/* =================================================================== */
/* STYLE.CSS HỢP NHẤT VÀ NÂNG CẤP (KHÔI PHỤC HEADER GỐC)    */
/* =================================================================== */

/* ----- 1. ĐỊNH NGHĨA BIẾN MÀU CHO TOÀN TRANG ----- */

/* Giao diện SÁNG (Mặc định, dựa trên code gốc của bạn) */
:root {
  --bg-main: #f4f9ff;
  --bg-deco-1: radial-gradient(circle, #185adb77 0%, #f4f9ff00 85%);
  --bg-deco-2: radial-gradient(circle, #9bc3ff99 0%, #f4f9ff00 100%);
  --text-primary: #222;
  --text-secondary: #334b7a;
  --text-intro: #185adb;
  --card-gradient: linear-gradient(145deg, #fff 60%, #e5eeff 100%);
  --card-border: #e7edfa;
  --card-hover-bg: #f7fbff;
  --card-hover-border: #185adb;
  --card-shadow: 0 2px 16px 0 #185adb22;
  --card-hover-shadow: 0 14px 36px 0 #185adb38;
  --feature-icon-bg: #f0f5ff;
  --feature-icon-border: #e4ebfd;
  --feature-icon-shadow: 0 2px 14px #185adb25;
  
  /* BIẾN MÀU CHO HEADER GỐC */
  --header-gradient: linear-gradient(110deg, #185adb 0%, #0a1931 100%);
  --header-text: #fff;
  --header-slogan-text: #b7d2fa;
  --header-shadow: 0 8px 32px 0 #1d2b4420;
  --logo-shadow: 0 3px 18px #fff5, 0 2px 18px #185adb55;
  --logo-border: #fff7;

  /* BIẾN MÀU CHO FOOTER */
  --footer-bg: rgba(255, 255, 255, 0.85);
  --footer-border: #e5e7eb;
  --footer-shadow: 0 -1px 4px rgba(0, 0, 0, 0.05);
  --footer-text-primary: #185adb;
  --footer-text-secondary: #374151;
  --footer-text-tertiary: #9ca3af;
  --footer-icon-bg: #fff;
  --footer-icon-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  --footer-icon-hover-bg: #f9fafb;
  --footer-icon-hover-shadow: 0 4px 8px rgba(24, 90, 219, 0.15);
}

/* Giao diện TỐI (Áp dụng khi người dùng cài đặt) */
@media (prefers-color-scheme: dark) {
  :root {
    --bg-main: #0f172a;
    --bg-deco-1: radial-gradient(circle, #185adb55 0%, #0f172a00 85%);
    --bg-deco-2: radial-gradient(circle, #9bc3ff44 0%, #0f172a00 100%);
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    
    /* CẬP NHẬT: Dùng màu Vàng Hổ Phách (nóng) làm điểm nhấn */
    --text-intro: #fcd34d; 
    
    /* Thẻ chức năng với nền tối (lạnh) */
    --card-gradient: linear-gradient(145deg, #1e293b 0%, #0f172a 100%);
    
    /* Viền và hiệu ứng hover màu Vàng Hổ Phách (nóng) */
    --card-border: #f59e0b; /* Viền màu vàng rực */
    --card-hover-border: #fcd34d; /* Viền sáng hơn khi hover */
    --card-hover-bg: #1e293b;
    --card-shadow: 0 0 20px rgba(245, 158, 11, 0.25); /* Bóng đổ màu vàng */
    --card-hover-shadow: 0 0 30px rgba(252, 211, 77, 0.35), 0 10px 30px 0 rgba(0,0,0,0.4);
    
    /* CẬP NHẬT: Icon với hiệu ứng "viền neon" */
    --feature-icon-bg: #1e293b; 
    --feature-icon-border: #f59e0b; /* Viền icon màu vàng rực */
    --feature-icon-shadow: 0 0 15px rgba(245, 158, 11, 0.2);
    
