/* ==========================================================================
   5th Biosciences Symposium — TU Darmstadt
   Main stylesheet (desktop-first base; responsive overrides in mobile.css)
   ========================================================================== */

/* ---- Design tokens ---- */
:root {
  --color-primary: #0f5a43;
  --color-primary-dark: #0a3e2f;
  --color-primary-light: #e5efeb;
  --color-accent: #b8943a;
  --color-accent-light: #f3e9d3;
  --color-bg: #ffffff;
  --color-bg-alt: #f7f6f1;
  --color-text: #1c2b27;
  --color-text-light: #5a6b66;
  --color-border: #e2e2dc;

  --font-heading: "Playfair Display", "Georgia", serif;
  --font-body: "Source Sans 3", "Segoe UI", Arial, sans-serif;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;

  --shadow-sm: 0 2px 10px rgba(15, 60, 45, 0.08);
  --shadow-md: 0 10px 30px rgba(15, 60, 45, 0.12);
  --shadow-lg: 0 20px 50px rgba(15, 60, 45, 0.18);

  --nav-height: 78px;
  --max-width: 1180px;
}

/* ---- Reset ---- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

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

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  color: var(--color-primary-dark);
  line-height: 1.2;
  margin: 0 0 0.5em;
}

p {
  margin: 0 0 1em;
}

ul {
  padding-left: 1.2em;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 32px;
}

/* ---- Skip link (accessibility) ---- */
.skip-link {
  position: absolute;
  left: -999px;
  top: auto;
  background: var(--color-primary);
  color: #fff;
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  z-index: 1000;
}

.skip-link:focus {
  left: 16px;
  top: 16px;
}

/* ==========================================================================
   Header / Navigation
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 500;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow 0.25s ease;
}

.site-header.scrolled {
  box-shadow: var(--shadow-sm);
}

.navbar {
  max-width: var(--max-width);
  margin: 0 auto;
  height: var(--nav-height);
  padding: 0 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand img {
  height: 42px;
  width: 42px;
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.brand-text .brand-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.08rem;
  color: var(--color-primary-dark);
}

.brand-text .brand-sub {
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent);
  font-weight: 600;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 6px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  display: inline-block;
  padding: 10px 16px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--color-text);
  transition: background 0.2s ease, color 0.2s ease;
}

.nav-links a:hover,
.nav-links a:focus-visible {
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
}

.nav-links a.active {
  background: var(--color-primary);
  color: #fff;
}

.nav-cta {
  margin-left: 8px;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

/* Overrides .nav-links a's own color rule, which otherwise wins over
   .btn-primary's color by specificity for the nav's CTA button. */
.nav-links .nav-cta a.btn-primary {
  color: #fff;
}

.nav-links .nav-cta a.btn-primary:hover {
  color: #fff;
}

.nav-toggle span {
  display: block;
  width: 26px;
  height: 2px;
  background: var(--color-primary-dark);
  margin: 6px 0;
  transition: transform 0.25s ease, opacity 0.25s ease;
}

/* ==========================================================================
   Buttons
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 30px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 1rem;
  border: 2px solid transparent;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease, color 0.2s ease;
  font-family: var(--font-body);
}

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

.btn-primary {
  background: var(--color-primary);
  color: #fff;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover,
.btn-primary:focus-visible {
  background: var(--color-primary-dark);
  box-shadow: var(--shadow-md);
}

.btn-gold {
  background: var(--color-accent);
  color: #fff;
  box-shadow: var(--shadow-sm);
}

.btn-gold:hover {
  background: #9c7c2e;
  box-shadow: var(--shadow-md);
}

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

.btn-outline:hover,
.btn-outline:focus-visible {
  background: var(--color-primary);
  color: #fff;
}

.btn-large {
  padding: 18px 42px;
  font-size: 1.1rem;
}

.btn-block {
  width: 100%;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

/* ==========================================================================
   Hero
   ========================================================================== */

.hero {
  position: relative;
  overflow: hidden;
  background: linear-gradient(180deg, #ffffff 0%, var(--color-bg-alt) 100%);
  padding: 96px 0 120px;
}

