/* Modern Minimalist Design Tokens */
:root {
  --primary-text: #212833;
  --secondary-text: #818aa3;
  --bg-color: #fafafa;
  --card-bg: #ffffff;
  --border-color: #efefef;
  --accent-color: #212833;
  --accent-hover: #11151b;
  --success-color: #03d743;
  --warning-color: #d79403;
  --danger-color: #d73403;
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --radius-card: 8px;
  --radius-btn: 4px;
  --radius-input: 4px;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--primary-text);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Background grid pattern */
.bg-pattern {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-image: radial-gradient(circle at 1px 1px, #e9ebed 1.5px, transparent 0);
  background-size: 32px 32px;
  z-index: -1;
  pointer-events: none;
}

/* Application Container */
.app-container {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  width: 100%;
}

/* App Header */
.app-header {
  max-width: 900px;
  width: 100%;
  margin: 0 auto;
  padding: 32px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-color);
  background-color: transparent;
}

.logo {
  font-size: 18px;
  font-weight: 600;
  color: var(--primary-text);
  letter-spacing: -0.5px;
}

.logo-accent {
  background-color: var(--primary-text);
  color: #ffffff;
  padding: 1px 6px;
  border-radius: var(--radius-btn);
  font-size: 13px;
  font-weight: 600;
  margin-left: 4px;
  vertical-align: middle;
}

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

.lang-switch {
  display: flex;
  border: 1px solid var(--border-color);
  background-color: var(--card-bg);
  border-radius: var(--radius-btn);
  padding: 2px;
}

.lang-btn {
  background: none;
  border: none;
  font-family: inherit;
  font-size: 11px;
  font-weight: 600;
  color: var(--secondary-text);
  padding: 4px 8px;
  border-radius: 3px;
  cursor: pointer;
  transition: background-color 0.1s ease, color 0.1s ease;
}

.lang-btn:hover {
  color: var(--primary-text);
}

.lang-btn.active {
  background-color: var(--primary-text);
  color: #ffffff;
}

.status-indicator {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  border: 1px solid var(--border-color);
  background-color: var(--card-bg);
  border-radius: 20px;
}

.status-dot {
  width: 6px;
  height: 6px;
  background-color: var(--success-color);
  border-radius: 50%;
}

.status-text {
  font-size: 12px;
  font-weight: 500;
  color: var(--secondary-text);
}

/* Content Wrapper */
.content-wrapper {
  flex: 1;
  max-width: 900px;
  width: 100%;
  margin: 0 auto;
  padding: 48px 24px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  position: relative;
}

/* Step Cards */
.step-card {
  display: none;
  opacity: 0;
  transform: translateY(8px);
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-card);
  padding: 40px;
  position: relative;
  transition: opacity 0.3s ease, transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.step-card.active {
  display: block;
}

.step-card.fade-in {
  opacity: 1;
  transform: translateY(0);
}

.step-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
}

.step-indicator {
  font-size: 13px;
  font-weight: 500;
  color: var(--secondary-text);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* Button & Nav styles */
.btn-back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: none;
  border: 1px solid var(--border-color);
  color: var(--secondary-text);
  padding: 6px 12px;
  font-size: 13px;
  font-weight: 500;
  border-radius: var(--radius-btn);
  cursor: pointer;
  transition: background-color 0.1s ease, color 0.1s ease;
}

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

/* Typography styles */
.section-title {
  font-size: 28px;
  font-weight: 600;
  color: var(--primary-text);
  margin-bottom: 8px;
  letter-spacing: -0.5px;
}

.section-subtitle {
  font-size: 15px;
  color: var(--secondary-text);
  margin-bottom: 32px;
}

/* Grid & Choice Layouts (Step 1) */
.button-grid {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.choice-btn {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  padding: 20px 24px;
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-card);
  text-align: left;
  font-family: inherit;
  font-size: 16px;
  font-weight: 500;
  color: var(--primary-text);
  cursor: pointer;
  transition: background-color 0.1s ease, border-color 0.1s ease;
}

