/* =========================================================
   TacHair Project Website
   Main Stylesheet
   ========================================================= */


/* =========================================================
   1. Global Reset
   ========================================================= */

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  background: #ffffff;
  color: #111827;

  font-family:
    Georgia,
    "Times New Roman",
    Times,
    serif;

  line-height: 1.6;

  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img,
video {
  max-width: 100%;
  display: block;
}

a {
  color: inherit;
}


/* =========================================================
   2. Site Header
   ========================================================= */

.site-header {
  width: 100%;

  background: rgba(255, 255, 255, 0.96);

  border-bottom: 1px solid #e5e7eb;

  position: sticky;
  top: 0;

  z-index: 1000;

  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.site-header.scrolled {
  box-shadow:
    0 2px 12px
    rgba(0, 0, 0, 0.06);
}


/* =========================================================
   3. Navigation Bar
   ========================================================= */

.navbar {
  width: min(1180px, 92%);
  height: 76px;

  margin: 0 auto;

  display: flex;
  align-items: center;
  justify-content: space-between;
}


/* Project logo */

.nav-brand {
  flex-shrink: 0;

  color: #111827;

  font-size: 30px;
  font-weight: 700;

  letter-spacing: -1.2px;

  line-height: 1;

  text-decoration: none;
}

.nav-brand span {
  color: #1769d2;
}


/* Navigation links */

.nav-links {
  display: flex;
  align-items: center;

  gap: 36px;

  margin-left: auto;
  margin-right: 34px;
}

.nav-links a {
  position: relative;

  color: #1f2937;

  font-family:
    Arial,
    Helvetica,
    sans-serif;

  font-size: 15px;
  font-weight: 500;

  text-decoration: none;

  padding: 27px 0 25px;

  transition: color 0.18s ease;
}

.nav-links a:hover {
  color: #1769d2;
}

.nav-links a.active {
  color: #1769d2;
}

.nav-links a.active::after {
  content: "";

  position: absolute;

  left: 0;
  right: 0;
  bottom: 17px;

  height: 2px;

  border-radius: 2px;

  background: #1769d2;
}


/* GitHub icon */

.nav-github {
  width: 32px;
  height: 32px;

  flex-shrink: 0;

  display: flex;
  align-items: center;
  justify-content: center;

  text-decoration: none;

  transition:
    transform 0.18s ease,
    opacity 0.18s ease;
}

.nav-github:hover {
  transform: translateY(-1px);
  opacity: 0.7;
}

.nav-github svg {
  width: 27px;
  height: 27px;

  fill: #111827;
}


/* =========================================================
   4. Hero Section
   ========================================================= */

.hero-section {
  width: 100%;

  background: #ffffff;
}

.hero-container {
  width: min(1120px, 92%);

  margin: 0 auto;

  padding:
    70px
    0
    55px;

  text-align: center;
}


/* =========================================================
   5. Project Name
   ========================================================= */

.project-name {
  margin: 0 0 28px;

  color: #111827;

  font-size: clamp(68px, 8vw, 104px);

  font-weight: 700;

  line-height: 0.95;

  letter-spacing: -5px;
}

.project-name span {
  color: #1769d2;
}


/* =========================================================
   6. Paper Title
   ========================================================= */

.paper-title {
  max-width: 1050px;

  margin:
    0
    auto;

  color: #111827;

  font-size: clamp(29px, 3.2vw, 46px);

  font-weight: 500;

  line-height: 1.16;

  letter-spacing: -1.2px;
}


/* =========================================================
   7. Authors
   ========================================================= */

.authors {
  margin-top: 31px;

  display: flex;
  align-items: center;
  justify-content: center;

  flex-wrap: wrap;

  column-gap: 10px;
  row-gap: 3px;

  color: #111827;

  font-size: 21px;

  line-height: 1.5;
}

.author {
  color: #111827;

  text-decoration: none;

  transition: color 0.18s ease;
}

.author:hover {
  color: #1769d2;
}

.author-separator {
  color: #6b7280;

  user-select: none;
}


/* =========================================================
   8. Institution
   ========================================================= */

