/* =========================================
   BIẾN MÀU SẮC & HIỆU ỨNG (CSS VARIABLES)
   ========================================= */
:root {
    --primary-color: #0d47a1; 
    --accent-color: #1976d2;  
    --gradient-bg: linear-gradient(135deg, #0d47a1 0%, #1976d2 100%);
    --bg-color: #f4f7f9;
    --text-color: #333333;
    --text-muted: #666666;
    --card-bg: #ffffff;
    --shadow-sm: 0 4px 6px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 15px 25px rgba(13, 71, 161, 0.15);
    --transition-speed: 0.3s;
}

/* =========================================
   CÀI ĐẶT CƠ BẢN
   ========================================= */
html { scroll-behavior: smooth; }
body {
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    margin: 0; padding: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* =========================================
   HEADER & NAVIGATION
   ========================================= */
header {
    background: var(--gradient-bg);
    color: white;
    padding: 1.5rem 0;
    text-align: center;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    position: sticky;
    top: 0;
    z-index: 100; 
}
nav { display: flex; justify-content: center; gap: 15px; }
nav a.nav-btn {
    text-decoration: none;
    color: rgba(255, 255, 255, 0.8);
    font-size: 16px;
    font-weight: 500;
    padding: 8px 20px;
    border-radius: 30px; 
    transition: all var(--transition-speed) ease;
    border: 1px solid transparent;
}
nav a.nav-btn:hover, nav a.nav-btn.active {
    background-color: rgba(255, 255, 255, 0.2);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.5);
    transform: translateY(-2px); 
}
.container { max-width: 1100px; margin: 40px auto; padding: 0 20px; }
.hidden { display: none !important; }

/* =========================================
   PHẦN GIỚI THIỆU (PROFILE)
   ========================================= */
.profile-header {
    display: flex; align-items: center; gap: 30px;
    background: var(--card-bg); padding: 30px;
    border-radius: 12px; box-shadow: var(--shadow-sm);
    margin-bottom: 40px; transition: transform var(--transition-speed);
}
.profile-header:hover { transform: translateY(-5px); box-shadow: var(--shadow-lg); }
.profile-img {
    width: 140px; height: 140px; border-radius: 50%;
    object-fit: cover; border: 4px solid var(--accent-color);
    padding: 3px; background-color: white;
}
.profile-header h2 { color: var(--primary-color); margin-top: 0; }

/* =========================================
   LƯỚI DỰ ÁN & PHẦN MỀM (CARDS)
   ========================================= */
.grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 30px;
}
.card-link { text-decoration: none; color: inherit; display: block; }
.card {
    background: var(--card-bg); border-radius: 12px;
    overflow: hidden; box-shadow: var(--shadow-sm);
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275); 
    height: 100%; position: relative;
}
.card:hover { transform: translateY(-10px); box-shadow: var(--shadow-lg); }
.card img {
    width: 100%; height: 200px; object-fit: cover;
    transition: transform 0.5s ease; display: block;
}
.card:hover img { transform: scale(1.08); }
.card-content { padding: 20px; }
.card-content h3 { margin: 0 0 10px 0; font-size: 20px; color: var(--primary-color); }
.card-content p { margin: 0; font-size: 15px; color: var(--text-muted); }

/* =========================================
   TRANG CHI TIẾT (MỞ BẰNG ID)
   ========================================= */
.detail-view {
    background: var(--card-bg); padding: 40px;
    border-radius: 12px; box-shadow: var(--shadow-lg);
    animation: slideUp 0.5s ease-out forwards;
    opacity: 0; transform: translateY(20px);
}
@keyframes slideUp { to { opacity: 1; transform: translateY(0); } }
.detail-img {
    width: 100%; max-height: 450px; object-fit: cover; 
    margin-bottom: 25px; border-radius: 8px; box-shadow: var(--shadow-sm);
}

/* Timeline (Lộ trình phát triển) */
.timeline {
    border-left: 3px solid var(--accent-color);
    padding-left: 25px;
    margin-left: 10px;
    margin-bottom: 30px;
}
.timeline-item {
    position: relative;
    margin-bottom: 25px;
}
.timeline-item::before {
    content: ''; position: absolute;
    left: -35px; top: 5px;
    width: 14px; height: 14px;
    background: var(--card-bg);
    border: 3px solid var(--accent-color);
    border-radius: 50%;
}
.timeline-item h4 { margin: 0 0 5px 0; color: var(--primary-color); font-size: 1.1rem; }
.timeline-item p { margin: 0; color: var(--text-muted); }

/* Các Nút Bấm Chức Năng */
.btn-action {
    display: inline-block; margin-top: 20px; padding: 12px 25px;
    text-decoration: none; border-radius: 6px; font-weight: 600;
    cursor: pointer; border: none; transition: all var(--transition-speed);
}
.btn-back { background-color: #e0e0e0; color: #333; margin-bottom: 25px; margin-top: 0; }
.btn-back:hover { background-color: #d5d5d5; padding-left: 20px; }

/* =========================================
   FORM HỖ TRỢ & LIÊN HỆ
   ========================================= */
.support-container {
    background: var(--card-bg); padding: 40px;
    border-radius: 12px; box-shadow: var(--shadow-sm); text-align: center;
}
.support-form {
    display: flex; flex-direction: column; gap: 20px;
    max-width: 550px; margin: 30px auto;
}
.support-form input, .support-form textarea {
    padding: 15px; border: 2px solid #e0e0e0; border-radius: 8px;
    font-family: inherit; font-size: 15px; transition: border-color var(--transition-speed);
}
.support-form input:focus, .support-form textarea:focus {
    outline: none; border-color: var(--accent-color);
}
.support-form button {
    background: var(--gradient-bg); color: white; border: none;
    padding: 15px; border-radius: 8px; cursor: pointer;
    font-size: 16px; font-weight: bold; transition: transform 0.2s, box-shadow 0.2s;
}
.support-form button:hover { transform: translateY(-2px); box-shadow: 0 4px 10px rgba(13, 71, 161, 0.3); }

/* Mạng xã hội */
.social-links { display: flex; justify-content: center; gap: 25px; margin-top: 40px; }
.social-links a img {
    width: 45px; height: 45px; transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    filter: grayscale(20%); 
}
.social-links a img:hover { transform: scale(1.2) rotate(5deg); filter: grayscale(0%); }
.container_footer {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 15px;
            color: #217cd6;
        }
.container_footer p {
    margin: 0px 0; /* Số 5px là khoảng cách trên dưới, bạn có thể chỉnh thành 0 nếu muốn sát hẳn */
} 
    .detail-view p {
        margin: 1.5px;
    }       
.btn-download {
    background: var(--gradient-bg);
    color: white;
    box-shadow: 0 4px 10px rgba(25, 118, 210, 0.3);
}