:root {
    --bg-color: #e0f7fa;
    --text-color: #0277bd;
    --btn-bg: #0288d1;
    --btn-bg-hover: #0277bd;
    --btn-text: white;
    --table-border: #0277bd;
    --th-bg: #b3e5fc;
    --input-bg: #ffffff;
    --input-text: #000000;
    --input-border: #cccccc;
    --card-bg: rgba(255, 255, 255, 0.7);
}

body.dark-mode {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --btn-bg: #333333;
    --btn-bg-hover: #555555;
    --btn-text: #ffffff;
    --table-border: #444444;
    --th-bg: #1e1e1e;
    --input-bg: #2a2a2a;
    --input-text: #ffffff;
    --input-border: #444444;
    --card-bg: rgba(30, 30, 30, 0.7);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0; /* Header handles padding */
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
}

.container {
    width: 100%;
    max-width: 900px;
    text-align: center;
}

h1 {
    margin-bottom: 30px;
    font-size: 2.5rem;
}

.controls-card {
    background-color: var(--card-bg);
    padding: 20px;
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    margin-bottom: 30px;
    backdrop-filter: blur(5px);
}

.controls {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    justify-content: center;
    align-items: center;
    margin-bottom: 20px;
}

.control-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 5px;
}

.control-group label {
    font-size: 0.9rem;
    font-weight: bold;
}

button {
    padding: 12px 24px;
    font-size: 16px;
    cursor: pointer;
    background-color: var(--btn-bg);
    color: var(--btn-text);
    border: none;
    border-radius: 8px;
    transition: transform 0.2s, background-color 0.3s;
    margin: 5px;
    font-weight: bold;
}

button:hover {
    background-color: var(--btn-bg-hover);
    transform: translateY(-2px);
}

button:active {
    transform: translateY(0);
}

input {
    padding: 8px 12px;
    font-size: 16px;
    background-color: var(--input-bg);
    color: var(--input-text);
    border: 1px solid var(--input-border);
    border-radius: 6px;
    outline: none;
    text-align: center;
}

#minSum,
#maxSum,
#excludeNumbers,
#includeNumbers {
    width: 80px;
}

.range-container {
    margin: 20px 0;
    padding: 15px;
    border-top: 1px solid var(--input-border);
}

.range-options {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    justify-content: center;
    margin-top: 10px;
}

.range-options label {
    cursor: pointer;
    padding: 5px 10px;
    background-color: var(--input-bg);
    border: 1px solid var(--input-border);
    border-radius: 20px;
    transition: all 0.2s;
}

.range-options label:has(input:checked) {
    background-color: var(--btn-bg);
    color: var(--btn-text);
    border-color: var(--btn-bg);
}

.range-options input {
    display: none;
}

.action-buttons {
    margin-top: 10px;
}

.table-wrapper {
    width: 100%;
    overflow-x: auto;
    margin-top: 30px;
    border-radius: 10px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
}

table {
    width: 100%;
    border-collapse: collapse;
    background-color: var(--card-bg);
}

th,
td {
    border-bottom: 1px solid var(--table-border);
    padding: 15px 10px;
    text-align: center;
}

th {
    background-color: var(--th-bg);
    font-weight: bold;
}

.theme-toggle-btn {
    position: fixed;
    top: 15px;
    right: 20px;
    z-index: 2000;
    margin: 0;
    padding: 10px 18px;
    width: auto; /* 고정 너비 해제 */
    font-size: 14px;
    font-weight: bold;
    background-color: var(--btn-bg);
    color: var(--btn-text);
    border: 2px solid var(--btn-text);
    border-radius: 30px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    white-space: nowrap;
}

.theme-toggle-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.3);
}

.circle {
    display: inline-block;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    line-height: 32px;
    color: white;
    font-weight: bold;
    text-align: center;
    margin: 3px;
    font-size: 14px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}

.range-0 { background-color: #fbc02d; } /* 0번대: 노랑 */
.range-10 { background-color: #1976d2; } /* 10번대: 파랑 */
.range-20 { background-color: #d32f2f; } /* 20번대: 빨강 */
.range-30 { background-color: #757575; } /* 30번대: 회색 */
.range-40 { background-color: #388e3c; } /* 40번대: 초록 */