.institution {
  margin-top: 3px;

  color: #374151;

  font-size: 21px;

  line-height: 1.5;
}


/* =========================================================
   9. Paper / Video / Code Buttons
   ========================================================= */

.project-links {
  margin-top: 35px;

  display: flex;
  align-items: center;
  justify-content: center;

  flex-wrap: wrap;

  gap: 17px;
}

.project-button {
  min-width: 175px;
  height: 54px;

  padding: 0 28px;

  display: inline-flex;
  align-items: center;
  justify-content: center;

  gap: 11px;

  border-radius: 9px;

  background: #edf0f4;

  color: #111827;

  font-family:
    Arial,
    Helvetica,
    sans-serif;

  font-size: 17px;
  font-weight: 500;

  line-height: 1;

  text-decoration: none;

  transition:
    transform 0.18s ease,
    background-color 0.18s ease,
    box-shadow 0.18s ease;
}

.project-button:hover {
  transform: translateY(-2px);

  background: #e3e7ec;
}

.primary-button {
  background: #1769d2;

  color: #ffffff;

  box-shadow:
    0
    5px
    16px
    rgba(23, 105, 210, 0.18);
}

.primary-button:hover {
  background: #125bb8;

  box-shadow:
    0
    7px
    20px
    rgba(23, 105, 210, 0.22);
}

.button-icon {
  width: 21px;
  height: 21px;

  flex-shrink: 0;

  fill: currentColor;
}


/* =========================================================
   10. Hero Media
   ========================================================= */

.hero-media {
  width: 100%;

  margin-top: 52px;

  aspect-ratio: 16 / 9;

  position: relative;

  overflow: hidden;

  border-radius: 14px;

  background: #e5e7eb;

  box-shadow:
    0
    2px
    13px
    rgba(0, 0, 0, 0.09);
}


/* Real hero video */

.hero-video {
  width: 100%;
  height: 100%;

  object-fit: cover;

  display: block;

  background: #000000;
}


/* =========================================================
   11. Hero Video Placeholder
   ========================================================= */

.hero-media > .video-placeholder {
  width: 100%;
  height: 100%;

  position: absolute;

  inset: 0;

  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;

  padding: 30px;

  color: #ffffff;

  background:
    linear-gradient(
      135deg,
      #d6dbe0 0%,
      #aeb6bf 48%,
      #919ba5 100%
    );
}


/* Play button */

.play-circle {
  width: 80px;
  height: 80px;

  margin-bottom: 20px;

  border: 3px solid rgba(255, 255, 255, 0.95);

  border-radius: 50%;

  display: flex;
  align-items: center;
  justify-content: center;
}

.play-triangle {
  width: 0;
  height: 0;

  margin-left: 6px;

  border-top: 13px solid transparent;
  border-bottom: 13px solid transparent;
  border-left: 21px solid #ffffff;
}

.video-placeholder-title {
  font-size: 25px;

  font-weight: 500;

  line-height: 1.35;
}

.video-placeholder-subtitle {
  margin-top: 3px;

  font-size: 21px;

  line-height: 1.4;

  opacity: 0.96;
}


/* =========================================================
   12. Scroll Hint
   ========================================================= */

.scroll-hint {
  width: fit-content;

  margin:
    35px
    auto
    0;

  display: flex;
  flex-direction: column;
  align-items: center;

  color: #6b7280;

  font-family:
    Arial,
    Helvetica,
    sans-serif;

  font-size: 14px;

  line-height: 1.2;

  text-decoration: none;

  transition:
    color 0.18s ease,
    transform 0.18s ease;
}

.scroll-hint:hover {
  color: #1769d2;

  transform: translateY(2px);
}

.scroll-arrow {
  margin-bottom: 4px;

  color: #64748b;

  font-size: 28px;

  line-height: 1;
}


/* =========================================================
   13. General Content Sections
   ========================================================= */

