:root {
    --primary-color: #4361ee;
    --secondary-color: #3f37c9;
    --accent-color: #4895ef;
    --light-color: #f8f9fa;
    --dark-color: #212529;
    --success-color: #4cc9f0;
    --warning-color: #f72585;
    --danger-color: #e63946;
    --border-radius: 12px;
    --box-shadow: 0 6px 16px rgba(0, 0, 0, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: linear-gradient(135deg, #0f0c29, #302b63, #24243e);
    color: white;
    min-height: 100vh;
}

header {
    background: rgba(10, 15, 35, 0.85);
    padding: 20px 0;
    box-shadow: var(--box-shadow);
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 28px;
    font-weight: 700;
}

.logo-icon {
    background: var(--primary-color);
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 10px rgba(67, 97, 238, 0.4);
}

nav ul {
    display: flex;
    list-style: none;
    gap: 20px;
}

nav ul li a {
    color: rgba(255, 255, 255, 0.85);
    text-decoration: none;
    font-weight: 600;
    padding: 8px 16px;
    border-radius: var(--border-radius);
    transition: all 0.3s;
    display: flex;
    align-items: center;
    gap: 8px;
}

nav ul li a:hover, nav ul li a.active {
    background: rgba(67, 97, 238, 0.2);
    color: white;
}

.auth-buttons {
    display: flex;
    gap: 15px;
}

.auth-buttons button {
    padding: 10px 24px;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s;
    border: none;
    display: flex;
    align-items: center;
    gap: 8px;
}

.auth-buttons .login-btn {
    background: transparent;
    border: 2px solid var(--accent-color);
    color: var(--accent-color);
}

.auth-buttons .signup-btn {
    background: linear-gradient(90deg, var(--accent-color), var(--primary-color));
    color: white;
    box-shadow: 0 4px 15px rgba(72, 149, 239, 0.3);
}

.auth-buttons button:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.2);
}

.user-profile {
    display: flex;
    align-items: center;
    gap: 15px;
}

.user-avatar {
    width: 40px;
    height: 40px;
    background: var(--primary-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
}

.logout-btn {
    padding: 8px 16px;
    background: var(--danger-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: background-color 0.3s;
}

.logout-btn:hover {
    background: #c82333;
}

.hidden {
    display: none !important;
}

/* Auth Modal Styles */
#auth-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.auth-container {
    background: white;
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    width: 100%;
    max-width: 400px;
    position: relative;
    color: var(--dark-color);
}

.close-auth-modal {
    position: absolute;
    top: 15px;
    right: 15px;
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--dark-color);
}

.auth-tabs {
    display: flex;
    margin-bottom: 20px;
    border-bottom: 1px solid #ddd;
}

.auth-tab {
    padding: 10px 20px;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    color: #666;
    position: relative;
}

.auth-tab.active {
    color: var(--primary-color);
}

.auth-tab.active::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--primary-color);
}

.auth-form {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.auth-form h2 {
    margin-bottom: 10px;
    color: var(--dark-color);
    text-align: center;
}

.auth-form input {
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: var(--border-radius);
    font-size: 16px;
}

.auth-btn {
    padding: 12px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.3s;
}

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

.main-content {
    padding: 40px 20px;
    text-align: center;
}

@media (max-width: 768px) {
    .container {
        flex-direction: column;
        gap: 20px;
    }
    
    nav ul {
        flex-wrap: wrap;
        justify-content: center;
    }
}