:root {
    --primary-color: #4a90e2;
    --secondary-color: #2c3e50;
    --accent-color: #e74c3c;
    --text-color: #333;
    --light-gray: #f5f6fa;
    --border-color: #eee;
    --max-width: 1200px;
    --header-height: 70px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
}

/* Header Styles */
.header {
    background: white;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
    height: var(--header-height);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
}

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

.logo span {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
}

.logo a {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 30px;
    list-style: none;
}

.nav-links a {
    text-decoration: none;
    color: var(--secondary-color);
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary-color);
}

.nav-links a.nav-donate {
    background: linear-gradient(135deg, #ff6b9d 0%, #ff8fab 100%);
    color: white !important;
    padding: 8px 16px;
    border-radius: 20px;
    transition: all 0.3s ease;
    box-shadow: 0 2px 8px rgba(255, 107, 157, 0.3);
}

.nav-links a.nav-donate:hover {
    background: linear-gradient(135deg, #ff5a8a 0%, #ff7a9d 100%);
    box-shadow: 0 4px 12px rgba(255, 107, 157, 0.4);
    transform: translateY(-1px);
}

.nav-links a.nav-donate i {
    color: white;
}

/* Language Switch Styles */
.lang-switch {
    display: flex;
    align-items: center;
    margin-left: 10px;
}

.lang-switch a {
    display: inline-flex;
    align-items: center;
    line-height: 1;
    gap: 5px;
    padding: 6px 8px;
    font-size: 0.9rem;
    color: var(--text-color);
    transition: color 0.3s ease;
}

.lang-switch a:hover {
    color: var(--primary-color);
}

.lang-switch a i {
    font-size: 0.9rem;
}

/* Main Content Styles */
main {
    margin-top: var(--header-height);
    min-height: calc(100vh - var(--header-height));
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #f8faff 0%, #e3f2fd 25%, #bbdefb 50%, #e3f2fd 75%, #f8faff 100%);
    color: #2c3e50;
    padding: 100px 20px 120px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 30% 20%, rgba(74, 144, 226, 0.1) 0%, transparent 50%),
                radial-gradient(circle at 70% 80%, rgba(41, 128, 185, 0.08) 0%, transparent 50%);
    pointer-events: none;
}

.hero-content {
    max-width: var(--max-width);
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 20px;
    color: #1a237e;
    font-weight: 700;
    text-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.hero .subtitle {
    font-size: 1.5rem;
    margin-bottom: 40px;
    color: #37474f;
    font-weight: 400;
    line-height: 1.6;
}

/* Features Section */
.features {
    padding: 80px 20px;
    background: linear-gradient(180deg, #f8faff 0%, #f5f6fa 100%);
    position: relative;
}

.features::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 60px;
    background: linear-gradient(180deg, transparent 0%, #f8faff 100%);
    pointer-events: none;
}

.features h2 {
    text-align: center;
    margin-bottom: 50px;
    font-size: 2.5rem;
    color: var(--secondary-color);
    position: relative;
    z-index: 1;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    max-width: var(--max-width);
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.feature-card {
    background: white;
    padding: 30px;
    border-radius: 10px;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: transform 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
}

.feature-card i {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.feature-card h3 {
    margin-bottom: 15px;
    color: var(--secondary-color);
}

/* Guide Section */
.guide {
    padding: 4rem 2rem;
    background-color: #f8f9fa;
}

.guide h2 {
    text-align: center;
    margin-bottom: 3rem;
    color: #2c3e50;
}

.feature-intro {
    max-width: 1200px;
    margin: 0 auto;
}

.feature-item {
    display: flex;
    align-items: center;
    margin-bottom: 4rem;
    gap: 3rem;
}

.feature-item.reverse {
    flex-direction: row-reverse;
}

.feature-text {
    flex: 1;
}

.feature-text h3 {
    font-size: 1.8rem;
    color: #2c3e50;
    margin-bottom: 1rem;
}

.feature-text p {
    font-size: 1.1rem;
    line-height: 1.6;
    color: #666;
}

.feature-image {
    flex: 1;
}

.feature-image img {
    width: 100%;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

@media (max-width: 768px) {
    .feature-item {
        flex-direction: column;
        text-align: center;
        gap: 1.5rem;
    }

    .feature-item.reverse {
        flex-direction: column;
    }

    .feature-text, .feature-image {
        flex: none;
        width: 100%;
    }
}

/* Changelog Styles */
.changelog {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: calc(var(--header-height) + 30px) 20px 40px;
}

.changelog h1 {
    text-align: center;
    margin-bottom: 30px;
    color: var(--secondary-color);
}

.version-item {
    margin-bottom: 20px;
    padding: 20px 24px;
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.version-item h2 {
    margin-bottom: 12px;
    color: var(--secondary-color);
    font-size: 1.3rem;
}

.version-item .date {
    font-size: 0.85rem;
    color: #666;
    margin-left: 10px;
    font-weight: normal;
}

.version-item ul {
    margin-left: 20px;
    margin-top: 0;
    margin-bottom: 0;
}

.version-item li {
    margin-bottom: 6px;
    line-height: 1.5;
}

/* Feedback Styles */
.feedback {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 80px 20px 60px;
}

.feedback h1 {
    text-align: center;
    margin-bottom: 50px;
    color: var(--secondary-color);
}

.feedback-channels {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.channel-item {
    text-align: center;
    padding: 30px;
    background: white;
    border-radius: 10px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    display: flex;
    flex-direction: column;
    height: 100%;
}

.channel-item i {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.channel-item h3 {
    margin-bottom: 15px;
    color: var(--secondary-color);
}

