body {
    font-family: 'Roboto', sans-serif;
    background: linear-gradient(135deg, #00b4db, #0083b0);
    margin: 0;
    padding: 0;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.container {
    background-color: rgba(255, 255, 255, 0.8);
    border-radius: 20px;
    padding: 2rem;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    text-align: center;
    max-width: 90%;
    width: 300px;
}

h1, h2 {
    color: #333;
    margin-bottom: 1rem;
}

.calculator {
    background-color: rgba(255, 255, 255, 0.9);
    border-radius: 10px;
    padding: 1rem;
    margin-bottom: 1rem;
}

#display-container {
    width: 100%;
    height: 50px;
    margin-bottom: 1rem;
    position: relative;
}

#display {
    width: 100%;
    height: 100%;
    font-size: 1.5rem;
    text-align: right;
    padding: 0.5rem;
    box-sizing: border-box;
    border: 1px solid #ccc;
    border-radius: 5px;
    position: absolute;
    top: 0;
    left: 0;
    outline: none;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.5rem;
}

button {
    padding: 0.5rem;
    font-size: 1.2rem;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s;
}

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

button:nth-child(4n), button:last-child {
    background-color: #f39c12;
}

button:nth-child(4n):hover, button:last-child:hover {
    background-color: #e67e22;
}

button:first-child {
    background-color: #e74c3c;
}

button:first-child:hover {
    background-color: #c0392b;
}

.voice-control {
    margin-bottom: 1rem;
}

#start-voice {
    background-color: #3498db;
    margin-bottom: 0.5rem;
}

#start-voice:hover {
    background-color: #2980b9;
}

#voice-status {
    margin: 0;
    font-style: italic;
}

.history {
    background-color: rgba(255, 255, 255, 0.9);
    border-radius: 10px;
    padding: 1rem;
    max-height: 200px;
    overflow-y: auto;
}

#history-list {
    list-style-type: none;
    padding: 0;
    margin: 0;
    text-align: left;
}

#history-list li {
    padding: 0.5rem 0;
    border-bottom: 1px solid #eee;
}

#history-list li:last-child {
    border-bottom: none;
}