.content-section {
  width: 100%;

  scroll-margin-top: 76px;
}

.section-container {
  width: min(1120px, 92%);

  margin: 0 auto;
}


/* =========================================================
   13.1 Shared Section Title
   ========================================================= */

.section-title {
  width: 100%;

  margin:
    0
    auto
    38px;

  color: #111827;

  font-size: 46px;
  font-weight: 700;

  line-height: 1.15;

  letter-spacing: -1.2px;

  text-align: center;
}


/* =========================================================
   13.2 Abstract Section
   ========================================================= */

#abstract {
  padding:
    80px
    0
    90px;

  background: #ffffff;
}

.abstract-content {
  max-width: 920px;

  margin: 0 auto;
}

.abstract-content p {
  color: #374151;

  font-size: 18px;

  line-height: 1.85;

  text-align: justify;
}

.abstract-content strong {
  color: #111827;

  font-weight: 600;
}


/* =========================================================
   13.3 Experiments Section
   ========================================================= */

#experiments {
  padding:
    90px
    0
    120px;

  background: #ffffff;
}


/* Main Experiments title */

#experiments > .section-container > .section-title {
  margin-bottom: 55px;
}


/* Individual experiment block */

.experiment-block {
  width: 100%;

  max-width: 1000px;

  margin:
    0
    auto
    100px;
}


/* Experiment subtitle */

.experiment-title {
  margin:
    0
    0
    28px;

  color: #111827;

  font-size: 30px;
  font-weight: 600;

  line-height: 1.25;

  letter-spacing: -0.4px;

  text-align: center;
}


/* =========================================================
   13.4 Main Experiment Videos
   ========================================================= */

.experiment-video {
  width: 100%;

  aspect-ratio: 16 / 9;

  border-radius: 14px;

  overflow: hidden;

  background: #000000;

  object-fit: cover;
}


/* Temporary placeholders for experiment videos */

.video-placeholder.experiment-video {
  position: relative;

  display: flex;
  align-items: center;
  justify-content: center;

  padding: 30px;

  color: #6b7280;

  background: #f3f4f6;

  border: 1px solid #e5e7eb;

  font-family:
    Arial,
    Helvetica,
    sans-serif;

  font-size: 15px;
  font-weight: 500;

  text-align: center;
}


/* =========================================================
   13.5 Generalization
   ========================================================= */

.generalization-block {
  max-width: 1120px;

  margin-bottom: 0;
}

.generalization-item {
  width: 100%;

  margin-bottom: 70px;
}

.generalization-item:last-child {
  margin-bottom: 0;
}


/* Head Geometries / Hair Conditions */

.video-title {
  margin:
    0
    0
    18px;

  color: #374151;

  font-size: 21px;
  font-weight: 600;

  line-height: 1.3;

  text-align: center;
}


/* Generalization videos */

.generalization-video {
  width: 100%;

  aspect-ratio: 16 / 9;

  border-radius: 12px;

  overflow: hidden;

  background: #000000;

  object-fit: cover;
}
/* Head Geometries video */

.generalization-video.headform-video {

  width: 100%;

  height: auto;

  aspect-ratio: auto;

  object-fit: contain;

  background: #000000;

}
/* Temporary generalization placeholders */

.video-placeholder.generalization-video {
  position: relative;

  display: flex;
  align-items: center;
  justify-content: center;

  padding: 24px;

  color: #6b7280;

  background: #f3f4f6;

  border: 1px solid #e5e7eb;

  font-family:
    Arial,
    Helvetica,
    sans-serif;

  font-size: 15px;
  font-weight: 500;

  text-align: center;
}


/* =========================================================
   14. Footer
   ========================================================= */

.site-footer {
  width: 100%;

  margin-top: 20px;

  border-top: 1px solid #e5e7eb;

  background: #ffffff;
}

.footer-container {
  width: min(1120px, 92%);

  margin: 0 auto;

  padding: 28px 0;

  color: #6b7280;

  font-family:
    Arial,
    Helvetica,
    sans-serif;

  font-size: 13px;

  text-align: center;
}


/* =========================================================
   15. Tablet
   ========================================================= */

