/* CSS Variables and Base Styles */
:root {
  /* Colors */
  --color-background: rgba(252, 252, 249, 1);
  --color-surface: rgba(255, 255, 253, 1);
  --color-text: rgba(19, 52, 59, 1);
  --color-text-secondary: rgba(98, 108, 113, 1);
  --color-primary: rgba(33, 128, 141, 1);
  --color-primary-hover: rgba(29, 116, 128, 1);
  --color-primary-active: rgba(26, 104, 115, 1);
  --color-secondary: rgba(94, 82, 64, 0.12);
  --color-secondary-hover: rgba(94, 82, 64, 0.2);
  --color-secondary-active: rgba(94, 82, 64, 0.25);
  --color-border: rgba(94, 82, 64, 0.2);
  --color-btn-primary-text: rgba(252, 252, 249, 1);
  --color-card-border: rgba(94, 82, 64, 0.12);
  --color-card-border-inner: rgba(94, 82, 64, 0.12);
  --color-error: rgba(192, 21, 47, 1);
  --color-success: rgba(33, 128, 141, 1);
  --color-warning: rgba(168, 75, 47, 1);
  --color-info: rgba(98, 108, 113, 1);
  --color-focus-ring: rgba(33, 128, 141, 0.4);

  /* Typography */
  --font-family-base: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-family-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  --font-size-xs: 11px;
  --font-size-sm: 12px;
  --font-size-base: 14px;
  --font-size-md: 14px;
  --font-size-lg: 16px;
  --font-size-xl: 18px;
  --font-size-2xl: 20px;
  --font-size-3xl: 24px;
  --font-size-4xl: 30px;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 550;
  --font-weight-bold: 600;
  --line-height-tight: 1.2;
  --line-height-normal: 1.5;
  --letter-spacing-tight: -0.01em;

  /* Spacing */
  --space-4: 4px;
  --space-6: 6px;
  --space-8: 8px;
  --space-10: 10px;
  --space-12: 12px;
  --space-16: 16px;
  --space-20: 20px;
  --space-24: 24px;
  --space-32: 32px;

  /* Border Radius */
  --radius-sm: 6px;
  --radius-base: 8px;
  --radius-md: 10px;
  --radius-lg: 12px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.02);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04), 0 1px 2px rgba(0, 0, 0, 0.02);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.04), 0 2px 4px -1px rgba(0, 0, 0, 0.02);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.04), 0 4px 6px -2px rgba(0, 0, 0, 0.02);

  /* Animation */
  --duration-fast: 150ms;
  --duration-normal: 250ms;
  --ease-standard: cubic-bezier(0.16, 1, 0.3, 1);

  /* Layout */
  --container-sm: 640px;
  --container-md: 768px;
  --container-lg: 1024px;
  --container-xl: 1280px;
}

/* Dark mode colors */
@media (prefers-color-scheme: dark) {
  :root {
    --color-background: rgba(31, 33, 33, 1);
    --color-surface: rgba(38, 40, 40, 1);
    --color-text: rgba(245, 245, 245, 1);
    --color-text-secondary: rgba(167, 169, 169, 0.7);
    --color-primary: rgba(50, 184, 198, 1);
    --color-primary-hover: rgba(45, 166, 178, 1);
    --color-primary-active: rgba(41, 150, 161, 1);
    --color-secondary: rgba(119, 124, 124, 0.15);
    --color-secondary-hover: rgba(119, 124, 124, 0.25);
    --color-secondary-active: rgba(119, 124, 124, 0.3);
    --color-border: rgba(119, 124, 124, 0.3);
    --color-error: rgba(255, 84, 89, 1);
    --color-success: rgba(50, 184, 198, 1);
    --color-warning: rgba(230, 129, 97, 1);
    --color-info: rgba(167, 169, 169, 1);
    --color-focus-ring: rgba(50, 184, 198, 0.4);
    --color-btn-primary-text: rgba(19, 52, 59, 1);
    --color-card-border: rgba(119, 124, 124, 0.2);
    --color-card-border-inner: rgba(119, 124, 124, 0.15);
  }
}

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

html {
  font-size: var(--font-size-base);
  font-family: var(--font-family-base);
  line-height: var(--line-height-normal);
  color: var(--color-text);
  background-color: var(--color-background);
  -webkit-font-smoothing: antialiased;
}

body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  background-color: var(--color-background);
  color: var(--color-text);
  line-height: var(--line-height-normal);
}

