/* --- BIẾN TOÀN CỤC (CSS VARIABLES) --- */
:root {
    --bg-deep-dark: #0a0e1a;
    --bg-dark-card: #121a2c;
    --primary-text: #f0f2f5;
    --secondary-text: #8899a6;
    --accent-blue: #00aeff;
    --accent-blue-hover: #33cfff;
    --border-color: #303a4c;
    --error-color: #ff4d4d;
    --note-bg: rgba(0, 174, 255, 0.05);
    --note-border: rgba(0, 174, 255, 0.3);
    --shadow-glow: 0 0 25px rgba(0, 174, 255, 0.15);
    
    /* [MỚI] Màu hoa anh đào (hồng nhạt) */
    --sakura-color: rgba(255, 192, 203, 0.3); 
}

/* --- THIẾT LẬP CƠ BẢN --- */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-deep-dark);
    color: var(--primary-text);
    line-height: 1.6;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 1rem;
    overflow-x: hidden; /* Ngăn cuộn ngang */
}

/* [MỚI] Canvas cho hiệu ứng hoa anh đào */
#sakura-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0; /* Nằm sau cùng */
    pointer-events: none; /* Xuyên qua, không bắt click */
}

/* --- PHẦN 1: MÀN HÌNH NHẬP KEY --- */
.login-container {
    background-color: var(--bg-dark-card);
    padding: 3rem;
    border-radius: 16px;
    text-align: center;
    max-width: 450px;
    width: 100%;
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
    z-index: 2; /* Nằm trên canvas */
    position: relative; /* Cho z-index hoạt động */

    /* [MỚI] Hiệu ứng viền phát sáng */
    box-shadow: 0 10px 40px rgba(0,0,0,0.3), 0 0 25px rgba(0, 174, 255, 0.1);
    animation: pulse-border 5s infinite ease-out;
}

.login-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 1.5rem auto;
    background-color: var(--bg-deep-dark);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--border-color);
}
.login-icon svg {
    width: 28px;
    height: 28px;
    color: var(--accent-blue);
}

.login-container h1 {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary-text);
    margin-bottom: 0.25rem;
}

.login-brand {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--accent-blue);
    margin-bottom: 1.5rem;
}

.login-container .login-prompt {
    font-size: 1rem;
    color: var(--secondary-text);
    margin-bottom: 1.5rem;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.login-container input[type="password"] {
    width: 100%;
    padding: 1rem 1.25rem;
    font-size: 1.1rem;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    font-family: 'Roboto Mono', monospace;
    background-color: var(--bg-deep-dark);
    color: var(--primary-text);
    text-align: center;
    letter-spacing: 2px;
    transition: all 0.3s ease;
}

.login-container input[type="password"]:focus {
    outline: none;
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(0, 174, 255, 0.2), var(--shadow-glow);
}

.login-container button {
    width: 100%;
    padding: 1rem 1.25rem;
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--bg-deep-dark);
    background: var(--accent-blue);
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.login-container button:hover {
    background: var(--accent-blue-hover);
    box-shadow: 0 0 20px rgba(0, 174, 255, 0.5);
    transform: translateY(-2px); /* Hiệu ứng nhấc lên */
}

.error-message {
    display: none;
    color: var(--error-color);
    font-size: 0.9rem;
    margin-top: 1rem;
}

/* --- PHẦN 2: TRANG DỊCH VỤ CHÍNH --- */
.main-container {
    display: none;
    width: 100%;
    max-width: 960px;
    margin: 2rem auto;
    background: var(--bg-dark-card);
    border-radius: 16px;
    overflow: hidden;
    border: 1px solid var(--border-color);
    z-index: 2; /* Nằm trên canvas */
    position: relative; /* Cho z-index hoạt động */

    /* [MỚI] Hiệu ứng viền phát sáng */
    box-shadow: 0 10px 50px rgba(0,0,0,0.5), 0 0 25px rgba(0, 174, 255, 0.1);
    animation: pulse-border 5s infinite ease-out;
}

