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

:root {
    --primary: #5c6d5e;
    --primary-light: #7a8b7c;
    --bg: #f7f5f2;
    --bg-chat: #ffffff;
    --text: #2d3436;
    --text-light: #636e72;
    --user-bg: #5c6d5e;
    --user-text: #ffffff;
    --assistant-bg: #ffffff;
    --shadow: 0 2px 8px rgba(0,0,0,0.08);
    --radius: 18px;
}

html, body {
    height: 100%;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.5;
}

.app {
    display: flex;
    flex-direction: column;
    height: 100%;
    max-width: 600px;
    margin: 0 auto;
    background: var(--bg-chat);
    box-shadow: var(--shadow);
}

.header {
    padding: 16px 20px;
    background: var(--primary);
    color: white;
    text-align: center;
}

.header h1 {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: 0.5px;
}

.subtitle {
    font-size: 0.85rem;
    opacity: 0.9;
    margin-top: 2px;
}

.chat-container {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.message {
    max-width: 85%;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.message.user {
    align-self: flex-end;
}

.message.assistant {
    align-self: flex-start;
}

.message-content {
    padding: 12px 16px;
    border-radius: var(--radius);
    white-space: pre-wrap;
    word-wrap: break-word;
}

.message.user .message-content {
    background: var(--user-bg);
    color: var(--user-text);
    border-bottom-right-radius: 4px;
}

.message.assistant .message-content {
    background: var(--assistant-bg);
    color: var(--text);
    border-bottom-left-radius: 4px;
    box-shadow: var(--shadow);
}

.message.loading .message-content {
    color: var(--text-light);
}

.message.error .message-content {
    background: #fff5f5;
    color: #c0392b;
}

.input-container {
    padding: 12px 16px 24px;
    background: var(--bg-chat);
    border-top: 1px solid rgba(0,0,0,0.06);
}

.input-form {
    display: flex;
    gap: 10px;
    align-items: flex-end;
}

textarea {
    flex: 1;
    padding: 12px 16px;
    border: 1px solid rgba(0,0,0,0.1);
    border-radius: 24px;
    font-size: 16px;
    font-family: inherit;
    line-height: 1.4;
    resize: none;
    outline: none;
    transition: border-color 0.2s;
}

textarea:focus {
    border-color: var(--primary);
}

button[type="submit"] {
    width: 44px;
    height: 44px;
    border: none;
    border-radius: 50%;
    background: var(--primary);
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.2s, transform 0.1s;
}

button[type="submit"]:hover {
    background: var(--primary-light);
}

button[type="submit"]:active {
    transform: scale(0.95);
}

button[type="submit"]:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

/* PWA standalone mode */
@media (display-mode: standalone) {
    .header {
        padding-top: env(safe-area-inset-top, 16px);
    }
    .input-container {
        padding-bottom: env(safe-area-inset-bottom, 24px);
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --bg: #1a1a1a;
        --bg-chat: #242424;
        --text: #e0e0e0;
        --text-light: #999;
        --assistant-bg: #2d2d2d;
        --shadow: 0 2px 8px rgba(0,0,0,0.3);
    }
}