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

body {
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    overflow-x: hidden;
    position: relative;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    position: relative;
    z-index: 1;
}

/* Birthday Animation */
.birthday-animation {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
}

.balloon {
    position: absolute;
    font-size: 3rem;
    animation: float 6s ease-in-out infinite;
}

.balloon1 {
    top: 10%;
    left: 10%;
    animation-delay: 0s;
}

.balloon2 {
    top: 20%;
    right: 15%;
    animation-delay: 2s;
}

.balloon3 {
    top: 15%;
    left: 50%;
    animation-delay: 4s;
}

.cake {
    position: absolute;
    bottom: 10%;
    right: 10%;
    font-size: 4rem;
    animation: bounce 3s ease-in-out infinite;
}

.sparkles span {
    position: absolute;
    font-size: 1.5rem;
    animation: sparkle 2s ease-in-out infinite;
}

.sparkles span:nth-child(1) { top: 20%; left: 20%; animation-delay: 0s; }
.sparkles span:nth-child(2) { top: 30%; right: 25%; animation-delay: 0.5s; }
.sparkles span:nth-child(3) { top: 60%; left: 30%; animation-delay: 1s; }
.sparkles span:nth-child(4) { top: 70%; right: 40%; animation-delay: 1.5s; }
.sparkles span:nth-child(5) { top: 40%; left: 60%; animation-delay: 2s; }

/* Floating Elements */
.floating-elements {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
}

.floating-icon {
    position: absolute;
    font-size: 2rem;
    opacity: 0.6;
    animation: float-slow 8s ease-in-out infinite;
}

.floating-icon:nth-child(1) { top: 15%; left: 5%; animation-delay: 0s; }
.floating-icon:nth-child(2) { top: 25%; right: 8%; animation-delay: 2s; }
.floating-icon:nth-child(3) { top: 55%; left: 8%; animation-delay: 4s; }
.floating-icon:nth-child(4) { top: 65%; right: 5%; animation-delay: 6s; }

/* Main Content */
.main-content {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-radius: 25px;
    padding: 40px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    margin-top: 20px;
    position: relative;
    z-index: 2;
}

.birthday-header {
    text-align: center;
    margin-bottom: 40px;
}

.title {
    font-size: 3.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, #ff6b6b, #feca57, #48dbfb, #ff9ff3);
    background-size: 400% 400%;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: gradient-shift 3s ease-in-out infinite;
    margin-bottom: 15px;
}

.subtitle {
    font-size: 1.2rem;
    color: #666;
    font-weight: 300;
}

/* Form Styles */
.tip-form {
    max-width: 600px;
    margin: 0 auto 40px;
}

.form-group {
    margin-bottom: 25px;
}

.form-group label {
    display: block;
    font-weight: 600;
    color: #333;
    margin-bottom: 8px;
    font-size: 1.1rem;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 15px;
    border: 2px solid #e1e5e9;
    border-radius: 12px;
    font-size: 1rem;
    font-family: inherit;
    transition: all 0.3s ease;
    background: #fff;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    transform: translateY(-2px);
}

.form-group small {
    display: block;
    margin-top: 5px;
    color: #888;
    font-size: 0.9rem;
}

/* Amount Options */
.amount-options {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(80px, 1fr));
    gap: 10px;
    margin-bottom: 15px;
}

.amount-btn {
    padding: 12px;
    border: 2px solid #e1e5e9;
    border-radius: 10px;
    background: #fff;
    color: #333;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1rem;
}

.amount-btn:hover {
    border-color: #667eea;
    background: #667eea;
    color: #fff;
    transform: translateY(-2px);
}

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

/* Submit Button */
.submit-btn {
    width: 100%;
    padding: 18px;
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: #fff;
    border: none;
    border-radius: 15px;
    font-size: 1.2rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    font-family: inherit;
}

.submit-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 30px rgba(102, 126, 234, 0.4);
}

.submit-btn:active {
    transform: translateY(-1px);
}

.btn-loading {
    display: none;
}

.submit-btn.loading .btn-text {
    display: none;
}

.submit-btn.loading .btn-loading {
    display: block;
}

/* Features Section */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.feature {
    text-align: center;
    padding: 30px 20px;
    background: rgba(255, 255, 255, 0.7);
    border-radius: 20px;
    transition: all 0.3s ease;
}

.feature:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.9);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 20px;
    display: block;
}

.feature h3 {
    font-size: 1.3rem;
    color: #333;
    margin-bottom: 10px;
    font-weight: 600;
}

.feature p {
    color: #666;
    line-height: 1.6;
}

/* Alerts */
.alert {
    padding: 15px 20px;
    border-radius: 12px;
    margin-bottom: 25px;
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 500;
}

.alert-error {
    background: #fee;
    color: #c53030;
    border: 1px solid #fed7d7;
}

.alert-success {
    background: #f0fff4;
    color: #38a169;
    border: 1px solid #c6f6d5;
}

/* Animations */
@keyframes float {
    0%, 100% { transform: translateY(0px) rotate(0deg); }
    50% { transform: translateY(-20px) rotate(5deg); }
}

@keyframes bounce {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-15px); }
}

@keyframes sparkle {
    0%, 100% { opacity: 0.3; transform: scale(0.8); }
    50% { opacity: 1; transform: scale(1.2); }
}

@keyframes float-slow {
    0%, 100% { transform: translateY(0px) translateX(0px); }
    50% { transform: translateY(-30px) translateX(10px); }
}

@keyframes gradient-shift {
    0%, 100% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    .main-content {
        padding: 25px;
        margin-top: 10px;
    }
    
    .title {
        font-size: 2.5rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .amount-options {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .features {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .balloon, .cake, .sparkles span {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .main-content {
        padding: 20px;
    }
    
    .title {
        font-size: 2rem;
    }
    
    .amount-options {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .form-group input,
    .form-group textarea {
        padding: 12px;
    }
    
    .submit-btn {
        padding: 15px;
        font-size: 1.1rem;
    }
}

/* Loading Animation */
.loading {
    opacity: 0.7;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid #fff;
    border-top: 2px solid transparent;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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