/* =================================== 
 * 1. RESET & VARIABLES 
 * =================================== */
*, *::before, *::after { box-sizing: border-box; }

:root {
  --primary-color: #007bff;
  --primary-hover: #0056b3;
  --danger-color: #dc2626;
  --danger-hover: #a00000;
  --secondary-color: #6c757d;
  --text-color: #333;
  --text-light: #6b7280;
  --bg-color: #f4f4f4;
  --border-color: #e5e7eb;
  --shadow-light: rgba(0, 0, 0, 0.1);
  --card-bg: #ffffff;
  --input-bg: #f9f9f9;
}

body.dark {
  --bg-color: #121212;
  --text-color: #e0e0e0;
  --primary-color: #4da3ff;
  --primary-hover: #5dbbff;
  --danger-color: #ef4444;
  --danger-hover: #cc0000;
  --border-color: #333;
  --shadow-light: rgba(255, 255, 255, 0.1);
  --card-bg: #1a1a1a;
  --input-bg: #1e1e1e;
}

body {
  font-family: 'Segoe UI', Tahoma, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  margin: 0;
  padding-top: 65px;
  transition: background 0.3s ease, color 0.3s ease;
  font-size: 16px;
  line-height: 1.6;
}

.hidden { display: none !important; }
.container { max-width: 900px; margin: auto; padding: 20px; }

/* =================================== 
 * 2. NAVBAR & SIDEBAR 
 * =================================== */
.navbar {
  position: fixed; top: 0; left: 0; width: 100%;
  background: var(--card-bg);
  box-shadow: 0 2px 6px var(--shadow-light);
  display: flex; justify-content: space-between; align-items: center;
  padding: 0.7rem 1.2rem;
  z-index: 1000;
  transition: transform 0.3s ease-in-out;
}
.navbar-hidden { transform: translateY(-100%); }
.nav-left, .nav-right { display: flex; align-items: center; gap: 10px; }
.nav-brand { font-weight: 700; font-size: 1.3rem; color: var(--primary-color); text-decoration: none; }
.hamburger-btn, .theme-toggle { font-size: 1.3rem; background: none; border: none; color: var(--text-color); cursor: pointer; padding: 0.6em 10px; transition: 0.2s; }
.nav-right a {
  padding: 0.5rem 1rem; border-radius: 8px; font-weight: 600; text-decoration: none;
  background: var(--primary-color); color: white; transition: 0.2s;
}
.nav-right a:hover { background: var(--primary-hover); }
.nav-right a:active { transform: scale(0.98); }
#username-display-nav { font-weight: 600; color: var(--text-light); margin-right: 10px; }

.sidebar {
  position: fixed; top: 0; left: -300px; width: 300px; max-width: 80%; height: 100%;
  background: var(--card-bg);
  box-shadow: 4px 0 12px var(--shadow-light);
  z-index: 1002; transition: left 0.3s ease-in-out;
  padding: 60px 20px 20px; display: flex; flex-direction: column;
}
.sidebar.open { left: 0; }
.sidebar-overlay {
  position: fixed; inset: 0; background: rgba(0, 0, 0, 0.5); z-index: 1001;
  opacity: 0; visibility: hidden; transition: 0.3s;
}
.sidebar-overlay.open { opacity: 1; visibility: visible; }
.close-sidebar-btn {
  position: absolute; top: 10px; right: 15px; font-size: 2.2rem;
  background: none; border: none; color: var(--text-color); cursor: pointer;
}
.close-sidebar-btn:hover { color: var(--danger-color); }
#username-display-sidebar { font-size: 1.2rem; font-weight: 700; color: var(--primary-color); margin-bottom: 20px; word-break: break-all; }
.sidebar-link {
  display: block; width: 100%; padding: 12px 10px; margin-bottom: 8px;
  text-decoration: none; color: var(--text-color); border-radius: 8px;
  font-weight: 500; background: none; border: none; text-align: left; font-size: 1rem; cursor: pointer;
  transition: 0.2s;
}
.sidebar-link:hover { background: var(--input-bg); }
.sidebar-link:active { background: var(--primary-color); color: white; transform: scale(0.98); }
.sidebar-action-link { background: var(--primary-color); color: white !important; text-align: center; margin-top: 10px; }
.sidebar-action-link:hover { background: var(--primary-hover); }
.sidebar-logout-btn {
  background: transparent !important; color: var(--danger-color) !important;
  border: 2px solid var(--danger-color); text-align: center; margin-top: 10px; font-weight: 600;
}
.sidebar-logout-btn:hover { background: var(--input-bg) !important; }
.sidebar-logout-btn:active { background: var(--danger-color) !important; color: white !important; }


