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

:root {
    --surface-primary: #ffffff;
    --surface-secondary: #f8f9fa;
    --surface-tertiary: #f1f3f5;
    --text-primary: #1a1a2e;
    --text-secondary: #495057;
    --text-inverse: #ffffff;
    --accent: #0a0a0a;
    --accent-soft: #2d2d3f;
    --border-light: rgba(0, 0, 0, 0.06);
    --border-medium: rgba(0, 0, 0, 0.1);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04), 0 1px 2px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.06), 0 2px 4px rgba(0, 0, 0, 0.04);
    --shadow-lg: 0 20px 40px rgba(0, 0, 0, 0.08), 0 8px 16px rgba(0, 0, 0, 0.04);
    --shadow-xl: 0 25px 50px rgba(0, 0, 0, 0.1);
    --radius-xs: 6px;
    --radius-sm: 12px;
    --radius-md: 16px;
    --radius-lg: 20px;
    --radius-xl: 24px;
    --radius-full: 50%;
    --transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-smooth: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --font-sans: 'Inter', 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    background: #f5f5f7;
    color: var(--text-primary);
    line-height: 1.5;
}

::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
    margin: 4px 0;
}

::-webkit-scrollbar-thumb {
    background: rgba(0, 0, 0, 0.15);
    border-radius: 20px;
    transition: background var(--transition-base);
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(0, 0, 0, 0.25);
}

/* Main Container */
.container {
    display: flex;
    height: 100vh;
    background: #f5f5f7;
    overflow: hidden;
}

/* Sidebar - Refined Minimal */
.sidebar {
    width: 72px;
    padding: 24px 16px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-right: 1px solid var(--border-light);
}

.sidebar .top {
    height: 44px;
    width: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--surface-primary);
    border: 1px solid var(--border-medium);
    border-radius: var(--radius-full);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-smooth);
    cursor: pointer;
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-primary);
}

.sidebar .top:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(0, 0, 0, 0.2);
}

/* Content Area */
.content {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 32px;
    max-width: 900px;
    margin: 0 auto;
    height: 100vh;
}

.content .chats-box {
    width: 100%;
    max-height: 100%;
    overflow-y: auto;
    padding-right: 12px;
    padding-bottom: 5rem;
    scroll-behavior: smooth;
}

/* Message Bubbles - Refined */
.your-message,
.bot-message {
    padding: 14px 20px;
    max-width: 75%;
    width: fit-content;
    clear: both;
    border-radius: var(--radius-lg);
    margin-bottom: 1.5rem;
    position: relative;
    font-size: 0.95rem;
    line-height: 1.6;
    letter-spacing: 0.01em;
    animation: messageSlide 0.3s ease-out;
}

@keyframes messageSlide {
    from {
        opacity: 0;
        transform: translateY(8px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.bot-message {
    float: left;
    background: var(--surface-primary);
    color: var(--text-primary);
    border: 1px solid var(--border-light);
    box-shadow: var(--shadow-sm);
    border-bottom-left-radius: var(--radius-xs);
}

.your-message {
    float: right;
    background: var(--accent);
    color: var(--text-inverse);
    box-shadow: var(--shadow-md);
    border-bottom-right-radius: var(--radius-xs);
}

/* Copy Button on Messages */
.your-message svg,
.bot-message svg {
    position: absolute;
    bottom: -12px;
    right: -8px;
    background: var(--accent);
    color: var(--text-inverse);
    padding: 8px;
    border-radius: var(--radius-full);
    cursor: pointer;
    width: 32px;
    height: 32px;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-smooth);
    opacity: 0;
    transform: scale(0.9);
}

.your-message:hover svg,
.bot-message:hover svg {
    opacity: 1;
    transform: scale(1);
}

.your-message svg {
    background: var(--surface-primary);
    color: var(--accent);
}

.your-message svg:hover,
.bot-message svg:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-lg);
}

/* Message Input Box */
.message-box {
    width: 100%;
    margin-top: 1rem;
    padding: 20px 24px;
    border-radius: var(--radius-xl);
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--border-light);
    box-shadow: var(--shadow-xl);
    display: flex;
    flex-direction: column;
    gap: 14px;
    transition: box-shadow var(--transition-smooth);
}

.message-box:focus-within {
    box-shadow: 0 30px 60px rgba(0, 0, 0, 0.12), 0 0 0 2px rgba(0, 0, 0, 0.05);
}

/* Tool Container */
.tool-container {
    display: flex;
    gap: 12px;
}

.translate-type,
.translate-lang,
.message-type {
    display: flex;
    flex-direction: column;
    gap: 6px;
    width: 100%;
}

