primary-dark: #e65c00;
    --primary-gradient: linear-gradient(135deg, #ff6f00, #ff8c42, #ffab70);
    --bg: #f7f7f7;
    --bg-card: #ffffff;
    --bg-section: #ffffff;
    --text: #333333;
    --text-secondary: #555555;
    --text-muted: #888888;
    --border: #f0f0f0;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 2px 12px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 6px 24px rgba(0, 0, 0, 0.1);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-full: 30px;
    --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark mode variables */
body.dark-mode {
    --bg: #1a1a2e;
    --bg-card: #2a2a3e;
    --bg-section: #222222;
    --text: #e0e0e0;
    --text-secondary: #bbbbbb;
    --text-muted: #888888;
    --border: #3a3a4e;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 2px 12px rgba(0, 0, 0, 0.25);
    --shadow-lg: 0 6px 24px rgba(0, 0, 0, 0.35);
}

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.8;
    font-size: 16px;
    transition: background var(--transition), color var(--transition);
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover {
    text-decoration: underline;
}

/* ===== Container ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ===== Header ===== */
header {
    background: var(--bg-card);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: background var(--transition), box-shadow var(--transition);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: 28px;
    font-weight: 800;
    color: var(--primary);
    letter-spacing: 1px;
    transition: transform var(--transition);
}

.logo:hover {
    transform: scale(1.03);
}

.logo span {
    color: var(--text);
}

.nav {
    display: flex;
    gap: 24px;
    align-items: center;
}

.nav a {
    font-size: 15px;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color var(--transition), transform var(--transition);
    position: relative;
}

.nav a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: width var(--transition);
}

.nav a:hover {
    color: var(--primary);
    transform: translateY(-1px);
    text-decoration: none;
}

.nav a:hover::after {
    width: 100%;
}

.nav .search-box {
    display: flex;
    align-items: center;
    background: var(--bg);
    border-radius: var(--radius-lg);
    padding: 4px 12px;
    transition: box-shadow var(--transition), background var(--transition);
    border: 1px solid transparent;
}

.nav .search-box:focus-within {
    box-shadow: 0 0 0 2px var(--primary);
    background: var(--bg-card);
}

.search-box input {
    border: none;
    background: transparent;
    padding: 6px 8px;
    font-size: 14px;
    outline: none;
    width: 160px;
    color: var(--text);
    transition: width var(--transition);
}

.search-box input:focus {
    width: 200px;
}

.search-box button {
    background: transparent;
    border: none;
    cursor: pointer;
    color: var(--primary);
    font-size: 16px;
    transition: transform var(--transition);
}

.search-box button:hover {
    transform: scale(1.15);
}

.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    cursor: pointer;
    padding: 4px;
    transition: opacity var(--transition);
}

.menu-toggle:hover {
    opacity: 0.7;
}

.menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text);
    border-radius: 2px;
    transition: all var(--transition);
}

.menu-toggle.open span:nth-child(1) {
    transform: rotate(45deg) translate(4px, 4px);
}

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

.menu-toggle.open span:nth-child(3) {
    transform: rotate(-45deg) translate(4px, -4px);
}

/* ===== Hero ===== */
.hero {
    background: var(--primary-gradient);
    color: #fff;
    padding: 80px 20px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 40%, rgba(255,255,255,0.1) 0%, transparent 60%),
                radial-gradient(circle at 70% 60%, rgba(255,255,255,0.08) 0%, transparent 50%);
    animation: heroGlow 8s ease-in-out infinite alternate;
}

@keyframes heroGlow {
    0% { transform: translate(0, 0); }
    100% { transform: translate(5%, 3%); }
}

.hero h1 {
    font-size: 42px;
    font-weight: 800;
    margin-bottom: 16px;
    text-shadow: 1px 2px 4px rgba(0,0,0,0.15);
    position: relative;
    z-index: 1;
    animation: fadeInUp 0.8s ease;
}

.hero p {
    font-size: 18px;
    max-width: 700px;
    margin: 0 auto 24px;
    opacity: .95;
    position: relative;
    z-index: 1;
    animation: fadeInUp 0.8s ease 0.2s both;
}

.hero .cta-btn {
    display: inline-block;
    background: #fff;
    color: var(--primary);
    padding: 14px 40px;
    border-radius: var(--radius-full);
    font-size: 18px;
    font-weight: 700;
    transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
    position: relative;
    z-index: 1;
    animation: fadeInUp 0.8s ease 0.4s both;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
}

.hero .cta-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.2);
    background: #fff8f0;
    text-decoration: none;
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(30px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===== Section ===== */
.section {
    padding: 60px 20px;
    background: var(--bg-section);
    margin-bottom: 4px;
    transition: background var(--transition);
}

.section:nth-child(even) {
    background: var(--bg);
}

.section-title {
    font-size: 30px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 40px;
    color: var(--text);
    position: relative;
}

.section-title:after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: var(--primary);
    margin: 12px auto 0;
    border-radius: 2px;
    transition: width var(--transition);
}

