/* 全局样式 */
:root {
    --primary-color: #4a6fa5;
    --secondary-color: #6c8fc7;
    --accent-color: #ff9800;
    --background-color: #f5f7fa;
    --card-background: #ffffff;
    --text-color: #333333;
    --text-light: #666666;
    --border-color: #e0e0e0;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Segoe UI', 'Microsoft YaHei', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* 头部样式 */
header {
    background-color: var(--primary-color);
    color: white;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow);
}

.logo {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.logo i {
    font-size: 1.8rem;
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 600;
}

.language-switch button {
    background-color: transparent;
    border: 1px solid white;
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition);
}

.language-switch button:hover {
    background-color: rgba(255, 255, 255, 0.2);
}

/* 主内容区域 */
main {
    display: grid;
    grid-template-columns: 250px 1fr 300px;
    gap: 1.5rem;
    padding: 1.5rem;
    max-width: 1400px;
    margin: 0 auto;
}

/* 侧边栏样式 */
.sidebar {
    background-color: var(--card-background);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 1.5rem;
    height: fit-content;
}

.search-container {
    display: flex;
    margin-bottom: 1.5rem;
}

.search-container input {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 4px 0 0 4px;
    font-size: 0.9rem;
}

.search-container button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 0 4px 4px 0;
    padding: 0 1rem;
    cursor: pointer;
    transition: var(--transition);
}

.search-container button:hover {
    background-color: var(--secondary-color);
}

.category-list {
    list-style: none;
}

.category-list li {
    padding: 0.75rem 1rem;
    margin-bottom: 0.5rem;
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.category-list li:hover {
    background-color: rgba(74, 111, 165, 0.1);
}

.category-list li.active {
    background-color: var(--primary-color);
    color: white;
}

.category-list li i {
    width: 20px;
    text-align: center;
}

.favorites-container {
    margin-top: 2rem;
    border-top: 1px solid var(--border-color);
    padding-top: 1.5rem;
}

.favorites-container h3 {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

#favorites-list {
    list-style: none;
}

#favorites-list li {
    padding: 0.75rem;
    margin-bottom: 0.5rem;
    background-color: rgba(74, 111, 165, 0.05);
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

#favorites-list li:hover {
    background-color: rgba(74, 111, 165, 0.1);
}

#favorites-list li button {
    background: none;
    border: none;
    color: #999;
    cursor: pointer;
    transition: var(--transition);
}

#favorites-list li button:hover {
    color: #f44336;
}

/* 转换器容器样式 */
.converter-container {
    background-color: var(--card-background);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 2rem;
}

.converter-header {
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.converter-header h2 {
    color: var(--primary-color);
    font-weight: 600;
}

.converter-body {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.input-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.value-input {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.value-input label {
    font-weight: 500;
    color: var(--text-light);
}

.value-input input {
    padding: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 1.1rem;
    transition: var(--transition);
}

.value-input input:focus {
    border-color: var(--primary-color);
    outline: none;
    box-shadow: 0 0 0 2px rgba(74, 111, 165, 0.2);
}

.unit-selectors {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.from-unit, .to-unit {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.from-unit label, .to-unit label {
    font-weight: 500;
    color: var(--text-light);
}

.from-unit select, .to-unit select {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 1rem;
    background-color: white;
    transition: var(--transition);
}

.from-unit select:focus, .to-unit select:focus {
    border-color: var(--primary-color);
    outline: none;
    box-shadow: 0 0 0 2px rgba(74, 111, 165, 0.2);
}

#swap-units {
    background-color: var(--secondary-color);
    color: white;
    border: none;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    align-self: flex-end;
    margin-bottom: 0.5rem;
}

#swap-units:hover {
    background-color: var(--primary-color);
    transform: rotate(180deg);
}

.result-section {
    background-color: rgba(74, 111, 165, 0.05);
    border-radius: 8px;
    padding: 1.5rem;
}

.result-display {
    margin-bottom: 1.5rem;
}

.result-display h3 {
    color: var(--text-light);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

#result-value {
    font-size: 2rem;
    font-weight: 600;
    color: var(--primary-color);
}

.result-actions {
    display: flex;
    gap: 1rem;
}

.result-actions button {
    padding: 0.75rem 1.25rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

#copy-result {
    background-color: var(--secondary-color);
    color: white;
}

#copy-result:hover {
    background-color: var(--primary-color);
}

#add-favorite {
    background-color: white;
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

#add-favorite:hover {
    background-color: #fff9e6;
    border-color: var(--accent-color);
    color: var(--accent-color);
}

#add-favorite.active {
    background-color: #fff9e6;
    border-color: var(--accent-color);
    color: var(--accent-color);
}

#add-favorite.active i {
    color: var(--accent-color);
}

.formula-section {
    margin-top: 1rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.formula-section h3 {
    color: var(--text-light);
    margin-bottom: 1rem;
    font-weight: 500;
}

#formula-display {
    background-color: #f8f9fa;
    padding: 1rem;
    border-radius: 4px;
    font-family: 'Courier New', Courier, monospace;
    white-space: pre-wrap;
}

.unit-info {
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.unit-info h3 {
    color: var(--text-light);
    margin-bottom: 1rem;
    font-weight: 500;
}

#unit-description {
    line-height: 1.8;
}

/* 历史记录部分 */
.history-section {
    background-color: var(--card-background);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 1.5rem;
    height: fit-content;
}

.history-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.history-header h3 {
    color: var(--primary-color);
    font-weight: 600;
}

#clear-history {
    background: none;
    border: none;
    color: var(--text-light);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

#clear-history:hover {
    color: #f44336;
}

#history-list {
    list-style: none;
    max-height: 500px;
    overflow-y: auto;
}

#history-list li {
    padding: 1rem;
    margin-bottom: 0.75rem;
    background-color: rgba(74, 111, 165, 0.05);
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition);
}

#history-list li:hover {
    background-color: rgba(74, 111, 165, 0.1);
}

.history-item-value {
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.history-item-units {
    font-size: 0.9rem;
    color: var(--text-light);
}

.history-item-time {
    font-size: 0.8rem;
    color: #999;
    margin-top: 0.5rem;
}

/* 页脚样式 */
footer {
    background-color: var(--primary-color);
    color: white;
    text-align: center;
    padding: 1.5rem;
    margin-top: 2rem;
}

/* 响应式设计 */
@media (max-width: 1200px) {
    main {
        grid-template-columns: 220px 1fr 250px;
    }
}

@media (max-width: 992px) {
    main {
        grid-template-columns: 200px 1fr;
    }
    
    .history-section {
        grid-column: 1 / -1;
        margin-top: 1.5rem;
    }
    
    #history-list {
        display: grid;
        grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
        gap: 1rem;
        max-height: none;
    }
}

@media (max-width: 768px) {
    main {
        grid-template-columns: 1fr;
    }
    
    .sidebar {
        position: sticky;
        top: 1.5rem;
    }
    
    .category-list {
        display: flex;
        flex-wrap: wrap;
        gap: 0.5rem;
    }
    
    .category-list li {
        flex: 1 0 auto;
        min-width: 120px;
        text-align: center;
        justify-content: center;
    }
    
    .unit-selectors {
        flex-direction: column;
    }
    
    #swap-units {
        align-self: center;
        margin: 0.5rem 0;
        transform: rotate(90deg);
    }
    
    #swap-units:hover {
        transform: rotate(270deg);
    }
}

@media (max-width: 576px) {
    header {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .converter-container {
        padding: 1.5rem 1rem;
    }
    
    .result-actions {
        flex-direction: column;
    }
    
    #history-list {
        grid-template-columns: 1fr;
    }
}