/* ============================================
   CSIA Website - Custom Styles
   CentraleSupélec Alumni IA Association
   ============================================ */

/* ----------------------------------------
   CSS Custom Properties (Design Tokens)
   ---------------------------------------- */
:root {
    /* Primary Colors - CentraleSupélec with Modern Blue Theme */
    --color-bg-primary: #0A1628;
    /* Deep midnight blue */
    --color-bg-secondary: #0F1D35;
    /* Navy blue */
    --color-bg-tertiary: #1A2744;
    /* Slate blue */

    /* Accent Colors - Dark Red and Dark Blue */
    --color-accent-red: #C1002A;
    /* Dark red (CentraleSupélec) */
    --color-accent-blue: #003C78;
    /* Dark blue (CentraleSupélec) */
    --color-accent-dark-red: #8B001F;
    /* Darker red */
    --color-accent-dark-blue: #002654;
    /* Darker blue */

    /* Text Colors */
    --color-text-primary: #E8EAED;
    /* Light gray/white text */
    --color-text-secondary: rgba(232, 234, 237, 0.8);
    /* Primary with 80% opacity */
    --color-text-muted: rgba(232, 234, 237, 0.5);
    /* Primary with 50% opacity */

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #C1002A 0%, #003C78 100%);
    --gradient-glow: linear-gradient(135deg, rgba(193, 0, 42, 0.5) 0%, rgba(0, 60, 120, 0.5) 100%);
    --gradient-bg: linear-gradient(180deg, #0F1D35 0%, #0A1628 100%);

    /* Shadows */
    --shadow-glow: 0 0 40px rgba(193, 0, 42, 0.25);
    --shadow-card: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.06);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
}

/* ----------------------------------------
   Base Styles
   ---------------------------------------- */
html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    background: var(--gradient-bg);
    color: var(--color-text-primary);
    position: relative;
}

/* Continuous radial gradient overlay */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background:
        radial-gradient(ellipse 800px 600px at 50% 0%, rgba(0, 60, 120, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse 600px 800px at 100% 50%, rgba(193, 0, 42, 0.1) 0%, transparent 50%),
        radial-gradient(ellipse 700px 700px at 0% 100%, rgba(0, 60, 120, 0.1) 0%, transparent 50%);
    pointer-events: none;
    z-index: 0;
}

/* ----------------------------------------
   Text Color Utilities
   ---------------------------------------- */
.text-red {
    color: var(--color-accent-red);
}

.text-blue {
    color: var(--color-accent-blue);
}

/* ----------------------------------------
   Glassmorphism Cards
   ---------------------------------------- */
.glass-card {
    background: rgba(15, 29, 53, 0.8);
    /* Slightly more opaque */
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(232, 234, 237, 0.15);
    /* Slightly brighter border */
    border-radius: 1rem;
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

/* ----------------------------------------
   Missing Animation Classes
   ---------------------------------------- */
.animate-fadeIn {
    animation: fadeIn var(--transition-slow) forwards;
}

.glass-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-glow);
}

/* ----------------------------------------
   Button Styles
   ---------------------------------------- */
.btn-primary {
    background: var(--gradient-primary);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
    display: inline-block;
    text-decoration: none;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 30px rgba(193, 0, 42, 0.4);
}

.btn-secondary {
    background: transparent;
    color: var(--color-accent-red);
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    border: 2px solid var(--color-accent-red);
    transition: all var(--transition-fast);
    display: inline-block;
    text-decoration: none;
}

.btn-secondary:hover {
    background: var(--color-accent-red);
    color: white;
}

/* ----------------------------------------
   Navigation Styles
   ---------------------------------------- */
.nav-link {
    position: relative;
    color: var(--color-text-secondary);
    transition: color var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-text-primary);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: width var(--transition-normal);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

/* ----------------------------------------
   Hero Section
   ---------------------------------------- */
.hero-gradient {
    background: radial-gradient(ellipse at top, rgba(0, 60, 120, 0.2) 0%, transparent 50%),
        radial-gradient(ellipse at bottom right, rgba(193, 0, 42, 0.15) 0%, transparent 50%);
}

/* Animated background orbs */
.orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(60px);
    opacity: 0.5;
    animation: float 8s ease-in-out infinite;
}

.orb-1 {
    width: 400px;
    height: 400px;
    background: rgba(0, 60, 120, 0.25);
    top: -100px;
    right: -100px;
    animation-delay: 0s;
}

