/* ==========================================
   CSS Variables
   ========================================== */
:root {
    --color-primary: #25D366;
    --color-primary-dark: #1EBE55;
    --color-secondary: #128C7E;
    --color-dark: #111B21;
    --color-text: #3B4A54;
    --color-text-light: #667781;
    --color-background: #F0F2F5;
    --color-white: #FFFFFF;
    --color-border: #E9EDEF;
    
    --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica', 'Arial', sans-serif;
    
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-xxl: 4rem;
    
    --border-radius-sm: 0.375rem;
    --border-radius-md: 0.5rem;
    --border-radius-lg: 1rem;
    --border-radius-full: 9999px;
    
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    
    --transition-base: all 0.2s ease-in-out;
}

/* ==========================================
   Base Styles
   ========================================== */
*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    font-family: var(--font-primary);
    font-size: 16px;
    line-height: 1.5;
    color: var(--color-text);
    background-color: var(--color-white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
    padding: 0;
    transition: var(--transition-base);
}

ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

h1, h2, h3, h4, h5, h6 {
    margin: 0;
    font-weight: 600;
}

/* ==========================================
   Button Component
   ========================================== */
.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius-full);
    font-size: 0.9375rem;
    font-weight: 500;
    line-height: 1.2;
    transition: var(--transition-base);
    white-space: nowrap;
}

.button:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.button--primary {
    background-color: var(--color-primary);
    color: var(--color-white);
    box-shadow: var(--shadow-sm);
}

.button--primary:hover {
    background-color: var(--color-primary-dark);
    box-shadow: var(--shadow-md);
    transform: translateY(-1px);
}

.button--primary:active {
    transform: translateY(0);
}

.button--secondary {
    background-color: transparent;
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

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

.button--join {
    width: 100%;
    max-width: 280px;
    padding: 1rem 2rem;
    background-color: var(--color-secondary);
    color: var(--color-white);
    font-size: 1rem;
    font-weight: 600;
    box-shadow: var(--shadow-lg);
}

.button--join:hover {
    background-color: #0F7268;
    box-shadow: var(--shadow-xl);
    transform: translateY(-2px);
}

.button--join:active {
    transform: translateY(0);
}

/* ==========================================
   Header
   ========================================== */
.header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: var(--color-white);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
}

.header__container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1440px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    height: 72px;
}

.header__logo {
    display: flex;
    align-items: center;
    gap: 0.625rem;
    color: var(--color-text);
    font-weight: 600;
    font-size: 1.125rem;
}

.header__logo:hover {
    opacity: 0.8;
}

.header__logo svg {
    flex-shrink: 0;
}

.header__logo-text {
    display: none;
}

.header__nav {
    display: none;
    align-items: center;
    gap: var(--spacing-md);
}

.header__nav-toggle {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    color: var(--color-text);
    font-size: 0.9375rem;
    padding: 0.5rem;
}

.header__nav-toggle:hover {
    color: var(--color-primary);
}

.header__nav-link {
    color: var(--color-text);
    font-size: 0.9375rem;
    padding: 0.5rem;
}

.header__nav-link:hover {
    color: var(--color-primary);
}

.header__actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

/* ==========================================
   Main Content
   ========================================== */
.main {
    min-height: calc(100vh - 72px - 400px);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-xl) var(--spacing-md);
    background-color: var(--color-background);
}

/* ==========================================
   Invite Card
   ========================================== */
.invite {
    width: 100%;
    max-width: 500px;
}

.invite__card {
    display: flex;
    flex-direction: column;
    align-items: center;
    background-color: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xxl) var(--spacing-lg);
    box-shadow: var(--shadow-xl);
}

.invite__logo {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    background: linear-gradient(135deg, #E8F5F7 0%, #F0F8FA 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.invite__logo-image {
    width: 140px;
    height: auto;
}

.invite__title {
    font-size: 2rem;
    font-weight: 600;
    color: var(--color-dark);
    margin-bottom: var(--spacing-xs);
    text-align: center;
}

.invite__subtitle {
    font-size: 1rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-xl);
    text-align: center;
}

.invite__download {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
    width: 100%;
}

.invite__download-text {
    font-size: 0.9375rem;
    color: var(--color-text-light);
    margin: 0;
}

.invite__download-link {
    color: #00A5F4;
    font-size: 0.9375rem;
    font-weight: 500;
}

.invite__download-link:hover {
    text-decoration: underline;
}

/* ==========================================
   Footer
   ========================================== */
.footer {
    background-color: var(--color-dark);
    color: var(--color-white);
    padding: var(--spacing-xxl) var(--spacing-md) var(--spacing-lg);
}

.footer__container {
    max-width: 1440px;
    margin: 0 auto;
}

.footer__top {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
    padding-bottom: var(--spacing-xl);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    margin-bottom: var(--spacing-lg);
}