.tool-container label {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--text-secondary);
    padding-left: 4px;
}

select {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--border-medium);
    border-radius: var(--radius-sm);
    background: var(--surface-primary);
    font-size: 0.9rem;
    font-family: var(--font-sans);
    color: var(--text-primary);
    cursor: pointer;
    outline: none;
    transition: all var(--transition-base);
    appearance: none;
    -webkit-appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg width='12' height='8' viewBox='0 0 12 8' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1.5L6 6.5L11 1.5' stroke='%23666' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 14px center;
    padding-right: 36px;
}

select:hover {
    border-color: rgba(0, 0, 0, 0.25);
}

select:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(0, 0, 0, 0.05);
}

/* Message Input Field */
.message-input {
    position: relative;
    background: var(--surface-primary);
    border: 1px solid var(--border-medium);
    border-radius: var(--radius-md);
    display: flex;
    align-items: flex-end;
    padding: 10px 14px;
    gap: 10px;
    transition: all var(--transition-base);
}

.message-input:focus-within {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(0, 0, 0, 0.04);
}

textarea {
    width: 100%;
    border: none;
    resize: none;
    outline: none;
    font-family: var(--font-sans);
    font-size: 0.95rem;
    line-height: 1.6;
    padding: 6px 0;
    color: var(--text-primary);
    background: transparent;
    min-height: 24px;
    max-height: 120px;
}

textarea::placeholder {
    color: #adb5bd;
}

/* Action Buttons */
.buttons {
    display: flex;
    gap: 8px;
    flex-shrink: 0;
}

.message-input button {
    padding: 10px 18px;
    border-radius: 24px;
    border: none;
    background: var(--accent);
    color: var(--text-inverse);
    font-weight: 500;
    font-size: 0.85rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    transition: all var(--transition-smooth);
    letter-spacing: 0.02em;
    white-space: nowrap;
    font-family: var(--font-sans);
}

.message-input button:hover {
    background: var(--accent-soft);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.message-input button:active {
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

#swap-btn {
    background: var(--surface-primary);
    border: 1px solid var(--border-medium);
    color: var(--text-primary);
    padding: 10px 12px;
    min-width: 40px;
}

#swap-btn:hover {
    background: var(--surface-tertiary);
    border-color: rgba(0, 0, 0, 0.2);
}

/* Tooltip - Clean & Modern */
.instant-tooltip {
    position: relative;
    cursor: pointer;
    display: inline-block;
    border-bottom: 1.5px dotted rgba(0, 0, 0, 0.3);
}

.instant-tooltip::after {
    content: attr(data-title);
    position: absolute;
    bottom: calc(100% + 8px);
    left: 50%;
    transform: translateX(-50%);
    background: var(--accent-soft);
    color: var(--text-inverse);
    padding: 6px 12px;
    border-radius: var(--radius-xs);
    font-size: 0.8rem;
    font-weight: 500;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-base);
    box-shadow: var(--shadow-md);
    letter-spacing: 0.02em;
}

.instant-tooltip::before {
    content: '';
    position: absolute;
    bottom: calc(100% + 2px);
    left: 50%;
    transform: translateX(-50%);
    border: 6px solid transparent;
    border-top-color: var(--accent-soft);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.instant-tooltip:hover::after,
.instant-tooltip:hover::before {
    opacity: 1;
}

/* Copy Alert Toast */
.copy-alert {
    position: fixed;
    top: 24px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--accent-soft);
    color: var(--text-inverse);
    padding: 10px 24px;
    border-radius: 30px;
    font-size: 0.85rem;
    font-weight: 500;
    box-shadow: var(--shadow-xl);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-smooth);
    z-index: 1000;
    letter-spacing: 0.02em;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

/* Responsive Design */
@media (max-width: 768px) {
    html {
        font-size: 15px;
    }

    .container {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
        flex-direction: row;
        justify-content: space-between;
        padding: 12px 20px;
        background: rgba(255, 255, 255, 0.9);
        border-right: none;
        border-bottom: 1px solid var(--border-light);
    }

    .sidebar .top {
        height: 38px;
        width: 38px;
        font-size: 1rem;
    }

    .content {
        width: 100%;
        max-width: 100%;
        padding: 16px;
        height: calc(100vh - 62px);
    }

    .tool-container {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 10px;
    }

    .message-box {
        padding: 16px;
        border-radius: var(--radius-lg);
    }

    .your-message,
    .bot-message {
        max-width: 85%;
    }
}

@media (max-width: 480px) {
    .tool-container {
        grid-template-columns: 1fr;
    }

    .buttons {
        flex-direction: row;
        width: 100%;
    }

    .buttons button {
        flex: 1;
    }

    .message-input {
        flex-wrap: wrap;
    }

    textarea {
        width: 100%;
        min-width: 100%;
    }

    .buttons {
        width: 100%;
        justify-content: flex-end;
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    html {
        font-size: 13px;
    }