.choice-btn:hover {
  background-color: #f7f8f9;
  border-color: var(--secondary-text);
}

.choice-btn-arrow {
  color: var(--secondary-text);
  transition: transform 0.1s ease, color 0.1s ease;
}

.choice-btn:hover .choice-btn-arrow {
  transform: translateX(4px);
  color: var(--primary-text);
}

/* Search Box & Student List (Step 2) */
.search-box-wrapper {
  position: relative;
  margin-bottom: 24px;
}

.search-icon-wrapper {
  position: absolute;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--secondary-text);
  pointer-events: none;
  display: flex;
  align-items: center;
}

#student-search {
  width: 100%;
  padding: 16px 16px 16px 48px;
  font-family: inherit;
  font-size: 16px;
  color: var(--primary-text);
  background-color: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-input);
  outline: none;
  transition: border-color 0.1s ease, background-color 0.1s ease;
}

#student-search:focus {
  border-color: var(--primary-text);
  background-color: var(--card-bg);
}

.students-list {
  display: flex;
  flex-direction: column;
  max-height: 320px;
  overflow-y: auto;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-card);
}

.student-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 20px;
  background-color: var(--card-bg);
  border: none;
  border-bottom: 1px solid var(--border-color);
  font-family: inherit;
  font-size: 15px;
  font-weight: 500;
  color: var(--primary-text);
  text-align: left;
  cursor: pointer;
  transition: background-color 0.1s ease;
}

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

.student-item:hover {
  background-color: #f7f8f9;
}

.student-item-arrow {
  color: var(--secondary-text);
  opacity: 0;
  transform: translateX(-4px);
  transition: opacity 0.1s ease, transform 0.1s ease;
}

.student-item:hover .student-item-arrow {
  opacity: 1;
  transform: translateX(0);
}

/* Step 3 - Result Layout */
.result-top-meta {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 24px;
}

.result-name {
  font-size: 24px;
  font-weight: 600;
  color: var(--primary-text);
  letter-spacing: -0.5px;
  margin-bottom: 4px;
}

.result-meta-hw {
  font-size: 14px;
  font-weight: 500;
  color: var(--secondary-text);
}

.rating-container {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 6px;
}

.rating-label {
  font-size: 11px;
  font-weight: 600;
  color: var(--secondary-text);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.stars {
  display: flex;
  gap: 3px;
}

.star-icon {
  width: 22px;
  height: 22px;
  stroke: var(--border-color);
  stroke-width: 1.5;
  fill: #ffffff;
  transition: stroke 0.2s ease, fill 0.2s ease, transform 0.2s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.star-icon.filled {
  stroke: var(--warning-color);
  fill: var(--warning-color);
}

.star-icon.animate {
  animation: star-pop 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
}

@keyframes star-pop {
  0% { transform: scale(0.8); }
  50% { transform: scale(1.25); }
  100% { transform: scale(1); }
}

.divider {
  border: 0;
  height: 1px;
  background-color: var(--border-color);
  margin: 28px 0;
}

.result-section {
  margin-bottom: 28px;
}

.result-section:last-child {
  margin-bottom: 0;
}

.result-section-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--secondary-text);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 12px;
}

.feedback-box {
  background-color: #fcfcfd;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-card);
  padding: 20px;
  font-size: 15px;
  color: var(--primary-text);
  white-space: pre-line;
}

/* Files Cards */
.files-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 12px;
}

.file-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px;
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-card);
  transition: border-color 0.1s ease;
}

.file-card:hover {
  border-color: var(--secondary-text);
}

.file-info {
  display: flex;
  align-items: center;
  gap: 12px;
  overflow: hidden;
}

