/* =========================================
   ១. ការកំណត់ទម្រង់ទូទៅ (Global Styles)
   ========================================= */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', 'Khmer OS Battambang', Arial, sans-serif;
    display: flex;
    height: 100vh;
    background-color: #f0f4f8; 
    color: #2c3e50;
    overflow: hidden; 
}

/* =========================================
   ២. ផ្នែកជំហៀងខាងឆ្វេង (Sidebar)
   ========================================= */
.sidebar {
    width: 250px; 
    background-color: #ffffff;
    padding: 25px 15px;
    display: flex;
    flex-direction: column;
    gap: 15px;
    border-right: none;
    box-shadow: 10px 0 20px rgba(0,0,0,0.03); 
    border-radius: 0 20px 20px 0; 
    z-index: 10;
}

.tab-btn {
    background-color: #ffffff;
    color: #546e7a;
    border: none;
    padding: 12px 15px;
    border-radius: 15px; 
    cursor: pointer;
    text-align: left;
    font-weight: bold;
    font-size: 15px;
    display: flex;
    align-items: center;
    gap: 12px; 
    transition: all 0.3s ease; 
    box-shadow: 4px 4px 10px #e6e9ee, -4px -4px 10px #ffffff;
}

.tab-btn:hover {
    background-color: #f8faff;
    color: #1877F2; /* ប្តូរទៅពណ៌ FB ពេលយកម៉ៅដាក់ពីលើ */
}

/* ប៊ូតុងដែលកំពុងសកម្ម (Active) - ពណ៌ខៀវ Facebook */
.tab-btn.active {
    background: linear-gradient(135deg, #1877F2 0%, #165EBD 100%);
    color: #ffffff;
    box-shadow: 0 4px 15px rgba(24, 119, 242, 0.4); 
}

.tab-btn img.icon-3d {
    width: 28px;
    height: 28px;
    object-fit: contain;
    filter: drop-shadow(0 4px 4px rgba(0,0,0,0.1)); 
}

/* =========================================
   ៣. ផ្នែកខ្លឹមសារកណ្ដាល (Main Content)
   ========================================= */
.main-content {
    flex: 1; 
    padding: 40px;
    overflow-y: auto; 
    background-color: #f0f4f8;
}

.main-content > * {
    animation: fadeIn 0.4s ease-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

h3 {
    font-size: 24px;
    font-weight: bold;
    margin-bottom: 20px;
    color: #1a252f;
}

p {
    line-height: 1.6;
    margin-bottom: 20px;
    color: #7f8c8d;
}

.info-box {
    background-color: #ffffff;
    padding: 25px;
    border-radius: 15px;
    border: 1px solid rgba(0,0,0,0.02);
    box-shadow: 8px 8px 16px #e6e9ee, -8px -8px 16px #ffffff;
    margin-bottom: 25px;
}

/* =========================================
   ៤. ស្ទីលសម្រាប់ប៊ូតុងទូទៅ (General Buttons)
   ========================================= */
.btn-general {
    background: linear-gradient(135deg, #1877F2 0%, #165EBD 100%);
    color: #ffffff;
    border: none;
    padding: 12px 24px;
    border-radius: 10px;
    cursor: pointer;
    font-size: 15px;
    font-weight: bold;
    width: 100%;
    transition: all 0.3s ease;
    box-shadow: 0 4px 10px rgba(24, 119, 242, 0.3);
}

.btn-general:hover {
    transform: translateY(-2px); 
    box-shadow: 0 6px 15px rgba(24, 119, 242, 0.4);
}

.btn-general:active {
    transform: scale(0.98) translateY(0);
}

/* ប៊ូតុង Facebook សម្រាប់ទំព័រ Login */
.btn-facebook {
    background-color: #1877F2; 
    color: white; 
    border: none; 
    padding: 14px; 
    width: 100%; 
    border-radius: 12px;
    font-size: 16px; 
    font-weight: bold; 
    cursor: pointer; 
    display: flex; 
    align-items: center; 
    justify-content: center; 
    gap: 10px;
    box-shadow: 0 4px 15px rgba(24, 119, 242, 0.3); 
    transition: 0.3s; 
    margin-top: 15px;
}

.btn-facebook:hover { 
    background-color: #165EBD; 
    transform: translateY(-2px); 
}

.btn-facebook img { 
    width: 22px; 
    filter: brightness(0) invert(1); /* ធ្វើឱ្យ Icon Facebook ទៅជាពណ៌ស */
}