:root {
    --primary-color: #2563eb;
    --bg-color: #f3f4f6;
    --container-bg: #ffffff;
    --text-color: #1f2937;
    --border-color: #e5e7eb;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--text-color);
    margin: 0;
    padding: 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    
    background-color: var(--bg-color);
    background-image: 
        linear-gradient(#e5e7eb 1px, transparent 1px), 
        linear-gradient(90deg, #e5e7eb 1px, transparent 1px);
    background-size: 20px 20px;
    min-height: 100vh;
}

header h1 {
    color: var(--primary-color);
    margin-bottom: 20px;
}

/* =========================================
   Navigation Bar (Pill Style)
   ========================================= */
nav {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 12px;               /* 버튼 사이 간격 넓힘 */
    margin-bottom: 30px;
    padding: 0 10px;
}

/* 기존 nav button 대신 클래스 선택자 사용 (.nav-btn) */
.nav-btn {
    text-decoration: none;   /* 링크 밑줄 제거 */
    display: inline-block;
    padding: 10px 20px;      /* 넉넉한 터치 영역 */
    border-radius: 50px;     /* ★완벽한 알약 모양★ */
    background-color: #ffffff;
    color: #4b5563;          /* 차분한 회색 텍스트 */
    border: 1px solid #e5e7eb; /* 아주 연한 테두리 */
    font-weight: 600;        /* 글자 두께 */
    font-size: 0.95rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.03); /* 아주 살짝 그림자 */
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1); /* 부드러운 움직임 */
    cursor: pointer;
}

/* 마우스 올렸을 때 (Hover) */
.nav-btn:hover {
    background-color: #eff6ff; /* 아주 연한 블루 */
    color: var(--primary-color);
    border-color: #bfdbfe;
    transform: translateY(-2px); /* 공중 부양 효과 */
    box-shadow: 0 4px 6px rgba(0,0,0,0.08);
}

/* 현재 페이지 (Active) */
.nav-btn.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3); /* 파란색 네온 빛 그림자 */
    transform: translateY(0);
}

/* 모바일 최적화 */
@media (max-width: 600px) {
    nav {
        gap: 8px; /* 모바일에서는 간격 좁게 */
    }
    .nav-btn {
        padding: 8px 16px; /* 버튼 크기 살짝 줄임 */
        font-size: 0.85rem;
    }
}

main {
    background-color: var(--container-bg);
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 700px;
}

.calculator {
    display: none;
    animation: fadeIn 0.3s ease-in-out; /* 탭 전환 시 부드럽게 */
}

.calculator.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.input-group {
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.input-group label {
    width: 120px;
    font-weight: 500;
}

.input-group input, .input-group select {
    padding: 8px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.input-group input {
    flex: 1;
}

textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    margin-bottom: 10px;
    box-sizing: border-box;
    font-family: monospace;
}

button[id^="calculate"], button[id^="check"] {
    width: 100%;
    padding: 12px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 1rem;
    cursor: pointer;
    margin-top: 10px;
}

button:hover {
    opacity: 0.9;
}

.result {
    margin-top: 20px;
    padding: 15px;
    background-color: #f8fafc;
    border-left: 4px solid var(--primary-color);
    white-space: pre-wrap;
    line-height: 1.6;
}

/* HED Layout Styling */
.hed-container {
    display: flex;
    gap: 20px;
    margin-bottom: 15px;
}

.hed-inputs {
    flex: 2;
}

.hed-reference {
    flex: 1;
    background-color: #f1f5f9;
    padding: 15px;
    border-radius: 8px;
    font-size: 0.85rem;
    height: fit-content;
}

.hed-reference h4 {
    margin-top: 0;
    margin-bottom: 10px;
    color: #4b5563;
    border-bottom: 1px solid #cbd5e1;
    padding-bottom: 5px;
}

