/* ==========================================================================
   Dr. Kaleab Tadesse Sigatu: personal website
   style.css  |  mobile-first, light + dark themes

   Contents
   1.  Design tokens (colours, type, spacing)
   2.  Reset & base
   3.  Layout helpers
   4.  Buttons & shared components
   5.  Header, navigation, hamburger
   6.  Hero
   7.  Credentials
   8.  Sections, cards, expertise, services
   9.  Publications
   10. Teaching
   11. BRIDGE banner
   12. Contact form
   13. Footer
   14. Scroll-reveal & motion preferences
   ========================================================================== */


/* 1. DESIGN TOKENS
   -------------------------------------------------------------------------- */
:root {
  /* Light theme (default) */
  --bg:          #F8F7F4;
  --bg-alt:      #F0EEE9;           /* alternating section background */
  --card:        #FFFFFF;
  --text:        #1C1B1A;
  --text-muted:  #5E5B57;
  --border:      rgba(28, 27, 26, 0.10);
  --accent:      #E07A5F;
  --accent-hover:#D96A4C;
  --accent-ink:  #1C1B1A;           /* text placed ON the accent colour */
  --accent-text: #B4492E;           /* accent for small text on the page (AA contrast) */
  --header-bg:   rgba(248, 247, 244, 0.82);

  --shadow-sm: 0 1px 2px rgba(28, 27, 26, 0.04), 0 2px 8px rgba(28, 27, 26, 0.04);
  --shadow-md: 0 2px 4px rgba(28, 27, 26, 0.04), 0 12px 32px rgba(28, 27, 26, 0.08);

  /* Typography */
  --font-sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-am:   "Noto Serif Ethiopic", "Abyssinica SIL", serif;

  /* Spacing, radius, layout */
  --radius-sm: 10px;
  --radius:    16px;
  --radius-lg: 24px;
  --gutter:    1.25rem;
  --section-y: 4.5rem;
  --header-h:  4rem;
  --container: 72rem;

  /* Motion */
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --t-fast: 160ms;
  --t: 280ms;
}

/* Dark theme: set by script.js via <html data-theme="dark"> */
:root[data-theme="dark"] {
  --bg:          #0F0F0F;
  --bg-alt:      #141414;
  --card:        #1C1C1C;
  --text:        #F0F0F0;
  --text-muted:  #A9A6A1;
  --border:      rgba(240, 240, 240, 0.10);
  --accent:      #E07A5F;
  --accent-hover:#E88C74;
  --accent-ink:  #141414;
  --accent-text: #E07A5F;
  --header-bg:   rgba(15, 15, 15, 0.82);

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.35), 0 16px 40px rgba(0, 0, 0, 0.45);

  color-scheme: dark;
}

/* Larger screens get more breathing room */
@media (min-width: 48em) {
  :root { --gutter: 2rem; --section-y: 6rem; --header-h: 4.5rem; }
}
@media (min-width: 75em) {
  :root { --section-y: 7.5rem; }
}


/* 2. RESET & BASE
   -------------------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 1rem);
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background-color var(--t) ease, color var(--t) ease;
}

/* Prevent the page jumping while the mobile menu is open */
body.menu-open { overflow: hidden; }

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

h1, h2, h3, p, ul, figure { margin: 0; }
ul { padding: 0; list-style: none; }

h1, h2, h3 {
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.12;
  text-wrap: balance;
}
h1 { font-size: clamp(2.25rem, 8vw, 4.25rem); letter-spacing: -0.035em; }
h2 { font-size: clamp(1.75rem, 5vw, 2.75rem); }
h3 { font-size: 1.25rem; line-height: 1.25; }

p { text-wrap: pretty; }

a { color: var(--accent-text); text-underline-offset: 3px; }

/* Visible keyboard focus everywhere */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 6px;
}

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

/* Skip link for keyboard / screen-reader users */
.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 200;
  padding: 0.6rem 1rem;
  background: var(--accent);
  color: var(--accent-ink);
  border-radius: var(--radius-sm);
  font-weight: 600;
  text-decoration: none;
  transform: translateY(-200%);
  transition: transform var(--t-fast) ease;
}
.skip-link:focus { transform: translateY(0); }


