/* ===================================================================
   styles.css - Sai Teja Lodagala Professional Engineering Portfolio
   Aesthetic: Executive Minimalist Engineering (Linear / Stripe / Stanford style)
   Theme: Adaptive Light (Alabaster) & Dark (Obsidian Amber Gold)
   =================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Fira+Code:wght@400;500;600&family=Inter:wght@300;400;500;600;700;800&family=Plus+Jakarta+Sans:wght@500;600;700;800&display=swap');

/* ===================================================================
   1. Theme Variables
   =================================================================== */

:root {
  /* Light Mode (Default Day) */
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --bg-nav: rgba(248, 250, 252, 0.9);
  --bg-panel: #ffffff;
  --bg-input: #f1f5f9;
  --bg-modal-backdrop: rgba(15, 23, 42, 0.4);
  --border-subtle: #e2e8f0;
  --border-card: #e2e8f0;
  --border-hover: rgba(217, 119, 6, 0.5);
  --text-main: #0f172a;
  --text-muted: #64748b;
  --text-body: #334155;
  --accent-color: #d97706;
  --accent-primary: #b45309;
  --accent-bg: rgba(245, 158, 11, 0.1);
  --accent-glow: rgba(217, 119, 6, 0.12);
  --selection-bg: #f59e0b;
  --selection-color: #ffffff;
  --grid-line: rgba(0, 0, 0, 0.035);
  --ambient-grad-1: rgba(245, 158, 11, 0.05);
  --ambient-grad-2: rgba(217, 119, 6, 0.03);
  --card-shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
  --card-shadow-hover: 0 10px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
  --scrollbar-thumb: #cbd5e1;
  --scrollbar-thumb-hover: #94a3b8;
}

html.dark {
  /* Dark Mode (Obsidian Amber Gold) */
  --bg-main: #08080a;
  --bg-card: #111115;
  --bg-nav: rgba(8, 8, 10, 0.92);
  --bg-panel: #111115;
  --bg-input: #18181f;
  --bg-modal-backdrop: rgba(0, 0, 0, 0.85);
  --border-subtle: rgba(255, 255, 255, 0.07);
  --border-card: rgba(255, 255, 255, 0.07);
  --border-hover: rgba(245, 158, 11, 0.4);
  --text-main: #fafafa;
  --text-muted: #a1a1aa;
  --text-body: #e4e4e7;
  --accent-color: #fbbf24;
  --accent-primary: #f59e0b;
  --accent-bg: rgba(245, 158, 11, 0.15);
  --accent-glow: rgba(245, 158, 11, 0.18);
  --selection-bg: #f59e0b;
  --selection-color: #08080a;
  --grid-line: rgba(255, 255, 255, 0.02);
  --ambient-grad-1: rgba(245, 158, 11, 0.06);
  --ambient-grad-2: rgba(251, 191, 36, 0.035);
  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.5);
  --card-shadow-hover: 0 10px 30px -10px rgba(0, 0, 0, 0.8), 0 0 20px -3px rgba(245, 158, 11, 0.15);
  --scrollbar-thumb: #27272a;
  --scrollbar-thumb-hover: #f59e0b;
}

* {
  box-sizing: border-box;
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background-color: var(--bg-main);
  color: var(--text-body);
  overflow-x: hidden;
  transition: background-color 0.25s ease, color 0.25s ease;
}

::selection {
  background-color: var(--selection-bg);
  color: var(--selection-color);
}

/* Custom Minimalist Scrollbar */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: var(--bg-main);
}

::-webkit-scrollbar-thumb {
  background: var(--scrollbar-thumb);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--scrollbar-thumb-hover);
}

/* Typography */
h1, h2, h3, h4, .font-heading {
  font-family: 'Plus Jakarta Sans', 'Inter', sans-serif;
  letter-spacing: -0.025em;
  color: var(--text-main);
}

code, pre, .font-mono {
  font-family: 'Fira Code', monospace;
}

/* Ambient Backdrop & Grid */
.ambient-bg {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: -1;
  pointer-events: none;
  background: 
    radial-gradient(circle at 50% 0%, var(--ambient-grad-1) 0%, transparent 60%),
    radial-gradient(circle at 10% 30%, var(--ambient-grad-2) 0%, transparent 40%),
    var(--bg-main);
  transition: background 0.3s ease;
}

.grid-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: -1;
  pointer-events: none;
  background-size: 40px 40px;
  background-image: 
    linear-gradient(to right, var(--grid-line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--grid-line) 1px, transparent 1px);
}

/* Navigation Bar */
.glass-nav {
  background: var(--bg-nav);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-subtle);
  transition: background 0.25s ease, border-color 0.25s ease;
}

/* Professional Cards */
.glass-card {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: 0.875rem;
  box-shadow: var(--card-shadow);
  transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

.glass-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-2px);
  box-shadow: var(--card-shadow-hover);
}

.glass-panel {
  background: var(--bg-panel);
  border: 1px solid var(--border-card);
  border-radius: 0.875rem;
}

/* Filter Pills */
.glass-pill {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  color: var(--text-muted);
  transition: all 0.2s ease;
  cursor: pointer;
}

.glass-pill:hover {
  color: var(--text-main);
  border-color: var(--accent-color);
}

.glass-pill.active {
  background: var(--accent-bg);
  border-color: var(--accent-color);
  color: var(--accent-color);
  font-weight: 600;
}

/* Modal Animations */
.modal-enter {
  opacity: 0;
  transform: scale(0.98) translateY(8px);
}

.modal-enter-active {
  opacity: 1;
  transform: scale(1) translateY(0);
  transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.modal-backdrop {
  background: var(--bg-modal-backdrop);
  backdrop-filter: blur(10px);
}

/* KaTeX equations in cards */
.katex-display {
  margin: 0.6em 0 !important;
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0.3em 0;
}

/* Light / Dark Mode Toast */
#toast {
  background-color: var(--bg-card);
  border: 1px solid var(--border-hover);
  color: var(--accent-color);
  box-shadow: var(--card-shadow-hover);
}