/* ==========================================================================
   1. THEME VARIABLES
   ========================================================================== */

:root {
    /* Light Theme (Default) */
    --bg-body: #f4f7fc;
    --text-primary: #111827;
    --text-secondary: #4b5563;
    --text-hero: #ffffff;
    --header-bg: rgba(255, 255, 255, 0.8);
    --hero-overlay: rgba(10, 10, 26, 0.7);
    --glow-color: rgba(0, 255, 255, 0.7);
    --btn-primary-text: #000000;
    --btn-gradient: linear-gradient(90deg, #00c6ff, #0072ff);
    --btn-shadow: rgba(0, 114, 255, 0.4);
    --btn-shadow-hover: rgba(0, 114, 255, 0.6);
    --title-gradient: -webkit-linear-gradient(#0072ff, #111827);
    --card-bg: #ffffff;
    --card-border: #e5e7eb;
    --card-bg-hover: #ffffff;
    --card-border-hover: #0072ff;
    --tech-card-bg: #ffffff;
    --tech-card-border: #e5e7eb;
    --tech-card-bg-hover: #f9fafb;
    --section-bg-accent: #ffffff;
    --modal-bg: #ffffff;
    --modal-border: #e5e7eb;
    --input-bg: #f3f4f6;
    --input-border: #d1d5db;
    --footer-bg: #e5e7eb;
    --footer-text: #4b5563;
    --accent-color: #0072ff;
}

[data-theme="dark"] {
    /* Dark Theme */
    --bg-body: #0a0a1a;
    --text-primary: #e0e0e0;
    --text-secondary: #9ca3af;
    --text-hero: #ffffff;
    --header-bg: rgba(17, 24, 39, 0.8);
    --hero-overlay: rgba(10, 10, 26, 0.7);
    --glow-color: rgba(0, 255, 255, 0.7);
    --btn-primary-text: #000000;
    --btn-gradient: linear-gradient(90deg, #00ffff, #007bff);
    --btn-shadow: rgba(0, 255, 255, 0.5);
    --btn-shadow-hover: rgba(0, 255, 255, 0.8);
    --title-gradient: -webkit-linear-gradient(#00ffff, #e0e0e0);
    --card-bg: rgba(255, 255, 255, 0.05);
    --card-border: rgba(0, 255, 255, 0.2);
    --card-bg-hover: rgba(0, 255, 255, 0.1);
    --card-border-hover: rgba(0, 255, 255, 0.5);
    --tech-card-bg: rgba(13, 30, 69, 0.6);
    --tech-card-border: rgba(0, 255, 255, 0.2);
    --tech-card-bg-hover: rgba(0, 255, 255, 0.1);
    --section-bg-accent: #00000020;
    --modal-bg: #0f172a;
    --modal-border: rgba(0, 255, 255, 0.3);
    --input-bg: #1f2937;
    --input-border: #4b5563;
    --footer-bg: rgba(0, 0, 0, 0.3);
    --footer-text: #9ca3af;
    --accent-color: #00ffff;
}


/* ==========================================================================
   2. GLOBAL STYLES
   ========================================================================== */

body {
    font-family: 'Montserrat', sans-serif;
    background-color: var(--bg-body);
    color: var(--text-primary);
    transition: background-color 0.3s ease, color 0.3s ease;
}


/* ==========================================================================
   3. LAYOUT & SECTIONS
   ========================================================================== */

header.scrolled {
    background-color: var(--header-bg);
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

/* ==========================================================================
   3. LAYOUT & SECTIONS
   ========================================================================== */

.hero-video-wrapper {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden; /* Ẩn các phần thừa của iframe */
    z-index: -1;      /* Đặt video nằm dưới tất cả nội dung khác */
}

.hero-video-wrapper iframe {
    /* Kỹ thuật để iframe luôn full màn hình và giữ đúng tỷ lệ 16:9 */
    position: absolute;
    top: 50%;
    left: 50%;
    width: 100vw;       /* Chiều rộng bằng 100% chiều rộng màn hình */
    height: 56.25vw;    /* Chiều cao tính theo tỷ lệ 16:9 (9 / 16 * 100) */
    min-height: 100vh;  /* Đảm bảo chiều cao luôn phủ hết màn hình */
    min-width: 177.77vh; /* Đảm bảo chiều rộng luôn phủ hết màn hình (cho màn hình dọc) */
    transform: translate(-50%, -50%);
    
    /* QUAN TRỌNG: Vô hiệu hóa mọi tương tác chuột với video */
    pointer-events: none;
}

.hero-overlay {
    background-color: var(--hero-overlay);
}

.hero-overlay {
    background-color: var(--hero-overlay);
}

.section-title {
    background: var(--title-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.section-accent {
    background-color: var(--section-bg-accent);
}


/* ==========================================================================
   4. COMPONENTS
   ========================================================================== */

/* Buttons */
.btn-primary {
    background: var(--btn-gradient);
    color: var(--btn-primary-text);
    transition: all 0.3s ease;
    box-shadow: 0 0 15px var(--btn-shadow);
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 0 25px var(--btn-shadow-hover);
}

/* Cards */
.project-card {
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    transition: all 0.3s ease;
}
.project-card:hover {
    transform: translateY(-5px);
    background-color: var(--card-bg-hover);
    border-color: var(--card-border-hover);
}

.tech-card, .philosophy-card {
    background: var(--tech-card-bg);
    border: 1px solid var(--tech-card-border);
    backdrop-filter: blur(10px);
    transition: all 0.3s ease;
}
 .tech-card:hover, .philosophy-card:hover {
    background: var(--tech-card-bg-hover);
    transform: translateY(-5px);
}

/* Modal */
.modal-backdrop {
    background-color: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(5px);
}


/* ==========================================================================
   5. UTILITY & ANIMATIONS
   ========================================================================== */

.text-glow {
    text-shadow: 0 0 8px var(--glow-color), 0 0 10px var(--glow-color);
}

.fade-in-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}
.fade-in-up.visible {
    opacity: 1;
    transform: translateY(0);
}