/* 3. LAYOUT HELPERS
   -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding-block: var(--section-y); }
.section-alt { background: var(--bg-alt); }

.section-head {
  display: grid;
  gap: 1rem;
  max-width: 46rem;
  margin-bottom: 2.5rem;
}
@media (min-width: 48em) { .section-head { margin-bottom: 3.5rem; } }

.section-intro {
  color: var(--text-muted);
  font-size: 1.0625rem;
}

.eyebrow {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-text);
}

.label {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
}


/* 4. BUTTONS & SHARED COMPONENTS
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-height: 3rem;                 /* comfortable touch target */
  padding: 0.75rem 1.5rem;
  border: 1px solid transparent;
  border-radius: 999px;
  font: inherit;
  font-weight: 600;
  font-size: 0.9375rem;
  line-height: 1.2;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
  transition: transform var(--t-fast) var(--ease),
              background-color var(--t-fast) ease,
              border-color var(--t-fast) ease,
              box-shadow var(--t) ease;
}
.btn:hover  { transform: translateY(-2px); }
.btn:active { transform: translateY(0) scale(0.98); }

.btn-primary {
  background: var(--accent);
  color: var(--accent-ink);
  box-shadow: 0 4px 14px rgba(224, 122, 95, 0.28);
}
.btn-primary:hover {
  background: var(--accent-hover);
  box-shadow: 0 8px 22px rgba(224, 122, 95, 0.38);
}

.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent-text); }

.btn-row { display: flex; flex-wrap: wrap; gap: 0.75rem; }

/* Card base */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  transition: transform var(--t) var(--ease),
              box-shadow var(--t) ease,
              border-color var(--t) ease,
              background-color var(--t) ease;
}
@media (hover: hover) {
  .card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
}

/* Image frames: show a soft placeholder until the real image exists */
.media {
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, var(--bg-alt), var(--border));
  border-radius: var(--radius);
}
.media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 700ms var(--ease);
}
.media-portrait { aspect-ratio: 4 / 5; border-radius: var(--radius-lg); }
.media-wide     { aspect-ratio: 16 / 10; }

/* Applied by script.js when an image file is missing */
.media.is-missing img { display: none; }
.media.is-missing::after {
  content: attr(data-placeholder);
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 1rem;
  color: var(--text-muted);
  font-size: 0.875rem;
  text-align: center;
}


/* 5. HEADER, NAVIGATION, HAMBURGER
   -------------------------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--header-bg);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--t) ease, box-shadow var(--t) ease, background-color var(--t) ease;
}
.site-header.is-scrolled {
  border-bottom-color: var(--border);
  box-shadow: var(--shadow-sm);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  height: var(--header-h);
}

.brand {
  color: var(--text);
  font-weight: 650;
  font-size: 1.0625rem;
  letter-spacing: -0.02em;
  text-decoration: none;
}
.brand::after { content: "."; color: var(--accent); }

.header-actions { display: flex; align-items: center; gap: 0.5rem; }

.icon-btn {
  display: grid;
  place-items: center;
  width: 2.75rem;
  height: 2.75rem;
  padding: 0;
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 50%;
  cursor: pointer;
  transition: background-color var(--t-fast) ease, border-color var(--t-fast) ease, transform var(--t-fast) var(--ease);
}
.icon-btn:hover  { background: var(--card); border-color: var(--accent); }
.icon-btn:active { transform: scale(0.94); }

.icon {
  width: 1.25rem;
  height: 1.25rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* Theme toggle: show the icon for the theme you would switch TO */
.icon-sun { display: none; }
:root[data-theme="dark"] .icon-sun  { display: block; }
:root[data-theme="dark"] .icon-moon { display: none; }