.hed-reference ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.hed-reference li {
    margin-bottom: 4px;
    display: flex;
    justify-content: space-between;
    padding: 2px 0;
    border-bottom: 1px dashed #e2e8f0; /* 각 동물 구분선 추가 */
}

.hed-group {
    background-color: #ffffff;
    border: 1px solid #e2e8f0;
    padding: 15px;
    border-radius: 6px;
    margin-bottom: 15px;
}

.hed-group h3 {
    margin-top: 0;
    font-size: 1rem;
    color: #4b5563;
    margin-bottom: 10px;
}

.warning-text {
    color: #b91c1c;
    font-size: 0.9rem;
    margin-bottom: 5px;
}

/* Responsive for mobile */
@media (max-width: 600px) {
    .hed-container {
        flex-direction: column;
    }
    .input-group {
        flex-direction: column;
        align-items: flex-start;
    }
    .input-group label {
        width: 100%;
        margin-bottom: 5px;
    }
    .input-group input, .input-group select {
        width: 100%;
    }
}

/* Help & Info Section Styling */
.help-block {
    background-color: #ffffff;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 20px;
    line-height: 1.6;
}

.help-block h3 {
    margin-top: 0;
    color: var(--primary-color);
    border-bottom: 2px solid #f3f4f6;
    padding-bottom: 10px;
    margin-bottom: 15px;
}

.help-block p {
    margin-bottom: 15px;
    color: #4b5563;
}

.formula-box {
    background-color: #eff6ff;
    color: var(--primary-color);
    padding: 15px;
    border-radius: 6px;
    font-family: monospace;
    font-weight: bold;
    text-align: center;
    margin: 15px 0;
    border: 1px dashed var(--primary-color);
}

.reference-box {
    background-color: #f8fafc;
    border-left: 4px solid #64748b;
    padding: 15px;
    margin-top: 15px;
    font-size: 0.9rem;
}

.reference-box a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

#help-section h2 {
    border-bottom: 2px solid var(--primary-color);
    display: inline-block;
    padding-bottom: 5px;
    margin-bottom: 25px;
}

#comments-section {
    min-height: 500px;
}

.ad-container {
    width: 100%;
    max-width: 700px;
    margin: 20px auto;
    text-align: center;
    background-color: #fafafa;
    height: 100px;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* =========================================
   Board Styles (게시판 전용)
   ========================================= */
.board-container {
    max-width: 800px;
    margin: 0 auto;
    text-align: left; /* 본문은 왼쪽 정렬 */
}

/* 글쓰기 박스 */
.write-box {
    background: #f8f9fa;
    padding: 20px;
    border: 1px solid #e9ecef;
    border-radius: 8px;
    margin-bottom: 40px;
}

.form-row {
    margin-bottom: 15px;
}

.write-box input, .write-box textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid #ced4da;
    border-radius: 4px;
    font-size: 1rem;
    box-sizing: border-box; /* 패딩 포함 크기 계산 */
    font-family: inherit;
}

.action-btn {
    background-color: #2563eb;
    color: white;
    border: none;
    padding: 10px 25px;
    border-radius: 5px;
    font-size: 1rem;
    cursor: pointer;
    font-weight: bold;
    transition: background 0.3s;
}

.action-btn:hover {
    background-color: #1d4ed8;
}

/* 게시글 목록 */
.list-box h3 {
    border-bottom: 2px solid #2563eb;
    padding-bottom: 10px;
    margin-bottom: 20px;
}

.post-card {
    background: white;
    border: 1px solid #e5e7eb;
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 15px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.post-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
    padding-bottom: 12px;
    border-bottom: 1px dashed #eee;
}

.post-title {
    font-size: 1.1rem;
    font-weight: bold;
    color: #111;
}

.post-info {
    font-size: 0.85rem;
    color: #6b7280;
}

.post-body {
    color: #374151;
    line-height: 1.6;
    white-space: pre-wrap; /* 줄바꿈 보존 */
}

.loading-msg {
    text-align: center;
    color: #888;
    padding: 20px;
}