/* ==========================================================================
   Rahul Kumar Portfolio — Stylesheet
   Theme: Black & Dark Red | Font: Syne Mono
   ========================================================================== */

/* --- Custom Properties (Dark default) --- */
:root,
[data-theme="dark"] {
  --color-bg: #0a0a0a;
  --color-bg-alt: #111111;
  --color-surface: #161616;
  --color-border: #2a2a2a;
  --color-text: #e8e8e8;
  --color-text-muted: #888888;
  --color-accent: #8b0000;
  --color-accent-light: #b22222;
  --color-accent-glow: rgba(139, 0, 0, 0.35);
  --color-header-bg: rgba(10, 10, 10, 0.92);
  --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.4);
  --logo-filter: none;
}

[data-theme="light"] {
  --color-bg: #f5f3f0;
  --color-bg-alt: #ebe8e4;
  --color-surface: #ffffff;
  --color-border: #d4d0cb;
  --color-text: #1a1a1a;
  --color-text-muted: #666666;
  --color-accent: #8b0000;
  --color-accent-light: #a00000;
  --color-accent-glow: rgba(139, 0, 0, 0.15);
  --color-header-bg: rgba(245, 243, 240, 0.92);
  --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.08);
  --logo-filter: invert(1);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 5rem;
}

body {
  font-family: "Syne Mono", monospace;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  overflow-x: hidden;
  transition: background-color 0.4s ease, color 0.4s ease;
}

body.loading {
  overflow: hidden;
}

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

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

.container {
  width: min(100% - 2rem, 72rem);
  margin-inline: auto;
}

.section {
  padding-block: 6rem;
}

.section__title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

.section__title--center {
  text-align: center;
}

.section__subtitle {
  text-align: center;
  color: var(--color-text-muted);
  margin-bottom: 3rem;
  max-width: 36rem;
  margin-inline: auto;
}

/* --- Loader --- */
.loader {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #0a0a0a;
  transition: opacity 0.6s ease, visibility 0.6s ease;
}

.loader.hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.loader__inner {
  text-align: center;
}

.loader__text {
  display: block;
  font-size: 1.25rem;
  color: #e8e8e8;
  letter-spacing: 0.05em;
  margin-bottom: 1.5rem;
  animation: loaderPulse 1.2s ease-in-out infinite;
}

.loader__bar {
  width: 12rem;
  height: 2px;
  background: #2a2a2a;
  overflow: hidden;
  margin-inline: auto;
}

.loader__bar-fill {
  display: block;
  height: 100%;
  width: 0%;
  background: #8b0000;
  animation: loaderFill 1.4s ease-in-out forwards;
}

@keyframes loaderPulse {
  0%, 100% { opacity: 0.5; }
  50% { opacity: 1; }
}

@keyframes loaderFill {
  to { width: 100%; }
}

/* --- Header --- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 100;
  background: var(--color-header-bg);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: background 0.4s ease;
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.5rem;
  gap: 1rem;
}

.nav__logo {
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--color-text);
  transition: color 0.25s ease;
}

.nav__logo:hover {
  color: var(--color-accent);
}

.nav__menu {
  display: flex;
  gap: 2rem;
}

.nav__link {
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  transition: color 0.25s ease;
  position: relative;
}

.nav__link::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--color-accent);
  transition: width 0.3s ease;
}

.nav__link:hover,
.nav__link.active {
  color: var(--color-text);
}

.nav__link:hover::after,
.nav__link.active::after {
  width: 100%;
}

.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav__toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.nav__toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav__toggle.open span:nth-child(2) {
  opacity: 0;
}

.nav__toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* --- Theme Toggle --- */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  background: var(--color-surface);
  color: var(--color-text);
  cursor: pointer;
  transition: border-color 0.25s ease, background 0.25s ease;
  flex-shrink: 0;
}

.theme-toggle:hover {
  border-color: var(--color-accent);
}

.theme-toggle__icon {
  width: 1.125rem;
  height: 1.125rem;
}

.theme-toggle__icon--sun { display: none; }
.theme-toggle__icon--moon { display: block; }

[data-theme="light"] .theme-toggle__icon--sun { display: block; }
[data-theme="light"] .theme-toggle__icon--moon { display: none; }

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  font-family: inherit;
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background 0.25s ease, color 0.25s ease, border-color 0.25s ease, transform 0.2s ease;
}

.btn:active {
  transform: scale(0.98);
}

.btn--primary {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

.btn--primary:hover {
  background: var(--color-accent-light);
  border-color: var(--color-accent-light);
}

.btn--outline {
  background: transparent;
  color: var(--color-text);
  border-color: var(--color-border);
}

