/* Reset and Base Styles */
* {
    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;
    color: #333;
    overflow-x: hidden;
}

body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 50%, rgba(120, 119, 198, 0.3) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(255, 119, 198, 0.3) 0%, transparent 50%),
        radial-gradient(circle at 40% 80%, rgba(120, 219, 255, 0.3) 0%, transparent 50%);
    z-index: -1;
    animation: backgroundShift 20s ease-in-out infinite;
}

@keyframes backgroundShift {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.8; }
}

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

/* Header */
.header {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(20px);
    border-radius: 20px;
    padding: 40px;
    text-align: center;
    margin-bottom: 30px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    animation: fadeInDown 0.8s ease-out;
}

.header-content h1 {
    color: #fff;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 10px;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.header-content h1 i {
    margin-right: 15px;
    color: #ffd700;
}

.header-content p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 1.1rem;
    font-weight: 300;
}

/* Main Content */
.main-content {
    display: grid;
    gap: 30px;
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

/* Section Styling */
section {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-radius: 20px;
    padding: 30px;
    border: 1px solid rgba(255, 255, 255, 0.3);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

section:hover {
    transform: translateY(-5px);
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.15);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 2px solid rgba(102, 126, 234, 0.2);
}

.client-actions-header {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.section-header h2 {
    color: #667eea;
    font-size: 1.5rem;
    font-weight: 600;
}

.section-header h2 i {
    margin-right: 10px;
}

/* Form Styling */
.invoice-form {
    width: 100%;
}

.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.form-group {
    position: relative;
}

.form-group label {
    display: block;
    font-weight: 600;
    color: #555;
    margin-bottom: 8px;
    font-size: 0.9rem;
}

.form-group label i {
    margin-right: 8px;
    color: #667eea;
    width: 16px;
}

.form-group input {
    width: 100%;
    padding: 15px 20px;
    border: 2px solid rgba(102, 126, 234, 0.2);
    border-radius: 12px;
    font-size: 1rem;
    background: rgba(255, 255, 255, 0.9);
    transition: all 0.3s ease;
    outline: none;
}

.form-group input:focus {
    border-color: #667eea;
    background: #fff;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    transform: translateY(-2px);
}

.form-group input:valid {
    border-color: #28a745;
}

/* Button Styling */
.btn {
    padding: 15px 30px;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 10px;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left 0.5s;
}

.btn:hover::before {
    left: 100%;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
}

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

.btn-secondary {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
    box-shadow: 0 10px 20px rgba(240, 147, 251, 0.3);
}

.btn-secondary:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 30px rgba(240, 147, 251, 0.4);
}

.btn-outline {
    background: transparent;
    color: #667eea;
    border: 2px solid #667eea;
}

.btn-outline:hover {
    background: #667eea;
    color: white;
    transform: translateY(-3px);
}

.btn-copy {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    color: white;
    box-shadow: 0 10px 20px rgba(79, 172, 254, 0.3);
}

.btn-copy:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 30px rgba(79, 172, 254, 0.4);
}

.form-actions {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
    justify-content: center;
}

/* Clients List */
.clients-list {
    display: grid;
    gap: 15px;
}

.client-card {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.9) 0%, rgba(255, 255, 255, 0.7) 100%);
    border-radius: 15px;
    padding: 20px;
    border: 1px solid rgba(102, 126, 234, 0.2);
    transition: all 0.3s ease;
    cursor: pointer;
}

.client-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
    background: linear-gradient(135deg, rgba(255, 255, 255, 1) 0%, rgba(255, 255, 255, 0.9) 100%);
}

.client-info {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 15px;
    align-items: center;
}

.client-details h3 {
    color: #333;
    font-size: 1.1rem;
    margin-bottom: 5px;
}

.client-details p {
    color: #666;
    font-size: 0.9rem;
    margin: 2px 0;
}

.client-actions {
    display: flex;
    gap: 10px;
}

.btn-small {
    padding: 8px 15px;
    font-size: 0.8rem;
    border-radius: 8px;
}

/* Email Template */
.email-template {
    position: relative;
}

.email-content {
    margin-bottom: 20px;
}

.email-content textarea {
    width: 100%;
    min-height: 200px;
    padding: 20px;
    border: 2px solid rgba(102, 126, 234, 0.2);
    border-radius: 12px;
    font-family: inherit;
    font-size: 0.95rem;
    line-height: 1.6;
    background: rgba(255, 255, 255, 0.9);
    resize: vertical;
    outline: none;
}

.email-content textarea:focus {
    border-color: #667eea;
    background: #fff;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(10px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.loading-content {
    background: rgba(255, 255, 255, 0.95);
    padding: 40px;
    border-radius: 20px;
    text-align: center;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.2);
}

.loading-content i {
    font-size: 3rem;
    color: #667eea;
    margin-bottom: 20px;
}

.loading-content p {
    font-size: 1.1rem;
    color: #333;
    font-weight: 600;
}

/* Toast Notifications */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1001;
}

.toast {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 15px 25px;
    border-radius: 12px;
    margin-bottom: 10px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
    animation: slideInRight 0.3s ease-out;
    display: flex;
    align-items: center;
    gap: 10px;
    max-width: 300px;
}

.toast.success {
    background: linear-gradient(135deg, #28a745 0%, #20c997 100%);
}

.toast.error {
    background: linear-gradient(135deg, #dc3545 0%, #e83e8c 100%);
}

.toast i {
    font-size: 1.2rem;
}

/* Footer */
.footer {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(20px);
    border-radius: 20px;
    padding: 20px;
    text-align: center;
    margin-top: 30px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    animation: fadeInUp 0.8s ease-out 0.4s both;
}

.footer p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 0.9rem;
}

/* Animations */
@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(100%);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    .header {
        padding: 30px 20px;
    }
    
    .header-content h1 {
        font-size: 2rem;
    }
    
    .form-grid {
        grid-template-columns: 1fr;
        gap: 15px;
    }
    
    .form-actions {
        flex-direction: column;
        align-items: stretch;
    }
    
    .section-header {
        flex-direction: column;
        gap: 15px;
        align-items: stretch;
    }
    
    .client-actions-header {
        justify-content: center;
    }
    
    .client-info {
        grid-template-columns: 1fr;
        gap: 10px;
    }
    
    .client-actions {
        justify-content: center;
    }
    
    section {
        padding: 20px;
    }
}

@media (max-width: 480px) {
    .header-content h1 {
        font-size: 1.5rem;
    }
    
    .btn {
        padding: 12px 20px;
        font-size: 0.9rem;
    }
    
    .loading-content {
        padding: 30px 20px;
        margin: 20px;
    }
    
    .toast {
        max-width: calc(100vw - 40px);
    }
}

/* Utility Classes */
.hidden {
    display: none !important;
}

.fade-in {
    animation: fadeInUp 0.5s ease-out;
}

.text-center {
    text-align: center;
}

.mb-20 {
    margin-bottom: 20px;
}

.mt-20 {
    margin-top: 20px;
}