.hero-artwork {
  position: absolute;
  top: -40px;
  right: -60px;
  width: 620px;
  max-width: 60vw;
  opacity: 0.16;
  pointer-events: none;
  z-index: 0;
}

.hero-inner {
  position: relative;
  z-index: 1;
  max-width: 760px;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 0.8rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  font-weight: 700;
  color: var(--color-accent);
  margin-bottom: 18px;
}

.eyebrow::before {
  content: "";
  width: 34px;
  height: 2px;
  background: var(--color-accent);
  display: inline-block;
}

.hero h1 {
  font-size: clamp(2.4rem, 5vw, 3.6rem);
  margin-bottom: 0.3em;
}

.hero h1 .ordinal {
  color: var(--color-accent);
  font-style: italic;
}

.hero .hero-tagline {
  font-size: 1.2rem;
  color: var(--color-text-light);
  max-width: 560px;
  margin-bottom: 1.6em;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 28px;
  margin-bottom: 40px;
}

.hero-meta-item {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  color: var(--color-primary-dark);
}

.hero-meta-item .icon-dot {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  background: var(--color-primary-light);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

/* ==========================================================================
   Sections
   ========================================================================== */

.section {
  padding: 90px 0;
}

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

.section-header {
  max-width: 680px;
  margin: 0 auto 56px;
  text-align: center;
}

.section-header .eyebrow {
  justify-content: center;
}

.section-header h2 {
  font-size: clamp(1.8rem, 3.2vw, 2.5rem);
}

.section-header p {
  color: var(--color-text-light);
  font-size: 1.08rem;
}

/* ---- Feature cards ---- */

.card-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 26px;
}

.card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 36px 26px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

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

.card img.card-icon {
  width: 56px;
  height: 56px;
  margin: 0 auto 18px;
}

.card h3 {
  font-size: 1.15rem;
  margin-bottom: 8px;
}

.card p {
  color: var(--color-text-light);
  font-size: 0.95rem;
  margin-bottom: 0;
}

/* ---- About ---- */

.about-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 60px;
  align-items: center;
}

.about-figures {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.figure-card {
  background: var(--color-primary);
  color: #fff;
  border-radius: var(--radius-md);
  padding: 28px 20px;
  text-align: center;
}

.figure-card .figure-number {
  font-family: var(--font-heading);
  font-size: 2.2rem;
  color: var(--color-accent-light);
  display: block;
}

.figure-card .figure-label {
  font-size: 0.85rem;
  letter-spacing: 0.04em;
  opacity: 0.9;
}

/* ---- Venue teaser ---- */

.venue-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0;
  background: #fff;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--color-border);
}

.venue-card-info {
  padding: 48px;
}

.venue-card-map {
  min-height: 320px;
  background: var(--color-primary-light);
}

.venue-card-map iframe {
  width: 100%;
  height: 100%;
  border: 0;
  min-height: 320px;
}

.venue-detail-row {
  display: flex;
  gap: 14px;
  margin-bottom: 18px;
}

.venue-detail-row .icon-dot {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--color-primary-light);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ---- Contact teaser / cards ---- */

.contact-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.contact-card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 28px;
  box-shadow: var(--shadow-sm);
}

.contact-card h3 {
  font-size: 1.05rem;
  margin-bottom: 6px;
}

.contact-card a {
  font-weight: 600;
}

/* ==========================================================================
   Footer
   ========================================================================== */

.site-footer {
  background: var(--color-primary-dark);
  color: #d8e6e0;
  padding: 56px 0 28px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-brand {
  display: flex;
  gap: 12px;
  align-items: center;
  margin-bottom: 14px;
}

.footer-brand img {
  height: 40px;
  width: 40px;
}

.footer-brand span {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  color: #fff;
}

.site-footer h4 {
  color: #fff;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 16px;
}

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

.site-footer li {
  margin-bottom: 10px;
}

.site-footer a {
  color: #cfe0d9;
}

.site-footer a:hover {
  color: var(--color-accent-light);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  padding-top: 22px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
  font-size: 0.85rem;
  color: #9db6ad;
}