.footer__brand {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    align-items: flex-start;
}

.footer__brand svg {
    opacity: 0.9;
}

.button--download-footer {
    background-color: var(--color-primary);
    color: var(--color-white);
    padding: 0.875rem 2rem;
    border-radius: var(--border-radius-full);
    font-size: 0.9375rem;
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    transition: var(--transition-base);
    box-shadow: var(--shadow-md);
}

.button--download-footer:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

.button--download-footer svg {
    width: 16px;
    height: 16px;
}

.footer__links {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
}

.footer__column-title {
    font-size: 0.75rem;
    color: rgba(255, 255, 255, 0.5);
    margin-bottom: var(--spacing-sm);
    font-weight: 400;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.footer__list {
    display: flex;
    flex-direction: column;
    gap: 0.625rem;
}

.footer__link {
    font-size: 1rem;
    color: var(--color-white);
    display: inline-block;
    transition: var(--transition-base);
}

.footer__link:hover {
    color: var(--color-primary);
}

/* Footer Bottom */
.footer__bottom {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    align-items: flex-start;
}

.footer__bottom-left {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.footer__copyright {
    font-size: 0.875rem;
    color: rgba(255, 255, 255, 0.6);
    margin: 0;
}

.footer__bottom-link {
    font-size: 0.875rem;
    color: rgba(255, 255, 255, 0.8);
    transition: var(--transition-base);
}

.footer__bottom-link:hover {
    color: var(--color-white);
}

.footer__bottom-center {
    display: flex;
    gap: var(--spacing-sm);
}

.footer__social {
    width: 44px;
    height: 44px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-white);
    transition: var(--transition-base);
}

.footer__social:hover {
    border-color: var(--color-white);
    background-color: rgba(255, 255, 255, 0.1);
    transform: translateY(-2px);
}

.footer__social svg {
    width: 20px;
    height: 20px;
}

.footer__bottom-right {
    margin-left: auto;
}

.footer__language-button {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: 0.75rem 1.5rem;
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: var(--border-radius-full);
    background-color: transparent;
    color: var(--color-white);
    font-size: 0.9375rem;
    transition: var(--transition-base);
}

.footer__language-button:hover {
    border-color: var(--color-white);
    background-color: rgba(255, 255, 255, 0.1);
}

.footer__language-button svg {
    width: 12px;
    height: 8px;
}

/* ==========================================
   Responsive Design
   ========================================== */

/* Tablet (768px and up) */
@media (min-width: 768px) {
    .header__logo-text {
        display: block;
    }
    
    .header__nav {
        display: flex;
    }
    
    .header__container {
        padding: 0 var(--spacing-lg);
    }
    
    .main {
        padding: var(--spacing-xxl) var(--spacing-lg);
    }
    
    .invite__card {
        padding: var(--spacing-xxl) var(--spacing-xl);
    }
    
    .invite__logo {
        width: 200px;
        height: 200px;
    }
    
    .invite__logo-image {
        width: 160px;
    }
    
    .invite__title {
        font-size: 2.5rem;
    }
    
    .invite__subtitle {
        font-size: 1.125rem;
    }
    
    .footer__top {
        flex-direction: row;
        justify-content: space-between;
    }
    
    .footer__brand {
        flex-direction: row;
        align-items: center;
        gap: var(--spacing-lg);
    }
    
    .footer__links {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-xl);
    }
    
    .footer__bottom {
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
    }
    
    .footer__bottom-left {
        flex-direction: row;
        align-items: center;
        gap: var(--spacing-md);
    }
    
    .footer__bottom-right {
        margin-left: 0;
    }
}

/* Desktop (1024px and up) */
@media (min-width: 1024px) {
    .header__container {
        padding: 0 var(--spacing-xl);
    }
    
    .header__nav {
        gap: var(--spacing-lg);
    }
    
    .invite__logo {
        width: 220px;
        height: 220px;
    }
    
    .invite__logo-image {
        width: 180px;
    }
    
    .footer__links {
        grid-template-columns: repeat(4, 1fr);
        gap: var(--spacing-xxl);
    }
    
    .footer__bottom {
        padding-top: var(--spacing-md);
    }
}

/* Large Desktop (1440px and up) */
@media (min-width: 1440px) {
    .header__container {
        padding: 0 var(--spacing-xxl);
    }
}

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

/* Focus styles for keyboard navigation */
a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
    border-radius: var(--border-radius-sm);
}

/* ==========================================
   Print Styles
   ========================================== */
@media print {
    .header,
    .footer {
        display: none;
    }
    
    .main {
        min-height: auto;
    }
    
    .invite__card {
        box-shadow: none;
        border: 1px solid var(--color-border);
    }
}