/* Hamburger: three bars that morph into an X */
.menu-bars {
  position: relative;
  display: block;
  width: 1.125rem;
  height: 0.875rem;
}
.menu-bars span {
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background: currentColor;
  border-radius: 2px;
  transition: transform var(--t) var(--ease), opacity var(--t-fast) ease, top var(--t) var(--ease);
}
.menu-bars span:nth-child(1) { top: 0; }
.menu-bars span:nth-child(2) { top: 6px; }
.menu-bars span:nth-child(3) { top: 12px; }

.menu-btn[aria-expanded="true"] .menu-bars span:nth-child(1) { top: 6px; transform: rotate(45deg); }
.menu-btn[aria-expanded="true"] .menu-bars span:nth-child(2) { opacity: 0; }
.menu-btn[aria-expanded="true"] .menu-bars span:nth-child(3) { top: 6px; transform: rotate(-45deg); }

/* Mobile navigation: full-screen panel under the header.
   (position: absolute, not fixed: the header's backdrop-filter would
   otherwise become the containing block for a fixed child.) */
.site-nav {
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  height: calc(100vh - var(--header-h));
  height: calc(100dvh - var(--header-h));
  padding: 1.5rem var(--gutter) 2rem;
  background: var(--bg);
  overflow-y: auto;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-0.75rem);
  transition: opacity var(--t) ease, transform var(--t) var(--ease), visibility 0s linear var(--t);
}
.site-nav.is-open {
  opacity: 1;
  visibility: visible;
  transform: none;
  transition-delay: 0s;
}

.nav-list { display: grid; gap: 0.25rem; }
.nav-list a {
  display: block;
  padding: 0.9rem 0.25rem;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  font-size: 1.375rem;
  font-weight: 500;
  letter-spacing: -0.02em;
  text-decoration: none;
  transition: color var(--t-fast) ease, padding-left var(--t) var(--ease);
}
.nav-list a:hover,
.nav-list a.is-active { color: var(--accent-text); padding-left: 0.5rem; }

/* Desktop navigation: inline links, no hamburger */
@media (min-width: 62em) {
  .menu-btn { display: none; }

  .site-nav {
    position: static;
    height: auto;
    padding: 0;
    background: transparent;
    overflow: visible;
    opacity: 1;
    visibility: visible;
    transform: none;
    margin-left: auto;
    margin-right: 0.5rem;
  }
  .nav-list { display: flex; gap: 0.25rem; }
  .nav-list a {
    position: relative;
    padding: 0.5rem 0.85rem;
    border: 0;
    font-size: 0.9375rem;
    font-weight: 500;
    letter-spacing: 0;
    color: var(--text-muted);
  }
  .nav-list a:hover,
  .nav-list a.is-active { padding-left: 0.85rem; color: var(--text); }

  /* Animated underline */
  .nav-list a::after {
    content: "";
    position: absolute;
    left: 0.85rem;
    right: 0.85rem;
    bottom: 0.2rem;
    height: 2px;
    background: var(--accent);
    border-radius: 2px;
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--t) var(--ease);
  }
  .nav-list a:hover::after,
  .nav-list a.is-active::after { transform: scaleX(1); }
}


/* 6. HERO
   -------------------------------------------------------------------------- */
.hero {
  padding-block: 2.5rem var(--section-y);
  background:
    radial-gradient(60rem 28rem at 85% -10%, rgba(224, 122, 95, 0.14), transparent 60%),
    var(--bg);
}

.hero-grid { display: grid; gap: 2.5rem; align-items: center; }

.hero-copy { display: grid; gap: 1.5rem; }
.hero-copy .lead {
  max-width: 38rem;
  color: var(--text-muted);
  font-size: clamp(1.0625rem, 2.4vw, 1.25rem);
  line-height: 1.6;
}
.hero-copy .btn-row { padding-top: 0.5rem; }

.hero-portrait { display: grid; gap: 1rem; max-width: 22rem; }
.hero-portrait .media { box-shadow: var(--shadow-md); }
.hero-portrait:hover .media img { transform: scale(1.03); }

.hero-portrait figcaption { display: grid; gap: 0.15rem; }
.hero-portrait .name { font-size: 1.125rem; font-weight: 600; letter-spacing: -0.01em; }
.hero-portrait .name-am { font-family: var(--font-am); color: var(--text-muted); }

