:root {
    --background-light: #F5F5F5;
    --element-light: #E2E2E2;
    --text-light: #333333;
    --text-secondary-light: #666666;
    --accent-light: #999999;
    --border-light: #CCCCCC;
    --background-dark: #262626;
    --element-dark: #3A3A3A;
    --text-dark: #f1f1f1;
    --text-secondary-dark: #A0A0A0;
    --accent-dark: #808080;
    --border-dark: #555555;
    --message-user-light: #D5D5D5;
    --message-user-dark: #484848;
    --transition-speed: 0.5s;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

html, body {
    height: 100%;
    overflow: hidden;
    margin: 0;
    padding: 0;
}

body {
    background: var(--background-light);
    color: var(--text-light);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background var(--transition-speed) ease, color var(--transition-speed) ease;
}

.app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    background-color: var(--background-light);
    color: var(--text-light);
    position: relative;
    overflow: hidden;
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
}

.chat-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    position: relative;
    height: calc(100vh - 20rem);
    width: 100%;
    max-width: 800px;
    margin: 3rem auto 0;
    overflow: hidden;
    background-color: transparent;
}

.dark-mode {
    background-color: var(--background-dark);
    color: var(--text-dark);
}

.dark-mode .page-buttons,
.dark-mode .message-input,
.dark-mode .clear-button,
.dark-mode .icon-button,
.dark-mode .language-icon,
.dark-mode h1,
.dark-mode .welcome-section p,
.dark-mode .message-link,
.dark-mode .custom-scrollbar .scrollbar-track,
.dark-mode .custom-scrollbar .scrollbar-thumb,
.dark-mode .typing-indicator span,
.dark-mode .send-button,
.dark-mode .input-form {
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease, border-color var(--transition-speed) ease, box-shadow var(--transition-speed) ease;
}

.dark-mode .page-buttons {
    background-color: transparent;
}

.dark-mode .message-input,
.dark-mode .clear-button,
.dark-mode .icon-button,
.dark-mode .input-form {
    background-color: var(--element-dark);
    color: var(--text-dark);
    border-color: var(--border-dark);
}

.dark-mode .language-icon {
    color: var(--text-dark);
}

.dark-mode h1,
.dark-mode .welcome-section p {
    color: var(--text-dark);
}

.dark-mode .welcome-section h1 {
    color: #ececec;
}

.dark-mode .message-input::placeholder {
    color: var(--text-secondary-dark);
}

.dark-mode .typing-indicator span {
    background-color: var(--text-secondary-dark);
}

.dark-mode .message-link {
    color: var(--accent-dark);
}

.dark-mode .custom-scrollbar .scrollbar-track {
    background: var(--element-dark);
}

.dark-mode .custom-scrollbar .scrollbar-thumb {
    background: var(--accent-dark);
}

.dark-mode .send-button {
    color: var(--accent-dark);
}

.page-buttons {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    padding: 0.4rem 0.6rem;
    background-color: transparent;
    position: fixed;
    top: 0;
    right: 0;
    width: auto;
    z-index: 1000;
    gap: 8px;
}

.messages-wrapper {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
    padding: 1rem 0;
    scrollbar-width: none;
    -ms-overflow-style: none;
    position: relative;
    background-color: transparent;
}

.messages-wrapper::-webkit-scrollbar {
    display: none;
}

.messages-wrapper.has-messages {
    padding-bottom: 120px;
}

.messages-list {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.welcome-section {
    position: absolute;
    top: 40%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    width: 100%;
    max-width: 600px;
    padding: 0 2rem;
    transition: opacity 0.3s ease;
    z-index: 5;
}

.welcome-section h1 {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-light);
    transition: color var(--transition-speed) ease;
}

.welcome-section p {
    font-size: 1rem;
    color: var(--text-secondary-light);
    transition: color var(--transition-speed) ease;
}

.has-messages .welcome-section {
    opacity: 0;
    pointer-events: none;
}

.input-container {
    position: absolute;
    bottom: 50%;
    left: 50%;
    transform: translate(-50%, 50%);
    width: 90%;
    max-width: 500px;
    padding: 1rem;
    background-color: transparent;
    z-index: 10;
    transition: all 0.3s ease, box-shadow 0.5s ease;
}

