/* ========================================
   Telegram中文版下载站 - 样式表
   ======================================== */

/* CSS Variables */
:root {
    --primary-color: #0088cc;
    --primary-dark: #006699;
    --primary-light: #4db8ff;
    --secondary-color: #24a1de;
    --accent-color: #31b545;
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --text-light: #999999;
    --bg-primary: #ffffff;
    --bg-secondary: #f5f7fa;
    --bg-dark: #17212b;
    --border-color: #e0e6ed;
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --transition: all 0.3s ease;
    --container-width: 1200px;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "PingFang SC", "Microsoft YaHei", sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

ul {
    list-style: none;
}

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
}

/* Container */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* ========================================
   Header
   ======================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--primary-color);
}

.logo-icon {
    font-size: 1.5rem;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 30px;
}

.nav-link {
    font-weight: 500;
    color: var(--text-secondary);
    position: relative;
}

.nav-link:hover {
    color: var(--primary-color);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: var(--transition);
}

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

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 5px;
}

.mobile-menu-toggle span {
    display: block;
    width: 25px;
    height: 2px;
    background: var(--text-primary);
    transition: var(--transition);
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
    padding: 140px 0 80px;
    background: linear-gradient(135deg, #f5f7fa 0%, #e8f4fc 50%, #f0f8ff 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 80%;
    height: 150%;
    background: radial-gradient(ellipse, rgba(0, 136, 204, 0.08) 0%, transparent 70%);
    pointer-events: none;
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 16px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
    font-weight: 500;
}

.hero-desc {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 32px;
    max-width: 500px;
}

.hero-cta {
    margin-bottom: 40px;
}

.hero-stats {
    display: flex;
    gap: 40px;
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* Phone Mockup */
.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.phone-mockup {
    width: 280px;
    height: 560px;
    background: var(--bg-dark);
    border-radius: 40px;
    padding: 12px;
    box-shadow: var(--shadow-lg), 0 20px 60px rgba(0, 136, 204, 0.2);
    transform: perspective(1000px) rotateY(-5deg) rotateX(5deg);
    transition: var(--transition);
}

.phone-mockup:hover {
    transform: perspective(1000px) rotateY(0deg) rotateX(0deg);
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: var(--bg-dark);
    border-radius: 32px;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.chat-header {
    background: var(--primary-color);
    padding: 16px;
    text-align: center;
}

.chat-title {
    color: white;
    font-weight: 600;
    font-size: 1rem;
}

.chat-messages {
    flex: 1;
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    overflow: hidden;
}

.message {
    max-width: 80%;
    padding: 10px 14px;
    border-radius: 18px;
    font-size: 0.875rem;
    position: relative;
    animation: fadeInUp 0.5s ease forwards;
    opacity: 0;
}

.message:nth-child(1) { animation-delay: 0.2s; }
.message:nth-child(2) { animation-delay: 0.4s; }
.message:nth-child(3) { animation-delay: 0.6s; }

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.message.received {
    background: #2b333b;
    color: white;
    align-self: flex-start;
    border-bottom-left-radius: 4px;
}

.message.sent {
    background: var(--primary-color);
    color: white;
    align-self: flex-end;
    border-bottom-right-radius: 4px;
}

.message-text {
    display: block;
    margin-bottom: 4px;
}

.message-time {
    font-size: 0.7rem;
    opacity: 0.7;
}

/* ========================================
   Buttons
   ======================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    transition: var(--transition);
    cursor: pointer;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    box-shadow: 0 4px 15px rgba(0, 136, 204, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 136, 204, 0.4);
}

.btn-large {
    padding: 16px 32px;
    font-size: 1.125rem;
}

.btn-download {
    background: var(--primary-color);
    color: white;
    width: 100%;
}

.btn-download:hover {
    background: var(--primary-dark);
}

.btn-secondary {
    background: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
    background: var(--primary-color);
    color: white;
}

.btn-icon {
    width: 20px;
    height: 20px;
}

/* ========================================
   Section Styles
   ======================================== */
section {
    padding: 80px 0;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: 48px;
}

/* ========================================
   Download Section
   ======================================== */
.download-section {
    background: var(--bg-secondary);
}

