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

:root {
    --primary-color: #7C3AED;
    --secondary-color: #3B82F6;
    --accent-color: #EC4899;
    --success-color: #22C55E;
    --warning-color: #F97316;
    --info-color: #0EA5E9;
    --text-primary: #1E293B;
    --text-secondary: #64748B;
    --text-tertiary: #94A3B8;
    --bg-primary: #FFFFFF;
    --bg-secondary: #F8FAFC;
    --bg-tertiary: #F1F5F9;
    --border-color: #E2E8F0;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    color: var(--text-primary);
    background: var(--bg-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.navbar {
    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);
    transition: var(--transition-normal);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 20px;
    color: var(--text-primary);
    text-decoration: none;
}

.logo-img {
    width: 32px;
    height: 32px;
    border-radius: 8px;
    object-fit: cover;
}

.logo-icon {
    font-size: 28px;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 15px;
    font-weight: 500;
    transition: var(--transition-fast);
    position: relative;
}

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    transition: var(--transition-fast);
}

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

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 28px;
    height: 20px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
    z-index: 1001;
}

.mobile-menu-btn span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--text-primary);
    transition: var(--transition-fast);
}

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

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

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

.mobile-menu {
    display: none;
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    padding: 16px;
    box-shadow: var(--shadow-lg);
    z-index: 999;
    transform: translateY(-100%);
    opacity: 0;
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.mobile-menu.active {
    transform: translateY(0);
    opacity: 1;
}

.mobile-link {
    display: block;
    padding: 12px 16px;
    color: var(--text-primary);
    text-decoration: none;
    font-size: 16px;
    font-weight: 500;
    border-bottom: 1px solid var(--border-color);
    transition: var(--transition-fast);
}

.mobile-link:last-child {
    border-bottom: none;
}

.mobile-link:hover {
    background: var(--bg-secondary);
    color: var(--primary-color);
}

.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 120px 24px 80px;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, #F8FAFC 0%, #E0E7FF 50%, #FCE7F3 100%);
    z-index: -1;
}

.hero-background::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, rgba(124, 58, 237, 0.1) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-background::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -10%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(236, 72, 153, 0.1) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-content {
    max-width: 500px;
    z-index: 1;
    margin-right: 150px;
}

.hero-badge {
    display: inline-block;
    padding: 6px 16px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 500;
    margin-bottom: 24px;
    animation: fadeInUp 0.6s ease;
}

.hero-title {
    font-size: 56px;
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: 16px;
    background: linear-gradient(135deg, var(--text-primary), var(--primary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: fadeInUp 0.6s ease 0.1s both;
}

.hero-subtitle {
    font-size: 28px;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 12px;
    animation: fadeInUp 0.6s ease 0.2s both;
}

.hero-description {
    font-size: 18px;
    color: var(--text-tertiary);
    margin-bottom: 32px;
    animation: fadeInUp 0.6s ease 0.3s both;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    margin-bottom: 48px;
    animation: fadeInUp 0.6s ease 0.4s both;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 14px 28px;
    border-radius: var(--radius-md);
    font-size: 16px;
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition-fast);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: white;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

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

.hero-stats {
    display: flex;
    gap: 48px;
    animation: fadeInUp 0.6s ease 0.5s both;
}

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

.stat-number {
    display: block;
    font-size: 32px;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    font-size: 14px;
    color: var(--text-tertiary);
}

.hero-phone {
    display: flex;
    justify-content: center;
    align-items: center;
    animation: fadeInRight 0.8s ease 0.3s both;
    min-height: 700px;
}

.phone-frame {
    width: 204px;
    height: 440px;
    background: #1E293B;
    border-radius: 28px;
    padding: 3px;
    box-shadow: var(--shadow-xl);
    transform: scale(1.5);
    transform-origin: center center;
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: white;
    border-radius: 25px;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

.phone-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    border-radius: 25px;
}

.phone-content {
    padding: 16px;
}

.phone-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    font-size: 14px;
    font-weight: 600;
}

.phone-icons {
    display: flex;
    gap: 4px;
}

.phone-widget {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 16px;
}

.widget-title {
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.widget-courses {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.widget-course {
    padding: 12px;
    border-radius: var(--radius-md);
    color: white;
    font-size: 12px;
    font-weight: 500;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.course-time {
    font-size: 10px;
    opacity: 0.9;
}

