/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --error-color: #ef4444;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --text-light: #64748b;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
}

/* Screen Layouts */
.screen {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

/* Login Screen */
.login-container {
    background: var(--card-bg);
    border-radius: 16px;
    padding: 40px;
    box-shadow: var(--shadow-lg);
    max-width: 420px;
    width: 100%;
    animation: fadeInUp 0.5s ease;
}

.login-container h1 {
    font-size: 28px;
    margin-bottom: 10px;
    color: var(--text-color);
    text-align: center;
}

.subtitle {
    color: var(--text-light);
    text-align: center;
    margin-bottom: 30px;
    font-size: 15px;
}

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

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

.input-group input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s ease;
}

.input-group input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.input-hint {
    display: block;
    margin-top: 6px;
    font-size: 13px;
    color: var(--text-light);
}

.info-text {
    color: var(--text-light);
    font-size: 14px;
    margin-bottom: 20px;
    text-align: center;
}

/* Buttons */
.btn-primary, .btn-secondary, .btn-small {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    width: 100%;
    margin-top: 10px;
}

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

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-primary:disabled {
    background: var(--secondary-color);
    cursor: not-allowed;
    transform: none;
}

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

.btn-secondary:hover {
    background: var(--bg-color);
    border-color: var(--text-light);
}

.btn-small {
    padding: 8px 16px;
    font-size: 14px;
    width: auto;
    margin: 0 0 0 12px;
    background: var(--success-color);
    color: white;
}

.btn-small:hover {
    background: #059669;
}

/* Error Messages */
.error-message {
    background: #fee2e2;
    color: var(--error-color);
    padding: 12px 16px;
    border-radius: 8px;
    margin-top: 20px;
    font-size: 14px;
    display: none;
    border-left: 4px solid var(--error-color);
}

/* App Screen */
#app-screen {
    display: block;
    padding: 0;
    background: var(--bg-color);
}

.app-header {
    background: white;
    padding: 20px 40px;
    box-shadow: var(--shadow-sm);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.app-header h1 {
    font-size: 24px;
    color: var(--text-color);
}

.header-controls {
    display: flex;
    align-items: center;
    gap: 20px;
}

.coin-display {
    display: flex;
    align-items: center;
    background: var(--bg-color);
    padding: 8px 16px;
    border-radius: 24px;
    font-weight: 600;
}

.coin-icon {
    font-size: 20px;
    margin-right: 8px;
}

#coin-count {
    font-size: 18px;
    color: var(--primary-color);
}

.app-main {
    max-width: 1200px;
    margin: 40px auto;
    padding: 0 40px;
}

.content {
    display: grid;
    gap: 24px;
}

.welcome-card, .action-card, .info-card {
    background: white;
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--shadow-sm);
}

.welcome-card h2 {
    color: var(--text-color);
    margin-bottom: 16px;
    font-size: 24px;
}

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

.action-card button {
    margin-top: 16px;
}

.info-card p {
    color: var(--text-light);
    margin-bottom: 8px;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.3s ease;
}

.modal-content {
    background: white;
    border-radius: 16px;
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow: auto;
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.3s ease;
}

.modal-header {
    padding: 24px 30px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h2 {
    font-size: 24px;
    color: var(--text-color);
}

.close-modal {
    font-size: 28px;
    color: var(--text-light);
    cursor: pointer;
    line-height: 1;
}

.close-modal:hover {
    color: var(--text-color);
}

.modal-body {
    padding: 30px;
}

.modal-subtitle {
    color: var(--text-light);
    margin-bottom: 20px;
    font-size: 15px;
}

/* Coin Packages */
#coin-packages-container {
    display: grid;
    gap: 16px;
}

.coin-package {
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.3s ease;
}

.coin-package:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.package-info h3 {
    font-size: 18px;
    color: var(--text-color);
    margin-bottom: 8px;
}

.package-info .coins {
    font-size: 20px;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 4px;
}

.package-info .price {
    font-size: 24px;
    font-weight: 700;
    color: var(--text-color);
}

.coin-package button {
    width: auto;
    margin: 0;
    padding: 12px 32px;
}

.loading {
    text-align: center;
    color: var(--text-light);
    padding: 40px;
}

.no-packages {
    text-align: center;
    color: var(--text-light);
    padding: 40px;
}

/* Success/Cancel Pages */
.success-container, .cancel-container {
    background: white;
    border-radius: 16px;
    padding: 60px 40px;
    box-shadow: var(--shadow-lg);
    text-align: center;
    max-width: 500px;
    animation: fadeInUp 0.5s ease;
}

.success-icon, .cancel-icon {
    font-size: 72px;
    margin-bottom: 20px;
}

.success-container h1 {
    color: var(--success-color);
    margin-bottom: 16px;
    font-size: 32px;
}

.cancel-container h1 {
    color: var(--error-color);
    margin-bottom: 16px;
    font-size: 32px;
}

.success-container p, .cancel-container p {
    color: var(--text-light);
    margin-bottom: 12px;
    font-size: 16px;
}

.success-container a, .cancel-container a {
    display: inline-block;
    margin-top: 24px;
    text-decoration: none;
}

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

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

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

/* Responsive Design */
@media (max-width: 768px) {
    .app-header {
        padding: 16px 20px;
        flex-direction: column;
        gap: 16px;
    }
    
    .app-main {
        padding: 0 20px;
        margin: 20px auto;
    }
    
    .login-container {
        padding: 30px 24px;
    }
    
    .coin-package {
        flex-direction: column;
        text-align: center;
        gap: 16px;
    }
    
    .coin-package button {
        width: 100%;
    }
    
    .modal-content {
        width: 95%;
    }
}