@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;700&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Oswald:wght@400;500&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;500&display=swap');

:root {
    --primary-color: #4a90e2;
    --secondary-color: #f5a623;
    --background-color: #f4f7f9;
    --container-bg: #ffffff;
    --text-color: #333333;
    --border-color: #dbe2e8;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --header-bg: #2c3e50;
    --footer-bg: #2c3e50;
    --link-hover-color: #f5a623;
}

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

body {
    font-family: 'Noto Sans SC', sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    display: block;
    min-height: 100vh;
    padding: 0;
}

.site-header {
    background-color: var(--header-bg);
    color: #fff;
    padding: 1rem 2rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}

.logo h1 {
    font-family: 'Oswald', sans-serif;
    font-size: 1.8rem;
    color: #fff;
    margin: 0;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    letter-spacing: 1px;
}

.logo h1 .fa-cube {
    color: var(--secondary-color);
}

.logo h1 span {
    font-family: 'Roboto', sans-serif;
    font-weight: 300;
    font-size: 1.7rem;
    letter-spacing: normal;
}

.main-nav ul {
    list-style: none;
    display: flex;
    gap: 1.5rem;
}

.main-nav a {
    color: #fff;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.main-nav a:hover {
    color: var(--link-hover-color);
}

.main-nav ul li a:hover {
    color: #f39c12;
}

/* Language Switcher Styles */
.language-switcher {
    position: relative;
    display: inline-block;
}

.language-switcher .lang-btn {
    background-color: transparent;
    color: #fff;
    padding: 8px 12px;
    font-size: 1rem;
    border: 1px solid #fff;
    border-radius: 5px;
    cursor: pointer;
    display: flex;
    align-items: center;
    transition: background-color 0.3s, color 0.3s;
}

.language-switcher .lang-btn:hover {
    background-color: #f39c12;
    border-color: #f39c12;
    color: #333;
}

.language-switcher .lang-btn i {
    margin-right: 8px;
}

.language-switcher-content {
    display: none;
    position: absolute;
    background-color: #333;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    z-index: 100;
    border-radius: 5px;
    padding: 5px 0;
    right: 0;
}

.language-switcher-content a {
    color: white;
    padding: 12px 16px;
    text-decoration: none;
    display: block;
    text-align: left;
}

.language-switcher-content a:hover {
    background-color: #575757;
}

.language-switcher:hover .language-switcher-content {
    display: block;
}

/* Language Suggestion Banner */
.language-suggestion-banner {
    background-color: #333;
    color: #fff;
    padding: 1rem 2rem;
    text-align: center;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
    z-index: 1001; /* Should be on top of the sticky header */
}

.language-suggestion-banner p {
    margin: 0;
}

.language-suggestion-banner .btn-switch-lang {
    background-color: var(--secondary-color);
    color: #fff;
    padding: 0.5rem 1rem;
    text-decoration: none;
    border-radius: 5px;
    font-weight: bold;
    transition: background-color 0.3s;
}

.language-suggestion-banner .btn-switch-lang:hover {
    background-color: #e09614;
}

.language-suggestion-banner .btn-dismiss-banner {
    background: none;
    border: none;
    color: #aaa;
    font-size: 1.5rem;
    cursor: pointer;
    position: absolute;
    right: 1rem;
    top: 50%;
    transform: translateY(-50%);
    padding: 0 0.5rem;
}

.language-suggestion-banner .btn-dismiss-banner:hover {
    color: #fff;
}

/* Main Content Styles */
.main-container {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    width: 100%;
    max-width: 1200px;
    align-items: center;
    padding: 2rem;
    margin: 0 auto;
}

.calculator-wrapper {
    display: flex;
    gap: 2rem;
    width: 100%;
    align-items: flex-start;
}

.calculator-container {
    background-color: var(--container-bg);
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: 0 10px 25px var(--shadow-color);
    width: 100%;
    max-width: 600px;
    flex-shrink: 0;
}

.calculator-container h2 {
    text-align: center;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.info-container {
    background-color: var(--container-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 10px 25px var(--shadow-color);
    width: 100%;
    flex-grow: 1;
    position: sticky;
    top: 100px;
}

.info-content {
    display: none;
}

.info-content.active {
    display: block;
}

.info-content img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    border: 1px solid var(--border-color);
}