/* ==========================================================================
   Page header (inner pages)
   ========================================================================== */

.page-header {
  background: var(--color-primary);
  background-image: radial-gradient(circle at 85% 20%, rgba(184, 148, 58, 0.35), transparent 55%);
  color: #fff;
  padding: 64px 0 56px;
  text-align: center;
}

.page-header h1 {
  color: #fff;
  font-size: clamp(2rem, 4vw, 2.8rem);
}

.page-header p {
  color: #d6e6df;
  max-width: 600px;
  margin: 0 auto;
  font-size: 1.05rem;
}

.breadcrumb {
  font-size: 0.85rem;
  color: var(--color-accent-light);
  margin-bottom: 14px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 600;
}

/* ==========================================================================
   Programme page
   ========================================================================== */

.schedule {
  max-width: 860px;
  margin: 0 auto;
}

.schedule-item {
  display: grid;
  grid-template-columns: 130px 1fr;
  gap: 24px;
  padding: 26px 0;
  border-bottom: 1px solid var(--color-border);
}

.schedule-item:last-child {
  border-bottom: none;
}

.schedule-time {
  font-family: var(--font-heading);
  font-weight: 700;
  color: var(--color-accent);
  font-size: 1.05rem;
}

.schedule-content h3 {
  font-size: 1.1rem;
  margin-bottom: 4px;
}

.schedule-content .tag {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  background: var(--color-primary-light);
  color: var(--color-primary);
  padding: 3px 10px;
  border-radius: 999px;
  margin-left: 10px;
  vertical-align: middle;
}

.schedule-content p {
  color: var(--color-text-light);
  margin-bottom: 0;
}

/* ==========================================================================
   Registration form
   ========================================================================== */

.form-shell {
  max-width: 820px;
  margin: 0 auto;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  padding: 48px;
}

.form-section {
  margin-bottom: 40px;
}

.form-section:last-of-type {
  margin-bottom: 0;
}

.form-section-title {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  color: var(--color-primary-dark);
  margin-bottom: 6px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-primary-light);
}

.form-section-desc {
  color: var(--color-text-light);
  font-size: 0.92rem;
  margin-bottom: 22px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 22px;
}

.form-group {
  margin-bottom: 22px;
}

.form-group label {
  display: block;
  font-weight: 700;
  font-size: 0.92rem;
  margin-bottom: 8px;
  color: var(--color-text);
}

.form-group label .required {
  color: var(--color-accent);
}

.form-group input[type="text"],
.form-group input[type="email"],
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 13px 16px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: 1rem;
  background: #fff;
  color: var(--color-text);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 4px var(--color-primary-light);
}

.form-group input.invalid,
.form-group textarea.invalid {
  border-color: #c0392b;
}

.field-error {
  color: #c0392b;
  font-size: 0.82rem;
  margin-top: 6px;
  display: none;
}

.field-error.show {
  display: block;
}

.help-text {
  font-size: 0.82rem;
  color: var(--color-text-light);
  margin-top: 6px;
}

/* Radio / checkbox groups */

.choice-group {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
}

.choice-option {
  position: relative;
}

.choice-option input {
  position: absolute;
  opacity: 0;
  width: 100%;
  height: 100%;
  margin: 0;
  cursor: pointer;
}

.choice-option label {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 13px 22px;
  border: 1.5px solid var(--color-border);
  border-radius: 999px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  margin: 0;
}

.choice-option input:checked + label {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}

.choice-option input:focus-visible + label {
  box-shadow: 0 0 0 4px var(--color-primary-light);
}

.checkbox-row {
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

.checkbox-row input[type="checkbox"] {
  width: 20px;
  height: 20px;
  margin-top: 3px;
  accent-color: var(--color-primary);
  flex-shrink: 0;
}

.checkbox-row label {
  font-weight: 500;
  font-size: 0.96rem;
  color: var(--color-text);
}

.conditional-block {
  display: none;
  margin-top: 18px;
  padding: 18px 20px;
  background: var(--color-accent-light);
  border-radius: var(--radius-sm);
  border-left: 4px solid var(--color-accent);
}