/* Timeline Container */
.timeline-container {
  max-width: var(--container-lg);
  margin: 0 auto;
  padding: var(--space-32) var(--space-16);
  position: relative;
}

/* Header */
.timeline-header {
  text-align: center;
  margin-bottom: var(--space-32);
  background-color: var(--color-surface);
  padding: var(--space-32);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-card-border);
  box-shadow: var(--shadow-md);
}

.project-logo {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-12);
  margin-bottom: var(--space-16);
}

.project-logo i {
  font-size: var(--font-size-3xl);
  color: var(--color-primary);
}

.timeline-header h1 {
  color: var(--color-text);
  font-size: var(--font-size-4xl);
  font-weight: var(--font-weight-bold);
  margin: 0;
  line-height: var(--line-height-tight);
  letter-spacing: var(--letter-spacing-tight);
}

.timeline-header h2 {
  color: var(--color-text);
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-semibold);
  margin: var(--space-8) 0;
}

.timeline-header p {
  color: var(--color-text-secondary);
  font-size: var(--font-size-lg);
  max-width: 600px;
  margin: 0 auto;
}

/* Timeline Content */
.timeline-content {
  position: relative;
  max-width: var(--container-lg);
  margin: 0 auto;
  padding: var(--space-32) 0;
}

/* Central Timeline Line */
.timeline-line {
  position: absolute;
  left: 50%;
  top: 0;
  bottom: 0;
  width: 4px;
  background: linear-gradient(180deg, var(--color-primary), var(--color-primary-hover));
  transform: translateX(-50%);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-sm);
  z-index: 1;
}

/* Timeline Items */
.timeline-item {
  position: relative;
  margin: var(--space-32) 0;
  width: 100%;
  opacity: 0;
  transform: translateY(50px);
  transition: all var(--duration-normal) var(--ease-standard);
}

.timeline-item.animate-in {
  opacity: 1;
  transform: translateY(0);
}

/* FIXED: Alternating Layout - Left Side (Odd items) */
.timeline-item:nth-child(odd) {
  display: flex;
  justify-content: flex-start;
  padding-right: calc(50% + 40px);
}

.timeline-item:nth-child(odd) .timeline-card {
  margin-left: 0;
  margin-right: auto;
  transform-origin: right center;
}

/* FIXED: Alternating Layout - Right Side (Even items) */
.timeline-item:nth-child(even) {
  display: flex;
  justify-content: flex-end;
  padding-left: calc(50% + 40px);
}

.timeline-item:nth-child(even) .timeline-card {
  margin-right: 0;
  margin-left: auto;
  transform-origin: left center;
}

/* Timeline Cards */
.timeline-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-lg);
  padding: var(--space-24);
  max-width: 450px;
  width: 100%;
  box-shadow: var(--shadow-sm);
  transition: all var(--duration-normal) var(--ease-standard);
  position: relative;
}

.timeline-card:hover {
  transform: translateY(-8px) scale(1.02);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
}

/* Timeline Markers (Center dots) */
.timeline-marker {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 40px;
  height: 40px;
  background: var(--color-primary);
  border-radius: var(--radius-full);
  border: 4px solid var(--color-surface);
  box-shadow: var(--shadow-md);
  z-index: 10;
  cursor: pointer;
  transition: all var(--duration-normal) var(--ease-standard);
  display: flex;
  align-items: center;
  justify-content: center;
}

.timeline-marker:hover {
  transform: translate(-50%, -50%) scale(1.2);
  box-shadow: 0 8px 25px rgba(33, 128, 141, 0.3);
}

.day-number {
  background: transparent;
  color: var(--color-btn-primary-text);
  font-weight: var(--font-weight-bold);
  font-size: var(--font-size-sm);
}

/* Card Content */
.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-16);
  border-bottom: 1px solid var(--color-card-border-inner);
  padding-bottom: var(--space-12);
}

.card-header h3 {
  color: var(--color-text);
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-semibold);
  margin: 0;
  line-height: var(--line-height-tight);
}

.date {
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
}

/* Tasks Container */
.tasks-container {
  display: grid;
  gap: var(--space-12);
}

