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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Open Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: #333;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
}

/* CSS Custom Properties */
:root {
    --primary-color: #1a2a3a;
    --secondary-color: #2c3e50;
    --accent-color: #3498db;
    --gold-color: #f39c12;
    --danger-color: #e74c3c;
    --success-color: #27ae60;
    --background-light: #f8f9fa;
    --text-dark: #2c3e50;
    --text-light: #7f8c8d;
    --border-color: #dee2e6;
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.15);
    --border-radius: 8px;
    --transition: all 0.3s ease;
    --header-height: 80px;
}

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

h1 { font-size: clamp(2rem, 4vw, 3rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2.5rem); }
h3 { font-size: clamp(1.25rem, 2.5vw, 2rem); }
h4 { font-size: clamp(1.125rem, 2vw, 1.5rem); }

p {
    margin-bottom: 1rem;
    line-height: 1.7;
}

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

/* Header and Navigation */
.header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    box-shadow: var(--shadow);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: var(--header-height);
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    height: 100%;
}

.nav-brand {
    color: white;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.tagline {
    font-size: 0.875rem;
    opacity: 0.8;
    margin-bottom: 0;
}

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

.nav-link {
    color: white;
    text-decoration: none;
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    background: rgba(255, 255, 255, 0.1);
    color: white;
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -0.5rem;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 3px;
    background: var(--gold-color);
    border-radius: 2px;
}

/* Hamburger Menu */
.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    background: none;
    border: none;
    padding: 0.5rem;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: white;
    margin: 3px 0;
    transition: var(--transition);
    border-radius: 2px;
}

.hamburger.active span:nth-child(1) {
    transform: rotate(-45deg) translate(-5px, 6px);
}

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: rotate(45deg) translate(-5px, -6px);
}

/* Main Content */
.main-content {
    margin-top: var(--header-height);
    min-height: calc(100vh - var(--header-height));
}

/* Page System */
.page {
    display: none;
    min-height: calc(100vh - var(--header-height) - 100px);
}

.page.active {
    display: block;
}

/* Search Section */
.search-section {
    background: linear-gradient(45deg, #ecf0f1 0%, #bdc3c7 100%);
    padding: 2rem 0;
}

.search-form {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.search-label {
    font-size: 1.125rem;
    font-weight: 500;
    color: var(--text-dark);
}

.date-input {
    padding: 0.875rem 1rem;
    border: 2px solid var(--accent-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    background: white;
    min-width: 200px;
    transition: var(--transition);
}

.date-input:focus {
    outline: none;
    border-color: var(--gold-color);
    box-shadow: 0 0 0 3px rgba(243, 156, 18, 0.1);
}

.search-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 2rem;
    background: linear-gradient(45deg, var(--accent-color) 0%, #2980b9 100%);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.search-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.search-btn:active {
    transform: translateY(0);
}

.search-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

/* Loading Indicator */
.loading {
    display: none;
    text-align: center;
    padding: 3rem 0;
}

.loading.show {
    display: block;
}

.loading-spinner {
    width: 50px;
    height: 50px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--accent-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

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

/* Error Message */
.error-message {
    display: none;
    background: white;
    border: 1px solid var(--danger-color);
    border-radius: var(--border-radius);
    margin: 2rem auto;
    max-width: 500px;
    box-shadow: var(--shadow);
}

.error-message.show {
    display: block;
}

.error-content {
    padding: 2rem;
    text-align: center;
}

.error-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.error-content h3 {
    color: var(--danger-color);
    margin-bottom: 0.5rem;
}

.retry-btn {
    padding: 0.5rem 1rem;
    background: var(--danger-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    margin-top: 1rem;
    transition: var(--transition);
}

.retry-btn:hover {
    background: #c0392b;
}

/* APOD Section */
.apod-section {
    padding: 3rem 0;
    display: none;
}

.apod-section.show {
    display: block;
}

.apod-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: start;
}

.image-container {
    position: relative;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: var(--transition);
}

.image-container:hover {
    box-shadow: var(--shadow-hover);
}

.apod-image {
    width: 100%;
    height: auto;
    display: block;
    transition: var(--transition);
}

.image-overlay {
    position: absolute;
    top: 1rem;
    right: 1rem;
    opacity: 0;
    transition: var(--transition);
}

.image-container:hover .image-overlay {
    opacity: 1;
}

.favorite-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 1rem 2rem;
    background: linear-gradient(45deg, var(--gold-color) 0%, #e67e22 100%);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    width: 100%;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.favorite-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.favorite-btn-overlay {
    background: rgba(0, 0, 0, 0.7);
    color: white;
    border: none;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    backdrop-filter: blur(10px);
}

.favorite-btn-overlay:hover {
    background: rgba(0, 0, 0, 0.9);
    transform: scale(1.1);
}

