:root {
        --primary-blue: #2c5aa0;
        --secondary-gold: #d4af37;
        --accent-light: #e8f4fd;
        --text-dark: #2c3e50;
    }

    body {
        background: linear-gradient(135deg, var(--primary-blue) 0%, #1e3c72 100%);
    }

    .main-container {
        padding: 2rem 0;
    }

    .form-card {
        background: rgba(255, 255, 255, 0.95);
        border-radius: 20px;
        box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
        overflow: hidden;
        margin-bottom: 2rem;
    }

    .header-section {
        background: linear-gradient(135deg, var(--primary-blue), #1e3c72);
        color: white;
        padding: 2rem;
        text-align: center;
        position: relative;
    }

    .header-section::before {
        content: '';
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 100" fill="rgba(255,255,255,0.1)"><path d="M0,0 Q250,50 500,25 T1000,0 L1000,100 L0,100 Z"/></svg>');
        background-size: cover;
    }

    .header-content {
        position: relative;
        z-index: 1;
    }

    .conference-title {
        font-size: 2.5rem;
        font-weight: 700;
        margin-bottom: 0.5rem;
        text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    }

    .conference-subtitle {
        font-size: 1.2rem;
        opacity: 0.9;
        margin-bottom: 1rem;
    }

    .conference-details {
        background: rgba(255, 255, 255, 0.1);
        padding: 1rem;
        border-radius: 10px;
        display: inline-block;
    }

    .form-section {
        padding: 2rem;
    }

    .section-title {
        color: var(--primary-blue);
        font-size: 1.5rem;
        font-weight: 600;
        margin-bottom: 1.5rem;
        display: flex;
        align-items: center;
        gap: 0.5rem;
    }

    .section-title i {
        color: var(--secondary-gold);
    }

    .form-group label {
        font-weight: 600;
        color: var(--text-dark);
        margin-bottom: 0.5rem;
    }

    .form-control {
        border: 2px solid #e1e8ed;
        border-radius: 10px;
        padding: 0.75rem 1rem;
        transition: all 0.3s ease;
        background: #fff;
    }

    .form-control:focus {
        border-color: var(--secondary-gold);
        box-shadow: 0 0 0 0.2rem rgba(212, 175, 55, 0.25);
        background: #fff;
    }

    .form-control.is-invalid {
        border-color: #dc3545;
    }

    .custom-select {
        border: 2px solid #e1e8ed;
        border-radius: 10px;
        /* padding: 0.75rem 1rem; */
        background: #fff;
    }

    .custom-select:focus {
        border-color: var(--secondary-gold);
        box-shadow: 0 0 0 0.2rem rgba(212, 175, 55, 0.25);
    }

    .custom-select.is-invalid {
        border-color: #dc3545;
    }

    .checkbox-group {
        background: var(--accent-light);
        padding: 1.5rem;
        border-radius: 15px;
        margin: 1rem 0;
    }

    .custom-control-label {
        font-weight: 500;
        color: var(--text-dark);
    }

    .custom-checkbox .custom-control-input:checked~.custom-control-label::before {
        background-color: var(--secondary-gold);
        border-color: var(--secondary-gold);
    }

    .custom-radio .custom-control-input:checked~.custom-control-label::before {
        background-color: var(--secondary-gold);
        border-color: var(--secondary-gold);
    }

    .btn-primary {
        background: linear-gradient(135deg, var(--secondary-gold), #b8941f);
        border: none;
        padding: 1rem 2rem;
        border-radius: 50px;
        font-weight: 600;
        font-size: 1.1rem;
        transition: all 0.3s ease;
        box-shadow: 0 4px 15px rgba(212, 175, 55, 0.3);
    }

    .btn-primary:hover {
        transform: translateY(-2px);
        box-shadow: 0 6px 20px rgba(212, 175, 55, 0.4);
        background: linear-gradient(135deg, #b8941f, var(--secondary-gold));
    }

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

    .required {
        color: #e74c3c;
    }

    .input-group-text {
        background: var(--secondary-gold);
        color: white;
        border: 2px solid var(--secondary-gold);
        border-radius: 10px 0 0 10px;
    }

    .input-group .form-control {
        border-left: none;
        border-radius: 0 10px 10px 0;
    }

    .success-message {
        background: linear-gradient(135deg, #203f77, #1e2b5f);
        color: white;
        padding: 2rem;
        border-radius: 15px;
        text-align: center;
        margin-top: 2rem;
        display: none;
        animation: slideInUp 0.5s ease-out;
    }

    .error-message-inline {
        color: #dc3545;
        font-size: 0.875em;
        margin-top: 0.25rem;
        display: none;
        /* Hidden by default */
    }

    .loading {
        display: none;
        text-align: center;
        margin: 1rem 0;
    }

    .spinner-border {
        color: var(--secondary-gold);
    }

    .time-select-group {
        display: flex;
        gap: 5px;
    }

    .time-select-group .custom-select {
        flex: 1;
        /* Distribute width equally */
        padding-right: 0.75rem;
        /* Adjust padding for better look with icon */
    }

    .passport-preview {
        margin-top: 1rem;
        text-align: center;
    }

    .passport-preview img {
        max-width: 100%;
        height: auto;
        border: 1px solid #ddd;
        border-radius: 8px;
        padding: 5px;
        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    }

    #passport_preview {
        max-width: 250px;
    }

    @media (max-width: 768px) {
        .conference-title {
            font-size: 2rem;
        }

        .form-section {
            padding: 1rem;
        }
    }