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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

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

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 20px 0;
    margin-bottom: 30px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

header h1 {
    font-size: 28px;
    font-weight: 700;
}

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

header .user-info .stamps {
    display: flex;
    align-items: center;
    gap: 8px;
    background: rgba(255,255,255,0.2);
    padding: 8px 15px;
    border-radius: 20px;
    font-size: 14px;
}

nav {
    background: white;
    padding: 15px 0;
    margin-bottom: 30px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

nav ul {
    display: flex;
    list-style: none;
    gap: 5px;
}

nav a {
    text-decoration: none;
    color: #555;
    padding: 10px 20px;
    border-radius: 5px;
    transition: all 0.3s;
    font-weight: 500;
}

nav a:hover {
    background: #f0f0f0;
    color: #667eea;
}

nav a.active {
    background: #667eea;
    color: white;
}

.card {
    background: white;
    border-radius: 10px;
    padding: 25px;
    margin-bottom: 20px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.card h2 {
    margin-bottom: 20px;
    color: #333;
    font-size: 20px;
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.3s;
}

.btn-primary {
    background: #667eea;
    color: white;
}

.btn-primary:hover {
    background: #5568d3;
}

.btn-secondary {
    background: #6c757d;
    color: white;
}

.btn-danger {
    background: #dc3545;
    color: white;
}

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

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: #555;
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 14px;
    transition: border-color 0.3s;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: #667eea;
}

.form-group textarea {
    min-height: 150px;
    resize: vertical;
}

.letter-list {
    display: grid;
    gap: 15px;
}

.letter-item {
    background: #f8f9fa;
    border-left: 4px solid #667eea;
    padding: 20px;
    border-radius: 5px;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
}

.letter-item:hover {
    transform: translateX(5px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.letter-item.unread {
    border-left-color: #28a745;
    background: #f0fff4;
}

.letter-item .sender {
    font-weight: 600;
    color: #333;
    margin-bottom: 5px;
}

.letter-item .subject {
    color: #555;
    margin-bottom: 10px;
}

.letter-item .meta {
    display: flex;
    gap: 15px;
    font-size: 12px;
    color: #888;
}

.letter-item .meta .status {
    padding: 3px 8px;
    border-radius: 10px;
    background: #e9ecef;
}

.letter-item .meta .status.delivered {
    background: #d4edda;
    color: #155724;
}

.letter-item .meta .status.registered {
    background: #fff3cd;
    color: #856404;
}

.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;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: white;
    border-radius: 10px;
    max-width: 800px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px;
    border-bottom: 1px solid #eee;
}

.modal-close {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: #888;
}

.modal-body {
    padding: 30px;
}

.template-selector {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 15px;
    margin-top: 15px;
}

.template-option {
    padding: 15px;
    border: 2px solid #ddd;
    border-radius: 8px;
    cursor: pointer;
    text-align: center;
    transition: all 0.3s;
}

.template-option:hover {
    border-color: #667eea;
    background: #f8f9fa;
}

.template-option.selected {
    border-color: #667eea;
    background: #f0f4ff;
}

.template-option .preview {
    width: 100%;
    height: 80px;
    border-radius: 5px;
    margin-bottom: 10px;
}

.address-book-list,
.blocked-list {
    display: grid;
    gap: 10px;
}

.address-item,
.blocked-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px;
    background: #f8f9fa;
    border-radius: 5px;
}

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

.auth-container {
    max-width: 400px;
    margin: 50px auto;
}

.auth-form {
    background: white;
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.auth-form h2 {
    text-align: center;
    margin-bottom: 25px;
    color: #667eea;
}

.alert {
    padding: 12px 20px;
    border-radius: 5px;
    margin-bottom: 20px;
    font-size: 14px;
}

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

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

.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid #f3f3f3;
    border-top: 2px solid #667eea;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

.hidden {
    display: none;
}