.conditional-block.show {
  display: block;
  animation: fadeSlideIn 0.3s ease;
}

@keyframes fadeSlideIn {
  from {
    opacity: 0;
    transform: translateY(-6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Character counter */

.textarea-wrap {
  position: relative;
}

.char-counter {
  text-align: right;
  font-size: 0.8rem;
  color: var(--color-text-light);
  margin-top: 6px;
}

.char-counter.near-limit {
  color: var(--color-accent);
  font-weight: 700;
}

.char-counter.at-limit {
  color: #c0392b;
  font-weight: 700;
}

/* File upload / drag & drop */

.dropzone {
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-md);
  padding: 36px 20px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s ease, background 0.2s ease;
  background: var(--color-bg-alt);
}

.dropzone:hover,
.dropzone.dragover {
  border-color: var(--color-primary);
  background: var(--color-primary-light);
}

.dropzone input[type="file"] {
  display: none;
}

.dropzone .dz-icon {
  font-size: 2rem;
  margin-bottom: 10px;
}

.dropzone .dz-title {
  font-weight: 700;
  color: var(--color-primary-dark);
  margin-bottom: 4px;
}

.dropzone .dz-hint {
  font-size: 0.82rem;
  color: var(--color-text-light);
}

.file-preview {
  display: none;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-top: 14px;
  padding: 12px 16px;
  background: var(--color-primary-light);
  border-radius: var(--radius-sm);
}

.file-preview.show {
  display: flex;
}

.file-preview .file-name {
  font-weight: 600;
  font-size: 0.9rem;
  word-break: break-all;
}

.file-preview .file-remove {
  background: none;
  border: none;
  color: #c0392b;
  cursor: pointer;
  font-weight: 700;
  font-size: 0.85rem;
}

/* Submit area */

.form-submit-row {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
  margin-top: 12px;
}

.form-status {
  font-size: 0.92rem;
  text-align: center;
}

.form-status.error {
  color: #c0392b;
}

.spinner {
  display: none;
  width: 20px;
  height: 20px;
  border: 3px solid rgba(255, 255, 255, 0.4);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

.spinner.show {
  display: inline-block;
}

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

/* Success screen */

.success-screen {
  display: none;
  text-align: center;
  padding: 60px 20px;
  max-width: 560px;
  margin: 0 auto;
}

.success-screen.show {
  display: block;
  animation: fadeSlideIn 0.4s ease;
}

.success-check {
  width: 92px;
  height: 92px;
  border-radius: 50%;
  background: var(--color-primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 26px;
}

.success-check svg {
  width: 46px;
  height: 46px;
}

.success-screen h2 {
  font-size: 1.8rem;
}

.success-screen p {
  color: var(--color-text-light);
  font-size: 1.05rem;
}

/* ==========================================================================
   Scroll reveal
   ========================================================================== */

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

.reveal.in-view {
  opacity: 1;
  transform: translateY(0);
}

/* ==========================================================================
   Privacy page
   ========================================================================== */

.legal-content {
  max-width: 780px;
  margin: 0 auto;
}

.legal-content h2 {
  margin-top: 2em;
  font-size: 1.4rem;
}

.legal-content h2:first-child {
  margin-top: 0;
}

.legal-content ul {
  color: var(--color-text-light);
}

/* ==========================================================================
   Contact page details
   ========================================================================== */

.contact-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 50px;
  align-items: start;
}

.organizer-list {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.organizer {
  display: flex;
  gap: 16px;
  align-items: flex-start;
  padding: 20px;
  background: var(--color-bg-alt);
  border-radius: var(--radius-md);
}

.organizer .avatar {
  width: 52px;
  height: 52px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-heading);
  font-weight: 700;
  flex-shrink: 0;
}

.organizer h3 {
  font-size: 1.02rem;
  margin-bottom: 2px;
}

.organizer .role {
  color: var(--color-accent);
  font-size: 0.85rem;
  font-weight: 700;
  margin-bottom: 6px;
}