/* List page CSS: only base, header, card, button, and problem-list/card styles. */

:root {
  --primary: #0f9d58;
  --primary-dark: #0b7d46;
  --primary-light: #b7e4c7;
  --primary-lightest-bg: #f8fdfa;
  --primary-darkest-bg: #0a1f14;
  --gray-50: #ffffff;
  --gray-100: #f8f9fa;
  --gray-200: #e9ecef;
  --gray-300: #dee2e6;
  --gray-400: #adb5bd;
  --gray-500: #6c757d;
  --gray-600: #495057;
  --gray-700: #343a40;
  --gray-800: #212529;
  --gray-900: #121416;
  --red: rgb(255, 0, 0);
  --orange: rgb(255, 128, 0);
  --yellow: rgb(240, 200, 0);
  --green: rgb(0, 180, 0);
  --cyan: rgb(0, 192, 192);
  --blue: rgb(54, 54, 255);
  --purple: #6a1b9a;
  --brown: rgb(170, 100, 0);
  color-scheme: light dark;
}

:root[data-mode="light"] {
  --bg-color: var(--primary-lightest-bg);
  --text-color: var(--gray-800);
  --card-bg: white;
  --card-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
  --card-hover-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1),
    0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --border-color: var(--gray-200);
  --hover-bg: var(--gray-100);
  --header-bg: var(--gray-50);
  --title-color: var(--gray-900);
  --difficulty-color: var(--gray-700);
  --empty-color: var(--gray-400);
  --empty-border-color: var(--gray-300);
}

:root[data-mode="dark"] {
  --bg-color: var(--primary-darkest-bg);
  --text-color: var(--gray-100);
  --card-bg: var(--gray-800);
  --card-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.3), 0 1px 2px 0 rgba(0, 0, 0, 0.2);
  --card-hover-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.4),
    0 4px 6px -2px rgba(0, 0, 0, 0.3);
  --border-color: var(--gray-600);
  --hover-bg: var(--gray-700);
  --header-bg: var(--gray-800);
  --title-color: var(--gray-50);
  --difficulty-color: var(--gray-100);
  --empty-color: var(--gray-500);
  --empty-border-color: var(--gray-600);
}

body {
  font-family: "Inter", sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.5;
  padding: 0;
  margin: 0;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
  width: 100%;
}

header {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  padding: 1.5rem 0;
  margin-bottom: 1.5rem;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1),
    0 2px 4px -1px rgba(0, 0, 0, 0.06);
  position: relative;
  overflow: hidden;
}

:root[data-mode="dark"] header {
  background: linear-gradient(135deg, #22313a 0%, var(--primary-dark) 100%);
}

.header-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  position: relative;
  z-index: 2;
}

.header-bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
  opacity: 0.1;
}

.header-bg-circle {
  position: absolute;
  border-radius: 50%;
  background: white;
  animation: float 6s ease-in-out infinite;
}

.circle-1 {
  width: 300px;
  height: 300px;
  top: -150px;
  left: -100px;
  animation-delay: 0s;
}

.circle-2 {
  width: 200px;
  height: 200px;
  bottom: -100px;
  right: -50px;
  animation-delay: 2s;
}

.header-content h1 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  animation: fadeInDown 0.8s ease-out;
  opacity: 0;
  animation-fill-mode: forwards;
}

.header-content h2 {
  font-size: 1.25rem;
  font-weight: 500;
  opacity: 0;
  animation: fadeInUp 0.8s ease-out 0.3s;
  animation-fill-mode: forwards;
}

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

.card {
  background-color: var(--card-bg);
  border-radius: 0.75rem;
  box-shadow: var(--card-shadow);
  overflow: hidden;
  margin-bottom: 2rem;
  transition: transform 0.2s, box-shadow 0.2s, background-color 0.3s ease;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--card-hover-shadow);
}

.card-header {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: var(--header-bg);
  transition: background-color 0.3s ease, border-color 0.3s ease;
}

.card-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--title-color);
  animation: fadeInRight 0.8s ease-out;
  transition: color 0.3s ease;
}