.favorite-btn-overlay.favorited .star-icon {
    color: var(--gold-color);
}

.star-icon {
    font-size: 1.5rem;
    transition: var(--transition);
}

.info-panel {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    height: fit-content;
}

.info-content {
    padding: 2rem;
}

.apod-title {
    color: var(--text-dark);
    margin-bottom: 0.5rem;
    font-size: 1.5rem;
}

.apod-date {
    color: var(--text-light);
    font-size: 1rem;
    margin-bottom: 1.5rem;
    font-weight: 500;
}

.description-container {
    margin-bottom: 2rem;
}

.apod-description {
    color: var(--text-dark);
    line-height: 1.7;
    margin-bottom: 0;
}

.info-actions {
    display: flex;
    gap: 1rem;
}

.share-btn {
    padding: 0.75rem 1.5rem;
    background: var(--gold-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.share-btn:hover {
    background: #e67e22;
    transform: translateY(-2px);
}

/* Page Headers */
.page-header {
    text-align: center;
    padding: 3rem 0 2rem;
}

.page-title {
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.page-subtitle {
    color: var(--text-light);
    font-size: 1.125rem;
}

/* Favorites Page */
.favorites-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--accent-color);
    font-family: 'Montserrat', sans-serif;
}

.stat-label {
    color: var(--text-light);
    font-size: 1rem;
    font-weight: 500;
}

.favorites-actions {
    display: flex;
    gap: 1rem;
}

.clear-all-btn {
    padding: 0.75rem 1.5rem;
    background: var(--danger-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.clear-all-btn:hover {
    background: #c0392b;
    transform: translateY(-2px);
}

.favorites-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
}

/* Home Favorites Section */
.home-favorites-section {
    padding: 3rem 0;
    background: var(--background-light);
}

.favorites-title {
    font-size: 1.75rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 2rem;
    text-align: left;
}

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

.favorite-item {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: var(--transition);
}

.favorite-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.favorite-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
    cursor: pointer;
}

.favorite-info {
    padding: 1.5rem;
}

.favorite-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
    line-height: 1.3;
}

.favorite-date {
    color: var(--text-light);
    font-size: 0.875rem;
    margin-bottom: 1rem;
}

.favorite-actions {
    display: flex;
    gap: 0.5rem;
}

.remove-btn, .view-btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.875rem;
    font-weight: 500;
}

.remove-btn {
    background: var(--danger-color);
    color: white;
}

.remove-btn:hover {
    background: #c0392b;
}

.view-btn {
    background: var(--accent-color);
    color: white;
}

.view-btn:hover {
    background: #2980b9;
}

.empty-home-favorites {
    grid-column: 1 / -1;
    text-align: center;
    padding: 3rem 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.empty-home-favorites .empty-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.empty-home-favorites h3 {
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.empty-home-favorites p {
    color: var(--text-light);
}

.empty-favorites {
    grid-column: 1 / -1;
    text-align: center;
    padding: 4rem 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.empty-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
}

.empty-favorites h3 {
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.empty-favorites p {
    color: var(--text-light);
    margin-bottom: 2rem;
}

.explore-btn {
    padding: 1rem 2rem;
    background: linear-gradient(45deg, var(--accent-color) 0%, #2980b9 100%);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    font-size: 1rem;
}

.explore-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

/* About Page */
.about-hero {
    text-align: center;
    padding: 3rem 0;
    background: linear-gradient(135deg, rgba(52, 152, 219, 0.05) 0%, rgba(155, 89, 182, 0.05) 100%);
    border-radius: var(--border-radius);
    margin-bottom: 3rem;
}

.about-intro {
    font-size: 1.25rem;
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto;
}

.about-content {
    display: flex;
    flex-direction: column;
    gap: 3rem;
}

.about-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
    background: white;
    padding: 3rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.about-section.reverse {
    direction: rtl;
}

.about-section.reverse .about-text {
    direction: ltr;
}

.about-text h3 {
    color: var(--text-dark);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.about-text p {
    color: var(--text-dark);
    line-height: 1.7;
}

.features-list {
    list-style: none;
    padding: 0;
}

.features-list li {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-dark);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.about-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.placeholder-image {
    width: 200px;
    height: 200px;
    background: linear-gradient(135deg, var(--accent-color) 0%, var(--gold-color) 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    color: white;
    box-shadow: var(--shadow);
}

.credits-section {
    background: white;
    padding: 3rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-top: 2rem;
}

.credits-section h3 {
    text-align: center;
    color: var(--text-dark);
    margin-bottom: 2rem;
}

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

.credit-item {
    text-align: center;
    padding: 2rem;
    background: var(--background-light);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}

.credit-item h4 {
    color: var(--accent-color);
    margin-bottom: 1rem;
}

.credit-item p {
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.credit-item a {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