.orb-2 {
    width: 300px;
    height: 300px;
    background: rgba(193, 0, 42, 0.2);
    bottom: -50px;
    left: -50px;
    animation-delay: -4s;
}

@keyframes float {

    0%,
    100% {
        transform: translate(0, 0) scale(1);
    }

    50% {
        transform: translate(30px, -30px) scale(1.1);
    }
}

/* ----------------------------------------
   Event Cards
   ---------------------------------------- */
.event-card {
    position: relative;
    overflow: hidden;
}

.event-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: var(--gradient-primary);
}

/* ----------------------------------------
   Tab Navigation
   ---------------------------------------- */
.tab-btn {
    padding: 0.75rem 1.5rem;
    color: var(--color-text-secondary);
    border-bottom: 2px solid transparent;
    transition: all var(--transition-fast);
    background: transparent;
    cursor: pointer;
}

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

.tab-btn.active {
    color: var(--color-accent-red);
    border-bottom-color: var(--color-accent-red);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
    animation: fadeIn var(--transition-normal);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ----------------------------------------
   Form Styles
   ---------------------------------------- */
.form-input {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-bg-tertiary);
    border-radius: 0.5rem;
    padding: 0.75rem 1rem;
    color: var(--color-text-primary);
    width: 100%;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-input:focus {
    outline: none;
    border-color: var(--color-accent-red);
    box-shadow: 0 0 0 3px rgba(193, 0, 42, 0.2);
}

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

/* ----------------------------------------
   Newsletter Section
   ---------------------------------------- */
.newsletter-section {
    /* Blends with continuous background */
    position: relative;
}

/* ----------------------------------------
   Resource Cards
   ---------------------------------------- */
.resource-card {
    overflow: hidden;
    transition: transform var(--transition-normal);
}

.resource-card:hover {
    transform: scale(1.02);
}

.resource-card img,
.resource-card iframe {
    transition: transform var(--transition-slow);
}

.resource-card:hover img,
.resource-card:hover iframe {
    transform: scale(1.05);
}

/* ----------------------------------------
   Social Icons
   ---------------------------------------- */
.social-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 52px;
    height: 52px;
    border-radius: 50%;
    background: var(--color-bg-secondary);
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
}

.social-icon:hover {
    background: var(--gradient-primary);
    color: white;
    transform: translateY(-3px);
}

/* ----------------------------------------
   Footer Styles
   ---------------------------------------- */
.footer-link {
    color: var(--color-text-secondary);
    transition: color var(--transition-fast);
}

.footer-link:hover {
    color: var(--color-accent-red);
}

/* ----------------------------------------
   Video Embed Container
   ---------------------------------------- */
.video-container {
    position: relative;
    padding-bottom: 56.25%;
    /* 16:9 aspect ratio */
    height: 0;
    overflow: hidden;
    border-radius: 0.75rem;
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
    border-radius: 0.75rem;
}

/* ----------------------------------------
   Calendar Embed Container
   ---------------------------------------- */
.calendar-container {
    border-radius: 0.75rem;
    overflow: hidden;
    background: var(--color-bg-secondary);
}

.calendar-container iframe {
    border: none;
    width: 100%;
    min-height: 600px;
}

/* ----------------------------------------
   Mobile Menu
   ---------------------------------------- */
.mobile-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg-secondary);
    border-top: 1px solid rgba(193, 0, 42, 0.15);
    padding: 1rem;
    animation: slideDown var(--transition-normal);
}

.mobile-menu.open {
    display: block;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ----------------------------------------
   Responsive Adjustments
   ---------------------------------------- */
@media (max-width: 768px) {
    .orb {
        opacity: 0.3;
    }

    .orb-1 {
        width: 200px;
        height: 200px;
    }

    .orb-2 {
        width: 150px;
        height: 150px;
    }
}

/* ----------------------------------------
   Loading Animation
   ---------------------------------------- */
.loading-spinner {
    width: 24px;
    height: 24px;
    border: 3px solid var(--color-bg-tertiary);
    border-top-color: var(--color-accent-red);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* ----------------------------------------
   Success/Error States
   ---------------------------------------- */
.form-success {
    background: rgba(34, 197, 94, 0.1);
    border: 1px solid rgba(34, 197, 94, 0.3);
    color: #22c55e;
    padding: 1rem;
    border-radius: 0.5rem;
    display: none;
}

.form-error {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.3);
    color: #ef4444;
    padding: 1rem;
    border-radius: 0.5rem;
    display: none;
}