/* ============================================================
   styles.css — Ethan Teo Portfolio
   Table of contents:
   00. CSS Custom Properties (Variables)
   01. Reset & Base
   02. Typography
   03. Utilities
   04. Layout Helpers
   05. Components — Buttons
   06. Components — Navigation
   07. Components — Hero
   08. Components — About
   09. Components — Skills
   10. Components — Portfolio
   11. Components — Contact
   12. Components — Footer
   13. Animations & Reveal
   14. Media Queries
   ============================================================ */

/* ============================================================
   00. CSS Custom Properties
   ============================================================ */
:root {
  /* Colours */
  --clr-bg:           #0d0f14;
  --clr-surface:      #13161e;
  --clr-surface-2:    #1c2030;
  --clr-surface-3:    #252a3a;
  --clr-primary:      #6c63ff;
  --clr-primary-dim:  #6c63ff33;
  --clr-accent:       #00d4aa;
  --clr-accent-dim:   #00d4aa33;
  --clr-text:         #e2e8f0;
  --clr-text-muted:   #8892a4;
  --clr-border:       #252a3a;
  --clr-white:        #ffffff;

  /* Gradient shorthand */
  --gradient-primary: linear-gradient(135deg, var(--clr-primary), var(--clr-accent));

  /* Typography */
  --font-body:    'Inter', sans-serif;
  --font-heading: 'Space Grotesk', sans-serif;

  /* Sizing */
  --nav-height:    70px;
  --container-max: 1140px;
  --radius:        12px;
  --radius-sm:     6px;

  /* Transitions */
  --transition: 0.3s ease;
  --transition-slow: 0.6s ease;

  /* Shadows */
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.4);
  --shadow-card-hover: 0 8px 40px rgba(108, 99, 255, 0.25);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  background-color: var(--clr-bg);
  color: var(--clr-text);
  font-family: var(--font-body);
  line-height: 1.7;
  overflow-x: hidden;
}

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

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

ul {
  list-style: none;
}

button {
  cursor: pointer;
  border: none;
  background: none;
  font-family: inherit;
}

/* ============================================================
   02. Typography
   ============================================================ */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  line-height: 1.2;
  color: var(--clr-white);
}

h1 { font-size: clamp(2.4rem, 6vw, 4.2rem); font-weight: 700; }
h2 { font-size: clamp(1.8rem, 4vw, 2.8rem); font-weight: 700; }
h3 { font-size: 1.2rem; font-weight: 600; }

p {
  color: var(--clr-text-muted);
  margin-bottom: 1rem;
}

p:last-child { margin-bottom: 0; }

/* ============================================================
   03. Utilities
   ============================================================ */
.text-gradient {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.section {
  padding: 6rem 0;
}

.section__eyebrow {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--clr-primary);
  margin-bottom: 0.75rem;
}

.section__title {
  margin-bottom: 1rem;
}

.section__subtitle {
  max-width: 520px;
  color: var(--clr-text-muted);
}

.section__header {
  text-align: center;
  margin-bottom: 3rem;
}

.section__header .section__subtitle {
  margin: 0 auto;
}

/* ============================================================
   04. Layout Helpers
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: 1.5rem;
}

/* ============================================================
   05. Components — Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  transition: transform var(--transition), box-shadow var(--transition), background var(--transition), color var(--transition), border-color var(--transition);
  white-space: nowrap;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn:active {
  transform: translateY(0);
}

.btn--primary {
  background: var(--gradient-primary);
  color: var(--clr-white);
  box-shadow: 0 4px 20px rgba(108, 99, 255, 0.35);
}

.btn--primary:hover {
  box-shadow: 0 8px 30px rgba(108, 99, 255, 0.5);
}

.btn--outline {
  background: transparent;
  color: var(--clr-text);
  border: 2px solid var(--clr-border);
}

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

.btn--small {
  padding: 0.5rem 1.2rem;
  font-size: 0.875rem;
}

.btn--full {
  width: 100%;
}

/* ============================================================
   06. Components — Navigation
   ============================================================ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-height);
  background: transparent;
  transition: background var(--transition), box-shadow var(--transition), backdrop-filter var(--transition);
}

.site-header.scrolled {
  background: rgba(13, 15, 20, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 0 var(--clr-border);
}

.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.nav-logo {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--clr-white);
  transition: color var(--transition);
}

.nav-logo:hover {
  color: var(--clr-primary);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2.5rem;
}

.nav-link {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--clr-text-muted);
  transition: color var(--transition);
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-primary);
  border-radius: 2px;
  transition: width var(--transition);
}

.nav-link:hover,
.nav-link.active {
  color: var(--clr-white);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

/* Hamburger */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 28px;
  height: 20px;
  padding: 0;
  z-index: 101;
}

.hamburger {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--clr-text);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