@media (min-width: 48em) {
  .hero { padding-top: 4rem; }
  .hero-grid { grid-template-columns: 1.4fr 1fr; gap: 4rem; }
  .hero-portrait { max-width: none; justify-self: end; width: 100%; }
}


/* 7. CREDENTIALS
   -------------------------------------------------------------------------- */
.credentials {
  background: var(--card);
  border-block: 1px solid var(--border);
  transition: background-color var(--t) ease;
}
.credentials-grid {
  display: grid;
  gap: 1.5rem 2rem;
  padding-block: 2rem;
}
.credential { display: grid; gap: 0.15rem; font-size: 0.9375rem; line-height: 1.5; color: var(--text-muted); }
.credential strong { color: var(--text); font-weight: 600; }

@media (min-width: 36em) { .credentials-grid { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 62em) { .credentials-grid { grid-template-columns: repeat(4, 1fr); } }


/* 8. SECTIONS, CARDS, EXPERTISE, SERVICES
   -------------------------------------------------------------------------- */
.card-grid { display: grid; gap: 1.25rem; }

@media (min-width: 40em) {
  .card-grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 62em) {
  .card-grid-3 { grid-template-columns: repeat(3, 1fr); gap: 1.5rem; }
  .card-grid-4 { grid-template-columns: repeat(4, 1fr); }
}

/* Expertise cards (image on top, text below) */
.expertise-card { overflow: hidden; display: flex; flex-direction: column; }
.expertise-card .media { border-radius: 0; }
@media (hover: hover) { .expertise-card:hover .media img { transform: scale(1.05); } }

.card-body { display: grid; gap: 1rem; padding: 1.5rem; align-content: start; flex: 1; }
@media (min-width: 48em) { .card-body { padding: 1.75rem; } }

.card-index {
  color: var(--accent-text);
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.08em;
}
.card-body p { color: var(--text-muted); font-size: 0.9688rem; }

.track-record {
  display: grid;
  gap: 0.75rem;
  margin-top: auto;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border);
}
.track-record ul { display: grid; gap: 0.5rem; }
.track-record li {
  position: relative;
  padding-left: 1.1rem;
  font-size: 0.9063rem;
  line-height: 1.55;
  color: var(--text);
}
.track-record li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.62em;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
}

/* Services */
.service-card { display: grid; gap: 0.75rem; align-content: start; padding: 1.75rem; }
.service-card h3 { font-size: 1.1875rem; }
.service-card p  { color: var(--text-muted); font-size: 0.9688rem; }
.service-card::before {
  content: "";
  width: 2rem;
  height: 3px;
  margin-bottom: 0.5rem;
  background: var(--accent);
  border-radius: 3px;
  transition: width var(--t) var(--ease);
}
@media (hover: hover) { .service-card:hover::before { width: 3.5rem; } }


/* 9. PUBLICATIONS
   -------------------------------------------------------------------------- */
.pub-list { border-top: 1px solid var(--border); }

.pub {
  display: grid;
  gap: 0.5rem;
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--border);
  transition: padding-left var(--t) var(--ease);
}
@media (hover: hover) { .pub:hover { padding-left: 0.75rem; } }

.pub-type {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--accent-text);
}
.pub-title { font-size: 1.25rem; font-weight: 600; letter-spacing: -0.015em; line-height: 1.35; }
.pub-title-am { font-family: var(--font-am); font-weight: 400; letter-spacing: 0; }
.pub-meta { margin-top: 0.4rem; color: var(--text-muted); font-size: 0.9375rem; }

@media (min-width: 48em) {
  .pub { grid-template-columns: 11rem 1fr; gap: 2rem; padding: 1.75rem 0; }
  .pub-type { padding-top: 0.3rem; }
}


/* 10. TEACHING
   -------------------------------------------------------------------------- */
.teaching-grid { display: grid; gap: 2.5rem; }
.teaching-copy { display: grid; gap: 1rem; align-content: start; }
.teaching-image { margin-top: 1.5rem; box-shadow: var(--shadow-md); }