/* Media Queries */
@media (max-width: 600px) {
    h1 { font-size: 1.8rem; }
    .theme-toggle-btn { 
        top: 10px; 
        right: 10px; 
        padding: 8px; 
        font-size: 18px; /* 아이콘 크기 강조 */
        width: 44px; /* 모바일에서 원형에 가깝게 */
        height: 44px;
        border-radius: 50%;
        gap: 0;
    }
    .theme-toggle-btn .theme-text {
        display: none; /* 모바일에서 텍스트 숨김 */
    }
    .controls { gap: 10px; }
    .circle { width: 28px; height: 28px; line-height: 28px; font-size: 12px; margin: 2px; }
    th, td { padding: 10px 5px; font-size: 14px; }
    button { width: 100%; max-width: 250px; }
    .theme-toggle-btn { width: 44px; } /* 전역 button 스타일 덮어쓰기 */
}

.disqus-container {
    margin-top: 50px;
    padding: 30px;
    background-color: var(--card-bg);
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(5px);
    text-align: left;
}

/* Header & Navigation */
.main-header {
    width: 100%;
    box-sizing: border-box;
    background-color: var(--card-bg);
    backdrop-filter: blur(10px);
    padding: 15px 40px;
    position: sticky;
    top: 0;
    z-index: 1100;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    display: flex;
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
}

.header-top {
    padding: 0;
    width: auto;
    text-align: left;
}

.main-logo {
    font-size: 2rem; /* 가로 배치에 맞게 축소 */
    font-weight: 900;
    color: var(--text-color);
    text-decoration: none;
    letter-spacing: -1.5px;
    text-transform: uppercase;
    background: linear-gradient(135deg, var(--text-color), var(--btn-bg));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-container {
    width: auto;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    padding-right: 140px; /* 다크모드 테마 버튼과 겹치지 않게 여백 추가 */
    box-sizing: border-box;
}

.nav-links {
    list-style: none;
    display: flex;
    flex-direction: row; /* 가로 정렬로 변경 */
    gap: 25px;
    margin: 0;
    padding: 0;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 600;
    font-size: 1.05rem;
    transition: all 0.2s;
    display: inline-block;
    padding: 5px 0;
}

.nav-links a:hover,
.nav-links a.active {
    opacity: 1;
    color: var(--btn-bg);
    border-bottom: 2px solid var(--btn-bg); /* 가로 메뉴에 어울리는 언더라인 */
    padding-left: 0;
    border-left: none;
}

/* Footer */
.main-footer {
    width: 100%;
    max-width: 900px;
    margin-top: 80px;
    padding: 40px 20px;
    border-top: 1px solid var(--input-border);
    text-align: center;
    font-size: 0.9rem;
    color: var(--text-color);
    opacity: 0.8;
}

.footer-links {
    margin-top: 15px;
}

.footer-links a {
    color: var(--text-color);
    text-decoration: none;
    margin: 0 5px;
}

.footer-links a:hover {
    text-decoration: underline;
}

/* Document Content (About, Privacy, etc.) */
.doc-content {
    text-align: left;
    padding: 40px 20px;
}

.doc-content h1 {
    font-size: 2.2rem;
    margin-bottom: 40px;
    border-left: 5px solid var(--btn-bg);
    padding-left: 15px;
}

.content-card {
    background-color: var(--card-bg);
    padding: 30px;
    border-radius: 15px;
    line-height: 1.8;
    margin-bottom: 30px;
}

.content-card h2 {
    margin-top: 0;
    color: var(--btn-bg);
}

.back-btn {
    display: inline-block;
    padding: 10px 20px;
    background-color: var(--btn-bg);
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: bold;
}

hr {
    border: none;
    border-top: 1px solid var(--input-border);
    margin: 25px 0;
}

/* Strategy Section on Main Page */
.info-section {
    text-align: left;
    margin-top: 60px;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin-top: 20px;
}

.info-card {
    background-color: var(--card-bg);
    padding: 25px;
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
}

.info-card h3 {
    margin-top: 0;
    color: var(--btn-bg);
    display: flex;
    align-items: center;
    gap: 10px;
}

/* Blog Styles */
.blog-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(380px, 1fr));
    gap: 25px;
    margin-top: 30px;
}

.blog-card {
    background-color: var(--card-bg);
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    text-align: left;
    display: flex;
    flex-direction: column;
}

.blog-card:hover {
    transform: translateY(-6px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.blog-card-thumb {
    width: 100%;
    height: 180px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    background: linear-gradient(135deg, var(--btn-bg), var(--th-bg));
}

