:root {
    --primary-color: #0D7377;
    --primary-dark: #0a5d61;
    --secondary-color: #FFB84D;
    --secondary-dark: #ff9f1c;
    --accent-color: #F5F5F5;
    --dark-color: #1a1a1a;
    --text-color: #333;
    --light-gray: #f8f9fa;
    --border-color: #e0e0e0;
    --success-color: #27AE60;
    --danger-color: #E74C3C;
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.12);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.16);
    --radius: 12px;
    --radius-sm: 8px;
    --radius-lg: 16px;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--light-gray);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

/* Modern Header */
.header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    text-decoration: none;
    color: var(--dark-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: transform 0.3s ease;
}

.logo:hover {
    transform: translateY(-2px);
}

.logo-icon {
    width: 36px;
    height: 36px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.nav-links a {
    color: var(--text-color);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    transition: all 0.3s ease;
    font-weight: 500;
}

.nav-links a:hover {
    background-color: var(--light-gray);
    color: var(--primary-color);
}

/* Mobile Menu */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.mobile-menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--dark-color);
    transition: all 0.3s ease;
}

.mobile-menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.875rem 1.75rem;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    text-align: center;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.2);
    transition: left 0.5s ease;
}

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

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
    box-shadow: 0 4px 12px rgba(13, 115, 119, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(13, 115, 119, 0.4);
}

.btn-secondary {
    background: linear-gradient(135deg, var(--secondary-color), var(--secondary-dark));
    color: var(--dark-color);
    box-shadow: 0 4px 12px rgba(255, 184, 77, 0.3);
}

.btn-secondary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 184, 77, 0.4);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
    padding: 6rem 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: pulse 20s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1) rotate(0deg); }
    50% { transform: scale(1.1) rotate(180deg); }
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
    font-weight: 800;
    position: relative;
    z-index: 1;
}

.hero p {
    font-size: 1.375rem;
    margin-bottom: 2.5rem;
    opacity: 0.95;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    position: relative;
    z-index: 1;
}

/* Features Section */
.features-section {
    padding: 5rem 0;
    background: white;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.feature-card {
    padding: 2rem;
    border-radius: var(--radius);
    background: var(--light-gray);
    text-align: center;
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    background: white;
}

.feature-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

/* Forms */
.form-container {
    max-width: 450px;
    margin: 4rem auto;
    background: white;
    padding: 3rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
}

.form-group {
    margin-bottom: 1.75rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.75rem;
    font-weight: 600;
    color: var(--dark-color);
}

.form-group input {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    transition: all 0.3s ease;
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(13, 115, 119, 0.1);
}

/* Dashboard */
.dashboard {
    margin: 2rem 0 4rem;
    flex: 1;
}

.dashboard-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 3rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.dashboard-header h1 {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--dark-color);
}

.stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.stat-card {
    background: white;
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.stat-card h3 {
    color: var(--primary-color);
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    font-weight: 800;
}

.stat-card p {
    color: var(--text-color);
    font-weight: 500;
}

/* Habits Grid */
.habits-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 2rem;
}

.habit-card {
    background: white;
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    position: relative;
    transition: all 0.3s ease;
    border-left: 5px solid var(--primary-color);
}

.habit-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.habit-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.habit-name {
    font-size: 1.375rem;
    font-weight: 700;
    color: var(--dark-color);
}

.habit-streak {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--secondary-color);
    font-weight: 700;
    font-size: 1.125rem;
}

.habit-actions {
    display: flex;
    gap: 0.75rem;
}

.btn-check {
    background: linear-gradient(135deg, var(--success-color), #229954);
    color: white;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
}

.btn-check:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(39, 174, 96, 0.3);
}

.btn-check.checked {
    background: linear-gradient(135deg, #95a5a6, #7f8c8d);
}

.btn-delete {
    background: linear-gradient(135deg, var(--danger-color), #c0392b);
    color: white;
    padding: 0.75rem;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-delete:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(231, 76, 60, 0.3);
}

/* Add Habit Form */
.add-habit-form {
    background: white;
    padding: 2.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    margin-bottom: 3rem;
}

.add-habit-form h3 {
    margin-bottom: 2rem;
    font-size: 1.5rem;
    color: var(--dark-color);
}

.form-inline {
    display: flex;
    gap: 1.5rem;
    align-items: flex-end;
    flex-wrap: wrap;
}

/* Pricing */
.pricing-section {
    padding: 5rem 0;
    background: linear-gradient(to bottom, var(--light-gray), white);
}

.pricing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2.5rem;
    max-width: 800px;
    margin: 3rem auto 0;
}

.pricing-card {
    background: white;
    padding: 3rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    text-align: center;
    position: relative;
    transition: all 0.3s ease;
}

.pricing-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
}

.pricing-card.featured {
    border: 3px solid var(--secondary-color);
    transform: scale(1.05);
}

.pricing-card.featured:hover {
    transform: scale(1.08) translateY(-5px);
}

.pricing-card h3 {
    font-size: 1.75rem;
    margin-bottom: 1.5rem;
    color: var(--dark-color);
}

.price {
    font-size: 3.5rem;
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
}

.price span {
    font-size: 1.125rem;
    color: #666;
    font-weight: 400;
}

.features {
    list-style: none;
    margin-bottom: 2.5rem;
}

.features li {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-color);
}

.features li:last-child {
    border-bottom: none;
}

/* Alert Messages */
.alert {
    padding: 1.25rem;
    margin-bottom: 1.5rem;
    border-radius: var(--radius-sm);
    font-weight: 500;
}

.alert-success {
    background-color: #d1f2eb;
    color: #0e6655;
    border: 1px solid #a3e4d7;
}

.alert-error {
    background-color: #fadbd8;
    color: #922b21;
    border: 1px solid #f5b7b1;
}

/* Footer */
.footer {
    background: var(--dark-color);
    color: white;
    padding: 4rem 0 2rem;
    margin-top: auto;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1.5rem;
    font-weight: 700;
}

.footer-logo {
    font-size: 1.5rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.75rem;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section a:hover {
    color: white;
}

.social-links {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}

.social-links a {
    width: 40px;
    height: 40px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.social-links a:hover {
    background: var(--primary-color);
    transform: translateY(-3px);
}

.footer-bottom {
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
    color: rgba(255, 255, 255, 0.6);
}

/* Responsive Design */
@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: flex;
    }
    
    .nav-links {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 1rem;
        box-shadow: var(--shadow-lg);
        border-radius: 0 0 var(--radius) var(--radius);
        opacity: 0;
        visibility: hidden;
        transform: translateY(-10px);
        transition: all 0.3s ease;
    }
    
    .nav-links.active {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
    }
    
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .hero p {
        font-size: 1.125rem;
    }
    
    .habits-grid {
        grid-template-columns: 1fr;
    }
    
    .form-inline {
        flex-direction: column;
    }
    
    .form-inline .form-group {
        width: 100%;
    }
    
    .stats {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .social-links {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .form-container {
        padding: 2rem;
    }
    
    .pricing-card {
        padding: 2rem;
    }
    
    .price {
        font-size: 2.5rem;
    }
}

/* Loading Animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Smooth Scrolling */
html {
    scroll-behavior: smooth;
}

/* Focus Visible */
:focus-visible {
    outline: 3px solid var(--primary-color);
    outline-offset: 2px;
}

/* Print Styles */
@media print {
    .header, .footer, .btn, .form-inline {
        display: none;
    }
    
    .habit-card {
        break-inside: avoid;
    }
}