/* ============================================
   NỒI HƠI ĐẠI VIỆT TIẾN — Design System
   Modern Industrial Theme 2026
   ============================================ */

/* --- CSS Reset & Base --- */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* === Color Palette — Industrial Premium === */
    --color-primary: #1B4D7A;          /* Deep Steel Blue */
    --color-primary-light: #2A6FAF;
    --color-primary-dark: #0F3356;
    --color-secondary: #E8651A;        /* Industrial Orange */
    --color-secondary-light: #FF8A3D;
    --color-secondary-dark: #C24E0E;
    --color-accent: #00B4D8;           /* Cyan Accent */

    /* Neutrals */
    --color-bg: #FAFBFC;
    --color-bg-dark: #0D1B2A;
    --color-bg-card: #FFFFFF;
    --color-bg-section: #F0F4F8;
    --color-surface: #FFFFFF;
    --color-border: #E2E8F0;
    --color-border-light: #F1F5F9;

    /* Text */
    --color-text: #1E293B;
    --color-text-secondary: #64748B;
    --color-text-muted: #94A3B8;
    --color-text-light: #FFFFFF;

    /* Status */
    --color-success: #10B981;
    --color-warning: #F59E0B;
    --color-error: #EF4444;

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #1B4D7A 0%, #2A6FAF 100%);
    --gradient-secondary: linear-gradient(135deg, #E8651A 0%, #FF8A3D 100%);
    --gradient-hero: linear-gradient(135deg, #0D1B2A 0%, #1B4D7A 50%, #2A6FAF 100%);
    --gradient-dark: linear-gradient(180deg, #0D1B2A 0%, #1B2D44 100%);
    --gradient-glass: linear-gradient(135deg, rgba(255,255,255,0.1) 0%, rgba(255,255,255,0.05) 100%);

    /* === Typography === */
    --font-heading: 'Outfit', 'Segoe UI', sans-serif;
    --font-body: 'Inter', 'Segoe UI', system-ui, sans-serif;
    --font-mono: 'JetBrains Mono', 'Consolas', monospace;

    --text-xs: 0.75rem;    /* 12px */
    --text-sm: 0.875rem;   /* 14px */
    --text-base: 1rem;     /* 16px */
    --text-lg: 1.125rem;   /* 18px */
    --text-xl: 1.25rem;    /* 20px */
    --text-2xl: 1.5rem;    /* 24px */
    --text-3xl: 1.875rem;  /* 30px */
    --text-4xl: 2.25rem;   /* 36px */
    --text-5xl: 3rem;      /* 48px */
    --text-6xl: 3.75rem;   /* 60px */

    --leading-tight: 1.25;
    --leading-normal: 1.6;
    --leading-relaxed: 1.75;

    /* === Spacing === */
    --space-1: 0.25rem;    /* 4px */
    --space-2: 0.5rem;     /* 8px */
    --space-3: 0.75rem;    /* 12px */
    --space-4: 1rem;       /* 16px */
    --space-5: 1.25rem;    /* 20px */
    --space-6: 1.5rem;     /* 24px */
    --space-8: 2rem;       /* 32px */
    --space-10: 2.5rem;    /* 40px */
    --space-12: 3rem;      /* 48px */
    --space-16: 4rem;      /* 64px */
    --space-20: 5rem;      /* 80px */
    --space-24: 6rem;      /* 96px */

    /* === Layout === */
    --container-max: 1280px;
    --container-padding: var(--space-6);
    --header-height: 80px;

    /* === Border Radius === */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 9999px;

    /* === Shadows === */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.05), 0 2px 4px rgba(0, 0, 0, 0.04);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.08), 0 4px 10px rgba(0, 0, 0, 0.04);
    --shadow-xl: 0 20px 50px rgba(0, 0, 0, 0.12), 0 8px 20px rgba(0, 0, 0, 0.06);
    --shadow-glow: 0 0 30px rgba(27, 77, 122, 0.15);
    --shadow-orange-glow: 0 0 30px rgba(232, 101, 26, 0.2);

    /* === Transitions === */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;
    --transition-spring: 500ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* === Dark Mode Support === */
[data-theme="dark"] {
    --color-bg: #0D1B2A;
    --color-bg-card: #1B2D44;
    --color-bg-section: #152238;
    --color-surface: #1B2D44;
    --color-border: #2A3F5A;
    --color-text: #E2E8F0;
    --color-text-secondary: #94A3B8;
    --color-text-muted: #64748B;
}

/* === Base Styles === */
html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-body);
    font-size: var(--text-base);
    line-height: var(--leading-normal);
    color: var(--color-text);
    background-color: var(--color-bg);
    overflow-x: hidden;
}

/* === Typography === */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: var(--leading-tight);
    color: var(--color-text);
}

h1 { font-size: var(--text-5xl); }
h2 { font-size: var(--text-4xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }
h5 { font-size: var(--text-lg); }

p {
    margin-bottom: var(--space-4);
    color: var(--color-text-secondary);
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-primary-light);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

ul, ol {
    list-style: none;
}

/* === Container === */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* === Section === */
.section {
    padding: var(--space-20) 0;
}

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

.section__header {
    text-align: center;
    margin-bottom: var(--space-12);
}

.section__title {
    font-size: var(--text-4xl);
    margin-bottom: var(--space-4);
    position: relative;
    display: inline-block;
}

.section__title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: var(--gradient-secondary);
    border-radius: var(--radius-full);
}

.section__subtitle {
    font-size: var(--text-lg);
    color: var(--color-text-secondary);
    max-width: 600px;
    margin: var(--space-6) auto 0;
}

/* === Utility Classes === */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-primary { color: var(--color-primary); }
.text-secondary { color: var(--color-secondary); }
.text-muted { color: var(--color-text-muted); }

.mt-4 { margin-top: var(--space-4); }
.mt-8 { margin-top: var(--space-8); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-8 { margin-bottom: var(--space-8); }

.flex { display: flex; }
.flex-wrap { flex-wrap: wrap; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

/* === Grid === */
.grid {
    display: grid;
    gap: var(--space-6);
}

.grid--2 { grid-template-columns: repeat(2, 1fr); }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--4 { grid-template-columns: repeat(4, 1fr); }

/* === Responsive === */
@media (max-width: 1024px) {
    .grid--4 { grid-template-columns: repeat(2, 1fr); }
    .grid--3 { grid-template-columns: repeat(2, 1fr); }
    h1 { font-size: var(--text-4xl); }
    h2 { font-size: var(--text-3xl); }
}

@media (max-width: 768px) {
    :root {
        --container-padding: var(--space-4);
        --header-height: 64px;
    }
    .grid--4, .grid--3, .grid--2 { grid-template-columns: 1fr; }
    h1 { font-size: var(--text-3xl); }
    h2 { font-size: var(--text-2xl); }
    .section { padding: var(--space-12) 0; }
    .section__title { font-size: var(--text-2xl); }
}

/* === Animations — Keyframes === */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-40px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(40px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

@keyframes shimmer {
    0% { background-position: -200% center; }
    100% { background-position: 200% center; }
}

.animate-fade-in-up {
    animation: fadeInUp 0.6s ease forwards;
}

.animate-fade-in {
    animation: fadeIn 0.5s ease forwards;
}

/* Staggered animation delays */
.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; }
.delay-4 { animation-delay: 0.4s; }