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

:root {
    /* Light Theme (Default) */
    --primary-color: #3B82F6;
    --primary-hover: #2563EB;
    --secondary-color: #6B7280;
    --success-color: #10B981;
    --danger-color: #EF4444;
    --background: #F9FAFB;
    --surface: #FFFFFF;
    --border-color: #E5E7EB;
    --text-primary: #111827;
    --text-secondary: #6B7280;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    /* Dark Theme */
    --primary-color: #60A5FA;
    --primary-hover: #3B82F6;
    --secondary-color: #9CA3AF;
    --success-color: #34D399;
    --danger-color: #F87171;
    --background: #111827;
    --surface: #1F2937;
    --border-color: #374151;
    --text-primary: #F9FAFB;
    --text-secondary: #D1D5DB;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.4);
}

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;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
header {
    background: var(--surface);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    box-shadow: var(--shadow);
}

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

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

nav {
    display: flex;
    gap: 0.5rem;
    align-items: center;
    flex-wrap: wrap;
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    padding: 0.5rem 0.875rem;
    border-radius: 0.375rem;
    transition: all 0.2s;
    font-weight: 500;
    font-size: 0.9375rem;
}

.nav-link:hover {
    background: var(--border-color);
    color: var(--text-primary);
}

.nav-link.active {
    background: var(--primary-color);
    color: white;
    font-weight: 600;
}

.user-info {
    color: var(--text-secondary);
    padding: 0 0.5rem;
}

/* Theme Toggle */
.theme-toggle {
    background: var(--surface);
    border: 1.5px solid var(--border-color);
    border-radius: 0.375rem;
    padding: 0.5rem 0.75rem;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 1.25rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    background: var(--border-color);
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.theme-icon {
    display: block;
    line-height: 1;
}

/* Messages */
.messages-container {
    max-width: 1400px;
    margin: 1rem auto;
    padding: 0 20px;
}

.message {
    padding: 1rem;
    border-radius: 0.375rem;
    margin-bottom: 1rem;
}

.message.success {
    background: #D1FAE5;
    color: #065F46;
    border-left: 4px solid var(--success-color);
}

[data-theme="dark"] .message.success {
    background: rgba(52, 211, 153, 0.15);
    color: var(--success-color);
}

.message.error {
    background: #FEE2E2;
    color: #991B1B;
    border-left: 4px solid var(--danger-color);
}

[data-theme="dark"] .message.error {
    background: rgba(248, 113, 113, 0.15);
    color: var(--danger-color);
}

.message.info {
    background: #DBEAFE;
    color: #1E40AF;
    border-left: 4px solid var(--primary-color);
}

[data-theme="dark"] .message.info {
    background: rgba(96, 165, 250, 0.15);
    color: var(--primary-color);
}

/* Main Content */
main {
    padding: 2rem 0;
    min-height: calc(100vh - 80px);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.625rem 1.25rem;
    border: none;
    border-radius: 0.375rem;
    font-size: 0.9375rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.2s;
    margin: 0.25rem;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    text-shadow: none;
}

.btn-primary:hover {
    background: var(--primary-hover);
    color: white;
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.btn-secondary {
    background: var(--surface);
    color: var(--text-primary);
    border: 1.5px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--border-color);
    border-color: var(--text-secondary);
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
}

.btn-block {
    display: block;
    width: 100%;
}

/* Forms */
.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.form-group input[type="text"],
.form-group input[type="email"],
.form-group input[type="password"],
.form-group input[type="datetime-local"],
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.375rem;
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.form-group small {
    display: block;
    margin-top: 0.25rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.checkbox-group label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
}

.checkbox-group input[type="checkbox"] {
    width: auto;
    cursor: pointer;
}

.form-actions {
    display: flex;
    gap: 0.75rem;
    margin-top: 2rem;
    flex-wrap: wrap;
}

.form-actions .btn {
    margin: 0;
}

.form-errors {
    background: #FEE2E2;
    color: #991B1B;
    padding: 1rem;
    border-radius: 0.375rem;
    margin-bottom: 1rem;
    border-left: 4px solid var(--danger-color);
}

[data-theme="dark"] .form-errors {
    background: rgba(248, 113, 113, 0.15);
    color: var(--danger-color);
}

/* Auth Pages */
.auth-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: var(--background);
}

.auth-card {
    background: var(--surface);
    padding: 2rem;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 400px;
}

.auth-card h1 {
    text-align: center;
    margin-bottom: 0.5rem;
    font-size: 2rem;
}

.auth-card h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--text-secondary);
    font-size: 1.25rem;
    font-weight: normal;
}

.auth-footer {
    margin-top: 1.5rem;
    text-align: center;
    color: var(--text-secondary);
}

.auth-footer a {
    color: var(--primary-color);
    text-decoration: none;
}

.auth-footer a:hover {
    text-decoration: underline;
}

/* Preferences */
.preferences-container {
    max-width: 800px;
    margin: 0 auto;
    background: var(--surface);
    padding: 2rem;
    border-radius: 0.5rem;
    box-shadow: var(--shadow);
}

.preferences-form h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.form-section {
    margin-bottom: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.form-section:last-of-type {
    border-bottom: none;
}

.timezone-sync-container {
    display: flex;
    gap: 0.5rem;
    align-items: stretch;
}

.timezone-sync-container select {
    flex: 1;
}

.timezone-sync-container button {
    white-space: nowrap;
    transition: all 0.3s ease;
}

#detectedTimezone {
    display: block;
    font-size: 0.875rem;
}

/* Responsive */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }

    nav {
        flex-wrap: wrap;
        justify-content: center;
    }

    .container {
        padding: 0 15px;
    }
}