.section-header {
    text-align: center;
    margin-bottom: 48px;
}

.section-title {
    font-size: 40px;
    font-weight: 700;
    margin-bottom: 12px;
    background: linear-gradient(135deg, var(--text-primary), var(--primary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-subtitle {
    font-size: 18px;
    color: var(--text-tertiary);
}

.features {
    padding: 100px 24px;
    background: var(--bg-primary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

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

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

.feature-icon {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
}

.feature-title {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.feature-description {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.6;
}

.download {
    padding: 100px 24px;
    background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.download-cards {
    display: flex;
    justify-content: center;
    gap: 24px;
    flex-wrap: wrap;
}

.download-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: 40px;
    width: 100%;
    max-width: 400px;
    text-align: center;
    border: 1px solid var(--border-color);
    transition: var(--transition-normal);
}

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

.download-icon {
    color: var(--text-primary);
    margin-bottom: 20px;
}

.android-icon {
    display: flex;
    justify-content: center;
    align-items: center;
}

.download-title {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.download-version {
    font-size: 16px;
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 4px;
}

.download-size {
    font-size: 14px;
    color: var(--text-tertiary);
    margin-bottom: 20px;
}

.download-features {
    list-style: none;
    margin-bottom: 24px;
    text-align: left;
}

.download-features li {
    padding: 8px 0;
    color: var(--text-secondary);
    font-size: 14px;
}

.download-buttons {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.btn-download {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    width: 100%;
}

.btn-download:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.btn-download-secondary:hover {
    background: var(--bg-tertiary);
}

.download-notice {
    text-align: center;
    margin-top: 32px;
    padding: 16px 24px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 14px;
}

.download-notice code {
    background: var(--bg-secondary);
    padding: 2px 8px;
    border-radius: 4px;
    font-family: monospace;
    color: var(--primary-color);
}

.changelog {
    padding: 100px 24px;
    background: var(--bg-primary);
}

.changelog-timeline {
    max-width: 800px;
    margin: 0 auto;
}

.changelog-current {
    max-width: 800px;
    margin: 0 auto;
}

.changelog-more {
    text-align: center;
    margin-top: 32px;
}

.changelog-page {
    padding: 120px 24px 80px;
    min-height: calc(100vh - 200px);
}

.page-header {
    text-align: center;
    margin-bottom: 48px;
}

.page-title {
    font-size: 40px;
    font-weight: 700;
    margin-bottom: 12px;
    background: linear-gradient(135deg, var(--text-primary), var(--primary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.page-subtitle {
    font-size: 18px;
    color: var(--text-tertiary);
}

.changelog-item {
    position: relative;
    padding-left: 32px;
    padding-bottom: 40px;
    border-left: 2px solid var(--border-color);
    margin-left: 12px;
}

.changelog-item:last-child {
    border-left: 2px solid transparent;
    padding-bottom: 0;
}

.changelog-item::before {
    content: '';
    position: absolute;
    left: -8px;
    top: 0;
    width: 16px;
    height: 16px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 50%;
}

.changelog-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.changelog-version {
    font-size: 18px;
    font-weight: 700;
    color: var(--text-primary);
}

.changelog-date {
    font-size: 14px;
    color: var(--text-tertiary);
}

.changelog-badge {
    padding: 4px 10px;
    background: linear-gradient(135deg, var(--success-color), #10B981);
    color: white;
    border-radius: 12px;
    font-size: 11px;
    font-weight: 600;
}

.changelog-content {
    background: white;
    border-radius: var(--radius-lg);
    padding: 24px;
    border: 1px solid var(--border-color);
}

.changelog-content h4 {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.changelog-content ul{
    list-style: none;
}

.changelog-content li{
    padding: 6px 0;
    color: var(--text-secondary);
    font-size: 14px;
    position: relative;
    padding-left: 20px;
}

.changelog-content li::before{
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--success-color);
}

.feedback {
    padding: 100px 24px;
    background: var(--bg-secondary);
}

.feedback-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    max-width: 1000px;
    margin: 0 auto;
}

.feedback-form {
    background: white;
    border-radius: var(--radius-xl);
    padding: 32px;
    border: 1px solid var(--border-color);
}

