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

:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f6f8fa;
    --bg-tertiary: #f3f4f6;
    --border-color: #d0d7de;
    --border-color-light: #e1e4e8;
    --text-primary: #1f2328;
    --text-secondary: #59636e;
    --text-tertiary: #818b98;
    --accent-color: #0969da;
    --accent-hover: #0550ae;
    --success-color: #1a7f37;
    --error-color: #d1242f;
    --warning-color: #9a6700;
    --shadow-sm: 0 1px 2px rgba(31, 35, 40, 0.04);
    --shadow-md: 0 4px 12px rgba(31, 35, 40, 0.08);
    --shadow-lg: 0 8px 24px rgba(31, 35, 40, 0.12);
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --transition: all 0.15s ease;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #0d1117;
        --bg-secondary: #161b22;
        --bg-tertiary: #21262d;
        --border-color: #30363d;
        --border-color-light: #21262d;
        --text-primary: #e6edf3;
        --text-secondary: #8b949e;
        --text-tertiary: #6e7681;
        --accent-color: #4493f8;
        --accent-hover: #58a6ff;
        --success-color: #2ea043;
        --error-color: #f85149;
        --warning-color: #d29922;
        --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
        --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
        --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.4);
    }
}

body {
    font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans", Helvetica, Arial, sans-serif;
    font-size: 14px;
    line-height: 1.5;
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    max-width: 1440px;
    margin: 0 auto;
    padding: 0 24px;
}

.app-header {
    padding: 20px 0;
    border-bottom: 1px solid var(--border-color);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 600;
    font-size: 18px;
    color: var(--text-primary);
}

.logo svg {
    color: var(--accent-color);
}

.header-status {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    font-size: 13px;
}

.status-indicator {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background-color: var(--success-color);
    transition: var(--transition);
}

.status-indicator.loading {
    background-color: var(--warning-color);
    animation: pulse 1.5s infinite;
}

.status-indicator.error {
    background-color: var(--error-color);
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.main-content {
    flex: 1;
    padding: 32px 0;
}

.language-bar {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-bottom: 24px;
}

.language-selector {
    position: relative;
    flex: 1;
    max-width: 240px;
}

.lang-btn {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    padding: 10px 16px;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.lang-btn:hover {
    border-color: var(--accent-color);
    background-color: var(--bg-secondary);
}

.lang-btn svg {
    color: var(--text-tertiary);
    transition: var(--transition);
}

.lang-btn:hover svg {
    color: var(--text-primary);
}

.lang-dropdown {
    position: absolute;
    top: calc(100% + 4px);
    left: 0;
    right: 0;
    max-height: 280px;
    overflow-y: auto;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    z-index: 100;
}

.dropdown-item {
    padding: 10px 16px;
    cursor: pointer;
    transition: var(--transition);
    color: var(--text-primary);
}

.dropdown-item:hover {
    background-color: var(--bg-tertiary);
}

.dropdown-item.active {
    background-color: var(--accent-color);
    color: white;
}

.swap-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
    flex-shrink: 0;
}

.swap-btn:hover {
    border-color: var(--accent-color);
    color: var(--accent-color);
    background-color: var(--bg-secondary);
}

.translation-panels {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 24px;
}

@media (max-width: 768px) {
    .translation-panels {
        grid-template-columns: 1fr;
        gap: 16px;
    }
    
    .language-bar {
        flex-wrap: wrap;
    }
    
    .language-selector {
        max-width: calc(50% - 28px);
    }
}

.panel {
    display: flex;
    flex-direction: column;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    min-height: 360px;
}

.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 16px;
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color-light);
}

.char-count {
    font-size: 12px;
    color: var(--text-tertiary);
}

.clear-btn, .action-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    background: transparent;
    border: none;
    border-radius: var(--radius-sm);
    color: var(--text-tertiary);
    cursor: pointer;
    transition: var(--transition);
}

.clear-btn:hover, .action-btn:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.panel-actions {
    display: flex;
    gap: 4px;
}

.translation-textarea {
    flex: 1;
    width: 100%;
    padding: 16px;
    background-color: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 16px;
    line-height: 1.6;
    font-family: inherit;
    resize: none;
    outline: none;
}

.translation-textarea::placeholder {
    color: var(--text-tertiary);
}

.translation-textarea:focus {
    background-color: var(--bg-secondary);
}

.translation-result-container {
    flex: 1;
    position: relative;
    min-height: 200px;
}

.translation-result {
    padding: 16px;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    white-space: pre-wrap;
    word-break: break-word;
    max-height: 500px;
    overflow-y: auto;
}

.result-textarea {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--bg-primary);
}

.loading-indicator {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px;
    color: var(--text-secondary);
}

.typing-indicator {
    display: flex;
    gap: 4px;
}

.typing-indicator span {
    width: 6px;
    height: 6px;
    background-color: var(--text-tertiary);
    border-radius: 50%;
    animation: typing 1.4s infinite;
}

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

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

@keyframes typing {
    0%, 60%, 100% {
        transform: translateY(0);
        opacity: 0.4;
    }
    30% {
        transform: translateY(-6px);
        opacity: 1;
    }
}

.action-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: 8px;
}

.primary-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 24px;
    background-color: var(--accent-color);
    border: 1px solid transparent;
    border-radius: var(--radius-md);
    color: white;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.primary-btn:hover {
    background-color: var(--accent-hover);
    box-shadow: var(--shadow-md);
}

.primary-btn:active {
    transform: scale(0.98);
}

.primary-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

.model-selector {
    display: flex;
    align-items: center;
    gap: 12px;
}

.model-label {
    color: var(--text-secondary);
    font-size: 13px;
}

.model-select {
    padding: 8px 32px 8px 12px;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 13px;
    font-family: inherit;
    cursor: pointer;
    transition: var(--transition);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 16 16'%3E%3Cpath d='M4 6L8 10L12 6' stroke='%2359636e' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 8px center;
}

.model-select:hover {
    border-color: var(--accent-color);
}

.model-select:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

.app-footer {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 24px 0;
    color: var(--text-tertiary);
    font-size: 12px;
    border-top: 1px solid var(--border-color-light);
}

.divider {
    color: var(--border-color);
}

.toast {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%);
    padding: 8px 16px;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    color: var(--text-primary);
    font-size: 13px;
    z-index: 1000;
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from {
        transform: translate(-50%, 100%);
        opacity: 0;
    }
    to {
        transform: translate(-50%, 0);
        opacity: 1;
    }
}