.blog-card-body {
    padding: 20px 25px 25px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.blog-card-category {
    display: inline-block;
    background-color: var(--btn-bg);
    color: var(--btn-text);
    font-size: 0.75rem;
    font-weight: 700;
    padding: 4px 12px;
    border-radius: 20px;
    margin-bottom: 10px;
    width: fit-content;
    letter-spacing: 0.5px;
}

.blog-card-title {
    font-size: 1.2rem;
    font-weight: 700;
    margin: 0 0 10px;
    color: var(--text-color);
    line-height: 1.4;
}

.blog-card-excerpt {
    font-size: 0.9rem;
    color: var(--text-color);
    opacity: 0.75;
    line-height: 1.6;
    margin: 0;
    flex: 1;
}

.blog-card-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid var(--input-border);
    font-size: 0.8rem;
    color: var(--text-color);
    opacity: 0.6;
}

.blog-card-link {
    text-decoration: none;
    color: inherit;
    display: block;
}

.blog-card-link:hover {
    color: inherit;
}

/* Blog Article Detail */
.blog-article {
    text-align: left;
    padding: 40px 20px;
}

.blog-article h1 {
    font-size: 2rem;
    margin-bottom: 15px;
    line-height: 1.4;
    border-left: 5px solid var(--btn-bg);
    padding-left: 15px;
}

.blog-article-meta {
    display: flex;
    gap: 20px;
    align-items: center;
    margin-bottom: 35px;
    font-size: 0.9rem;
    color: var(--text-color);
    opacity: 0.65;
    flex-wrap: wrap;
}

.blog-article-meta .category-tag {
    background-color: var(--btn-bg);
    color: var(--btn-text);
    font-size: 0.75rem;
    font-weight: 700;
    padding: 4px 12px;
    border-radius: 20px;
    opacity: 1;
}

.blog-article .content-card {
    font-size: 1.05rem;
}

.blog-article .content-card h2 {
    margin-top: 35px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--btn-bg);
}

.blog-article .content-card h2:first-child {
    margin-top: 0;
}

.blog-article .content-card h3 {
    color: var(--btn-bg);
    margin-top: 25px;
}

.blog-article .content-card ul,
.blog-article .content-card ol {
    padding-left: 25px;
}

.blog-article .content-card li {
    margin-bottom: 8px;
}

.blog-article .content-card blockquote {
    border-left: 4px solid var(--btn-bg);
    margin: 20px 0;
    padding: 15px 20px;
    background-color: var(--input-bg);
    border-radius: 0 10px 10px 0;
    font-style: italic;
}

.blog-article .content-card table {
    width: 100%;
    border-collapse: collapse;
    margin: 20px 0;
    border-radius: 10px;
    overflow: hidden;
}

.blog-article .content-card table th,
.blog-article .content-card table td {
    padding: 12px 15px;
    text-align: center;
    border-bottom: 1px solid var(--table-border);
}

.blog-article .content-card table th {
    background-color: var(--th-bg);
    font-weight: bold;
}

.blog-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 40px;
    gap: 15px;
    flex-wrap: wrap;
}

.blog-nav a {
    display: inline-block;
    padding: 10px 20px;
    background-color: var(--btn-bg);
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: bold;
    transition: all 0.2s;
}

.blog-nav a:hover {
    background-color: var(--btn-bg-hover);
    transform: translateY(-2px);
}

.highlight-box {
    background: linear-gradient(135deg, var(--btn-bg), var(--th-bg));
    color: var(--btn-text);
    padding: 20px 25px;
    border-radius: 12px;
    margin: 20px 0;
    font-weight: 600;
}

@media (max-width: 600px) {
    body { padding: 0; flex-direction: column; align-items: center; }
    .main-header { flex-direction: column; padding: 15px 20px; }
    .nav-container { padding-right: 0; justify-content: center; margin-top: 15px; }
    .nav-links { gap: 10px; flex-wrap: wrap; justify-content: center; }
    .nav-links a { font-size: 0.95rem; }
    .doc-content h1 { font-size: 1.8rem; }
    .blog-list { grid-template-columns: 1fr; }
    .blog-article h1 { font-size: 1.6rem; }
    .blog-nav { flex-direction: column; }
    .blog-nav a { text-align: center; }
}