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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: #f0f2f5;
    color: #333;
}

.container {
    max-width: 100%;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    background-color: #1a1a1a;
    color: white;
    padding: 1rem;
    text-align: center;
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 100;
}

header h1 {
    font-size: 1.5rem;
    font-weight: 600;
}

main {
    flex: 1;
    padding: 4rem 0 5rem 0;
    height: calc(100vh - 9rem);
}

.chat-container {
    padding: 1rem;
    overflow-y: auto;
    height: calc(100vh - 14rem);
}

.message {
    margin-bottom: 1rem;
    padding: 0.8rem;
    border-radius: 1rem;
    max-width: 80%;
    word-wrap: break-word;
}

.user-message {
    background-color: #007AFF;
    color: white;
    margin-left: auto;
    border-radius: 1rem 1rem 0 1rem;
}

.ai-message {
    background-color: #E9ECEF;
    color: #333;
    margin-right: auto;
    border-radius: 1rem 1rem 1rem 0;
}

.input-container {
    position: fixed;
    bottom: 0;
    width: 100%;
    padding: 1rem;
    background-color: white;
    box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.1);
    display: flex;
    gap: 0.5rem;
}

textarea {
    flex: 1;
    padding: 0.8rem;
    border: 1px solid #ddd;
    border-radius: 1.5rem;
    resize: none;
    font-size: 1rem;
    font-family: inherit;
}

button {
    padding: 0.8rem 1.5rem;
    background-color: #007AFF;
    color: white;
    border: none;
    border-radius: 1.5rem;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.2s;
}

button:active {
    background-color: #0056b3;
}

.loading {
    display: flex;
    gap: 0.3rem;
    padding: 0.5rem;
}

.loading span {
    width: 0.5rem;
    height: 0.5rem;
    background-color: #999;
    border-radius: 50%;
    animation: bounce 1.4s infinite ease-in-out;
}

.loading span:nth-child(1) { animation-delay: -0.32s; }
.loading span:nth-child(2) { animation-delay: -0.16s; }

@keyframes bounce {
    0%, 80%, 100% { transform: scale(0); }
    40% { transform: scale(1); }
}