/* Open state */
.nav-toggle.open .hamburger:nth-child(1) {
  transform: translateY(9px) rotate(45deg);
}
.nav-toggle.open .hamburger:nth-child(2) {
  opacity: 0;
}
.nav-toggle.open .hamburger:nth-child(3) {
  transform: translateY(-9px) rotate(-45deg);
}

/* ============================================================
   07. Components — Hero
   ============================================================ */
.hero {
  position: relative;
  min-height: 100svh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  overflow: hidden;
  padding-top: var(--nav-height);
}

/* Subtle grid background */
.hero__bg-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(108, 99, 255, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(108, 99, 255, 0.05) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 50%, black 0%, transparent 100%);
  -webkit-mask-image: radial-gradient(ellipse 80% 60% at 50% 50%, black 0%, transparent 100%);
}

/* Glow orb */
.hero::before {
  content: '';
  position: absolute;
  top: 20%;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(108, 99, 255, 0.12) 0%, transparent 70%);
  pointer-events: none;
}

.hero__content {
  position: relative;
  z-index: 1;
  max-width: 720px;
}

.hero__greeting {
  display: block;
  font-size: 1rem;
  font-weight: 500;
  color: var(--clr-primary);
  letter-spacing: 0.08em;
  margin-bottom: 0.5rem;
}

.hero__name {
  margin-bottom: 1.25rem;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__tagline {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--clr-text-muted);
  max-width: 560px;
  margin: 0 auto 2.5rem;
}

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

/* Scroll hint arrow */
.hero__scroll-hint {
  position: absolute;
  bottom: 2.5rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
}

.hero__scroll-hint span {
  display: block;
  width: 24px;
  height: 38px;
  border: 2px solid var(--clr-border);
  border-radius: 12px;
  position: relative;
}

.hero__scroll-hint span::before {
  content: '';
  position: absolute;
  top: 5px;
  left: 50%;
  transform: translateX(-50%);
  width: 4px;
  height: 4px;
  background: var(--clr-primary);
  border-radius: 50%;
  animation: scroll-dot 1.6s ease infinite;
}

@keyframes scroll-dot {
  0%   { opacity: 1; top: 5px; }
  80%  { opacity: 0; top: 22px; }
  100% { opacity: 0; top: 22px; }
}

/* ============================================================
   08. Components — About
   ============================================================ */
.about__grid {
  display: grid;
  grid-template-columns: 1fr 1.4fr;
  gap: 4rem;
  align-items: center;
}

.about__image-wrap {
  position: relative;
}

.about__image-placeholder {
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--clr-border);
  line-height: 0;
}

.about__image-placeholder svg,
.about__image-placeholder img {
  width: 100%;
  height: auto;
  display: block;
}

/* Decorative corner gradient */
.about__image-wrap::before {
  content: '';
  position: absolute;
  inset: -2px;
  background: var(--gradient-primary);
  border-radius: calc(var(--radius) + 2px);
  z-index: -1;
  opacity: 0.5;
}

.about__badge {
  position: absolute;
  bottom: -1.25rem;
  right: -1.25rem;
  background: var(--clr-surface-2);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-sm);
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--clr-white);
  box-shadow: var(--shadow-card);
}

.about__text .section__title {
  margin-bottom: 1.25rem;
}

.about__text p {
  margin-bottom: 1.25rem;
}

/* ============================================================
   09. Components — Skills
   ============================================================ */
.skills {
  background: var(--clr-surface);
}

.skills__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 1.5rem;
}

.skill-card {
  background: var(--clr-surface-2);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  padding: 2rem 1.5rem;
  text-align: center;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.skill-card:hover {
  transform: translateY(-6px);
  border-color: var(--clr-primary);
  box-shadow: var(--shadow-card-hover);
}

.skill-card__icon {
  width: 56px;
  height: 56px;
  margin: 0 auto 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.skill-card__icon svg {
  width: 100%;
  height: 100%;
}

.skill-card__name {
  font-size: 1rem;
  font-weight: 600;
  color: var(--clr-white);
  margin-bottom: 0.25rem;
}

.skill-card__level {
  font-size: 0.8rem;
  color: var(--clr-primary);
  font-weight: 500;
  margin-bottom: 0;
}

/* ============================================================
   10. Components — Portfolio
   ============================================================ */
.portfolio__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.project-card {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.project-card:hover {
  transform: translateY(-6px);
  border-color: var(--clr-primary);
  box-shadow: var(--shadow-card-hover);
}

.project-card__image {
  position: relative;
  aspect-ratio: 16 / 9;
  background: var(--clr-surface-2);
  overflow: hidden;
}

.project-card__image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}

.project-card:hover .project-card__image img {
  transform: scale(1.05);
}

.project-card__image-placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--clr-surface-2);
}

.project-card__image-placeholder svg {
  width: 60%;
  height: auto;
}

.project-card__tag {
  position: absolute;
  top: 0.75rem;
  left: 0.75rem;
  background: rgba(13, 15, 20, 0.85);
  backdrop-filter: blur(6px);
  border: 1px solid var(--clr-border);
  color: var(--clr-accent);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 0.25rem 0.65rem;
  border-radius: 4px;
}