.btn--outline:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* --- Hero --- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  padding-top: 4.5rem;
}

.hero__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.hero__eyebrow {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--color-accent);
  margin-bottom: 1rem;
}

.hero__title {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 1.5rem;
}

.hero__accent {
  color: var(--color-accent);
}

.hero__desc {
  color: var(--color-text-muted);
  max-width: 32rem;
  margin-bottom: 2rem;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.hero__visual {
  display: flex;
  justify-content: center;
}

.hero__frame {
  position: relative;
  width: min(100%, 22rem);
  aspect-ratio: 1;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  overflow: hidden;
}

.hero__canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.hero__scroll {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.6875rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-text-muted);
  animation: scrollBounce 2s ease-in-out infinite;
}

@keyframes scrollBounce {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(6px); }
}

/* --- About --- */
.about {
  background: var(--color-bg-alt);
}

.about__grid {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 4rem;
  align-items: center;
}

.about__image-wrap {
  position: relative;
  max-width: 24rem;
  margin-inline: auto;
}

.about__image {
  width: 100%;
  aspect-ratio: 4/5;
  object-fit: cover;
  border: 1px solid var(--color-border);
  position: relative;
  z-index: 1;
}

.about__image-border {
  position: absolute;
  inset: -12px -12px 12px 12px;
  border: 1px solid var(--color-accent);
  z-index: 0;
  opacity: 0.5;
}

.about__lead {
  font-size: 1.0625rem;
  margin-bottom: 1rem;
}

.about__text {
  color: var(--color-text-muted);
  margin-bottom: 2rem;
}

.about__skills {
  display: flex;
  flex-wrap: wrap;
  gap: 0.625rem;
}

.about__skills li {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.4rem 0.875rem;
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  transition: border-color 0.25s ease, color 0.25s ease;
}

.about__skills li:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* --- Project --- */
.project__grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.project__card {
  position: relative;
  display: grid;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-card);
  overflow: hidden;
  transition: border-color 0.3s ease;
}

.project__card:hover {
  border-color: var(--color-accent);
}

.project__card-accent {
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-light));
}

.project__card-body {
  padding: 2.5rem;
}

.project__tag {
  font-size: 0.6875rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-accent);
  display: block;
  margin-bottom: 0.75rem;
}

.project__title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 1rem;
}

.project__desc {
  color: var(--color-text-muted);
  margin-bottom: 1.75rem;
  max-width: 36rem;
}

/* --- Contact --- */
.contact {
  background: var(--color-bg-alt);
}

.contact__grid {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 3rem;
  align-items: start;
}

.contact__text {
  color: var(--color-text-muted);
  max-width: 28rem;
}

.contact__options {
  display: flex;
  flex-direction: column;
  gap: 0;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
}

.contact__item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--color-border);
  transition: background 0.25s ease, padding-left 0.25s ease;
}

.contact__item:last-child {
  border-bottom: none;
}

.contact__item:hover {
  background: var(--color-bg-alt);
  padding-left: 2rem;
}

.contact__label {
  font-size: 0.6875rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-accent);
}

.contact__value {
  font-size: 0.875rem;
  color: var(--color-text);
}

/* --- Footer --- */
.footer {
  border-top: 1px solid var(--color-border);
  padding-block: 2rem;
}

.footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer__copy {
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

.footer__nav {
  display: flex;
  gap: 1.5rem;
}

.footer__nav a {
  font-size: 0.6875rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  transition: color 0.25s ease;
}

.footer__nav a:hover {
  color: var(--color-accent);
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .nav__toggle {
    display: flex;
  }

  .nav__menu {
    position: fixed;
    top: 4.5rem;
    left: 0;
    width: 100%;
    flex-direction: column;
    align-items: center;
    gap: 0;
    background: var(--color-header-bg);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    padding-block: 1rem;
    transform: translateY(-120%);
    opacity: 0;
    visibility: hidden;
    transition: transform 0.35s ease, opacity 0.35s ease, visibility 0.35s ease;
  }

  .nav__menu.open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .nav__menu li {
    width: 100%;
    text-align: center;
  }

  .nav__link {
    display: block;
    padding: 0.875rem;
  }

  .hero__grid,
  .about__grid,
  .contact__grid {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .hero__visual {
    order: -1;
  }

  .hero__frame {
    width: 14rem;
  }

  .project__grid {
    grid-template-columns: 1fr;
  }

  .section {
    padding-block: 4rem;
  }

  .footer__inner {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .hero__actions {
    flex-direction: column;
  }

  .btn {
    width: 100%;
    justify-content: center;
  }

  .project__card-body {
    padding: 1.5rem;
  }
}