.floating-button {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  width: 3rem;
  height: 3rem;
  border-radius: 50%;
  background-color: var(--primary);
  color: white;
  display: flex;
  justify-content: center;
  align-items: center;
  box-shadow: var(--card-shadow);
  cursor: pointer;
  transition: all 0.2s ease;
  z-index: 50;
  text-decoration: none;
}

.floating-button:hover {
  transform: translateY(-2px);
  box-shadow: var(--card-hover-shadow);
  background-color: var(--primary-dark);
}

.floating-button svg {
  width: 24px;
  height: 24px;
  stroke: white;
}

.theme-toggle {
  position: fixed;
  bottom: 5rem;
  right: 1.5rem;
  width: 3rem;
  height: 3rem;
  border-radius: 50%;
  background-color: var(--primary);
  color: white;
  display: flex;
  justify-content: center;
  align-items: center;
  box-shadow: var(--card-shadow);
  cursor: pointer;
  transition: all 0.2s ease;
  z-index: 50;
}

.theme-toggle:hover {
  transform: translateY(-2px);
  box-shadow: var(--card-hover-shadow);
  background-color: var(--primary-dark);
}

.theme-toggle svg {
  width: 24px;
  height: 24px;
  stroke: white;
}

.theme-toggle .moon-icon {
  display: none;
}

:root[data-mode="dark"] .theme-toggle .sun-icon {
  display: none;
}

:root[data-mode="dark"] .theme-toggle .moon-icon {
  display: block;
}

.color-theme-toggle {
  position: fixed;
  bottom: 8.5rem;
  right: 1.5rem;
  width: 3rem;
  height: 3rem;
  border-radius: 50%;
  background-color: var(--primary);
  color: white;
  display: flex;
  justify-content: center;
  align-items: center;
  box-shadow: var(--card-shadow);
  cursor: pointer;
  transition: all 0.2s ease;
  z-index: 50;
}

.color-theme-toggle:hover {
  transform: translateY(-2px);
  box-shadow: var(--card-hover-shadow);
  background-color: var(--primary-dark);
}

.color-theme-toggle svg {
  width: 24px;
  height: 24px;
  stroke: white;
}

/* Modern card-based problem list layout for lists only */
.problem-list {
  display: flex;
  flex-direction: column;
  gap: 18px;
  list-style: none;
  padding: 0;
  margin: 0 0 24px 0;
}

.problem-card {
  background: var(--card-bg);
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
  padding: 18px 20px;
  transition: box-shadow 0.2s, background 0.2s;
  display: flex;
  flex-direction: column;
}
.problem-card:hover {
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
  background: var(--hover-bg);
}
.problem-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.problem-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--title-color);
}
.problem-badge {
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.95em;
  font-weight: 500;
  color: #fff;
  margin-left: 10px;
  text-transform: capitalize;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.07);
}
.color-grey {
  background: #868e96;
}
.color-brown {
  background: #a87950;
}
.color-green {
  background: #4caf50;
}
.color-cyan {
  background: #00bcd4;
}
.color-blue {
  background: #1976d2;
}
.color-yellow {
  background: #ffd600;
  color: #222;
}
.color-orange {
  background: #ff9800;
}
.color-red {
  background: #e53935;
}

.color-bronze {
  background: #cd7f32;
}

.color-silver {
  background: #c0c0c0;
  color: #222;
}

.color-gold {
  background: #ffd700;
  color: #222;
}

.problem-meta {
  margin-top: 8px;
  font-size: 0.97em;
  color: var(--difficulty-color);
  display: flex;
  align-items: center;
  gap: 16px;
}
.problem-id {
  background: var(--header-bg);
  border-radius: 6px;
  padding: 2px 8px;
  font-size: 0.93em;
  color: var(--difficulty-color);
}
.external-link {
  margin-left: auto;
  color: var(--primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  font-weight: 500;
  transition: color 0.2s;
}
.external-link:hover {
  color: var(--primary-dark);
  text-decoration: underline;
}
.external-link svg {
  margin-left: 4px;
  width: 1em;
  height: 1em;
  vertical-align: middle;
}

