:root {
    --primary: #00d2ff;
    --primary-glow: rgba(0, 210, 255, 0.4);
    --secondary: #3a7bd5;
    --bg-dark: #0f172a;
    --bg-card: rgba(30, 41, 59, 0.7);
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --accent: #10b981;
    --border: rgba(255, 255, 255, 0.1);
    --glass-bg: rgba(255, 255, 255, 0.03);
    --glass-border: rgba(255, 255, 255, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

body {
    background-color: var(--bg-dark);
    color: var(--text-main);
    min-height: 100vh;
    overflow-x: hidden;
    background-image: 
        radial-gradient(circle at 20% 20%, rgba(0, 210, 255, 0.05) 0%, transparent 40%),
        radial-gradient(circle at 80% 80%, rgba(58, 123, 213, 0.05) 0%, transparent 40%);
}

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

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 1rem;
    margin-bottom: 2rem;
    position: sticky;
    top: 1rem;
    z-index: 100;
    transition: padding 0.3s ease, background 0.3s ease, box-shadow 0.3s ease;
    will-change: padding, background;
}

nav.scrolled {
    padding: 0.6rem 1.5rem;
    background: rgba(15, 23, 42, 0.9);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
}

nav.scrolled .logo {
    font-size: 1.2rem;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    background: linear-gradient(to right, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-links {
    display: flex;
    gap: 1.5rem;
}

.nav-link {
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    cursor: pointer;
}

.nav-link:hover, .nav-link.active {
    color: var(--primary);
    text-shadow: 0 0 10px var(--primary-glow);
}

.card {
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    border: 1px solid var(--border);
    border-radius: 1.5rem;
    padding: 2rem;
    margin-bottom: 2rem;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.2), 0 10px 10px -5px rgba(0, 0, 0, 0.1);
}

h1, h2, h3 {
    margin-bottom: 1.5rem;
    color: var(--text-main);
}

.btn {
    padding: 0.75rem 1.5rem;
    border-radius: 0.75rem;
    border: none;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    box-shadow: 0 4px 15px var(--primary-glow);
}

.btn-primary:hover {
    filter: brightness(1.1);
    transform: scale(1.02);
}

.btn-secondary {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    color: var(--text-main);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
}

/* Tablet Mode Specific Styles */
body.tablet-mode {
    background: #000;
}

body.tablet-mode .nav-links, body.tablet-mode .logo {
    display: none;
}

body.tablet-mode .app-container {
    max-width: 800px;
    padding-top: 5rem;
}

/* Form Styles */
.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-muted);
    font-size: 0.9rem;
}

input, select, textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    color: white;
    outline: none;
    transition: border-color 0.3s ease;
}

input:focus, select:focus {
    border-color: var(--primary);
    background: rgba(255, 255, 255, 0.1);
}

.grid-cols-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

/* Hidden elements */
.hidden {
    display: none !important;
}

/* Responsive Design Queries */
@media (max-width: 1024px) {
    .app-container {
        padding: 1rem;
    }
}

@media (max-width: 768px) {
    nav {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
        text-align: center;
    }

    .nav-links {
        width: 100%;
        justify-content: center;
        gap: 1rem;
        flex-wrap: wrap;
    }

    .nav-link {
        font-size: 0.9rem;
    }

    .grid-cols-2 {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .card {
        padding: 1.5rem;
        border-radius: 1rem;
    }

    h1 {
        font-size: 1.5rem;
    }

    .header-actions {
        flex-direction: column;
        align-items: flex-start !important;
        gap: 1rem;
    }

    .search-box {
        width: 100%;
    }

    /* Table adjustments for mobile */
    #athletes-table th, #athletes-table td {
        padding: 0.75rem 0.5rem;
        font-size: 0.85rem;
    }

    /* Modal adjustments */
    #evaluation-modal .card {
        width: 95%;
        padding: 1.25rem;
    }
}

@media (max-width: 480px) {
    .nav-links {
        gap: 0.5rem;
    }

    .nav-link {
        font-size: 0.8rem;
        padding: 0.5rem;
        background: rgba(255,255,255,0.05);
        border-radius: 0.5rem;
    }

    .btn {
        width: 100%;
        margin-bottom: 0.5rem;
    }
}

/* Welcome Popup Styles */
.welcome-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(8px);
    z-index: 2000;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: opacity 0.5s ease;
}

.welcome-card {
    background: var(--bg-card);
    border: 2px solid var(--primary);
    border-radius: 2rem;
    padding: 3rem;
    text-align: center;
    box-shadow: 0 0 50px var(--primary-glow);
    animation: welcomePop 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.welcome-icon {
    font-size: 5rem;
    color: var(--accent);
    margin-bottom: 1.5rem;
    text-shadow: 0 0 20px rgba(16, 185, 129, 0.4);
}

.welcome-card h2 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    background: linear-gradient(to right, #fff, var(--primary));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.welcome-card p {
    font-size: 1.2rem;
    color: var(--text-muted);
}

.welcome-card strong {
    color: var(--accent);
    font-size: 1.5rem;
}

@keyframes welcomePop {
    from { opacity: 0; transform: scale(0.5); }
    to { opacity: 1; transform: scale(1); }
}