@media (max-width: 1000px) {

  .nav-links {
    gap: 22px;

    margin-right: 25px;
  }

  .nav-links a {
    font-size: 14px;
  }

  .hero-container {
    padding-top: 60px;
  }


  /* Experiments */

  .experiment-block {
    max-width: 900px;
  }

}


/* =========================================================
   16. Mobile
   ========================================================= */

@media (max-width: 800px) {

  /* Header */

  .navbar {
    height: 66px;
  }

  .nav-brand {
    font-size: 26px;
  }

  .nav-links {
    display: none;
  }

  .nav-github svg {
    width: 25px;
    height: 25px;
  }


  /* Hero */

  .hero-container {
    width: min(92%, 680px);

    padding:
      48px
      0
      42px;
  }

  .project-name {
    margin-bottom: 23px;

    font-size: clamp(58px, 18vw, 78px);

    letter-spacing: -3.5px;
  }

  .paper-title {
    font-size: clamp(25px, 7vw, 32px);

    line-height: 1.2;

    letter-spacing: -0.7px;
  }

  .desktop-break {
    display: none;
  }


  /* Authors */

  .authors {
    margin-top: 27px;

    font-size: 18px;

    column-gap: 8px;
  }

  .institution {
    margin-top: 5px;

    font-size: 18px;
  }


  /* Buttons */

  .project-links {
    margin-top: 29px;

    gap: 10px;
  }

  .project-button {
    min-width: 135px;

    height: 50px;

    padding: 0 20px;

    font-size: 16px;
  }


  /* Hero video */

  .hero-media {
    margin-top: 40px;

    aspect-ratio: 16 / 9;

    border-radius: 11px;
  }

  .play-circle {
    width: 65px;
    height: 65px;

    margin-bottom: 16px;
  }

  .play-triangle {
    border-top-width: 10px;
    border-bottom-width: 10px;
    border-left-width: 17px;
  }

  .video-placeholder-title {
    font-size: 20px;
  }

  .video-placeholder-subtitle {
    max-width: 400px;

    font-size: 17px;
  }


  /* Section titles */

  .section-title {
    margin:
      0
      auto
      28px;

    font-size: 38px;

    text-align: center;
  }


  /* Abstract */

  #abstract {
    padding:
      60px
      0
      70px;
  }

  .abstract-content p {
    font-size: 16px;

    line-height: 1.75;

    text-align: left;
  }


  /* Experiments */

  #experiments {
    padding:
      65px
      0
      80px;
  }

  #experiments > .section-container > .section-title {
    margin-bottom: 42px;
  }

  .experiment-block {
    margin-bottom: 70px;
  }

  .experiment-title {
    margin-bottom: 20px;

    font-size: 25px;
  }

  .experiment-video {
    border-radius: 10px;
  }


  /* Generalization */

  .generalization-item {
    margin-bottom: 50px;
  }

  .video-title {
    margin-bottom: 14px;

    font-size: 19px;
  }

  .generalization-video {
    border-radius: 10px;
  }

}


/* =========================================================
   17. Small Mobile
   ========================================================= */

@media (max-width: 520px) {

  .project-name {
    font-size: 58px;
  }

  .paper-title {
    font-size: 25px;
  }

  .authors {
    font-size: 17px;
  }

  .institution {
    font-size: 17px;
  }

  .project-links {
    flex-direction: column;
  }

  .project-button {
    width: min(280px, 100%);
  }

  .video-placeholder-subtitle {
    font-size: 15px;
  }


  /* Sections */

  .section-title {
    font-size: 34px;
  }

  .experiment-title {
    font-size: 23px;
  }


  /* Experiments */

  #experiments {
    padding-bottom: 65px;
  }

  .experiment-block {
    margin-bottom: 60px;
  }

}


/* =========================================================
   18. Accessibility
   ========================================================= */

@media (prefers-reduced-motion: reduce) {

  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }

}