:root {
    --primary-color: #512BD4;
    --primary-dark: #3D1FA3;
    --primary-light: #7A4FE8;
    --secondary-color: #8B5CF6;
    --accent-color: #A78BFA;
    --background: #FAFAFA;
    --surface: #FFFFFF;
    --text-primary: #1F2937;
    --text-secondary: #6B7280;
    --border-color: #E5E7EB;
    --success: #10B981;
    --warning: #F59E0B;
    --danger: #EF4444;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: linear-gradient(180deg, #F3F4F6 0%, #FAFAFA 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

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

/* Navigation */
.navbar {
    background: var(--surface);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 20px;
    display: flex;
    align-items: baseline;
    gap: 1rem;
}

.logo {
    font-size: 2rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-subtitle {
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 4rem 0;
    text-align: center;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    animation: fadeInUp 0.8s ease;
}

.hero-subtitle {
    font-size: 1.25rem;
    opacity: 0.95;
    max-width: 600px;
    margin: 0 auto;
    animation: fadeInUp 0.8s ease 0.2s both;
}

/* Download Section */
.download-section {
    padding: 3rem 0;
    margin-top: -2rem;
}

.download-card {
    background: var(--surface);
    border-radius: 16px;
    padding: 3rem;
    box-shadow: var(--shadow-xl);
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
    animation: fadeInUp 0.8s ease 0.4s both;
}

.download-card h2 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.version-info {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-size: 0.875rem;
}

.download-button-container {
    margin: 2rem 0;
}

.download-button {
    display: inline-flex;
    align-items: center;
    gap: 1rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 1.25rem 2.5rem;
    border-radius: 12px;
    text-decoration: none;
    font-weight: 600;
    box-shadow: var(--shadow-lg);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.download-button:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.1);
    transform: translateX(-100%);
    transition: transform 0.3s ease;
}

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

.download-button:hover:before {
    transform: translateX(0);
}

.android-icon {
    width: 32px;
    height: 32px;
}

.button-text {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.main-text {
    font-size: 1.25rem;
    font-weight: 600;
}

.sub-text {
    font-size: 0.875rem;
    opacity: 0.9;
}

.download-note {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-top: 1.5rem;
}

.info-icon {
    width: 20px;
    height: 20px;
    color: var(--primary-color);
}

/* Instructions Section */
.instructions {
    padding: 3rem 0;
}

.tabs {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    border-bottom: 2px solid var(--border-color);
}

.tab-button {
    background: none;
    border: none;
    padding: 1rem 2rem;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    position: relative;
    transition: all 0.3s ease;
}

.tab-button:hover {
    color: var(--primary-color);
}

.tab-button.active {
    color: var(--primary-color);
}

.tab-button.active:after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--primary-color);
    border-radius: 3px 3px 0 0;
}

.tab-content {
    display: none;
    animation: fadeIn 0.5s ease;
}

.tab-content.active {
    display: block;
}

.tab-content h2 {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

/* Steps */
.step {
    display: flex;
    gap: 2rem;
    margin-bottom: 3rem;
    background: var(--surface);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.step-number {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
}

.step-content {
    flex: 1;
}

.step-content h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.step-content p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.sub-steps {
    margin-top: 1.5rem;
}

.sub-steps h4 {
    font-size: 1.125rem;
    margin: 1.5rem 0 0.75rem;
    color: var(--primary-color);
}

.sub-steps ol, .sub-steps ul {
    margin-left: 1.5rem;
    color: var(--text-secondary);
}

.sub-steps li {
    margin-bottom: 0.5rem;
    line-height: 1.8;
}

.sub-steps strong {
    color: var(--text-primary);
    font-weight: 600;
}

/* Warning Box */
.warning-box {
    background: linear-gradient(135deg, #FEF3C7, #FDE68A);
    border-left: 4px solid var(--warning);
    padding: 1.5rem;
    border-radius: 8px;
    margin: 2rem 0;
}

