:root {
    --primary-color: #6668ad;
    --primary-dark: #4a4c7f;
    --primary-light: #9092d0;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --light-bg: #f8f9fa;
    --white: #ffffff;
    --text-dark: #333333;
    --text-light: #666666;
    --border-color: #dee2e6;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    min-height: 100vh;
    padding: 20px;
    color: var(--text-dark);
}

.container {
    max-width: 1000px;
    margin: 0 auto;
}

header {
    text-align: center;
    color: var(--white);
    margin-bottom: 40px;
    padding: 30px 20px;
}

header h1 {
    font-size: 3rem;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
}

main {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.card {
    background: var(--white);
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--shadow);
}

.card h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
    font-size: 1.5rem;
}

.form-group {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

input[type="text"] {
    flex: 1;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

input[type="text"]:focus {
    outline: none;
    border-color: var(--primary-color);
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    white-space: nowrap;
}

.btn-primary {
    background: var(--primary-color);
    color: var(--white);
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(102, 104, 173, 0.4);
}

.btn-danger {
    background: var(--danger-color);
    color: var(--white);
    margin-right: 10px;
}

.btn-danger:hover {
    background: #c82333;
    transform: translateY(-2px);
}

.participant-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.participant-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 16px;
    background: var(--light-bg);
    border-radius: 8px;
    transition: background 0.3s;
}

.participant-item:hover {
    background: #e9ecef;
}

.participant-name {
    font-weight: 500;
    color: var(--text-dark);
}

.remove-btn {
    background: var(--danger-color);
    color: var(--white);
    border: none;
    padding: 6px 12px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background 0.3s;
}

.remove-btn:hover {
    background: #c82333;
}

.assignment-result {
    min-height: 50px;
}

.result-success {
    background: var(--success-color);
    color: var(--white);
    padding: 20px;
    border-radius: 8px;
    text-align: center;
    font-size: 1.1rem;
    font-weight: 600;
    animation: slideIn 0.5s ease-out;
}

.result-error {
    background: var(--danger-color);
    color: var(--white);
    padding: 20px;
    border-radius: 8px;
    text-align: center;
    font-weight: 600;
    animation: slideIn 0.5s ease-out;
}

.result-warning {
    background: var(--warning-color);
    color: var(--text-dark);
    padding: 20px;
    border-radius: 8px;
    text-align: center;
    font-weight: 600;
    animation: slideIn 0.5s ease-out;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.info-text {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-bottom: 15px;
    font-style: italic;
}

.tracking-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.tracking-item {
    padding: 12px 16px;
    background: var(--light-bg);
    border-radius: 8px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.tracking-name {
    font-weight: 500;
    color: var(--text-dark);
}

.tracking-id {
    font-family: 'Courier New', monospace;
    color: var(--text-light);
    font-size: 0.9rem;
    background: var(--white);
    padding: 4px 8px;
    border-radius: 4px;
}

.empty-state {
    text-align: center;
    color: var(--text-light);
    padding: 40px;
    font-style: italic;
}

@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .form-group {
        flex-direction: column;
    }

    .card {
        padding: 20px;
    }

    .tracking-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }
}