.feedback-form h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 24px;
    color: var(--text-primary);
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 14px;
    font-family: inherit;
    transition: var(--transition-fast);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(124, 58, 237, 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 100px;
}

.feedback-list {
    background: white;
    border-radius: var(--radius-xl);
    padding: 32px;
    border: 1px solid var(--border-color);
}

.feedback-list h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 24px;
    color: var(--text-primary);
}

.feedback-scroll {
    max-height: 400px;
    overflow-y: auto;
    padding-right: 8px;
}

.feedback-scroll::-webkit-scrollbar {
    width: 6px;
}

.feedback-scroll::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
    border-radius: 3px;
}

.feedback-scroll::-webkit-scrollbar-thumb {
    background: var(--text-tertiary);
    border-radius: 3px;
}

.feedback-item {
    padding: 16px;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    margin-bottom: 12px;
}

.feedback-item:last-child {
    margin-bottom: 0;
}

.feedback-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 8px;
}

.feedback-author {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
}

.feedback-type-badge {
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 11px;
    font-weight: 500;
}

.feedback-type-badge.suggestion {
    background: rgba(124, 58, 237, 0.1);
    color: var(--primary-color);
}

.feedback-type-badge.bug {
    background: rgba(239, 68, 68, 0.1);
    color: #EF4444;
}

.feedback-type-badge.praise {
    background: rgba(34, 197, 94, 0.1);
    color: var(--success-color);
}

.feedback-type-badge.other {
    background: rgba(100, 116, 139, 0.1);
    color: var(--text-secondary);
}

.feedback-text {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.5;
    margin-bottom: 8px;
}

.feedback-time {
    font-size: 12px;
    color: var(--text-tertiary);
}

.about {
    padding: 100px 24px;
    background: var(--bg-primary);
}

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

.about-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: 32px;
    text-align: center;
    border: 1px solid var(--border-color);
    transition: var(--transition-normal);
}

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

.about-icon {
    font-size: 48px;
    margin-bottom: 16px;
}

.about-card h3{
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.about-card p{
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.6;
}

.footer {
    background: var(--text-primary);
    color: white;
    padding: 40px 24px;
}

.footer-content {
    text-align: center;
}

.footer-brand {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 16px;
}

.footer-logo {
    width: 40px;
    height: 40px;
    border-radius: 10px;
    object-fit: cover;
}

.footer-brand .logo-icon{
    font-size: 32px;
}

.footer-copyright {
    font-size: 14px;
    color: var(--text-tertiary);
}

.footer-stats {
    font-size: 12px;
    color: var(--text-tertiary);
    margin-top: 8px;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

.footer-stats.visible {
    opacity: 0.7;
    visibility: visible;
}

.footer-logo {
    cursor: pointer;
}

.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all 0.3s ease;
    z-index: 999;
}

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:active {
    transform: scale(0.95);
}

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

@keyframes fadeInRight {
    from {
        opacity: 0;
        transform: translateX(40px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@media (max-width: 768px) {
    .navbar {
        padding: 0 16px;
    }
    
    .nav-links {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        width: 28px;
        height: 20px;
        background: transparent;
        border: none;
        cursor: pointer;
        padding: 0;
        z-index: 1001;
    }
    
    .mobile-menu-btn span {
        display: block;
        width: 100%;
        height: 2px;
        background: var(--text-primary);
        transition: var(--transition-fast);
    }
    
    .mobile-menu-btn.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .mobile-menu-btn.active span:nth-child(2) {
        opacity: 0;
    }
    
    .mobile-menu-btn.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }
    
    .mobile-menu {
        display: block;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: white;
        border-bottom: 1px solid var(--border-color);
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: transform 0.3s ease, opacity 0.3s ease, visibility 0.3s ease;
        z-index: 999;
    }
    
    .mobile-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .mobile-link {
        display: block;
        padding: 16px 24px;
        color: var(--text-primary);
        text-decoration: none;
        font-size: 16px;
        font-weight: 500;
        border-bottom: 1px solid var(--border-color);
        transition: var(--transition-fast);
    }
    
    .mobile-link:hover {
        background: var(--bg-secondary);
        color: var(--primary-color);
    }
    