.channel-item p {
    margin-bottom: 20px;
    flex-grow: 1;
}

.channel-item .button,
.channel-item .qrcode-wrapper {
    margin-top: auto;
}

.channel-item a.button {
    padding: 8px 30px;
}

.qrcode {
    margin: 20px 0;
}

.qrcode img {
    max-width: 200px;
    border-radius: 10px;
}

.qrcode-tip {
    font-size: 0.9rem;
    color: #666;
}

/* Button Styles */
.button,
.cta-button {
    display: inline-block;
    padding: 12px 30px;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 5px;
    transition: background 0.3s;
}

.button:hover,
.cta-button:hover {
    background: #357abd;
}

.cta-button {
    font-size: 1.2rem;
    padding: 12px 32px;
    background: #3273dc;
    color: white;
    font-weight: 600;
    border-radius: 30px;
    border: none;
    transition: all 0.3s ease;
    letter-spacing: 0.5px;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.cta-button:hover {
    background: #2860b5;
}

.cta-button:active {
    transform: translateY(0);
}

.cta-button i {
    color: white;
    font-size: 1.1rem;
}

/* Download Buttons Container */
.download-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Responsive design for download buttons */
@media (max-width: 768px) {
    .download-buttons {
        flex-direction: column;
        align-items: center;
        gap: 12px;
    }
    
    .download-buttons .cta-button {
        width: 100%;
        max-width: 280px;
        justify-content: center;
    }
}

/* Footer Styles */
.footer {
    background: var(--secondary-color);
    color: white;
    padding: 40px 20px;
}

.footer-content {
    max-width: var(--max-width);
    margin: 0 auto;
    text-align: center;
}

.footer-links {
    margin-bottom: 20px;
}

.footer-links a {
    color: white;
    text-decoration: none;
    margin: 0 15px;
    transition: opacity 0.3s;
    display: inline-block;
}

.footer-links a i,
.footer-links a .fab,
.footer-links a .fas {
    font-size: 1.8rem;
}

.footer-links a:hover {
    opacity: 0.8;
}

.copyright {
    opacity: 0.8;
    font-size: 0.9rem;
}

.copyright a {
    color: white;
    text-decoration: none;
    margin-left: 10px;
    opacity: 0.8;
    transition: opacity 0.3s;
}

.copyright a:hover {
    opacity: 1;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .guide-content {
        grid-template-columns: 1fr;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .hero .subtitle {
        font-size: 1.2rem;
    }
    
    .features h2,
    .guide h2 {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .logo span {
        display: none;
    }
    
    .feature-card,
    .channel-item {
        padding: 20px;
    }
}

/* QRCode Tooltip Styles */
.qrcode-wrapper {
    position: relative;
    display: inline-block;
}

.qrcode-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 1rem;
    padding: 10px 24px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background 0.3s;
}

.qrcode-btn:hover {
    background: #357abd;
}

.channel-item .qrcode-btn i {
    font-size: 1.2rem;
    color: white;
    display: inline-block;
    margin: 0;
}

.qrcode-tooltip {
    position: absolute;
    top: calc(100% + 10px);
    left: 50%;
    transform: translateX(-50%);
    background: white;
    padding: 15px;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    display: none;
    z-index: 100;
    width: 240px;
}

.qrcode-tooltip::after {
    content: '';
    position: absolute;
    top: -8px;
    left: 50%;
    transform: translateX(-50%);
    border-left: 8px solid transparent;
    border-right: 8px solid transparent;
    border-bottom: 8px solid white;
    border-top: none;
}

.qrcode-tooltip img {
    width: 100%;
    height: auto;
    border-radius: 4px;
}

.qrcode-tooltip .qrcode-tip {
    margin: 0;
    font-size: 0.9rem;
    color: #666;
    text-align: center;
}

.qrcode-wrapper:hover .qrcode-tooltip {
    display: block;
}

/* Feedback Form Styles */
.feedback-form {
    width: 100%;
}

.feedback-form .form-group {
    margin-bottom: 15px;
    width: 100%;
}

.feedback-form input,
.feedback-form textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    font-size: 0.9rem;
    transition: border-color 0.3s;
}

.feedback-form textarea {
    height: 100px;
    resize: vertical;
    min-height: 100px;
    max-height: 200px;
}

.feedback-form input:focus,
.feedback-form textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.feedback-form button {
    width: 100%;
    border: none;
    cursor: pointer;
}

.feedback-form .error {
    color: var(--accent-color);
    font-size: 0.85rem;
    margin-top: 5px;
    display: none;
}

.toast {
    opacity: 0;
    visibility: hidden;
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translateX(-50%) translateY(-10px);
    background-color: white;
    color: #333;
    padding: 12px 20px;
    border-radius: 8px;
    z-index: 3000;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    transition: visibility 0s linear 0.3s, opacity 0.3s ease, transform 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
}

.toast::before {
    content: '';
    width: 20px;
    height: 20px;
    background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path fill="%234CAF50" d="M12 2C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2zm-2 15l-5-5 1.41-1.41L10 14.17l7.59-7.59L19 8l-9 9z"/></svg>');
    background-size: contain;
    background-repeat: no-repeat;
    transition: background-image 0.3s ease;
}

.toast.error {
    background-color: #f8d7da;
    color: #dc2626;
}

.toast.error::before {
    background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path fill="%23dc2626" d="M12 2C6.47 2 2 6.47 2 12s4.47 10 10 10 10-4.47 10-10S17.53 2 12 2zm5 13.59L15.59 17 12 13.41 8.41 17 7 15.59 10.59 12 7 8.41 8.41 7 12 10.59 15.59 7 17 8.41 13.41 12 17 15.59z"/></svg>');
}

.toast.show {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
    transition-delay: 0s;
}