/* [MỚI] Animation viền phát sáng */
@keyframes pulse-border {
    0% { box-shadow: 0 10px 50px rgba(0,0,0,0.5), 0 0 25px rgba(0, 174, 255, 0.1); }
    50% { box-shadow: 0 10px 50px rgba(0,0,0,0.5), 0 0 35px rgba(0, 174, 255, 0.3); }
    100% { box-shadow: 0 10px 50px rgba(0,0,0,0.5), 0 0 25px rgba(0, 174, 255, 0.1); }
}

/* [MỚI] Header Banner với Gradient động */
.main-header {
    position: relative;
    padding: 4.5rem 2rem;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
    overflow: hidden; /* Ẩn gradient thừa */
    
    /* Lưới công nghệ tĩnh */
    background-color: var(--bg-deep-dark);
    background-image: 
        linear-gradient(rgba(48, 58, 76, 0.5) 1px, transparent 1px),
        linear-gradient(90deg, rgba(48, 58, 76, 0.5) 1px, transparent 1px);
    background-size: 30px 30px;
}

/* [MỚI] Lớp phủ Gradient động */
.main-header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
    background: linear-gradient(135deg, rgba(0, 174, 255, 0.2), rgba(10, 14, 26, 0.7), rgba(255, 192, 203, 0.1));
    background-size: 200% 200%;
    animation: gradient-flow 10s ease infinite;
}

@keyframes gradient-flow {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}


.header-overlay {
    position: relative;
    z-index: 2; /* Nằm trên lớp phủ gradient */
}

.main-header h1 {
    font-size: 3rem;
    font-weight: 700;
    letter-spacing: -1px;
    margin-bottom: 0.5rem;
    color: var(--primary-text);
}

.main-header p {
    font-size: 1.2rem;
    color: var(--secondary-text);
}
.header-brand {
    color: var(--accent-blue);
    font-weight: 500;
}

/* Tabs Navigation */
.tabs-nav {
    display: flex;
    background-color: var(--bg-dark-card);
    border-bottom: 1px solid var(--border-color);
    padding: 0 2rem;
}

.tab-button {
    flex: none;
    padding: 1.25rem 1rem;
    font-size: 1rem;
    font-weight: 500;
    color: var(--secondary-text);
    background: none;
    border: none;
    border-bottom: 3px solid transparent;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-right: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.tab-button svg {
    width: 20px;
    height: 20px;
}

.tab-button:hover {
    color: var(--primary-text);
}

.tab-button.active {
    color: var(--accent-blue);
    font-weight: 700;
    border-bottom-color: var(--accent-blue);
}

/* Nội dung Tab */
.content-area {
    padding: 2.5rem 3rem;
}

.tab-content {
    display: none;
}
.tab-content.active {
    display: block;
    animation: fadeIn 0.5s ease;
}
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.tab-content h2 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-text);
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
}

/* Tab Hỗ trợ CM */
#content-cm p {
    margin-bottom: 1rem;
    font-size: 1.05rem;
    line-height: 1.7;
    color: var(--secondary-text);
}
#content-cm ul {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}
#content-cm li {
    margin-bottom: 0.75rem;
    font-size: 1.05rem;
    color: var(--primary-text);
}
.tech-image-placeholder {
    width: 100%;
    height: 200px;
    border-radius: 12px;
    background-color: var(--bg-deep-dark);
    border: 1px dashed var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--secondary-text);
    margin-top: 2rem;
}


/* --- THIẾT KẾ FORM --- */
.important-note {
    background: var(--note-bg);
    border: 1px solid var(--note-border);
    padding: 1.5rem;
    border-radius: 10px;
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: 2.5rem;
    color: #cceeff;
}
.important-note strong {
    color: var(--accent-blue-hover);
    font-weight: 700;
}