    /* BIẾN MÀU CHO HEADER GỐC Ở CHẾ ĐỘ TỐI */
    --header-gradient: linear-gradient(110deg, #1e3a8a 0%, #1e293b 100%);
    --header-text: #e0e7ff;
    --header-slogan-text: #93c5fd;
    --header-shadow: 0 8px 32px 0 #00000030;
    --logo-shadow: 0 3px 18px #0005, 0 2px 18px #1e3a8a55;
    --logo-border: #ffffffaa;

    /* BIẾN MÀU CHO FOOTER Ở CHẾ ĐỘ TỐI */
    --footer-bg: rgba(15, 23, 42, 0.7);
    --footer-border: rgba(45, 55, 72, 0.5);
    --footer-shadow: 0 -2px 16px rgba(0,0,0,0.2);
    --footer-text-primary: #a5b4fc;
    --footer-text-secondary: #cbd5e1;
    --footer-text-tertiary: #64748b;
    --footer-icon-bg: rgba(30, 41, 59, 0.8);
    --footer-icon-shadow: 0 2px 8px rgba(0,0,0,0.2);
    --footer-icon-hover-bg: rgba(51, 65, 85, 0.9);
    --footer-icon-hover-shadow: 0 4px 16px rgba(0,0,0,0.3);
  }
}

/* ----- 2. STYLE CHUNG CHO TRANG ----- */
html, body {
  height: 100%;
  margin: 0;
  padding: 0;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-family: 'Montserrat', Arial, sans-serif;
  background: var(--bg-main);
  color: var(--text-primary);
  position: relative;
  overflow-x: hidden;
  transition: background-color 0.3s, color 0.3s;
}

main {
  flex: 1 0 auto;
  position: relative;
  z-index: 2;
  max-width: 1120px;
  margin: 0 auto;
  padding: 54px 16px 12px 16px;
  min-height: 630px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.bg-deco {
  position: fixed; z-index: 0; pointer-events: none;
  filter: blur(32px) opacity(.78);
  transition: background 0.3s;
}
.bg-deco.left {
  top: -90px; left: -140px; width: 390px; height: 700px;
  background: var(--bg-deco-1);
  border-radius: 56% 44% 46% 54% / 47% 42% 58% 53%;
}
.bg-deco.right {
  bottom: -140px; right: -150px; width: 400px; height: 600px;
  background: var(--bg-deco-2);
  border-radius: 53% 47% 59% 41% / 53% 47% 53% 47%;
}
.star-canvas {
  position: fixed; left:0; top:0; z-index:1; pointer-events:none; width:100vw; height:100vh;
}

/* ----- 3. STYLE CHO HEADER GỐC (ĐÃ SỬ DỤNG BIẾN MÀU) ----- */
header {
  background: var(--header-gradient);
  color: var(--header-text);
  padding: 36px 0 30px 0;
  text-align: center;
  box-shadow: var(--header-shadow);
  position: relative;
  z-index: 2;
  border-radius: 0 0 44px 44px;
}
.logo {
  display: inline-block;
  width: 56px;
  height: 56px;
  object-fit: cover;
  border-radius: 50%;
  margin-bottom: 10px;
  box-shadow: var(--logo-shadow);
  border: 2.5px solid var(--logo-border);
  background: #fff;
}
.site-title {
  font-size: 2.15rem;
  font-weight: 700;
  margin: 7px 0 0 0;
  letter-spacing: 1.2px;
  text-shadow: 0 4px 22px #0008;
}
.site-slogan {
  font-size: 1.18rem;
  margin: 9px 0 0 0;
  color: var(--header-slogan-text);
  font-weight: 400;
  text-shadow: 0 2px 18px #0002;
}