.credit-item a:hover {
    color: var(--gold-color);
}

.contact-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: 3rem;
    border-radius: var(--border-radius);
    text-align: center;
    margin-top: 2rem;
}

.contact-section h3 {
    color: white;
    margin-bottom: 1rem;
}

.contact-section p {
    margin-bottom: 2rem;
    opacity: 0.9;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.contact-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background: rgba(255, 255, 255, 0.1);
    color: white;
    text-decoration: none;
    border-radius: var(--border-radius);
    transition: var(--transition);
    font-weight: 500;
}

.contact-link:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

/* Footer */
.footer {
    background: var(--primary-color);
    color: white;
    padding: 3rem 0 1rem;
    margin-top: 3rem;
}

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

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

.footer-section p {
    opacity: 0.8;
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: white;
    text-decoration: none;
    opacity: 0.8;
    transition: var(--transition);
    display: block;
    margin-bottom: 0.5rem;
}

.footer-section a:hover {
    opacity: 1;
    color: var(--gold-color);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 1rem;
    text-align: center;
    opacity: 0.7;
}

/* Toast Notification */
.toast {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-hover);
    padding: 1rem 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    transform: translateX(400px);
    transition: var(--transition);
    z-index: 1001;
    max-width: 400px;
    border-left: 4px solid var(--success-color);
}

.toast.show {
    transform: translateX(0);
}

.toast.error {
    border-left-color: var(--danger-color);
}

.toast-icon {
    font-size: 1.25rem;
}

.toast-message {
    flex: 1;
    color: var(--text-dark);
    font-weight: 500;
}

.toast-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-light);
    transition: var(--transition);
}

.toast-close:hover {
    color: var(--text-dark);
}

/* Responsive Design */

/* Tablet Responsiveness */
@media (max-width: 768px) {
    :root {
        --header-height: 70px;
    }

    .container {
        padding: 0 15px;
    }

    /* Navigation */
    .navbar {
        padding: 1rem 1.5rem;
    }

    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background: var(--primary-color);
        flex-direction: column;
        padding: 2rem;
        gap: 1rem;
        transform: translateY(-100vh);
        transition: var(--transition);
        box-shadow: var(--shadow);
    }

    .nav-menu.active {
        transform: translateY(0);
    }

    .hamburger {
        display: flex;
    }

    .logo {
        font-size: 1.25rem;
    }

    .tagline {
        font-size: 0.75rem;
    }

    /* Search Form */
    .search-form {
        flex-direction: row;
        gap: 1rem;
        justify-content: center;
    }

    .date-input {
        min-width: auto;
        width: auto;
        max-width: 200px;
    }

    /* APOD Content */
    .apod-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .image-overlay {
        opacity: 1;
    }

    /* About Sections */
    .about-section {
        grid-template-columns: 1fr;
        gap: 2rem;
        padding: 2rem;
    }

    .about-section.reverse {
        direction: ltr;
    }

    .placeholder-image {
        width: 150px;
        height: 150px;
        font-size: 3rem;
    }

    /* Favorites */
    .favorites-stats {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }

    .home-favorites-grid,
    .favorites-grid {
        grid-template-columns: 1fr;
    }

    /* Footer */
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    /* Toast */
    .toast {
        bottom: 1rem;
        right: 1rem;
        left: 1rem;
        max-width: none;
    }

    /* Contact Links */
    .contact-links {
        flex-direction: column;
        align-items: center;
    }
}


/* Mobile Responsiveness */
@media (max-width: 480px) {
    .container {
        padding: 0 10px;
    }

    .search-section,
    .page-header {
        padding: 2rem 0;
    }

    .about-section,
    .credits-section,
    .contact-section {
        padding: 1.5rem;
    }

    .info-content {
        padding: 1.5rem;
    }

    .favorites-stats {
        padding: 1.5rem;
    }

    .empty-favorites {
        padding: 2rem 1rem;
    }
}

/* Print Styles */
@media print {
    .header,
    .footer,
    .search-section,
    .toast,
    .hamburger {
        display: none !important;
    }

    .main-content {
        margin-top: 0;
    }

    .page {
        display: block !important;
    }

    body {
        background: white;
        color: black;
    }

    .apod-content,
    .about-section {
        break-inside: avoid;
    }
}

/* Accessibility Improvements */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus Styles for Better Accessibility */
button:focus,
input:focus,
a:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
    :root {
        --shadow: 0 0 0 1px #000;
        --border-color: #000;
    }

    .nav-link:hover,
    .nav-link.active {
        background: #000;
        color: #fff;
    }
}

/* Smooth scroll behavior enhancement */
@media (prefers-reduced-motion: no-preference) {
    html {
        scroll-behavior: smooth;
    }
}