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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container {
    background: white;
    border-radius: 15px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.1);
    padding: 30px;
    width: 100%;
    max-width: 450px;
}

h1 {
    text-align: center;
    color: #333;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.logo {
    font-size: 24px;
    font-weight: bold;
    color: #667eea;
}

.info-box {
    background: #fff3cd;
    color: #856404;
    border: 1px solid #ffeaa7;
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: 14px;
}

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

label {
    display: block;
    margin-bottom: 8px;
    color: #333;
    font-weight: 600;
}

input {
    width: 100%;
    padding: 12px;
    border: 2px solid #e1e5e9;
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s;
}

input:focus {
    outline: none;
    border-color: #667eea;
}

.amount-buttons {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    margin-top: 10px;
}

.amount-btn {
    padding: 10px;
    background: #f8f9fa;
    border: 2px solid #e1e5e9;
    border-radius: 6px;
    cursor: pointer;
    text-align: center;
    transition: all 0.3s;
}

.amount-btn:hover {
    border-color: #667eea;
    background: #f0f4ff;
}

.amount-btn.active {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

button {
    width: 100%;
    padding: 14px;
    background: #667eea;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    cursor: pointer;
    margin-top: 10px;
    transition: background 0.3s;
}

button:hover {
    background: #5a6fd8;
}

button:disabled {
    background: #ccc;
    cursor: not-allowed;
}

.btn-success {
    background: #28a745;
}

.btn-success:hover {
    background: #218838;
}

.result {
    margin-top: 15px;
    padding: 15px;
    border-radius: 8px;
    display: none;
}

.success {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.error {
    background: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.user-info {
    background: #e7f3ff;
    color: #004085;
    border: 1px solid #b8daff;
    margin: 15px 0;
    padding: 15px;
    border-radius: 8px;
    display: none;
}

.loader {
    display: none;
    text-align: center;
    margin: 20px 0;
}

.loader::after {
    content: '';
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid #f3f3f3;
    border-top: 3px solid #667eea;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

.payment-info {
    background: #e8f5e8;
    border: 1px solid #c3e6cb;
    padding: 15px;
    border-radius: 8px;
    margin: 15px 0;
    display: none;
}

.success-icon {
    font-size: 80px;
    color: #28a745;
    margin-bottom: 20px;
    text-align: center;
}

.info {
    background: #d4edda;
    color: #155724;
    padding: 20px;
    border-radius: 10px;
    margin: 20px 0;
}

.btn {
    display: inline-block;
    padding: 12px 30px;
    background: #667eea;
    color: white;
    text-decoration: none;
    border-radius: 8px;
    margin-top: 20px;
    text-align: center;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}