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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: #f5f5f5;
    color: #1a1a1a;
    line-height: 1.5;
}

/* Login page */
.container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.login-card {
    background: #fff;
    border-radius: 8px;
    padding: 40px;
    width: 100%;
    max-width: 400px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 30px;
    text-align: center;
}

.intro {
    color: #666;
    margin-bottom: 20px;
    font-size: 0.95rem;
}

.info {
    color: #666;
    font-size: 0.9rem;
    margin-bottom: 15px;
}

input[type="text"] {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 1rem;
    margin-bottom: 15px;
}

input[type="text"]:focus {
    outline: none;
    border-color: #1a1a1a;
}

button {
    background: #1a1a1a;
    color: #fff;
    border: none;
    padding: 12px 24px;
    border-radius: 6px;
    font-size: 1rem;
    cursor: pointer;
    width: 100%;
    transition: background 0.2s;
}

button:hover {
    background: #333;
}

button:disabled {
    background: #999;
    cursor: not-allowed;
}

.error {
    color: #d32f2f;
    font-size: 0.9rem;
    margin-top: 15px;
}

/* Session select */
#sessionList {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.session-btn {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    text-align: left;
    padding: 15px;
    background: #f9f9f9;
    border: 1px solid #eee;
}

.session-btn:hover:not(:disabled) {
    background: #f0f0f0;
    border-color: #ddd;
}

.session-btn.disabled {
    opacity: 0.6;
    background: #f5f5f5;
}

.session-name {
    font-weight: 500;
    margin-bottom: 4px;
}

.session-deadline {
    font-size: 0.85rem;
    color: #666;
}

/* Chat page */
.chat-container {
    height: 100vh;
    display: flex;
    flex-direction: column;
    background: #fff;
}

.chat-header {
    padding: 15px 20px;
    border-bottom: 1px solid #eee;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.chat-header h1 {
    font-size: 1.1rem;
    font-weight: 600;
}

.header-info {
    display: flex;
    align-items: center;
    gap: 15px;
    font-size: 0.85rem;
    color: #666;
}

/* Intro screen */
.intro-screen {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.intro-content {
    max-width: 500px;
    text-align: center;
}

.intro-content h2 {
    font-size: 1.4rem;
    margin-bottom: 20px;
}

.intro-content p {
    color: #666;
    margin-bottom: 15px;
}

.intro-examples {
    background: #f9f9f9;
    border-radius: 8px;
    padding: 20px;
    margin: 25px 0;
    text-align: left;
}

.intro-examples p {
    margin-bottom: 10px;
}

.intro-examples p:last-child {
    margin-bottom: 0;
}

.intro-content button {
    max-width: 200px;
    margin: 0 auto;
}

/* Chat screen */
.chat-screen {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.messages {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.message {
    max-width: 80%;
    padding: 12px 16px;
    border-radius: 12px;
}

.message-user {
    align-self: flex-end;
    background: #1a1a1a;
    color: #fff;
}

.message-assistant {
    align-self: flex-start;
    background: #f0f0f0;
    color: #1a1a1a;
}

.message-system {
    align-self: center;
    background: #e8f5e9;
    color: #2e7d32;
    font-size: 0.9rem;
    text-align: center;
}

.message-text {
    white-space: pre-wrap;
    word-break: break-word;
}

/* Input area */
.input-area {
    padding: 15px 20px;
    border-top: 1px solid #eee;
    display: flex;
    gap: 10px;
    align-items: flex-end;
}

.input-area textarea {
    flex: 1;
    padding: 12px 15px;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
    resize: none;
    min-height: 44px;
    max-height: 150px;
}

.input-area textarea:focus {
    outline: none;
    border-color: #1a1a1a;
}

.input-area button {
    width: auto;
    padding: 12px 20px;
    flex-shrink: 0;
}

#finishBtn {
    background: #2e7d32;
}

#finishBtn:hover {
    background: #1b5e20;
}

/* Completed screen */
.completed-screen,
.unavailable-screen {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.completed-content,
.unavailable-content {
    text-align: center;
    max-width: 400px;
}

.completed-content h2,
.unavailable-content h2 {
    font-size: 1.4rem;
    margin-bottom: 15px;
}

.completed-content p,
.unavailable-content p {
    color: #666;
}

/* Mobile */
@media (max-width: 600px) {
    .login-card {
        padding: 25px;
    }
    
    .chat-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    
    .message {
        max-width: 90%;
    }
    
    .input-area {
        padding: 10px 15px;
    }
}