:root {
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-card: rgba(255, 255, 255, 0.03);
    --text-primary: #ffffff;
    --text-secondary: #a0a0b0;
    --accent-1: #6366f1;
    --accent-2: #8b5cf6;
    --accent-3: #ec4899;
    --gradient: linear-gradient(135deg, var(--accent-1), var(--accent-2), var(--accent-3));
    --strava-orange: #fc4c02;
    --strava-orange-dark: #e04500;
    --success: #22c55e;
    --error: #ef4444;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Animated background */
.bg-gradient {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
}

.bg-gradient::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 20% 80%, rgba(99, 102, 241, 0.15) 0%, transparent 50%),
                radial-gradient(circle at 80% 20%, rgba(139, 92, 246, 0.15) 0%, transparent 50%),
                radial-gradient(circle at 40% 40%, rgba(236, 72, 153, 0.1) 0%, transparent 50%);
    animation: float 20s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    33% { transform: translate(2%, 2%) rotate(1deg); }
    66% { transform: translate(-1%, 1%) rotate(-1deg); }
}

/* Grid pattern overlay */
.grid-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image:
        linear-gradient(rgba(255, 255, 255, 0.02) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.02) 1px, transparent 1px);
    background-size: 50px 50px;
    z-index: -1;
}

/* Navigation */
nav {
    position: fixed;
    top: 0;
    width: 100%;
    padding: 1.5rem 3rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 1000;
    background: rgba(10, 10, 15, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-decoration: none;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.nav-title {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
}

/* Buttons */
.btn {
    padding: 0.875rem 2rem;
    border-radius: 100px;
    font-size: 0.95rem;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-small {
    padding: 0.5rem 1rem;
    font-size: 0.85rem;
}

.btn-primary {
    background: var(--gradient);
    color: white;
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 30px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: rgba(255, 255, 255, 0.2);
}

.btn-ghost {
    background: transparent;
    color: var(--text-secondary);
    padding: 0.5rem 1rem;
}

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

.btn-strava {
    background: var(--strava-orange);
    color: white;
    box-shadow: 0 4px 20px rgba(252, 76, 2, 0.4);
}

.btn-strava:hover {
    background: var(--strava-orange-dark);
    transform: translateY(-2px);
    box-shadow: 0 6px 30px rgba(252, 76, 2, 0.5);
}

.btn-strava svg {
    width: 20px;
    height: 20px;
}

.sync-icon {
    transition: transform 0.3s ease;
}

.btn:hover .sync-icon {
    transform: rotate(180deg);
}

/* Main content */
main {
    flex: 1;
    padding: 8rem 3rem 4rem;
    max-width: 900px;
    margin: 0 auto;
    width: 100%;
}

/* Auth Section */
.auth-section {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 60vh;
}

.auth-content {
    text-align: center;
    max-width: 400px;
}

.strava-logo {
    width: 80px;
    height: 80px;
    margin: 0 auto 2rem;
    color: var(--strava-orange);
}

.strava-logo svg {
    width: 100%;
    height: 100%;
}

.auth-content h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.auth-content p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

/* Dashboard Section */
.dashboard-section {
    animation: fadeIn 0.5s ease;
}

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

/* Athlete Header */
.athlete-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 3rem;
    padding: 1.5rem;
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 16px;
}

.athlete-avatar {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    object-fit: cover;
    background: var(--gradient);
}

.athlete-info {
    flex: 1;
}

.athlete-info h2 {
    font-size: 1.25rem;
    font-weight: 600;
}

.athlete-location {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Section Headers */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.section-header h3 {
    font-size: 1.25rem;
    font-weight: 600;
}

.week-range {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1rem;
    margin-bottom: 3rem;
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 16px;
    padding: 1.5rem;
    text-align: center;
    transition: all 0.3s ease;
}

.stat-card:hover {
    border-color: rgba(99, 102, 241, 0.3);
    transform: translateY(-3px);
}

.stat-value {
    font-size: 1.75rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.25rem;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Activities List */
.activities-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.activity-card {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.25rem 1.5rem;
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 12px;
    transition: all 0.3s ease;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
}

.activity-card:hover {
    border-color: rgba(99, 102, 241, 0.3);
    transform: translateX(5px);
}

.activity-icon {
    width: 40px;
    height: 40px;
    background: var(--gradient);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    flex-shrink: 0;
}

.activity-details {
    flex: 1;
    min-width: 0;
}

.activity-name {
    font-weight: 600;
    font-size: 0.95rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.activity-date {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.activity-stats {
    display: flex;
    gap: 1.5rem;
    flex-shrink: 0;
}

.activity-stat {
    text-align: right;
}

.activity-stat-value {
    font-weight: 600;
    font-size: 0.95rem;
}

.activity-stat-label {
    font-size: 0.7rem;
    color: var(--text-secondary);
    text-transform: uppercase;
}

/* Loading & Error States */
.loading-section,
.error-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 60vh;
    text-align: center;
}

.loading-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 3rem;
    color: var(--text-secondary);
}

.spinner {
    width: 24px;
    height: 24px;
    border: 3px solid rgba(255, 255, 255, 0.1);
    border-top-color: var(--accent-1);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

.spinner.large {
    width: 48px;
    height: 48px;
    border-width: 4px;
    margin-bottom: 1.5rem;
}

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

.error-content {
    max-width: 400px;
}

.error-content svg {
    color: var(--error);
    margin-bottom: 1.5rem;
}

.error-content h2 {
    margin-bottom: 0.5rem;
}

.error-content p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem;
    color: var(--text-secondary);
    font-size: 0.85rem;
}

footer a {
    color: var(--strava-orange);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

/* Empty state */
.empty-state {
    text-align: center;
    padding: 3rem;
    color: var(--text-secondary);
}

.empty-state svg {
    width: 48px;
    height: 48px;
    margin-bottom: 1rem;
    opacity: 0.5;
}

/* Responsive */
@media (max-width: 768px) {
    nav {
        padding: 1rem 1.5rem;
    }

    main {
        padding: 6rem 1.5rem 3rem;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .athlete-header {
        flex-wrap: wrap;
    }

    .activity-card {
        flex-wrap: wrap;
    }

    .activity-stats {
        width: 100%;
        justify-content: flex-start;
        margin-top: 0.5rem;
        padding-left: 56px;
    }

    .activity-stat {
        text-align: left;
    }
}

@media (max-width: 480px) {
    .stats-grid {
        grid-template-columns: 1fr 1fr;
        gap: 0.75rem;
    }

    .stat-card {
        padding: 1rem;
    }

    .stat-value {
        font-size: 1.5rem;
    }
}