.project-card__body {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  flex: 1;
  gap: 0.75rem;
}

.project-card__title {
  font-size: 1.1rem;
  color: var(--clr-white);
}

.project-card__desc {
  font-size: 0.9rem;
  color: var(--clr-text-muted);
  flex: 1;
  margin-bottom: 0;
}

/* ============================================================
   11. Components — Contact
   ============================================================ */
.contact {
  background: var(--clr-surface);
}

.contact__grid {
  display: grid;
  grid-template-columns: 1fr 1.4fr;
  gap: 4rem;
  align-items: start;
}

.contact__info .section__title {
  margin-bottom: 1rem;
}

.contact__info p {
  margin-bottom: 2rem;
}

.contact__details {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.contact__details li {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  color: var(--clr-text-muted);
  font-size: 0.95rem;
}

.contact__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  background: var(--clr-primary-dim);
  color: var(--clr-primary);
  flex-shrink: 0;
}

.contact__icon svg {
  width: 18px;
  height: 18px;
}

/* Form */
.contact__form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form-group label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--clr-text);
}

.form-group input,
.form-group textarea {
  background: var(--clr-surface-2);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-sm);
  color: var(--clr-text);
  font-family: var(--font-body);
  font-size: 0.95rem;
  padding: 0.75rem 1rem;
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
  resize: vertical;
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: var(--clr-text-muted);
}

.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--clr-primary);
  box-shadow: 0 0 0 3px var(--clr-primary-dim);
}

.form-group input.error,
.form-group textarea.error {
  border-color: #f87171;
}

.form-error {
  font-size: 0.8rem;
  color: #f87171;
  min-height: 1rem;
}

.form-success {
  text-align: center;
  color: var(--clr-accent);
  font-size: 0.9rem;
  font-weight: 500;
  min-height: 1.4rem;
}

/* ============================================================
   12. Components — Footer
   ============================================================ */
.site-footer {
  background: var(--clr-bg);
  border-top: 1px solid var(--clr-border);
  padding: 2.5rem 0;
}

.footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1.5rem;
}

.footer__name {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--clr-white);
  margin-bottom: 0;
}

.footer__copy {
  font-size: 0.85rem;
  color: var(--clr-text-muted);
  margin-bottom: 0;
}

.footer__socials {
  display: flex;
  gap: 1rem;
}

.footer__socials a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--clr-border);
  color: var(--clr-text-muted);
  transition: color var(--transition), border-color var(--transition), background var(--transition);
}

.footer__socials a:hover {
  color: var(--clr-white);
  border-color: var(--clr-primary);
  background: var(--clr-primary-dim);
}

.footer__socials svg {
  width: 18px;
  height: 18px;
}

/* ============================================================
   13. Animations & Reveal
   ============================================================ */

/* Scroll-reveal: .will-reveal is added by JS only to elements that are
   genuinely off-screen at page load, so in-viewport content is always
   visible (including in no-JS / headless / screenshot environments). */
.will-reveal {
  opacity: 0;
  transform: translateY(30px);
}

.reveal {
  transition: opacity 0.65s ease, transform 0.65s ease;
}

.reveal.visible {
  opacity: 1 !important;
  transform: translateY(0) !important;
}

/* Stagger children in grids */
.skills__grid .reveal:nth-child(2)  { transition-delay: 0.08s; }
.skills__grid .reveal:nth-child(3)  { transition-delay: 0.16s; }
.skills__grid .reveal:nth-child(4)  { transition-delay: 0.24s; }
.skills__grid .reveal:nth-child(5)  { transition-delay: 0.32s; }
.skills__grid .reveal:nth-child(6)  { transition-delay: 0.40s; }

.portfolio__grid .reveal:nth-child(2) { transition-delay: 0.12s; }
.portfolio__grid .reveal:nth-child(3) { transition-delay: 0.24s; }

/* ============================================================
   14. Media Queries
   ============================================================ */

/* Tablet — ≤ 900px */
@media (max-width: 900px) {
  .about__grid,
  .contact__grid {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .about__image-wrap {
    max-width: 320px;
    margin-inline: auto;
  }

  .about__badge {
    right: -0.75rem;
    bottom: -0.75rem;
  }
}

/* Mobile — ≤ 680px */
@media (max-width: 680px) {
  .nav-toggle {
    display: flex;
  }

  .nav-links {
    position: fixed;
    inset: 0;
    flex-direction: column;
    justify-content: center;
    gap: 2.5rem;
    background: var(--clr-bg);
    font-size: 1.3rem;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition);
    z-index: 99;
  }

  .nav-links.open {
    opacity: 1;
    pointer-events: all;
  }

  .hero__actions {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    max-width: 300px;
  }

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

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

  .section {
    padding: 4rem 0;
  }
}

/* Very small — ≤ 400px */
@media (max-width: 400px) {
  html { font-size: 15px; }
}