.info-content h3 {
    color: var(--primary-color);
    margin-bottom: 0.75rem;
}

.info-content p {
    line-height: 1.6;
    color: #555;
}

.content-article {
    background-color: var(--container-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 10px 25px var(--shadow-color);
    margin-top: 2rem;
    max-width: 1200px;
    margin: 2rem auto;
    width: 100%;
    padding: 2rem;
}

.content-article h2 {
    color: var(--primary-color);
    margin-top: 2rem;
    margin-bottom: 1rem;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.content-article h2:first-of-type {
    margin-top: 0;
}

.content-article p, .content-article li {
    line-height: 1.7;
    margin-bottom: 1rem;
    color: #444;
}

.content-article ol {
    padding-left: 2rem;
}

.content-article details {
    margin-bottom: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
}

.content-article summary {
    font-weight: bold;
    cursor: pointer;
    color: var(--primary-color);
}

.site-footer {
    background-color: var(--footer-bg);
    color: #fff;
    padding: 2rem;
    text-align: center;
    margin-top: 2rem;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.back-to-top {
    color: #fff;
    text-decoration: none;
    transition: color 0.3s ease;
}

.back-to-top:hover {
    color: var(--link-hover-color);
}

h1 {
    /* 移除旧的 h1 样式，由 header 内的 h1 代替 */
}

.subtitle {
    text-align: center;
    margin-bottom: 2rem;
    color: #666;
}

.shape-selector {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    justify-content: center;
}

.shape-btn {
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    background-color: #fff;
    color: var(--primary-color);
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.3s ease;
}

.shape-btn:hover {
    background-color: #e9f2fe;
    border-color: var(--primary-color);
}

.shape-btn.active {
    background-color: var(--primary-color);
    color: #fff;
    border-color: var(--primary-color);
}

.form-group {
    display: none;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    padding: 1.5rem;
    border: 1px dashed var(--border-color);
    border-radius: 8px;
    margin-bottom: 1.5rem;
}

.form-group.active {
    display: grid;
}

.input-group {
    display: flex;
    flex-direction: column;
}

.input-with-unit {
    display: flex;
    gap: 0.5rem;
}

.input-with-unit input {
    flex-grow: 1;
    width: 100%; /* Fallback for browsers that don't support flex-grow well in all cases */
}

.input-with-unit select {
    padding: 0.75rem 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background-color: #fff;
    font-size: 0.9rem;
    flex-shrink: 0;
    cursor: pointer;
    transition: border-color 0.3s;
}

.input-with-unit select:focus {
    outline: none;
    border-color: var(--primary-color);
}

.input-group label {
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    font-weight: 500;
}

.input-group input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 1rem;
    transition: border-color 0.3s, box-shadow 0.3s;
}

.input-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.2);
}

#calculate-btn {
    width: 100%;
    padding: 1rem;
    background-color: var(--secondary-color);
    color: #fff;
    border: none;
    border-radius: 8px;
    font-size: 1.2rem;
    font-weight: 700;
    cursor: pointer;
    transition: background-color 0.3s ease;
    margin-bottom: 1.5rem;
}

#calculate-btn:hover {
    background-color: #e09614;
}

#result {
    background-color: #e9f2fe;
    border: 1px solid var(--primary-color);
    border-radius: 8px;
    padding: 1.5rem;
    text-align: center;
}

#result .result-controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

#result .result-controls label {
    font-size: 1rem;
    font-weight: 500;
}

#result .result-controls select {
    padding: 0.5rem;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    font-size: 0.9rem;
    cursor: pointer;
}

#result h2 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}

#result p {
    font-size: 1.1rem;
}

#volume-result {
    font-weight: 700;
    font-size: 1.8rem;
    color: var(--secondary-color);
}

@media (max-width: 992px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }
    .main-container {
        flex-direction: column;
    }
    .calculator-container, .info-container {
        max-width: 100%;
    }
    .info-container {
        position: static;
    }
}

@media (max-width: 640px) {
    body {
        /* padding: 1rem; */
    }
    .calculator-container {
        padding: 1.5rem;
    }
    .form-group {
        grid-template-columns: 1fr;
    }
    .main-nav ul {
        flex-direction: column;
        gap: 0.5rem;
        align-items: center;
    }
}

.header-right {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}