    .mobile-link:last-child {
        border-bottom: none;
    }
    
    .logo-text {
        font-size: 18px;
    }
    
    .logo-img {
        width: 28px;
        height: 28px;
    }
    
    .hero {
        flex-direction: column;
        padding: 100px 16px 60px;
        text-align: center;
        min-height: auto;
    }
    
    .hero-content {
        margin-right: 0;
        max-width: 100%;
    }
    
    .hero-badge {
        font-size: 12px;
        padding: 5px 12px;
    }
    
    .hero-title {
        font-size: 32px;
        line-height: 1.2;
    }
    
    .hero-subtitle {
        font-size: 18px;
    }
    
    .hero-description {
        font-size: 15px;
    }
    
    .hero-buttons {
        flex-direction: column;
        gap: 12px;
        width: 100%;
    }
    
    .btn {
        width: 100%;
        padding: 12px 24px;
    }
    
    .hero-stats {
        justify-content: center;
        flex-wrap: wrap;
        gap: 20px;
        margin-top: 32px;
    }
    
    .stat-number {
        font-size: 24px;
    }
    
    .stat-label {
        font-size: 12px;
    }
    
    .hero-phone {
        margin-top: 40px;
        min-height: auto;
    }
    
    .phone-frame {
        width: 180px;
        height: 380px;
        transform: scale(1);
    }
    
    .section-title {
        font-size: 28px;
    }
    
    .section-subtitle {
        font-size: 15px;
    }
    
    .section-header {
        margin-bottom: 32px;
    }
    
    .features {
        padding: 60px 16px;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
        gap: 16px;
    }
    
    .feature-card {
        padding: 24px;
    }
    
    .feature-title {
        font-size: 18px;
    }
    
    .feature-description {
        font-size: 14px;
    }
    
    .download {
        padding: 60px 16px;
    }
    
    .download-cards {
        flex-direction: column;
        align-items: center;
    }
    
    .download-card {
        padding: 32px 24px;
        max-width: 100%;
    }
    
    .download-title {
        font-size: 20px;
    }
    
    .download-buttons {
        gap: 10px;
    }
    
    .download-notice {
        padding: 12px 16px;
        font-size: 13px;
    }
    
    .changelog {
        padding: 60px 16px;
    }
    
    .changelog-page {
        padding: 100px 16px 60px;
    }
    
    .page-title {
        font-size: 28px;
    }
    
    .changelog-item {
        padding-left: 24px;
        padding-bottom: 24px;
    }
    
    .changelog-header {
        flex-wrap: wrap;
        gap: 8px;
    }
    
    .changelog-version {
        font-size: 16px;
    }
    
    .changelog-content {
        padding: 16px;
    }
    
    .changelog-content h4 {
        font-size: 14px;
    }
    
    .changelog-content li {
        font-size: 13px;
    }
    
    .feedback {
        padding: 60px 16px;
    }
    
    .feedback-container {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    
    .feedback-form,
    .feedback-list {
        padding: 24px;
    }
    
    .feedback-form h3,
    .feedback-list h3 {
        font-size: 18px;
    }
    
    .form-group input,
    .form-group select,
    .form-group textarea {
        padding: 10px 14px;
        font-size: 14px;
    }
    
    .feedback-scroll {
        max-height: 300px;
    }
    
    .about {
        padding: 60px 16px;
    }
    
    .about-content {
        grid-template-columns: 1fr;
        gap: 16px;
    }
    
    .about-card {
        padding: 24px;
    }
    
    .about-icon {
        font-size: 36px;
    }
    
    .about-card h3 {
        font-size: 18px;
    }
    
    .about-card p {
        font-size: 14px;
    }
    
    .footer {
        padding: 32px 16px;
    }
    
    .footer-brand {
        font-size: 20px;
    }
    
    .footer-logo {
        width: 32px;
        height: 32px;
    }
    
    .footer-copyright {
        font-size: 12px;
    }
    
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 44px;
        height: 44px;
    }
    
    .container {
        padding: 0 16px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 28px;
    }
    
    .hero-subtitle {
        font-size: 16px;
    }
    
    .section-title {
        font-size: 24px;
    }
    
    .phone-frame {
        width: 160px;
        height: 340px;
    }
    
    .hero-stats {
        gap: 16px;
    }
    
    .stat-item {
        flex: 1;
        min-width: 80px;
    }
}