/* Variables */
:root {
  --color-bg: #ffffff;
  --color-bg-alt: #f4f5fb;
  --color-surface: #ffffff;
  --color-text: #1e1f2b;
  --color-text-muted: #5b5f73;
  --color-primary: #6c5ce7;
  --color-primary-hover: #5848d6;
  --color-on-primary: #ffffff;
  --color-border: #e1e3ee;
  --color-error: #d63031;
  --color-success: #00875a;
  --color-header-bg-scrolled: rgba(255, 255, 255, 0.92);
  --shadow-sm: 0 2px 8px rgba(30, 31, 43, 0.08);
  --shadow-md: 0 10px 24px rgba(30, 31, 43, 0.14);

  --font-base:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "Apple SD Gothic Neo",
    "Noto Sans KR", sans-serif;

  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 3rem;
  --space-xl: 5rem;

  --radius: 12px;
  --header-height: 64px;
  --transition: 0.25s ease;
}

[data-theme="dark"] {
  --color-bg: #12131a;
  --color-bg-alt: #1a1c26;
  --color-surface: #1f212d;
  --color-text: #eceef8;
  --color-text-muted: #a3a8c0;
  --color-primary: #a29bfe;
  --color-primary-hover: #b9b3ff;
  --color-on-primary: #12131a;
  --color-border: #2f3244;
  --color-error: #ff7675;
  --color-success: #55efc4;
  --color-header-bg-scrolled: rgba(18, 19, 26, 0.92);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 10px 24px rgba(0, 0, 0, 0.55);
}

/* Base (mobile first) */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
}

body {
  margin: 0;
  font-family: var(--font-base);
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
}

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

a {
  color: inherit;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

.container {
  width: 100%;
  max-width: 1100px;
  margin-inline: auto;
  padding-inline: var(--space-md);
}

:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
}

/* Header / Navigation (Flexbox) */
.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  background-color: transparent;
  transition:
    background-color var(--transition),
    box-shadow var(--transition);
}

.site-header.scrolled {
  background-color: var(--color-header-bg-scrolled);
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(8px);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
}

.logo {
  font-size: 1.25rem;
  font-weight: 800;
  text-decoration: none;
  color: var(--color-primary);
}

/* 모바일: 메뉴는 숨기고 햄버거로 토글 */
.nav-menu {
  position: absolute;
  top: var(--header-height);
  left: 0;
  right: 0;
  display: none;
  flex-direction: column;
  padding: var(--space-sm) var(--space-md);
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.nav-menu.active {
  display: flex;
}

.nav-link {
  display: block;
  padding: var(--space-xs) 0;
  text-decoration: none;
  font-weight: 600;
  color: var(--color-text);
  transition: color var(--transition);
}

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

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 0;
  font-size: 1.1rem;
  color: var(--color-text);
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  cursor: pointer;
  transition: background-color var(--transition);
}

.icon-btn:hover {
  background-color: var(--color-bg-alt);
}

.hamburger {
  flex-direction: column;
  gap: 4px;
}

.hamburger .bar {
  display: block;
  width: 18px;
  height: 2px;
  background-color: currentColor;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  font: inherit;
  font-weight: 700;
  text-align: center;
  text-decoration: none;
  border: 2px solid var(--color-primary);
  border-radius: var(--radius);
  cursor: pointer;
  transition:
    background-color var(--transition),
    color var(--transition),
    transform var(--transition),
    box-shadow var(--transition);
}

.btn:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.btn-primary {
  color: var(--color-on-primary);
  background-color: var(--color-primary);
}

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

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

.btn-outline:hover {
  color: var(--color-on-primary);
  background-color: var(--color-primary);
}

/* Hero */
.hero {
  display: flex;
  align-items: center;
  min-height: 100vh;
  padding-top: var(--header-height);
  background: linear-gradient(160deg, var(--color-bg) 40%, var(--color-bg-alt));
}

.hero-eyebrow {
  margin-bottom: var(--space-xs);
  font-weight: 700;
  color: var(--color-primary);
}

.hero h1 {
  margin-bottom: var(--space-sm);
  font-size: 2rem;
  line-height: 1.3;
}

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

.hero-desc {
  margin-bottom: var(--space-md);
  color: var(--color-text-muted);
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

/* Sections */
.section {
  padding-block: var(--space-xl);
}

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

.section-title {
  margin-bottom: var(--space-md);
  font-size: 1.75rem;
}

.section-sub {
  margin-bottom: var(--space-md);
  color: var(--color-text-muted);
}