.warning-box h4 {
    color: #92400E;
    margin-bottom: 0.5rem;
}

.warning-box p {
    color: #78350F;
}

/* Info Box */
.info-box {
    background: linear-gradient(135deg, #EDE9FE, #DDD6FE);
    border-left: 4px solid var(--primary-color);
    padding: 1.5rem;
    border-radius: 8px;
    margin: 2rem 0;
}

.info-box h4 {
    color: var(--primary-dark);
    margin-bottom: 0.5rem;
}

.info-box ul {
    margin-left: 1.5rem;
    color: #4C1D95;
}

.info-box li {
    margin-bottom: 0.5rem;
}

/* Feature Grid */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.feature {
    background: linear-gradient(135deg, #F9FAFB, #F3F4F6);
    padding: 1.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.feature h4 {
    font-size: 1.125rem;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

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

/* Help Section */
.help-section {
    background: var(--surface);
    padding: 2rem;
    border-radius: 12px;
    margin-top: 3rem;
    border: 2px solid var(--primary-light);
}

.help-section h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.help-section ul {
    margin-left: 1.5rem;
    color: var(--text-secondary);
}

.help-section li {
    margin-bottom: 0.5rem;
}

/* Tip */
.tip {
    background: linear-gradient(135deg, #F0FDF4, #DCFCE7);
    padding: 1rem;
    border-radius: 8px;
    margin: 1rem 0;
    color: #14532D;
    border-left: 3px solid var(--success);
}

/* Footer */
footer {
    background: var(--text-primary);
    color: white;
    padding: 2rem 0;
    margin-top: 4rem;
    text-align: center;
}

.footer-note {
    opacity: 0.8;
    font-size: 0.875rem;
    margin-top: 0.5rem;
}

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

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

/* Password Protection Styles */
.password-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    z-index: 10000;
    display: flex;
    align-items: center;
    justify-content: center;
}

.password-container {
    width: 100%;
    max-width: 400px;
    padding: 20px;
}

.password-card {
    background: var(--surface);
    border-radius: 16px;
    padding: 3rem 2rem;
    box-shadow: var(--shadow-xl);
    text-align: center;
    animation: fadeInUp 0.6s ease;
}

.password-logo {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 1.5rem;
}

.password-card h2 {
    font-size: 1.5rem;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.password-card p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

#passwordForm {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.password-input {
    width: 100%;
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
    transition: all 0.3s ease;
}

.password-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(81, 43, 212, 0.1);
}

.password-input.error {
    border-color: var(--danger);
    animation: shake 0.5s ease;
}

.password-submit {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border: none;
    padding: 1rem 2rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.password-submit:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.1);
    transform: translateX(-100%);
    transition: transform 0.3s ease;
}

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

.password-submit:hover:before {
    transform: translateX(0);
}

.password-submit:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.error-message {
    color: var(--danger);
    font-size: 0.875rem;
    margin-top: 1rem;
    min-height: 20px;
    animation: fadeIn 0.3s ease;
}

.password-footer {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

.password-footer p {
    margin: 0.25rem 0;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.password-footer p:first-child {
    font-weight: 500;
    color: var(--text-primary);
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
    20%, 40%, 60%, 80% { transform: translateX(5px); }
}

/* Success Animation */
.password-overlay.success {
    animation: fadeOut 0.5s ease forwards;
}

@keyframes fadeOut {
    to {
        opacity: 0;
        visibility: hidden;
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .download-card {
        padding: 2rem 1.5rem;
    }
    
    .download-button {
        padding: 1rem 1.5rem;
    }
    
    .main-text {
        font-size: 1.125rem;
    }
    
    .tabs {
        flex-direction: column;
        border-bottom: none;
    }
    
    .tab-button {
        border-bottom: 1px solid var(--border-color);
        text-align: left;
    }
    
    .tab-button.active:after {
        display: none;
    }
    
    .step {
        flex-direction: column;
        gap: 1rem;
    }
    
    .feature-grid {
        grid-template-columns: 1fr;
    }
}