.file-icon {
  flex-shrink: 0;
  color: var(--secondary-text);
}

.file-name {
  font-size: 14px;
  font-weight: 500;
  color: var(--primary-text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.btn-download {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-btn);
  background-color: transparent;
  border: 1px solid var(--border-color);
  color: var(--primary-text);
  cursor: pointer;
  transition: background-color 0.1s ease, border-color 0.1s ease;
}

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

/* Links List */
.links-flex {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.link-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 18px;
  background-color: var(--accent-color);
  color: #ffffff;
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  border-radius: var(--radius-btn);
  transition: background-color 0.1s ease;
}

.link-btn:hover {
  background-color: var(--accent-hover);
}

.link-btn svg {
  transition: transform 0.1s ease;
}

.link-btn:hover svg {
  transform: translate(2px, -2px);
}

/* Loaders and Spinners */
.loader-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 60px 20px;
  text-align: center;
}

.spinner {
  position: relative;
  width: 56px;
  height: 56px;
  margin-bottom: 24px;
}

.spinner-ring {
  width: 100%;
  height: 100%;
  border: 3px solid var(--border-color);
  border-top-color: var(--primary-text);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

.spinner-dot {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 8px;
  height: 8px;
  background-color: var(--primary-text);
  border-radius: 50%;
}

.spinner-sm {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-color);
  border-top-color: var(--primary-text);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

.loader-title {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 6px;
  letter-spacing: -0.3px;
}

.loader-subtitle {
  font-size: 14px;
  color: var(--secondary-text);
}

.sub-loader {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 32px 0;
  color: var(--secondary-text);
  font-size: 14px;
  font-weight: 500;
}

.sub-loader-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(255, 255, 255, 0.8);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  border-radius: var(--radius-card);
  z-index: 10;
  color: var(--secondary-text);
  font-size: 14px;
}

/* Empty States */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 48px 24px;
  color: var(--secondary-text);
}

.empty-state svg {
  margin-bottom: 12px;
  color: var(--secondary-text);
}

.empty-state h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--primary-text);
  margin-bottom: 4px;
}

.empty-state p {
  font-size: 13px;
}

/* Error Card component */
.error-card {
  display: flex;
  gap: 16px;
  padding: 24px;
  background-color: #fffafb;
  border: 1px solid rgba(215, 52, 3, 0.1);
  border-radius: var(--radius-card);
  color: var(--danger-color);
  margin-bottom: 24px;
}

.error-icon-wrapper {
  flex-shrink: 0;
}

.error-details h3 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 4px;
  color: #9e2300;
}

.error-details p {
  font-size: 13px;
  color: var(--secondary-text);
}

/* Toast System */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  z-index: 1000;
}

.toast {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 20px;
  background-color: var(--primary-text);
  color: #ffffff;
  border-radius: var(--radius-card);
  font-size: 14px;
  font-weight: 500;
  animation: slide-in 0.25s cubic-bezier(0.16, 1, 0.3, 1) forwards;
  max-width: 360px;
}

.toast.toast-danger {
  background-color: var(--danger-color);
}

@keyframes slide-in {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Helper Utilities */
.hidden {
  display: none !important;
}

/* Footer styles */
.app-footer {
  max-width: 900px;
  width: 100%;
  margin: 0 auto;
  padding: 32px 24px;
  text-align: center;
  border-top: 1px solid var(--border-color);
  font-size: 12px;
  color: var(--secondary-text);
}

/* Responsive adjustments */
@media (max-width: 768px) {
  .app-header, .content-wrapper, .app-footer {
    padding-left: 16px;
    padding-right: 16px;
  }
  .content-wrapper {
    padding-top: 32px;
    padding-bottom: 32px;
  }
  .step-card {
    padding: 24px;
  }
  .section-title {
    font-size: 24px;
  }
  .result-top-meta {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
  }
  .rating-container {
    align-items: flex-start;
  }
  .files-grid {
    grid-template-columns: 1fr;
  }
  .link-btn {
    width: 100%;
    justify-content: center;
  }
}