/* About */
.about {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-md);
}

.about-img {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  object-fit: cover;
  box-shadow: var(--shadow-md);
}

.about-text p {
  color: var(--color-text-muted);
}

/* Skills */
.skills-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.skill-item {
  padding: 0.5rem 1.1rem;
  font-weight: 600;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  box-shadow: var(--shadow-sm);
}

/* Projects (Grid + 상태 UI) */
.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: var(--space-md);
}

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

.project-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-md);
}

.project-name {
  margin-bottom: var(--space-xs);
  font-size: 1.15rem;
}

.project-name a {
  text-decoration: none;
  color: var(--color-primary);
}

.project-name a:hover {
  text-decoration: underline;
}

.project-desc {
  flex: 1;
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

.project-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin: 0;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.state-box {
  padding: var(--space-lg) var(--space-md);
  text-align: center;
  color: var(--color-text-muted);
  background-color: var(--color-surface);
  border: 1px dashed var(--color-border);
  border-radius: var(--radius);
}

.state-title {
  margin-bottom: var(--space-xs);
  font-weight: 700;
  color: var(--color-text);
}

.state-detail {
  margin-bottom: var(--space-sm);
  font-size: 0.9rem;
}

.spinner {
  width: 36px;
  height: 36px;
  margin: 0 auto var(--space-sm);
  border: 4px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* Contact Form */
.contact-form {
  max-width: 600px;
}

.form-group {
  margin-bottom: var(--space-md);
}

.form-group label {
  display: block;
  margin-bottom: 0.35rem;
  font-weight: 600;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.7rem 0.9rem;
  font: inherit;
  color: var(--color-text);
  background-color: var(--color-surface);
  border: 2px solid var(--color-border);
  border-radius: var(--radius);
}

.form-group textarea {
  resize: vertical;
}

.form-group .invalid {
  border-color: var(--color-error);
}

.error-msg {
  min-height: 1.4em;
  margin: 0.3rem 0 0;
  font-size: 0.875rem;
  color: var(--color-error);
}

.form-success {
  margin: var(--space-sm) 0 0;
  font-weight: 600;
  color: var(--color-success);
}

/* Footer / Scroll-top */
.site-footer {
  padding-block: var(--space-md);
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-xs);
  text-align: center;
}

.footer-inner p {
  margin: 0;
}

.social-list {
  display: flex;
  gap: var(--space-md);
}

.social-list a {
  font-weight: 600;
  text-decoration: none;
  transition: color var(--transition);
}

.social-list a:hover {
  color: var(--color-primary);
}

.scroll-top {
  position: fixed;
  right: var(--space-md);
  bottom: var(--space-md);
  z-index: 90;
  width: 48px;
  height: 48px;
  font-size: 1.25rem;
  color: var(--color-on-primary);
  background-color: var(--color-primary);
  border: none;
  border-radius: 50%;
  box-shadow: var(--shadow-md);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition:
    opacity var(--transition),
    transform var(--transition),
    visibility var(--transition),
    background-color var(--transition);
}

.scroll-top.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.scroll-top:hover {
  background-color: var(--color-primary-hover);
}

/* Scroll reveal */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition:
    opacity 0.6s ease,
    transform 0.6s ease;
}

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

/* Tablet: 768px+ */
@media (min-width: 768px) {
  .hamburger {
    display: none;
  }

  /* 데스크톱형 메뉴: 로고 왼쪽, 메뉴 오른쪽 */
  .nav-menu {
    position: static;
    display: flex;
    flex-direction: row;
    gap: var(--space-md);
    padding: 0;
    background: transparent;
    border: none;
    box-shadow: none;
    margin-left: auto;
    margin-right: var(--space-md);
  }

  .hero h1 {
    font-size: 2.75rem;
  }

  .about {
    flex-direction: row;
    gap: var(--space-lg);
  }

  .about-img {
    flex-shrink: 0;
    width: 220px;
    height: 220px;
  }

  .footer-inner {
    flex-direction: row;
    justify-content: space-between;
  }
}

/* Desktop: 1024px+ */
@media (min-width: 1024px) {
  .container {
    padding-inline: var(--space-lg);
  }

  .hero h1 {
    font-size: 3.5rem;
  }

  .section-title {
    font-size: 2.25rem;
  }

  .about-img {
    width: 260px;
    height: 260px;
  }
}