    * {
        font-size: 13px;
    }

    .container {
        flex-direction: column;
        height: 100vh;
        overflow: hidden;
    }

    .sidebar {
        width: 100%;
        flex-direction: row;
        justify-content: space-between;
        padding: 10px 16px;
        background: rgba(255, 255, 255, 0.95);
        border-right: none;
        border-bottom: 1px solid var(--border-light);
        min-height: 50px;
        max-height: 50px;
        flex-shrink: 0;
    }

    .sidebar .top {
        height: 32px;
        width: 32px;
        font-size: 0.9rem;
    }

    .sidebar .bottom {
        display: flex;
        align-items: center;
        gap: 8px;
    }

    .content {
        width: 100%;
        max-width: 100%;
        padding: 12px;
        height: calc(100vh - 50px);
        display: flex;
        flex-direction: column;
        justify-content: flex-start;
    }

    .content .chats-box {
        flex: 1;
        max-height: calc(100vh - 250px);
        padding-right: 8px;
        padding-bottom: 1rem;
        margin-bottom: 0;
    }

    .tool-container {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 8px;
    }

    .translate-type,
    .translate-lang,
    .message-type {
        gap: 4px;
    }

    .tool-container label {
        font-size: 0.65rem;
        letter-spacing: 0.03em;
    }

    select {
        padding: 8px 10px;
        padding-right: 30px;
        font-size: 0.78rem;
        border-radius: 10px;
        background-position: right 8px center;
        background-size: 10px 6px;
    }

    .message-box {
        width: 100%;
        padding: 12px 14px;
        border-radius: 18px;
        gap: 10px;
        margin-top: 0.5rem;
        flex-shrink: 0;
        position: sticky;
        bottom: 0;
        background: rgba(255, 255, 255, 0.95);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        z-index: 10;
    }

    .message-input {
        padding: 8px 10px;
        gap: 8px;
        border-radius: 14px;
        flex-wrap: nowrap;
    }

    textarea {
        font-size: 0.82rem;
        padding: 4px 0;
        min-height: 20px;
        max-height: 80px;
        flex: 1;
        min-width: 0;
    }

    textarea::placeholder {
        font-size: 0.78rem;
    }

    .buttons {
        display: flex;
        gap: 6px;
        flex-shrink: 0;
    }

    .message-input button {
        padding: 8px 14px;
        font-size: 0.75rem;
        border-radius: 20px;
        white-space: nowrap;
    }

    #swap-btn {
        padding: 8px 10px;
        min-width: 34px;
    }

    .your-message,
    .bot-message {
        max-width: 88%;
        padding: 10px 14px;
        margin-bottom: 1rem;
        font-size: 0.82rem;
        border-radius: 16px;
    }

    .your-message svg,
    .bot-message svg {
        width: 26px;
        height: 26px;
        padding: 6px;
        bottom: -10px;
        right: -6px;
    }

    .copy-alert {
        top: 16px;
        padding: 8px 18px;
        font-size: 0.75rem;
    }
}

/* Extra Small Devices */
@media (max-width: 400px) {
    html {
        font-size: 12px;
    }

    * {
        font-size: 12px;
    }

    .tool-container {
        /* grid-template-columns: 1fr; */
        gap: 6px;
    }

    .content {
        padding: 8px;
    }

    .content .chats-box {
        max-height: calc(100vh - 280px);
    }

    .message-box {
        padding: 10px;
        border-radius: 16px;
        gap: 8px;
    }

    .message-input {
        flex-direction: column;
        align-items: stretch;
        gap: 6px;
        padding: 8px;
    }

    .buttons {
        width: 100%;
        justify-content: space-between;
    }

    .buttons button {
        flex: 1;
        font-size: 0.7rem;
        padding: 8px 10px;
    }

    textarea {
        width: 100%;
        font-size: 0.78rem;
    }

    .your-message,
    .bot-message {
        max-width: 92%;
        font-size: 0.78rem;
        padding: 8px 12px;
    }

    .sidebar {
        padding: 8px 12px;
        min-height: 44px;
        max-height: 44px;
    }

    .sidebar .top {
        height: 28px;
        width: 28px;
        font-size: 0.8rem;
    }
}

/* Landscape Mode Fix */
@media (max-width: 768px) and (orientation: landscape) {
    .content .chats-box {
        max-height: calc(100vh - 200px);
    }

    .tool-container {
        grid-template-columns: 1fr 1fr 1fr;
    }

    .message-box {
        padding: 10px 12px;
    }

    textarea {
        max-height: 40px;
    }
}