:root {
    --primary-color: #0f172a; /* Deep slate */
    --secondary-color: #3b82f6; /* Modern blue */
    --accent-color: #10b981; /* Emerald green */
    --background-color: #f8fafc;
    --card-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --error-color: #ef4444;
    --font-family: 'Inter', system-ui, -apple-system, sans-serif;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

a {
    color: var(--secondary-color);
    text-decoration: none;
    transition: color 0.2s;
}
a:hover {
    color: #2563eb;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.btn-primary {
    background-color: var(--secondary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    border: none;
    cursor: pointer;
    transition: all 0.2s;
    width: 100%;
    font-size: 1rem;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    background-color: #2563eb;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-primary:disabled {
    background-color: var(--text-secondary);
    cursor: not-allowed;
    transform: none;
}

.btn-outline {
    background-color: transparent;
    color: var(--secondary-color);
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    border: 1px solid var(--secondary-color);
    cursor: pointer;
    transition: all 0.2s;
    text-align: center;
    display: inline-block;
}

.btn-outline:hover {
    background-color: #eff6ff;
}

/* Event Banner Hero */
.hero-banner {
    width: 100%;
    height: auto;
    max-height: 250px;
    object-fit: contain;
    border-radius: 1rem;
    margin-top: 2rem;
    box-shadow: var(--shadow-lg);
    display: block;
    background-color: var(--primary-color);
}

/* Registration Form Card */
.registration-container {
    max-width: 600px;
    margin: 3rem auto 4rem;
}

.card {
    background: var(--card-bg);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
    font-size: 0.95rem;
}

.form-control {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.2s, box-shadow 0.2s;
    background-color: #f8fafc;
}

.form-control:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
    background-color: #ffffff;
}

.error-message {
    color: var(--error-color);
    font-size: 0.85rem;
    margin-top: 0.25rem;
    display: none;
}

.alert {
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1.5rem;
    display: none;
}
.alert-error {
    background-color: #fef2f2;
    color: #991b1b;
    border: 1px solid #fecaca;
}

.alert-success {
    background-color: #ecfdf5;
    color: #065f46;
    border: 1px solid #a7f3d0;
}

/* Success Page */
.success-container {
    text-align: center;
    max-width: 600px;
    margin: 3rem auto;
}
.success-icon {
    font-size: 4rem;
    color: var(--accent-color);
    margin-bottom: 1rem;
}
.qr-container {
    background: #ffffff;
    padding: 2.5rem 2rem;
    border-radius: 1rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
    margin: 2rem auto;
    max-width: 450px;
}

.qr-container h3 {
    margin: 0;
    color: var(--text-secondary);
    font-size: 1.1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.qr-container img {
    width: 220px;
    height: 220px;
    border-radius: 0.75rem;
    padding: 10px;
    background: white;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.registration-no {
    font-size: 2.5rem;
    font-weight: 800;
    letter-spacing: 3px;
    color: var(--primary-color);
    margin: 0;
    padding: 1rem 2rem;
    background: #f8fafc;
    border: 2px dashed #cbd5e1;
    border-radius: 0.75rem;
    display: inline-block;
    width: 100%;
    text-align: center;
}

/* Responsive */
@media (max-width: 768px) {
    .hero-banner {
        border-radius: 0;
        margin-top: 0;
        max-height: 250px;
    }
    .card {
        padding: 1.5rem;
        border-radius: 0;
        box-shadow: none;
        border-left: none;
        border-right: none;
    }
    .registration-container {
        margin-top: 0;
    }
}