.input-container.has-messages {
    position: fixed;
    bottom: 0;
    transform: translateX(-50%);
    background-color: transparent;
    padding: 1.5rem 1rem 1rem;
    width: 100%;
    max-width: 500px;
    transition: all 0.3s ease, box-shadow 0.5s ease;
}

.input-form {
    display: flex;
    position: relative;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);
    border-radius: 12px;
    background-color: var(--element-light);
    transition: box-shadow 0.5s ease, background-color 0.5s ease;
}

.dark-mode .input-form {
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
    background-color: var(--element-dark);
}

.message-input {
    flex: 1;
    border: 1px solid var(--border-light);
    border-radius: 12px;
    padding: 0.6rem 2rem 0.6rem 0.8rem;
    font-size: 1rem;
    background-color: var(--element-light);
    color: var(--text-light);
    min-height: 40px;
    max-height: 200px;
    resize: none;
    overflow-y: hidden;
    line-height: 1.5;
    box-shadow: 0 2px 6px rgba(0,0,0,0.1);
    transition: border-color var(--transition-speed) ease, background-color var(--transition-speed) ease, color var(--transition-speed) ease, box-shadow var(--transition-speed) ease;
}

.message-input:focus {
    outline: none;
    border-color: var(--accent-light);
    box-shadow: 0 2px 6px rgba(0,0,0,0.15);
}

.dark-mode .message-input:focus {
    border-color: var(--accent-dark);
}

.message-input::placeholder {
    color: var(--text-secondary-light);
    transition: color var(--transition-speed) ease;
}

.send-button {
    position: absolute;
    right: 0.6rem;
    top: 50%;
    transform: translateY(-50%);
    border: none;
    background: transparent;
    cursor: pointer;
    padding: 0.4rem;
    color: var(--accent-light);
    transition: color var(--transition-speed) ease;
}

.send-button:hover {
    color: var(--text-light);
}

.dark-mode .send-button:hover {
    color: var(--text-dark);
}

.send-button svg {
    stroke: currentColor;
    fill: none;
    stroke-width: 2;
    transition: stroke var(--transition-speed) ease;
}

.clear-button,
.icon-button {
    background-color: var(--element-light);
    color: var(--text-light);
    border: 1px solid var(--border-light);
    border-radius: 8px;
    cursor: pointer;
    box-shadow: 0 1px 2px rgba(0,0,0,0.1);
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease, border-color var(--transition-speed) ease, box-shadow var(--transition-speed) ease;
}

.clear-button {
    padding: 0.3rem 0.6rem;
    font-size: 0.85rem;
    font-weight: 500;
    height: 30px;
    display: flex;
    align-items: center;
}

.icon-button {
    padding: 0.3rem;
    width: 30px;
    height: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.language-icon {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-light);
    display: flex;
    align-items: center;
    justify-content: center;
    text-transform: uppercase;
}

.clear-button:hover,
.icon-button:hover {
    background-color: var(--accent-light);
    color: var(--background-light);
    box-shadow: 0 1px 3px rgba(0,0,0,0.15);
}

.dark-mode .clear-button:hover,
.dark-mode .icon-button:hover {
    background-color: var(--accent-dark);
    color: var(--background-dark);
}

.icon-button svg {
    stroke: currentColor;
    fill: none;
    stroke-width: 2;
    transition: stroke var(--transition-speed) ease;
}

.message {
    margin-bottom: 0.5rem;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.message-wrapper {
    display: flex;
    width: 100%;
}

.message-content {
    max-width: 80%;
    padding: 0.4rem 0.7rem;
    font-size: 0.95rem;
    border-radius: 10px;
    transition: background-color var(--transition-speed) ease;
}

.assistant-message .message-content {
    background: transparent;
    padding: 0.4rem 0;
}

.user-message .message-content {
    background-color: var(--message-user-light);
    margin-left: auto;
    box-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

.dark-mode .user-message .message-content {
    background-color: var(--message-user-dark);
}

.message-body {
    font-size: 0.95rem;
    line-height: 1.4;
    text-align: justify; /* Justify chat text */
}

.message-line {
    margin-bottom: 0.5rem;
}

.message-line:last-child {
    margin-bottom: 0;
}

.message-link {
    color: var(--accent-light);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition-speed) ease;
}