.task-item {
  background: var(--color-secondary);
  border-radius: var(--radius-md);
  padding: var(--space-12);
  border-left: 4px solid;
  transition: all var(--duration-normal) var(--ease-standard);
  opacity: 0;
  transform: translateX(-20px);
}

.task-item.animate {
  opacity: 1;
  transform: translateX(0);
}

.task-item:hover {
  background: var(--color-secondary-hover);
  transform: translateX(8px);
}

/* Member Tags */
.member-tag {
  display: inline-block;
  font-weight: var(--font-weight-semibold);
  font-size: var(--font-size-xs);
  margin-bottom: var(--space-6);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: var(--space-4) var(--space-8);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-standard);
}

/* Team member colors */
.member-tag.kishlaya, .task-item:has(.kishlaya) { border-left-color: var(--color-primary); }
.member-tag.madhav, .task-item:has(.madhav) { border-left-color: var(--color-error); }
.member-tag.ramam, .task-item:has(.ramam) { border-left-color: var(--color-info); }
.member-tag.arjit, .task-item:has(.arjit) { border-left-color: var(--color-success); }

.member-tag.kishlaya { 
  color: var(--color-primary); 
  background: rgba(33, 128, 141, 0.1);
}
.member-tag.madhav { 
  color: var(--color-error); 
  background: rgba(192, 21, 47, 0.1);
}
.member-tag.ramam { 
  color: var(--color-info); 
  background: rgba(98, 108, 113, 0.1);
}
.member-tag.arjit { 
  color: var(--color-success); 
  background: rgba(33, 128, 141, 0.1);
}

.task-item p {
  color: var(--color-text);
  font-size: var(--font-size-sm);
  margin: 0;
  line-height: var(--line-height-normal);
}

/* Footer */
.timeline-footer {
  text-align: center;
  margin-top: var(--space-32);
  padding: var(--space-24);
  background-color: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-card-border);
}

.timeline-footer h4 {
  color: var(--color-text);
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  margin-bottom: var(--space-16);
}

.tech-icons {
  display: flex;
  justify-content: center;
  gap: var(--space-16);
  flex-wrap: wrap;
}

.tech-item {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
}

.tech-item i {
  color: var(--color-primary);
  font-size: var(--font-size-lg);
}

/* Animations */
@keyframes slideInLeft {
  from {
    opacity: 0;
    transform: translateX(-100px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(100px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes pulse {
  0%, 100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.1);
  }
}

/* Highlight effects */
.timeline-item.highlighted .timeline-card {
  border-color: var(--color-primary) !important;
  transform: translateY(-10px) scale(1.03) !important;
  box-shadow: 0 20px 40px rgba(33, 128, 141, 0.2) !important;
}

.timeline-item.highlighted .timeline-marker {
  background: var(--color-error) !important;
  transform: translate(-50%, -50%) scale(1.3) !important;
  animation: pulse 1s infinite;
}

/* Responsive Design */
@media (max-width: 768px) {
  .timeline-line {
    left: 30px;
    transform: none;
  }

  .timeline-item:nth-child(odd),
  .timeline-item:nth-child(even) {
    display: block;
    padding: 0 0 0 60px;
    justify-content: flex-start;
  }

  .timeline-marker {
    left: 30px;
    transform: translateY(-50%);
  }

  .timeline-card {
    max-width: 100%;
    margin: 0;
  }

  .timeline-header h1 {
    font-size: var(--font-size-3xl);
  }

  .timeline-header h2 {
    font-size: var(--font-size-xl);
  }

  .card-header {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-8);
  }

  .tech-icons {
    flex-direction: column;
    gap: var(--space-8);
  }
}

@media (max-width: 480px) {
  .timeline-container {
    padding: var(--space-16) var(--space-8);
  }

  .timeline-header {
    padding: var(--space-20);
    margin-bottom: var(--space-24);
  }

  .timeline-header h1 {
    font-size: var(--font-size-2xl);
  }

  .timeline-header p {
    font-size: var(--font-size-md);
  }

  .timeline-card {
    padding: var(--space-16);
  }

  .timeline-item {
    margin: var(--space-24) 0;
  }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .timeline-item {
    opacity: 1;
    transform: none;
  }
}

/* Print Styles */
@media print {
  body {
    background: white;
    color: black;
  }

  .timeline-card {
    background: white;
    border: 2px solid #333;
    box-shadow: none;
  }
}

/* Focus styles for accessibility */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}