/* CSS Custom Properties */
:root {
    --primary-color: #6366f1;
    --secondary-color: #8b5cf6;
    --accent-color: #06b6d4;
    --background-color: #0f172a;
    --surface-color: #1e293b;
    --surface-light: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #64748b;
    --border-color: #475569;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    --gradient-primary: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    --gradient-secondary: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%);
    --gradient-accent: linear-gradient(135deg, #ec4899 0%, #8b5cf6 100%);
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.3);
    --border-radius: 12px;
    --border-radius-lg: 16px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
}

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

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    margin-bottom: 1rem;
}

h1 {
    font-size: 3rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

h2 {
    font-size: 2.5rem;
    color: var(--text-primary);
}

h3 {
    font-size: 1.5rem;
    color: var(--text-primary);
}

p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--secondary-color);
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: var(--transition);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    transition: var(--transition);
}

.nav-logo:hover {
    transform: scale(1.05);
}

.nav-logo img {
    width: 32px;
    height: 32px;
}

.nav-menu {
    display: flex;
    gap: 2rem;
}

.nav-link {
    color: var(--text-secondary);
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--text-primary);
    background: rgba(99, 102, 241, 0.1);
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.5rem;
    cursor: pointer;
}

/* Hero Section */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 30% 20%, rgba(99, 102, 241, 0.1) 0%, transparent 50%),
                radial-gradient(circle at 70% 80%, rgba(139, 92, 246, 0.1) 0%, transparent 50%);
}

.particles {
    position: absolute;
    width: 100%;
    height: 100%;
    overflow: hidden;
}

.particles::before,
.particles::after {
    content: '';
    position: absolute;
    width: 4px;
    height: 4px;
    background: var(--primary-color);
    border-radius: 50%;
    animation: float 6s ease-in-out infinite;
}

.particles::before {
    top: 20%;
    left: 20%;
    animation-delay: -2s;
}

.particles::after {
    top: 60%;
    right: 20%;
    animation-delay: -4s;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
}

.hero-content {
    text-align: center;
    z-index: 1;
    position: relative;
}

.hero-title {
    font-size: clamp(2.5rem, 5vw, 4rem);
    margin-bottom: 1.5rem;
    animation: fadeInUp 1s ease-out;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    animation: fadeInUp 1s ease-out 0.2s both;
}

.hero-features {
    display: flex;
    justify-content: center;
    gap: 3rem;
    margin-top: 3rem;
    animation: fadeInUp 1s ease-out 0.4s both;
}

.feature {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.feature i {
    color: var(--primary-color);
    width: 20px;
    height: 20px;
}

/* Calculator Section */
.calculator-section {
    padding: 6rem 0;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.05) 0%, rgba(139, 92, 246, 0.05) 100%);
}

.calculator-card {
    background: rgba(30, 41, 59, 0.8);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(71, 85, 105, 0.3);
    border-radius: var(--border-radius-lg);
    padding: 3rem;
    box-shadow: var(--shadow-xl);
    position: relative;
    overflow: hidden;
}

.calculator-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: var(--gradient-primary);
}

.calculator-header {
    text-align: center;
    margin-bottom: 3rem;
}

.calculator-header h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.calculator-header p {
    font-size: 1.1rem;
    color: var(--text-secondary);
}

.calculator-modes {
    display: flex;
    gap: 1rem;
    margin-bottom: 3rem;
    justify-content: center;
}

.mode-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 2rem;
    background: rgba(51, 65, 85, 0.5);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-secondary);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

.mode-btn:hover {
    background: rgba(51, 65, 85, 0.8);
    transform: translateY(-2px);
}

.mode-btn.active {
    background: var(--gradient-primary);
    color: white;
    border-color: var(--primary-color);
    box-shadow: var(--shadow-glow);
}

.calculator-form {
    display: grid;
    gap: 2rem;
    margin-bottom: 3rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-weight: 500;
    color: var(--text-primary);
}

.age-select {
    padding: 1rem;
    background: rgba(51, 65, 85, 0.5);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-primary);
    font-size: 1rem;
    transition: var(--transition);
}

.age-select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.time-picker-container {
    display: flex;
    justify-content: center;
}

.time-picker {
    background: rgba(51, 65, 85, 0.5);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    text-align: center;
    transition: var(--transition);
}

.time-picker:hover {
    border-color: var(--primary-color);
}

.time-display {
    margin-bottom: 1rem;
}

.time-value {
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-primary);
}

.time-controls {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 0.5rem;
    max-width: 300px;
    margin: 0 auto;
}

.time-btn {
    padding: 0.5rem;
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid var(--primary-color);
    border-radius: var(--border-radius);
    color: var(--primary-color);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

