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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    min-height: 100vh;
    padding: 20px;
    background: #f8fafc;
    color: #334155;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    border-radius: 15px;
    overflow: hidden;
}

header {
    padding: 20px;
    text-align: center;
}

h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    font-weight: 700;
    color: #1e293b;
}

.subtitle {
    font-size: 1.1rem;
    font-weight: 300;
}

main {
    padding: 20px 30px;
}

.intro {
    text-align: center;
    margin-bottom: 40px;
    font-size: 1.1rem;
}

.input-section {
    padding: 30px;
    border-radius: 10px;
    margin-bottom: 30px;
}

.input-group {
    display: flex;
    gap: 15px;
    align-items: stretch;
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
}

textarea {
    flex: 1;
    padding: 15px;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
    resize: vertical;
    min-height: 120px;
    line-height: 1.5;
    width: 100%;
    background: white;
    color: #1e293b;
}

textarea:focus {
    outline: none;
    border-color: #3b82f6;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

button {
    padding: 15px 30px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.2s ease;
    background: #3b82f6;
    color: white;
}

button:hover:not(:disabled) {
    background: #2563eb;
    transform: translateY(-1px);
}

button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

#msgError {
    margin-top: 15px;
    padding: 10px;
    border-radius: 5px;
    border-left: 4px solid #e74c3c;
    background: #fdf2f2;
    color: #e74c3c;
    display: none;
}

#msgError.show {
    display: block;
}

.messages-section {
    margin-top: 40px;
}

.messages-title {
    font-size: 1.5rem;
    margin-bottom: 20px;
    text-align: center;
}

#stringList {
    list-style: none;
    max-height: 400px;
    overflow-y: auto;
    padding: 10px;
    border-radius: 10px;
}

.list-item {
    background: white;
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 15px;
    border-left: 4px solid #3b82f6;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.user-name {
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 5px;
}

.user-address {
    font-family: 'Courier New', monospace;
    font-size: 0.8rem;
    padding: 2px 6px;
    border-radius: 4px;
    background: #f1f5f9;
    color: #64748b;
}

.user-string {
    font-size: 1.1rem;
    line-height: 1.5;
    margin-top: 10px;
    word-wrap: break-word;
}

footer {
    padding: 30px;
    border-top: 1px solid #e9ecef;
    text-align: center;
    line-height: 1.8;
}

footer a {
    text-decoration: none;
    color: #3b82f6;
}

footer a:hover {
    text-decoration: underline;
}

.warning {
    border: 1px solid;
    border-radius: 8px;
    padding: 15px;
    margin-bottom: 20px;
}

.warning strong {
    display: block;
    margin-bottom: 5px;
}

@media (max-width: 768px) {
    .container {
        margin: 10px;
        border-radius: 10px;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    .input-group {
        flex-direction: column;
    }
    
    textarea, button {
        width: 100%;
    }
    
    main {
        padding: 20px;
    }
    
    header {
        padding: 30px 20px;
    }
}