@media (max-width: 768px) {
  .container {
    padding: 0 0.75rem;
  }
  header {
    padding: 1.25rem 0;
    margin-bottom: 1.25rem;
  }
  h1 {
    font-size: 1.75rem;
  }
  h2 {
    font-size: 1.125rem;
  }
  .card-header {
    padding: 0.875rem 1rem;
  }
  .card-title {
    font-size: 1.125rem;
  }
  .card-body {
    padding: 1rem;
  }
  /* Problem list adjustments for tablets */
  .problem-list {
    gap: 14px;
  }
  .problem-card {
    padding: 16px 18px;
  }
  .problem-title {
    font-size: 1.1rem;
  }
  .problem-badge {
    padding: 2px 8px;
    font-size: 0.9em;
  }
  .problem-meta {
    font-size: 0.95em;
    gap: 12px;
  }
  .problem-id {
    padding: 2px 6px;
    font-size: 0.9em;
  }
  /* Adjust floating buttons for tablets */
  .floating-button,
  .theme-toggle,
  .color-theme-toggle,
  .home-button {
    width: 2.75rem;
    height: 2.75rem;
    right: 1rem;
  }
  .floating-button svg,
  .theme-toggle svg,
  .color-theme-toggle svg,
  .home-button svg {
    width: 20px;
    height: 20px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 0.5rem;
  }
  header {
    padding: 1rem 0;
    margin-bottom: 1rem;
  }
  h1 {
    font-size: 1.5rem;
  }
  h2 {
    font-size: 1rem;
  }
  .card-header {
    padding: 0.75rem;
  }
  .card-title {
    font-size: 1rem;
  }
  .card-body {
    padding: 0.75rem;
  }
  /* Problem list adjustments for mobile */
  .problem-list {
    gap: 12px;
  }
  .problem-card {
    padding: 14px 16px;
  }
  .problem-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }
  .problem-title {
    font-size: 1rem;
    width: 100%;
  }
  .problem-badge {
    padding: 2px 6px;
    font-size: 0.85em;
    margin-left: 0;
  }
  .problem-meta {
    font-size: 0.9em;
    gap: 8px;
    flex-wrap: wrap;
  }
  .problem-id {
    padding: 2px 4px;
    font-size: 0.85em;
  }
  .external-link {
    margin-left: 0;
    margin-top: 4px;
  }
  /* Adjust floating buttons for mobile */
  .floating-button,
  .theme-toggle,
  .color-theme-toggle,
  .home-button {
    width: 2.5rem;
    height: 2.5rem;
    right: 0.75rem;
  }
  .floating-button svg,
  .theme-toggle svg,
  .color-theme-toggle svg,
  .home-button svg {
    width: 18px;
    height: 18px;
  }
}

:root[data-color="green"] {
  --primary: #0f9d58;
  --primary-dark: #0b7d46;
  --primary-light: #b7e4c7;
  --primary-lightest-bg: #f8fdfa;
  --primary-darkest-bg: #0a1f14;
  --tab-hover-bg: rgba(15, 157, 88, 0.08);
}
:root[data-color="blue"] {
  --primary: #3b82f6;
  --primary-dark: #1d4ed8;
  --primary-light: #bfdbfe;
  --primary-lightest-bg: #f8fbff;
  --primary-darkest-bg: #0a1428;
  --tab-hover-bg: rgba(59, 130, 246, 0.08);
}
:root[data-color="purple"] {
  --primary: #7c3aed;
  --primary-dark: #5b21b6;
  --primary-light: #ddd6fe;
  --primary-lightest-bg: #faf9ff;
  --primary-darkest-bg: #1a0f2e;
  --tab-hover-bg: rgba(124, 58, 237, 0.08);
}
:root[data-color="orange"] {
  --primary: #f97316;
  --primary-dark: #c2410c;
  --primary-light: #fed7aa;
  --primary-lightest-bg: #fffbf7;
  --primary-darkest-bg: #2a1508;
  --tab-hover-bg: rgba(249, 115, 22, 0.08);
}
:root[data-color="pink"] {
  --primary: #ec4899;
  --primary-dark: #be185d;
  --primary-light: #fbcfe8;
  --primary-lightest-bg: #fff9fc;
  --primary-darkest-bg: #2a0a1a;
  --tab-hover-bg: rgba(236, 72, 153, 0.08);
}

.home-button {
  bottom: 12rem;
}