/* ----- 4. STYLE CHO CÁC THÀNH PHẦN TRANG CHỦ ----- */
.intro {
  font-size: 1.23rem;
  color: var(--text-intro);
  text-align: center;
  margin-bottom: 28px;
  font-weight: 600;
  letter-spacing: .3px;
}
.dashboard {
  width: 100%;
  display: grid;
  grid-template-columns: repeat(auto-fit,minmax(240px,1fr));
  gap: 38px 32px;
  margin: 0 auto;
  z-index: 2;
  padding-bottom: 38px;
}
.feature {
  background: var(--card-gradient);
  border-radius: 22px;
  box-shadow: var(--card-shadow);
  padding: 35px 20px 25px 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
  transition: transform .23s, box-shadow .23s, border-color .22s;
  cursor: pointer;
  border: 2px solid var(--card-border);
  text-align: center;
  text-decoration: none !important;
  position: relative;
  overflow: hidden;
  min-height: 220px;
}
.feature:hover {
  transform: translateY(-7px) scale(1.035);
  box-shadow: var(--card-hover-shadow);
  border-color: var(--card-hover-border);
  background: var(--card-hover-bg);
}
.feature-img {
  width: 70px; height: 70px; object-fit: cover;
  border-radius: 50%;
  margin-bottom: 16px;
  background: var(--feature-icon-bg);
  box-shadow: var(--feature-icon-shadow);
  border: 2.5px solid var(--feature-icon-border);
  transition: box-shadow 0.22s, background-color 0.3s, border-color 0.3s;
}
.feature-title {
  font-weight: 700;
  font-size: 1.15rem;
  margin-bottom: 10px;
  color: var(--text-intro);
  letter-spacing: .1px;
}
.feature-desc {
  font-size: .99rem;
  color: var(--text-secondary);
  margin-bottom: 7px;
  line-height: 1.45;
  min-height: 48px;
  max-width: 90%;
  margin-left: auto; margin-right: auto;
}

/* ----- 5. STYLE CHO FOOTER (ĐỒNG BỘ) ----- */
.ai-footer {
    width: 100%;
    padding: 18px 24px 14px 24px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    box-sizing: border-box;
    font-family: 'Montserrat', Arial, sans-serif;
    background: var(--footer-bg);
    border-top: 1.5px solid var(--footer-border);
    box-shadow: var(--footer-shadow);
    border-radius: 24px 24px 0 0;
    transition: background-color 0.3s, border-color 0.3s;
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
}
.ai-footer-copyright {
    font-size: 1rem; font-weight: 500;
    color: var(--footer-text-secondary);
    text-align: center;
}
.ai-footer-copyright .brand { font-weight: 700; color: var(--footer-text-primary); }
.ai-footer-copyright .separator { color: var(--footer-text-tertiary); margin: 0 4px; }
.ai-footer-copyright .designer a { color: var(--footer-text-primary); text-decoration: none; font-weight: 600; }
.ai-footer-social-links { display: flex; align-items: center; gap: 16px; }
.ai-footer-social-icon {
    display: inline-flex; align-items: center; justify-content: center;
    width: 42px; height: 42px;
    border-radius: 50%;
    background: var(--footer-icon-bg);
    box-shadow: var(--footer-icon-shadow);
    transition: transform 0.2s ease-in-out, box-shadow .17s, background .13s;
}
.ai-footer-social-icon:hover, .ai-footer-social-icon:focus {
    transform: translateY(-3px);
    background: var(--footer-icon-hover-bg) !important;
    box-shadow: var(--footer-icon-hover-shadow) !important;
}
@media (prefers-color-scheme: dark) {
    .yt-icon-play { fill: var(--footer-icon-bg); }
    .fb-icon-f { fill: var(--footer-text-primary); }
}

/* ----- 6. RESPONSIVE ----- */
@media (max-width:900px) {
  .dashboard { grid-template-columns: 1fr 1fr;}
}
@media (max-width:650px) {
  .dashboard {grid-template-columns: 1fr;}
  .feature {padding: 15px 3vw 10px 3vw; min-height: 200px;}
}