/* =================================== 
 * 3. FORMS, INPUTS & COMMON BUTTONS 
 * =================================== */
.form-container, .create-post-container {
  background: var(--card-bg); padding: 25px 35px; border-radius: 12px;
  box-shadow: 0 3px 10px var(--shadow-light); width: 90%; max-width: 500px;
  margin: 80px auto 20px; text-align: center;
}
.form-container h1, .create-post-container h1 { color: var(--primary-color); font-size: 1.8rem; margin-bottom: 20px; }

input, textarea {
  background-color: var(--input-bg); color: var(--text-color);
  border: 1px solid var(--border-color); border-radius: 6px;
  padding: 12px; width: 100%; margin-bottom: 12px; font-size: 15px;
}
input:focus, textarea:focus { border-color: var(--primary-color); outline: none; box-shadow: 0 0 0 2px rgba(0, 123, 255, 0.2); }

button, .join-btn, .refresh-btn, .save-btn {
  background: var(--primary-color); color: #fff; border: none;
  padding: 12px; border-radius: 6px; font-size: 16px; cursor: pointer;
  transition: 0.2s; display: inline-block;
  font-weight: bold; /* Thêm vào từ .save-btn */
}
button:hover, .join-btn:hover, .refresh-btn:hover, .save-btn:hover:not(:disabled) { 
  background: var(--primary-hover); 
  transform: scale(1.02); /* Chỉ áp dụng cho nút không phải .save-btn */
  opacity: 0.9; /* Thêm vào từ .save-btn */
}
button:active, .join-btn:active, .refresh-btn:active { transform: scale(0.98); }
.save-btn:disabled { background: #ccc; cursor: wait; opacity: 1; transform: none; }

/* Password Toggle */
.input-group { position: relative; margin-bottom: 12px; }
.input-group input { padding-right: 40px; margin-bottom: 0 !important; }
.toggle-password {
  position: absolute; top: 50%; right: 12px; transform: translateY(-50%);
  cursor: pointer; color: var(--text-light); font-size: 1.1em;
}

/* =================================== 
 * 4. CARDS, COMMENTS & POST ELEMENTS
 * =================================== */
.post-list { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 20px; }

/* Base Card Style */
.post-card, .post-card-admin, .knowledge-card, .knowledge-item {
  background: var(--card-bg); padding: 20px; border-radius: 12px;
  box-shadow: 0 3px 10px var(--shadow-light); transition: 0.2s; position: relative;
}
.post-card:hover, .post-card-admin:hover, .knowledge-item:hover { transform: translateY(-3px); box-shadow: 0 8px 20px var(--shadow-light); }

/* Specific Card Styles */
.post-card { border-left: 4px solid var(--primary-color); padding-right: 60px; }
.post-card-link { display: block; text-decoration: none; color: inherit; transition: transform 0.2s; }
.post-card-admin { border-left: 6px solid #ff9800; margin-bottom: 20px; }
.knowledge-card { border-left: 6px solid #10b981; max-width: 600px; margin: 20px auto; text-align: center; padding: 24px; }
.knowledge-item { border-left: 5px solid #10b981; padding: 16px; margin-bottom: 16px; word-wrap: break-word; }

.post-card img, .comment-item img, .post-images img {
  max-width: 100%; border-radius: 8px; margin-top: 8px; cursor: pointer; transition: 0.2s; object-fit: cover;
}
.post-card img:hover { transform: scale(1.03); }

/* Comments */
.comment-item {
  background: var(--input-bg); padding: 12px; border-radius: 8px;
  border-left: 3px solid var(--primary-color); margin-top: 10px;
  position: relative; padding-right: 40px;
}
.load-more-btn { background: var(--secondary-color); margin-top: 12px; width: auto; }

/* Delete Buttons */
.delete-comment-btn, .delete-post-btn {
  background: transparent; border: 1px solid var(--danger-color); color: var(--danger-color);
  padding: 4px; border-radius: 6px; cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  width: 30px; height: 30px; z-index: 10; position: absolute;
}
.delete-comment-btn:hover, .delete-post-btn:hover { background: var(--danger-color); color: #fff; transform: scale(1.05); }
.post-card .delete-post-btn { top: 10px; right: 10px; }
.comment-item .delete-comment-btn { top: 6px; right: 6px; }

/* =================================== 
 * 5. PROFILE PAGE 
 * =================================== */
.profile-container {
  max-width: 600px;
  margin: 80px auto 40px;
  background: var(--card-bg); /* Sửa từ --bg-secondary */
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 4px 10px var(--shadow-light); /* Sửa shadow */
}

.profile-container h2, .profile-container h3 {
  text-align: center;
  margin-bottom: 20px;
  color: var(--text-color); /* Sửa từ --text-primary */
}

.avatar-wrapper {
  position: relative;
  width: 150px;
  height: 150px;
  margin: 0 auto 30px;
}

.profile-avatar {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--primary-color);
  background-color: var(--input-bg); /* Sửa từ #eee */
}