.form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    font-weight: 500;
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
    color: var(--secondary-text);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.form-group input[type="text"],
.form-group input[type="email"],
.form-group input[type="tel"],
.form-group input[type="date"],
.form-group textarea {
    width: 100%;
    padding: 0.9rem 1rem;
    font-size: 1rem;
    font-family: 'Inter', sans-serif;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--bg-deep-dark);
    color: var(--primary-text);
    transition: all 0.3s ease;
}
.form-group input[type="date"] {
    color-scheme: dark;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent-blue);
    background-color: var(--bg-dark-card);
    box-shadow: 0 0 0 3px rgba(0, 174, 255, 0.2);
}

.form-group textarea {
    min-height: 120px;
    resize: vertical;
}

.form-group .file-input {
    padding: 0;
    border: 1px dashed var(--border-color);
    background-color: var(--bg-deep-dark);
}
.form-group .file-input::file-selector-button {
    background-color: var(--border-color);
    color: var(--primary-text);
    padding: 0.9rem 1rem;
    border: none;
    border-right: 1px solid var(--border-color);
    margin-right: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}
.form-group .file-input:hover::file-selector-button {
    background-color: var(--accent-blue);
    color: var(--bg-deep-dark);
}


.form-group small {
    display: block;
    font-size: 0.9rem;
    color: var(--secondary-text);
    margin-top: 0.75rem;
}

.form-section-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-text);
    margin-top: 2.5rem;
    margin-bottom: 2rem;
    border-top: 1px solid var(--border-color);
    padding-top: 2rem;
}

.submit-btn {
    width: 100%;
    padding: 1.15rem;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--bg-deep-dark);
    background: var(--accent-blue);
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.submit-btn:hover {
    background: var(--accent-blue-hover);
    box-shadow: 0 0 25px rgba(0, 174, 255, 0.5);
    transform: translateY(-2px);
}
.submit-btn:disabled {
    background: var(--secondary-text);
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

/* --- FOOTER --- */
.main-footer {
    text-align: center;
    padding: 2rem;
    background-color: var(--bg-deep-dark);
    color: var(--secondary-text);
    font-size: 0.9rem;
    border-top: 1px solid var(--border-color);
}


/* --- RESPONSIVE CHO DI ĐỘNG --- */
@media (max-width: 768px) {
    body {
        padding: 0;
    }

    .login-container {
        width: 100%;
        max-width: 100%;
        padding: 2.5rem 1.5rem;
        border-radius: 0;
        min-height: 100vh;
        border: none;
        box-shadow: none;
    }

    .main-container {
        width: 100%;
        margin: 0;
        border-radius: 0;
        min-height: 100vh;
        border: none;
    }

    .main-header {
        padding: 3.5rem 1rem;
    }
    .main-header h1 {
        font-size: 2.2rem;
    }
    .main-header p {
        font-size: 1rem;
    }

    .tabs-nav {
        overflow-x: auto;
        white-space: nowrap;
        padding: 0 1rem;
    }

    .tab-button {
        padding: 1rem;
        font-size: 0.9rem;
    }

    .content-area {
        padding: 2rem 1.5rem;
    }

    .tab-content h2 {
        font-size: 1.6rem;
    }
    
    .form-grid {
        grid-template-columns: 1fr; /* 1 cột trên mobile */
        gap: 0;
    }
}

/* --- TOAST NOTIFICATION (HIỆN ĐẠI) --- */
.toast {
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translate(-50%, -100px); /* Ẩn ở trên */
    background-color: var(--accent-blue);
    color: var(--bg-deep-dark);
    padding: 1rem 1.5rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    z-index: 1000;
    opacity: 0;
    box-shadow: 0 5px 20px rgba(0, 174, 255, 0.4);
    transition: all 0.4s cubic-bezier(0.21, 1.02, 0.73, 1);
}

.toast.active {
    transform: translate(-50%, 0); /* Trượt xuống */
    opacity: 1;
}

.toast.error {
    background-color: var(--error-color);
    color: var(--primary-text);
    box-shadow: 0 5px 20px rgba(255, 77, 77, 0.4);
}