/*
Theme Name: Tahsin Rahit Portfolio
Theme URI: https://www.tahsinrahit.com
Author: K.M. Tahsin Hassan Rahit
Author URI: https://www.tahsinrahit.com
Description: A dark-themed academic portfolio WordPress theme featuring a comprehensive CV homepage, about, blog, and travel pages. Built with security-first architecture and modern animations.
Version: 1.0.0
Requires at least: 6.0
Tested up to: 6.7
Requires PHP: 8.0
License: GNU General Public License v2 or later
License URI: https://www.gnu.org/licenses/gpl-2.0.html
Text Domain: tahsinrahit
Tags: portfolio, dark, one-column, custom-menu, featured-images, theme-options, translation-ready
*/

/* ==========================================================================
   Design System — CSS Custom Properties
   ========================================================================== */

:root {
    /* --- Color Palette --- */
    --color-bg-primary: #0A1120;
    --color-bg-secondary: #0F1A2E;
    --color-bg-tertiary: #1E293B;
    --color-bg-card: rgba(30, 41, 59, 0.4);
    --color-bg-card-hover: rgba(30, 41, 59, 0.6);

    --color-accent: #00E5FF;
    --color-accent-secondary: #3B82F6;
    --color-accent-gradient: linear-gradient(135deg, #00E5FF, #3B82F6);

    --color-text-primary: #F8FAFC;
    --color-text-secondary: #CBD5E1;
    --color-text-muted: #64748B;

    --color-border: rgba(100, 116, 139, 0.2);
    --color-border-hover: rgba(0, 229, 255, 0.5);

    /* --- Typography --- */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;
    --text-5xl: 3rem;
    --text-6xl: 3.75rem;

    --leading-tight: 1.25;
    --leading-normal: 1.5;
    --leading-relaxed: 1.625;

    /* --- Spacing --- */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;
    --space-20: 5rem;
    --space-24: 6rem;

    /* --- Borders & Radius --- */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.625rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;

    /* --- Shadows --- */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.3);
    --shadow-2xl: 0 25px 50px rgba(0, 0, 0, 0.4);
    --shadow-accent: 0 0 20px rgba(0, 229, 255, 0.15);

    /* --- Transitions --- */
    --transition-fast: 150ms ease;
    --transition-base: 300ms ease;
    --transition-slow: 500ms ease;

    /* --- Layout --- */
    --container-max: 1280px;
    --nav-height: 64px;

    /* --- Z-Index --- */
    --z-bg: 0;
    --z-content: 10;
    --z-sticky: 20;
    --z-nav: 50;
    --z-overlay: 100;
    --z-modal: 200;
}

/* --- Light Mode Overrides --- */
body.light-mode {
    --color-bg-primary: #F8FAFC;
    --color-bg-secondary: #F1F5F9;
    --color-bg-tertiary: #E2E8F0;
    --color-bg-card: rgba(241, 245, 249, 0.8);
    --color-bg-card-hover: rgba(226, 232, 240, 0.8);

    --color-accent: #0891B2;
    --color-accent-secondary: #2563EB;
    --color-accent-gradient: linear-gradient(135deg, #0891B2, #2563EB);

    --color-text-primary: #0F172A;
    --color-text-secondary: #334155;
    --color-text-muted: #94A3B8;

    --color-border: rgba(148, 163, 184, 0.3);
    --color-border-hover: rgba(8, 145, 178, 0.5);

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.1);
    --shadow-2xl: 0 25px 50px rgba(0, 0, 0, 0.15);
    --shadow-accent: 0 0 20px rgba(8, 145, 178, 0.1);
}

/* ==========================================================================
   Base Reset & Typography
   ========================================================================== */

*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
    font-size: var(--text-base);
}

body {
    font-family: var(--font-sans);
    background-color: var(--color-bg-primary);
    color: var(--color-text-secondary);
    line-height: var(--leading-normal);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
    position: relative;
}

::selection {
    background-color: var(--color-accent);
    color: var(--color-text-primary);
}

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

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

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

h1, h2, h3, h4, h5, h6 {
    color: var(--color-text-primary);
    line-height: var(--leading-tight);
    font-weight: 700;
}

h1 { font-size: var(--text-5xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

code, pre {
    font-family: var(--font-mono);
}

/* ==========================================================================
   Layout Utilities
   ========================================================================== */

.container {
    width: 100%;
    max-width: var(--container-max);
    margin-left: auto;
    margin-right: auto;
    padding-left: var(--space-6);
    padding-right: var(--space-6);
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}