.message-link:hover {
    text-decoration: underline;
}

.typing-indicator {
    display: flex;
    gap: 0.3rem;
    padding: 0.4rem 0;
}

.typing-indicator span {
    width: 0.4rem;
    height: 0.4rem;
    border-radius: 50%;
    background-color: var(--text-secondary-light);
    animation: bounce 1.2s infinite ease-in-out;
    transition: background-color var(--transition-speed) ease;
}

.typing-indicator span:nth-child(1) { animation-delay: 0s; }
.typing-indicator span:nth-child(2) { animation-delay: 0.2s; }
.typing-indicator span:nth-child(3) { animation-delay: 0.4s; }

@keyframes bounce {
    0%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-5px); }
}

.custom-scrollbar {
    position: absolute;
    right: 2px;
    top: 50px;
    bottom: 0;
    width: 6px;
    z-index: 1000;
    opacity: 0;
    transition: opacity 0.3s ease;
    pointer-events: auto;
}

.messages-wrapper.has-messages:hover ~ .custom-scrollbar,
.custom-scrollbar:hover {
    opacity: 1;
}

.scrollbar-track {
    width: 100%;
    height: calc(100% - 100px);
    background: var(--element-light);
    border-radius: 3px;
    position: relative;
    transition: background var(--transition-speed) ease;
}

.scrollbar-thumb {
    width: 100%;
    background: var(--accent-light);
    border-radius: 3px;
    position: absolute;
    top: 0;
    cursor: pointer;
    transition: background var(--transition-speed) ease;
}

@media (max-width: 768px) {
    .chat-container {
        max-width: 95%;
    }
    .page-buttons {
        padding: 0.3rem 0.4rem;
    }
    .messages-list {
        padding: 0 1rem;
    }
    .welcome-section {
        max-width: 95%;
        padding: 0 1.5rem;
    }
    .welcome-section h1 {
        font-size: 1.7rem;
    }
    .welcome-section p {
        font-size: 0.9rem;
    }
    .input-container {
        width: 95%;
        padding: 0.8rem;
    }
    .input-container.has-messages {
        width: 95%;
        padding: 1rem 0.8rem 0.8rem;
    }
    .message-input {
        font-size: 0.9rem;
        min-height: 36px;
        padding: 0.5rem 1.8rem 0.5rem 0.7rem;
    }
    .message-content {
        font-size: 0.9rem;
        padding: 0.3rem 0.6rem;
    }
    .assistant-message .message-content {
        padding: 0.3rem 0;
    }
    .clear-button {
        font-size: 0.8rem;
        height: 28px;
    }
    .icon-button {
        width: 28px;
        height: 28px;
    }
    .language-icon {
        font-size: 0.7rem;
    }
    .send-button {
        right: 0.5rem;
        padding: 0.3rem;
    }
}

@media (max-width: 480px) {
    .chat-container {
        max-width: 100%;
    }
    .page-buttons {
        padding: 0.3rem 0.4rem;
    }
    .messages-list {
        padding: 0 0.8rem;
    }
    .welcome-section {
        max-width: 95%;
        padding: 0 1rem;
    }
    .welcome-section h1 {
        font-size: 1.5rem;
    }
    .welcome-section p {
        font-size: 0.85rem;
    }
    .input-container {
        width: 95%;
        padding: 0.8rem;
    }
    .input-container.has-messages {
        width: 100%;
        padding: 1rem 0.8rem 0.8rem;
    }
}

@media (max-width: 360px) {
    .page-buttons {
        padding: 0.3rem 0.4rem;
    }
    .messages-list {
        padding: 0 0.6rem;
    }
    .welcome-section {
        max-width: 98%;
        padding: 0 0.8rem;
    }
    .welcome-section h1 {
        font-size: 1.4rem;
    }
    .welcome-section p {
        font-size: 0.8rem;
    }
    .input-container {
        width: 98%;
        padding: 0.6rem;
    }
    .input-container.has-messages {
        padding: 0.8rem 0.6rem 0.6rem;
    }
    .message-input {
        font-size: 0.85rem;
        min-height: 34px;
        padding: 0.4rem 1.6rem 0.4rem 0.6rem;
    }
    .message-content {
        font-size: 0.85rem;
    }
    .clear-button {
        font-size: 0.75rem;
        height: 26px;
    }
    .icon-button {
        width: 26px;
        height: 26px;
    }
    .language-icon {
        font-size: 0.65rem;
    }
}