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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --background: #f8fafc;
    --surface: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border: #e2e8f0;
    --error: #ef4444;
    --success: #22c55e;
    --warning: #f59e0b;
    --info: #3b82f6;
    --sidebar-width: 250px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
}

/* Login Page */
.login-page {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: linear-gradient(135deg, #1e3a5f 0%, #2563eb 100%);
}

.login-container {
    background: var(--surface);
    border-radius: 12px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    padding: 40px;
    width: 100%;
    max-width: 400px;
}

.login-header {
    text-align: center;
    margin-bottom: 30px;
}

.login-header h1 {
    font-size: 28px;
    color: var(--primary-color);
    margin-bottom: 8px;
}

.login-header p {
    color: var(--text-secondary);
    font-size: 14px;
}

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

.login-form label,
.settings-form label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-primary);
}

.login-form input,
.login-form select,
.settings-form input {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 14px;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.login-form input:focus,
.login-form select:focus,
.settings-form input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

small {
    display: block;
    margin-top: 4px;
    font-size: 12px;
    color: var(--text-secondary);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    width: 100%;
}

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

.btn-secondary {
    background: var(--background);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: var(--border);
}

.btn-sm {
    padding: 6px 12px;
    font-size: 12px;
}

.error-message {
    background: #fef2f2;
    border: 1px solid #fecaca;
    color: var(--error);
    padding: 12px 16px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: 14px;
}

.success-message {
    background: #f0fdf4;
    border: 1px solid #bbf7d0;
    color: #166534;
    padding: 12px 16px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: 14px;
}

.info-message {
    background: #eff6ff;
    border: 1px solid #bfdbfe;
    color: #1e40af;
    padding: 12px 16px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: 14px;
}

.login-footer {
    text-align: center;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid var(--border);
    color: var(--text-secondary);
    font-size: 12px;
}

/* Main Layout */
.app-container {
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: var(--sidebar-width);
    background: var(--surface);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
}

.sidebar-header {
    padding: 20px;
    border-bottom: 1px solid var(--border);
}

.sidebar-header h2 {
    font-size: 18px;
    color: var(--primary-color);
}

.sidebar-header .user-email {
    font-size: 12px;
    color: var(--text-secondary);
    margin-top: 4px;
    word-break: break-all;
}

.sidebar-nav {
    flex: 1;
    padding: 16px;
}

.nav-item {
    display: flex;
    align-items: center;
    padding: 12px 16px;
    color: var(--text-primary);
    text-decoration: none;
    border-radius: 8px;
    margin-bottom: 4px;
    transition: background 0.2s;
}

.nav-item:hover {
    background: var(--background);
}

.nav-item.active {
    background: var(--primary-color);
    color: white;
}

.nav-item svg {
    width: 20px;
    height: 20px;
    margin-right: 12px;
}

.sidebar-footer {
    padding: 16px;
    border-top: 1px solid var(--border);
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 16px 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header h1 {
    font-size: 20px;
    font-weight: 600;
}

.header-actions {
    display: flex;
    gap: 12px;
}

/* Email List */
.email-list {
    flex: 1;
    overflow-y: auto;
    padding: 16px;
}

.email-item {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px;
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    transition: all 0.2s;
}

.email-item:hover {
    border-color: var(--primary-color);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.email-item.unread {
    border-left: 3px solid var(--primary-color);
}

.email-item.unread .email-subject {
    font-weight: 600;
}

.email-link {
    flex: 1;
    text-decoration: none;
    color: inherit;
}

.email-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 4px;
}

.email-from {
    font-weight: 500;
    color: var(--text-primary);
}

.email-date {
    font-size: 12px;
    color: var(--text-secondary);
}

.email-subject {
    font-size: 14px;
    color: var(--text-primary);
}

.email-delete {
    margin-left: 12px;
}

.btn-delete {
    background: none;
    border: none;
    padding: 8px;
    cursor: pointer;
    color: var(--text-secondary);
    border-radius: 4px;
    transition: all 0.2s;
}

.btn-delete:hover {
    background: #fef2f2;
    color: var(--error);
}

/* Email View */
.email-view {
    flex: 1;
    overflow-y: auto;
    padding: 24px;
}

.email-view-header {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 24px;
    margin-bottom: 16px;
}

.email-view-subject {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 16px;
}

.email-view-meta {
    display: flex;
    gap: 24px;
    font-size: 14px;
    color: var(--text-secondary);
    flex-wrap: wrap;
}

.email-view-meta span {
    display: flex;
    align-items: center;
    gap: 8px;
}

.email-view-body {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 24px;
    line-height: 1.8;
}

.email-attachments {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px;
    margin-top: 16px;
}

.email-attachments h3 {
    font-size: 14px;
    margin-bottom: 12px;
    color: var(--text-secondary);
}

.attachment-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 8px 0;
    border-bottom: 1px solid var(--border);
}

.attachment-item:last-child {
    border-bottom: none;
}

.email-view-actions {
    display: flex;
    gap: 12px;
    margin-top: 16px;
}

/* Compose Form */
.compose-form {
    flex: 1;
    padding: 24px;
}

.compose-container {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 24px;
}

.form-row {
    margin-bottom: 16px;
}

.form-row label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    font-size: 14px;
}

.form-row input,
.form-row textarea {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 14px;
    font-family: inherit;
}

.form-row textarea {
    min-height: 300px;
    resize: vertical;
}

.form-row input:focus,
.form-row textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* Settings */
.settings-content {
    padding: 24px;
}

.settings-section {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 24px;
    margin-bottom: 24px;
}

.settings-section h2 {
    font-size: 18px;
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--border);
}

.settings-section p {
    margin-bottom: 8px;
    font-size: 14px;
}

/* Empty State */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.empty-state svg {
    width: 64px;
    height: 64px;
    margin-bottom: 16px;
    opacity: 0.5;
}

.empty-state h3 {
    margin-bottom: 8px;
    color: var(--text-primary);
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        width: 60px;
    }
    
    .sidebar-header h2,
    .sidebar-header .user-email,
    .nav-item span {
        display: none;
    }
    
    .nav-item {
        justify-content: center;
        padding: 12px;
    }
    
    .nav-item svg {
        margin-right: 0;
    }
}