.download-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
}

.download-card {
    background: white;
    border-radius: var(--radius-lg);
    padding: 32px;
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.download-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.platform-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto 20px;
    color: var(--primary-color);
}

.platform-icon svg {
    width: 100%;
    height: 100%;
}

.platform-name {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 8px;
}

.platform-desc {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
}

/* ========================================
   Features Section
   ======================================== */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 32px;
}

.feature-item {
    padding: 32px;
    background: white;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.feature-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-3px);
}

.feature-icon {
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
    color: white;
}

.feature-icon svg {
    width: 28px;
    height: 28px;
}

.feature-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 12px;
}

.feature-desc {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ========================================
   Guide Section
   ======================================== */
.guide-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
}

.guide-section .section-title,
.guide-section .section-subtitle {
    color: white;
}

.guide-steps {
    display: flex;
    justify-content: center;
    gap: 40px;
    flex-wrap: wrap;
}

.step-item {
    display: flex;
    align-items: flex-start;
    gap: 20px;
    max-width: 300px;
}

.step-number {
    width: 48px;
    height: 48px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
    flex-shrink: 0;
}

.step-content h3 {
    font-size: 1.125rem;
    margin-bottom: 8px;
}

.step-content p {
    opacity: 0.9;
    font-size: 0.95rem;
}

/* ========================================
   FAQ Section
   ======================================== */
.faq-section {
    background: var(--bg-secondary);
}

.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    background: white;
    border-radius: var(--radius-md);
    margin-bottom: 16px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.faq-question {
    width: 100%;
    padding: 20px 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 1.1rem;
    font-weight: 600;
    text-align: left;
    background: white;
    transition: var(--transition);
}

.faq-question:hover {
    background: var(--bg-secondary);
}

.faq-question[aria-expanded="true"] {
    background: var(--bg-secondary);
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(180deg);
}

.faq-icon {
    width: 24px;
    height: 24px;
    color: var(--primary-color);
    transition: var(--transition);
    flex-shrink: 0;
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.faq-answer.active {
    max-height: 500px;
}

.faq-answer p {
    padding: 0 24px 20px;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background: var(--bg-dark);
    color: white;
    padding: 60px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 60px;
    margin-bottom: 40px;
}

.footer-brand .logo-icon {
    font-size: 2rem;
}

.footer-title {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    margin: 16px 0 8px;
}

.footer-desc {
    color: rgba(255, 255, 255, 0.7);
}

.footer-column h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 20px;
    color: white;
}

.footer-column ul li {
    margin-bottom: 12px;
}

.footer-column ul li a {
    color: rgba(255, 255, 255, 0.7);
    transition: var(--transition);
}

.footer-column ul li a:hover {
    color: var(--primary-light);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 30px;
    text-align: center;
    color: rgba(255, 255, 255, 0.5);
    font-size: 0.875rem;
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 992px) {
    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-desc {
        margin-left: auto;
        margin-right: auto;
    }

    .hero-stats {
        justify-content: center;
    }

    .hero-visual {
        order: -1;
    }

    .phone-mockup {
        width: 240px;
        height: 480px;
    }

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

@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 20px;
        gap: 0;
        box-shadow: var(--shadow-md);
    }

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

    .nav-menu li {
        width: 100%;
    }

    .nav-link {
        display: block;
        padding: 15px 0;
        border-bottom: 1px solid var(--border-color);
    }

    .mobile-menu-toggle {
        display: flex;
    }

    .hero {
        padding: 100px 0 60px;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1.25rem;
    }

    .hero-stats {
        flex-direction: column;
        gap: 20px;
    }

    .section-title {
        font-size: 2rem;
    }

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

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

    .guide-steps {
        flex-direction: column;
        align-items: center;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 40px;
        text-align: center;
    }

    .footer-column ul li a {
        display: inline-block;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.75rem;
    }

    .section-title {
        font-size: 1.5rem;
    }

    .btn-large {
        padding: 14px 24px;
        font-size: 1rem;
    }

    .phone-mockup {
        width: 200px;
        height: 400px;
    }
}

/* ========================================
   Accessibility
   ======================================== */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* Focus styles for keyboard navigation */
a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Skip to main content link for accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--primary-color);
    color: white;
    padding: 8px;
    z-index: 100;
}

.skip-link:focus {
    top: 0;
}