body {
    font-family: Futura, 'Trebuchet MS', Arial, sans-serif;
    display: grid;
    place-items: center;
    min-height: 100vh;
    margin: 0;
    transition: background-color 0.3s ease;
}

h1 {
    margin-bottom: 30px;
    color: #333;
}

div {
    display: grid;
    grid-template-columns: auto auto;
    gap: 10px;
}

#colorInput {
    padding: 10px 15px;
    font-size: 16px;
    border: 2px solid #ddd;
    border-radius: 5px;
    width: 250px;
}

#colorInput:focus {
    outline: none;
    border-color: #4CAF50;
}

#applyButton {
    padding: 10px 25px;
    font-size: 16px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

#applyButton:hover {
    background-color: #45a049;
}

#applyButton:active {
    background-color: #3d8b40;
}

.error {
    margin-top: 20px;
    padding: 12px 20px;
    background-color: #ffebee;
    color: #c62828;
    border: 2px solid #ef5350;
    border-radius: 5px;
    font-size: 14px;
    font-weight: 500;
    text-align: center;
    animation: shake 0.4s ease-in-out;
    max-width: 350px;
}

.error.hidden {
    display: none;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
    20%, 40%, 60%, 80% { transform: translateX(5px); }
}