.section-title:hover:after {
    width: 100px;
}

/* ===== Grid ===== */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

/* ===== Card ===== */
.card {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    padding: 24px;
    box-shadow: var(--shadow-md);
    transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
    border: 1px solid var(--border);
    position: relative;
    overflow: hidden;
    opacity: 0;
    transform: translateY(20px);
}

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

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--primary-gradient);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition);
}

.card:hover::before {
    transform: scaleX(1);
}

.card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.card h3 {
    font-size: 20px;
    margin-bottom: 12px;
    color: var(--text);
}

.card p {
    color: var(--text-secondary);
    font-size: 15px;
    line-height: 1.7;
}

.card .meta {
    font-size: 13px;
    color: var(--text-muted);
    margin-top: 12px;
}

.icon {
    width: 48px;
    height: 48px;
    margin-bottom: 16px;
    display: inline-block;
    transition: transform var(--transition);
}

.card:hover .icon {
    transform: scale(1.1) rotate(-5deg);
}

/* ===== Articles ===== */
.articles .article-item {
    padding: 20px 0;
    border-bottom: 1px solid var(--border);
    display: flex;
    gap: 20px;
    align-items: flex-start;
    transition: background var(--transition), padding var(--transition);
    border-radius: var(--radius-sm);
}

.article-item:hover {
    background: var(--bg);
    padding: 20px 12px;
}

.article-item:last-child {
    border-bottom: none;
}

.article-item .thumb {
    width: 120px;
    height: 80px;
    border-radius: var(--radius-sm);
    background: var(--border);
    flex-shrink: 0;
    overflow: hidden;
    transition: transform var(--transition), box-shadow var(--transition);
}

.article-item:hover .thumb {
    transform: scale(1.05);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.article-item .info {
    flex: 1;
}

.article-item h3 {
    font-size: 18px;
    margin-bottom: 6px;
    color: var(--text);
    transition: color var(--transition);
}

.article-item:hover h3 {
    color: var(--primary);
}

.article-item .summary {
    color: var(--text-secondary);
    font-size: 14px;
    line-height: 1.6;
}

.article-item .date {
    color: var(--text-muted);
    font-size: 13px;
    margin-top: 6px;
}

.article-item .read-more {
    color: var(--primary);
    font-size: 14px;
    font-weight: 500;
    transition: gap var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.article-item .read-more:hover {
    gap: 8px;
}

/* ===== FAQ ===== */
.faq-list {
    border-top: 1px solid var(--border);
}

.faq-item {
    border-bottom: 1px solid var(--border);
    padding: 16px 0;
    transition: background var(--transition);
}

.faq-item:hover {
    background: var(--bg);
    padding-left: 8px;
    padding-right: 8px;
    border-radius: var(--radius-sm);
}

.faq-question {
    font-weight: 600;
    font-size: 17px;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text);
    transition: color var(--transition);
}

.faq-question:hover {
    color: var(--primary);
}

.faq-question .arrow {
    transition: transform var(--transition);
    font-size: 14px;
}

.faq-answer {
    padding-top: 12px;
    color: var(--text-secondary);
    line-height: 1.7;
    display: none;
    font-size: 15px;
    animation: slideDown 0.3s ease;
}

@keyframes slideDown {
    from { opacity: 0; max-height: 0; }
    to { opacity: 1; max-height: 500px; }
}

.faq-item.active .faq-answer {
    display: block;
}

.faq-item.active .arrow {
    transform: rotate(180deg);
}

/* ===== HowTo Steps ===== */
.howto-steps {
    counter-reset: step;
    padding: 0;
    list-style: none;
}

.howto-steps li {
    counter-increment: step;
    padding: 16px 0 16px 50px;
    position: relative;
    border-bottom: 1px solid var(--border);
    font-size: 15px;
    color: var(--text-secondary);
    transition: background var(--transition), padding var(--transition);
}

.howto-steps li:hover {
    background: var(--bg);
    padding-left: 56px;
    border-radius: var(--radius-sm);
}

.howto-steps li:before {
    content: counter(step);
    position: absolute;
    left: 0;
    top: 14px;
    width: 34px;
    height: 34px;
    background: var(--primary-gradient);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 16px;
    transition: transform var(--transition), box-shadow var(--transition);
}

.howto-steps li:hover:before {
    transform: scale(1.1);
    box-shadow: 0 4px 12px rgba(255,111,0,0.3);
}

/* ===== Footer ===== */
.footer {
    background: #222;
    color: #aaa;
    padding: 40px 20px 20px;
    transition: background var(--transition);
}

body.dark-mode .footer {
    background: #111;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    max-width: 1200px;
    margin: 0 auto;
}

.footer h4 {
    color: #fff;
    font-size: 16px;
    margin-bottom: 12px;
    position: relative;
    display: inline-block;
}

.footer h4::after {
    content: '';
    display: block;
    width: 30px;
    height: 2px;
    background: var(--primary);
    margin-top: 4px;
    transition: width var(--transition);
}

.footer h4:hover::after {
    width: 50px;
}

.footer a {
    color: #aaa;
    display: block;
    margin-bottom: 6px;
    font-size: 14px;
    transition: color var(--transition), padding var(--transition);
}