.teaching-list { display: grid; gap: 1rem; align-content: start; }
.topic { display: grid; gap: 0.4rem; padding: 1.5rem; }
.topic-title { font-size: 1.125rem; font-weight: 500; letter-spacing: -0.01em; line-height: 1.4; }
.topic-dashed { background: transparent; border-style: dashed; box-shadow: none; }

@media (min-width: 62em) {
  .teaching-grid { grid-template-columns: 1fr 1fr; gap: 4rem; align-items: start; }
}


/* 11. BRIDGE BANNER
   -------------------------------------------------------------------------- */
.bridge-banner {
  display: grid;
  gap: 1.75rem;
  align-items: center;
  padding: 2rem 1.5rem;
  background:
    radial-gradient(40rem 20rem at 100% 0%, rgba(224, 122, 95, 0.16), transparent 60%),
    var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}
.bridge-copy { display: grid; gap: 1rem; max-width: 40rem; }
.bridge-copy p:not(.eyebrow) { color: var(--text-muted); font-size: 1.0625rem; }
.bridge-banner .btn { justify-self: start; }

@media (min-width: 48em) {
  .bridge-banner { grid-template-columns: 1fr auto; gap: 3rem; padding: 3.5rem; }
}


/* 12. CONTACT FORM
   -------------------------------------------------------------------------- */
.contact-grid { display: grid; gap: 2.5rem; }
.contact-copy { display: grid; gap: 1rem; align-content: start; }

.contact-email {
  justify-self: start;
  color: var(--text);
  font-size: 1.125rem;
  font-weight: 600;
  text-decoration-color: var(--accent);
  text-decoration-thickness: 2px;
  word-break: break-word;
}
.contact-email:hover { color: var(--accent-text); }
.contact-meta { color: var(--text-muted); font-size: 0.9375rem; }

.contact-form { display: grid; gap: 1.1rem; padding: 1.5rem; }
@media (min-width: 48em) { .contact-form { padding: 2.25rem; } }
@media (hover: hover) { .contact-form:hover { transform: none; } }  /* keep forms still */

.field { display: grid; gap: 0.4rem; }
.field label { font-size: 0.875rem; font-weight: 600; }

.field input,
.field select,
.field textarea {
  width: 100%;
  padding: 0.8rem 0.95rem;
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font: inherit;
  font-size: 1rem;                 /* 16px prevents iOS zoom-on-focus */
  transition: border-color var(--t-fast) ease, box-shadow var(--t-fast) ease, background-color var(--t) ease;
}
.field textarea { resize: vertical; min-height: 8rem; }

.field input:hover,
.field select:hover,
.field textarea:hover { border-color: var(--text-muted); }

.field input:focus,
.field select:focus,
.field textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(224, 122, 95, 0.22);
}
.field input.is-invalid,
.field textarea.is-invalid { border-color: #D64545; }

.contact-form .btn { justify-self: start; }

.form-status { min-height: 1.5em; font-size: 0.9375rem; color: var(--text-muted); }
.form-status.is-error { color: #D64545; }

@media (min-width: 62em) {
  .contact-grid { grid-template-columns: 1fr 1.1fr; gap: 5rem; align-items: start; }
}


/* 13. FOOTER
   -------------------------------------------------------------------------- */
.site-footer { border-top: 1px solid var(--border); padding-block: 1.75rem; }
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.5rem 1.5rem;
  color: var(--text-muted);
  font-size: 0.875rem;
}


/* 14. SCROLL-REVEAL & MOTION PREFERENCES
   -------------------------------------------------------------------------- */
/* Hidden state applies only when JS is running (script.js adds .js to <html>),
   so content is never invisible if scripts fail to load. */
.js .reveal {
  opacity: 0;
  transform: translateY(1.25rem);
  transition: opacity 700ms var(--ease), transform 700ms var(--ease);
  transition-delay: var(--reveal-delay, 0ms);
}
.js .reveal.is-visible { opacity: 1; transform: none; }

/* Respect users who prefer reduced motion */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0ms !important;
  }
  .js .reveal { opacity: 1; transform: none; }
}