.time-btn:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
}

.calculate-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 1.5rem 3rem;
    background: var(--gradient-primary);
    border: none;
    border-radius: var(--border-radius);
    color: white;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-lg);
    margin: 0 auto;
}

.calculate-btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl), var(--shadow-glow);
}

.calculate-btn:active {
    transform: translateY(-1px);
}

/* Results Container */
.results-container {
    display: none;
    gap: 1.5rem;
    margin-top: 3rem;
}

.results-container.show {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    animation: fadeInUp 0.6s ease-out;
}

.result-card {
    background: rgba(51, 65, 85, 0.5);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    text-align: center;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.result-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--gradient-primary);
}

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

.result-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.result-time {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.result-cycles {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.result-links {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.result-link {
    padding: 0.5rem 1rem;
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid var(--primary-color);
    border-radius: var(--border-radius);
    color: var(--primary-color);
    font-size: 0.9rem;
    transition: var(--transition);
}

.result-link:hover {
    background: var(--primary-color);
    color: white;
}

/* Motivational Quote */
.motivational-quote {
    background: rgba(139, 92, 246, 0.1);
    border: 1px solid rgba(139, 92, 246, 0.3);
    border-radius: var(--border-radius);
    padding: 2rem;
    text-align: center;
    margin-top: 3rem;
    display: none;
}

.motivational-quote.show {
    display: block;
    animation: fadeInUp 0.6s ease-out 0.3s both;
}

.quote-text {
    font-size: 1.1rem;
    font-style: italic;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.quote-author {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Sleep Cycle Section */
.sleep-cycle-section {
    padding: 6rem 0;
    text-align: center;
}

.sleep-cycle-section h2 {
    margin-bottom: 3rem;
}

.chart-container {
    display: flex;
    justify-content: center;
    margin-bottom: 2rem;
}

.sleep-chart {
    max-width: 100%;
    height: auto;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-lg);
}

.chart-description {
    max-width: 600px;
    margin: 0 auto;
    font-size: 1.1rem;
    color: var(--text-secondary);
}

/* Quick Tips */
.quick-tips {
    padding: 6rem 0;
    background: rgba(30, 41, 59, 0.3);
}

.quick-tips h2 {
    text-align: center;
    margin-bottom: 3rem;
}

.tips-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.tip-card {
    background: rgba(51, 65, 85, 0.5);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    text-align: center;
    transition: var(--transition);
}

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

.tip-card i {
    width: 48px;
    height: 48px;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

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

.tip-card p {
    color: var(--text-secondary);
}

/* Footer */
.footer {
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: 3rem 0 1rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    color: var(--text-primary);
    margin-bottom: 1rem;
}

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

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: var(--text-secondary);
    transition: var(--transition);
}

.footer-section ul li a:hover {
    color: var(--primary-color);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.footer-logo img {
    width: 32px;
    height: 32px;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: var(--gradient-primary);
    border: none;
    border-radius: 50%;
    color: white;
    cursor: pointer;
    transition: var(--transition);
    opacity: 0;
    visibility: hidden;
    z-index: 1000;
    box-shadow: var(--shadow-lg);
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl), var(--shadow-glow);
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 1rem;
    }
    
    .nav-menu {
        display: none;
    }
    
    .nav-toggle {
        display: block;
    }
    
    .hero-features {
        flex-direction: column;
        gap: 1rem;
    }
    
    .calculator-card {
        padding: 2rem;
    }
    
    .calculator-modes {
        flex-direction: column;
    }
    
    .mode-btn {
        justify-content: center;
    }
    
    .time-controls {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .result-links {
        flex-direction: column;
    }
    
    .tips-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .calculator-header h2 {
        font-size: 2rem;
    }
    
    .time-value {
        font-size: 1.5rem;
    }
    
    .result-time {
        font-size: 1.5rem;
    }
}

/* Loading States */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid var(--primary-color);
    border-top: 2px solid transparent;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Utility Classes */
.text-center {
    text-align: center;
}

.text-primary {
    color: var(--text-primary);
}

.text-secondary {
    color: var(--text-secondary);
}

.text-muted {
    color: var(--text-muted);
}

.mb-1 { margin-bottom: 0.25rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 1rem; }
.mb-4 { margin-bottom: 1.5rem; }
.mb-5 { margin-bottom: 3rem; }

.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 1rem; }
.mt-4 { margin-top: 1.5rem; }
.mt-5 { margin-top: 3rem; }

.p-1 { padding: 0.25rem; }
.p-2 { padding: 0.5rem; }
.p-3 { padding: 1rem; }
.p-4 { padding: 1.5rem; }
.p-5 { padding: 3rem; }