.footer a:hover {
    color: var(--primary);
    padding-left: 4px;
    text-decoration: none;
}

.footer-bottom {
    border-top: 1px solid #444;
    margin-top: 30px;
    padding-top: 20px;
    text-align: center;
    font-size: 13px;
    color: #777;
}

/* ===== Back to Top ===== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 48px;
    height: 48px;
    background: var(--primary-gradient);
    color: #fff;
    border: none;
    border-radius: 50%;
    font-size: 22px;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 999;
    transition: transform var(--transition), box-shadow var(--transition), opacity var(--transition);
    opacity: 0;
}

.back-to-top.visible {
    display: flex;
    opacity: 1;
}

.back-to-top:hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 6px 20px rgba(255,111,0,0.4);
}

/* ===== Banner Slider ===== */
.banner-slider {
    position: relative;
    overflow: hidden;
    border-radius: var(--radius-md);
    margin-bottom: 20px;
    background: #1a1a2e;
    height: 300px;
}

.banner-slide {
    position: absolute;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-size: 24px;
    font-weight: 700;
    transition: opacity 0.8s ease, transform 0.8s ease;
    opacity: 0;
    transform: scale(1.05);
}

.banner-slide.active {
    opacity: 1;
    transform: scale(1);
}

.banner-dots {
    position: absolute;
    bottom: 16px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 8px;
}

.banner-dots span {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: rgba(255,255,255,0.5);
    cursor: pointer;
    transition: all var(--transition);
}

.banner-dots span:hover {
    background: rgba(255,255,255,0.8);
    transform: scale(1.2);
}

.banner-dots span.active {
    background: var(--primary);
    width: 24px;
    border-radius: 5px;
}

/* ===== Dark Mode Toggle ===== */
body.dark-mode .section {
    background: var(--bg-section);
    color: var(--text);
}

body.dark-mode .card {
    background: var(--bg-card);
    border-color: var(--border);
}

body.dark-mode .card h3 {
    color: var(--text);
}

body.dark-mode .card p {
    color: var(--text-secondary);
}

body.dark-mode .nav a {
    color: var(--text-secondary);
}

body.dark-mode .search-box {
    background: var(--bg);
}

body.dark-mode .search-box input {
    color: var(--text);
}

body.dark-mode .faq-question {
    color: var(--text);
}

body.dark-mode .faq-answer {
    color: var(--text-secondary);
}

body.dark-mode .article-item {
    border-color: var(--border);
}

body.dark-mode .article-item .summary {
    color: var(--text-secondary);
}

body.dark-mode .article-item .date {
    color: var(--text-muted);
}

body.dark-mode .menu-toggle span {
    background: var(--text);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--bg-card);
        flex-direction: column;
        padding: 20px;
        gap: 16px;
        box-shadow: 0 8px 24px rgba(0,0,0,0.15);
        backdrop-filter: blur(12px);
        -webkit-backdrop-filter: blur(12px);
        animation: slideDown 0.3s ease;
    }

    .nav.open {
        display: flex;
    }

    .nav .search-box {
        width: 100%;
    }

    .search-box input {
        width: 100%;
    }

    .search-box input:focus {
        width: 100%;
    }

    .menu-toggle {
        display: flex;
    }

    .hero h1 {
        font-size: 30px;
    }

    .hero p {
        font-size: 16px;
    }

    .hero {
        padding: 60px 16px;
    }

    .section {
        padding: 40px 16px;
    }

    .section-title {
        font-size: 24px;
    }

    .grid {
        grid-template-columns: 1fr;
    }

    .article-item {
        flex-direction: column;
    }

    .article-item .thumb {
        width: 100%;
        height: 140px;
    }

    .banner-slider {
        height: 200px;
    }

    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 40px;
        height: 40px;
        font-size: 18px;
    }

    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 480px) {
    .footer-grid {
        grid-template-columns: 1fr;
    }

    .hero h1 {
        font-size: 24px;
    }

    .container {
        padding: 0 12px;
    }

    .card {
        padding: 16px;
    }
}

/* ===== Glassmorphism Effect ===== */
.glass {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
}

body.dark-mode .glass {
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.05);
}

/* ===== Scroll Animations ===== */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

.slide-in-left {
    opacity: 0;
    transform: translateX(-30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.slide-in-left.visible {
    opacity: 1;
    transform: translateX(0);
}

.slide-in-right {
    opacity: 0;
    transform: translateX(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.slide-in-right.visible {
    opacity: 1;
    transform: translateX(0);
}

/* ===== Number Stats Animation ===== */
.stat-number {
    display: inline-block;
    transition: all 0.3s ease;
}

/* ===== Smooth Scrolling ===== */
html {
    scroll-behavior: smooth;
}

/* ===== Selection ===== */
::selection {
    background: var(--primary);
    color: #fff;
}

/* ===== Focus Styles ===== */
:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* ===== Loading Spinner (for future use) ===== */
.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ===== Custom Scrollbar ===== */
::-webkit-scrollbar {
    width: 8px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--primary);
    border-radius: 4px;
}

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