.upload-label {
  position: absolute;
  bottom: 5px;
  right: 5px;
  background: var(--primary-color);
  color: white;
  padding: 10px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 16px;
  transition: background 0.3s;
}
.upload-label:hover { background: var(--primary-hover); }

#avatar-input { display: none; }

.form-group { margin-bottom: 20px; text-align: left; } /* Thêm text-align: left; */

.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: bold;
  color: var(--text-color); /* Sửa từ --text-primary */
}

.form-group input {
  width: 100%;
  padding: 12px;
  border-radius: 8px;
  border: 1px solid var(--border-color); /* Sửa từ #ccc */
  background: var(--input-bg); /* Sửa từ --bg-primary */
  color: var(--text-color); /* Sửa từ --text-primary */
  font-size: 16px;
}

.form-group input:disabled {
  background: var(--border-color); /* Thay đổi màu nền */
  cursor: not-allowed;
  opacity: 0.7;
}

#msg, #pwd-msg {
  text-align: center;
  min-height: 20px;
  margin-top: 10px;
  font-weight: 500;
}

/* =================================== 
 * 6. TOGGLE SWITCH (Tabs) 
 * =================================== */
.toggle-switch {
  position: relative; display: flex; width: 320px; height: 50px;
  margin: 25px auto; background: var(--input-bg); border-radius: 50px;
  box-shadow: inset 0 2px 8px rgba(0,0,0,0.2); overflow: hidden;
  border: 2px solid rgba(255,255,255,0.1);
}
.toggle-btn {
  flex: 1; border: none; background: transparent; color: var(--text-light);
  font-weight: 600; font-size: 1rem; z-index: 2; cursor: pointer; transition: color 0.4s;
  padding: 0; margin: 0; width: 50%;
}
.toggle-btn:hover { transform: none; background: transparent; }
.toggle-btn.active { color: white; }
.toggle-slider {
  position: absolute; top: 4px; left: 4px; width: calc(50% - 8px); height: calc(100% - 8px);
  background: linear-gradient(135deg, #667eea, #764ba2); border-radius: 50px;
  transition: transform 0.4s cubic-bezier(0.68, -0.55, 0.27, 1.55);
  box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4); pointer-events: none; z-index: 1;
}
.toggle-btn[data-tab="knowledge"].active ~ .toggle-slider { transform: translateX(100%); }
.tab-content { display: none; }
.tab-content.active { display: block; }

/* =================================== 
 * 7. PAGE SPECIFIC (Landing, Admin, Popups) 
 * =================================== */
/* Landing Page */
.landing-main { display: flex; flex-direction: column; align-items: center; text-align: center; }
.landing-header h1 { font-size: clamp(2rem, 5vw, 3rem); margin-bottom: 0.5rem; }
.landing-title { font-size: clamp(1.5rem, 4vw, 2.5rem); margin-bottom: 1rem; }
.landing-description { max-width: 600px; color: var(--text-light); margin-bottom: 2rem; font-size: clamp(1rem, 2.5vw, 1.25rem); }
.join-btn, .refresh-btn { width: auto; padding: 0.6em 1.5em; }

/* Admin */
.admin-container { max-width: 900px; margin: 20px auto; padding: 0 15px; }
.admin-header { text-align: center; margin-bottom: 30px; border-bottom: 3px solid var(--primary-color); padding-bottom: 15px; }
.pending-count { background: var(--primary-color); color: white; padding: 8px 16px; border-radius: 50px; font-weight: bold; display: inline-block; }
.admin-actions { display: flex; gap: 12px; margin-top: 20px; }
.btn-approve, .btn-reject { flex: 1; border-radius: 50px; padding: 12px; color: white; border: none; cursor: pointer; font-weight: bold;}
.btn-approve { background: #4caf50; }
.btn-reject { background: #f44336; }
.no-posts { text-align: center; color: var(--text-light); font-size: 1.2rem; margin: 50px 0; }

/* Popup & Image Viewer */
.popup, #img-viewer {
  position: fixed; inset: 0; background: rgba(0,0,0,0.85);
  display: none; justify-content: center; align-items: center; z-index: 3000;
}
#img-viewer img { max-width: 90%; max-height: 90%; border-radius: 10px; }
.popup-content { background: var(--card-bg); width: 90%; max-width: 600px; padding: 18px; border-radius: 12px; }

/* Knowledge Extras */
.knowledge-updates h3 { text-align: center; color: var(--primary-color); margin: 20px 0; font-size: 1.4rem; }
.knowledge-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 15px; }

/* =================================== 
 * 8. MEDIA QUERIES 
 * =================================== */
@media (max-width: 768px) {
  #login-link, #register-link { display: none; }
}
@media (max-width: 600px) {
  .admin-actions { flex-direction: column; }
  .post-images img { max-width: 100%; }
}