* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    text-decoration: none;
    border: none;
    outline: none;
    scroll-behavior: smooth;
    font-family: 'Poppins', sans-serif;
}

:root {
    --bg-color: #0a0a0a;
    --second-bg-color: #131313;
    --text-color: #f0f0f0;
    --main-color: #00ffee;
    --main-color-darker: #00b8a6;
    --card-bg-color: #1a1a1a;
    --border-color: #2c2c2c;
    --header-height: 7rem;
    --header-height-scrolled: 6rem;
    --fs-h2-section: clamp(3rem, 5vw + 1rem, 4.5rem);
    --fs-h3-card: clamp(2rem, 3vw + 0.5rem, 2.8rem);
    --fs-p: clamp(1.5rem, 2.5vw + 0.2rem, 1.8rem);
    --fs-nav: clamp(1.6rem, 2vw + 0.3rem, 1.8rem);
    --fs-skill-tag: clamp(1.3rem, 2vw + 0.1rem, 1.5rem);
    --padding-section-y: clamp(7rem, 12vh, 12rem);
    --padding-section-x: clamp(2rem, 8vw, 10%);
}

html {
    font-size: 62.5%;
    overflow-x: hidden;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

body.menu-open-no-scroll {
    overflow: hidden;
}

main {
    flex-grow: 1;
}

.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--header-height);
    padding: 0 var(--padding-section-x);
    background: rgba(8, 8, 8, 0.7);
    backdrop-filter: blur(10px);
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 1000;
    transition: top 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94), height 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
}

.header.header-scrolled {
    height: var(--header-height-scrolled);
    background: rgba(8, 8, 8, 0.85);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

.header.header-hidden {
    top: calc(-1 * var(--header-height-scrolled) - 10px);
}

.header.header-visible {
    top: 0;
}

.logo {
    font-size: clamp(2.2rem, 3vw + 0.5rem, 3rem);
    color: var(--text-color);
    font-weight: 700;
    transition: transform 0.3s ease;
}

.logo:hover {
    transform: scale(1.05);
}

.logo span {
    color: var(--main-color);
    text-shadow: 0 0 15px var(--main-color);
}

.navbar {
    display: flex;
    align-items: center;
}

.navbar a {
    font-size: var(--fs-nav);
    color: var(--text-color);
    margin-left: clamp(2rem, 4vw, 4rem);
    font-weight: 500;
    transition: color 0.3s ease, transform 0.2s ease;
    position: relative;
    padding-bottom: 0.5rem;
}

.navbar a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 3px;
    background-color: var(--main-color);
    transition: width 0.3s ease;
}

.navbar a:hover,
.navbar a.active {
    color: var(--main-color);
}

.navbar a:hover::after,
.navbar a.active::after {
    width: 100%;
}

#menu-icon {
    font-size: 3.6rem;
    color: var(--main-color);
    display: none;
    cursor: pointer;
    z-index: 1001;
    transition: transform 0.3s ease;
}

#menu-icon:hover {
    transform: scale(1.1);
}

.about {
    padding-top: calc(var(--header-height) + var(--padding-section-y) / 2);
    padding-bottom: 0; /* Zaman çizelgesi bölümü kendi padding'ini alacak */
    padding-left: var(--padding-section-x);
    padding-right: var(--padding-section-x);
}

.section-title {
    font-size: var(--fs-h2-section);
    font-weight: 700;
    text-align: center;
    margin-bottom: calc(var(--padding-section-y) / 2.5);
    color: var(--text-color);
}

.section-title span {
    color: var(--main-color);
    text-shadow: 0 0 10px var(--main-color);
}

.about-content {
    display: flex;
    flex-direction: row;
    align-items: center;
    gap: clamp(3rem, 6vw, 6rem);
    background-color: var(--card-bg-color);
    padding: clamp(2rem, 4vw, 4rem);
    border-radius: 15px;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
    border: 1px solid var(--border-color);
}

.about-img {
    flex-shrink: 0;
    width: clamp(22rem, 28vw, 35rem);
    height: clamp(22rem, 28vw, 35rem);
}

.about-img img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 50%;
    border: 4px solid var(--main-color);
    box-shadow: 0 0 30px rgba(0, 255, 238, 0.4), 0 0 15px var(--main-color-darker) inset;
    transition: transform 0.4s ease, box-shadow 0.4s ease;
}

.about-img img:hover {
    transform: scale(1.05) rotate(-2deg);
    box-shadow: 0 0 50px rgba(0, 255, 238, 0.7), 0 0 75px var(--main-color-darker), 0 0 25px var(--main-color) inset;
}

.about-img img:active {
    transform: scale(1.02) rotate(-1deg);
    transition: transform 0.1s ease-out;
}

.about-text {
    flex-grow: 1;
}

.about-text h3 {
    font-size: var(--fs-h3-card);
    color: var(--text-color);
    margin-bottom: 1.5rem;
    font-weight: 600;
}

.about-text h3 span {
    color: var(--main-color);
}

.about-text p {
    font-size: var(--fs-p);
    line-height: 1.8;
    margin-bottom: 2rem;
    color: #cccccc;
}

.about-text p:last-of-type {
    margin-bottom: 0;
}

.skills-section {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

.skills-section h3 {
    margin-bottom: 2rem;
}

.skills-list {
    display: flex;
    flex-wrap: wrap;
    gap: 1.2rem;
    justify-content: flex-start;
}

.skills-list span {
    background-color: var(--main-color-darker);
    color: var(--bg-color);
    padding: 0.8rem 1.5rem;
    border-radius: 25px;
    font-size: var(--fs-skill-tag);
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: 0.8rem;
    transition: transform 0.2s ease, background-color 0.2s ease;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}

.skills-list span i {
    font-size: calc(var(--fs-skill-tag) + 0.4rem);
}

.skills-list span:hover {
    transform: translateY(-3px);
    background-color: var(--main-color);
}

.footer {
    background-color: var(--second-bg-color);
    padding: 4rem var(--padding-section-x) 2rem;
    text-align: center;
    border-top: 1px solid var(--border-color);
    margin-top: auto;
}

.social-icons-footer {
    margin-bottom: 2rem;
}

.social-icons-footer a {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    width: 4.2rem;
    height: 4.2rem;
    background: transparent;
    border: 2px solid var(--main-color);
    font-size: 2rem;
    border-radius: 50%;
    color: var(--main-color);
    margin: 0 1rem;
    transition: all 0.3s ease-in-out;
}

.social-icons-footer a:hover {
    color: var(--bg-color);
    background-color: var(--main-color);
    transform: translateY(-5px) scale(1.1);
    box-shadow: 0 10px 20px rgba(0, 255, 238, 0.3);
}

.footer p {
    font-size: 1.4rem;
    color: #a0a0a0;
    line-height: 1.6;
}

.footer p:last-child {
    margin-top: 0.5rem;
    font-size: 1.2rem;
}

.footer p i {
    vertical-align: middle;
}

#scrollTopBtn {
    position: fixed;
    bottom: 3rem;
    right: 3rem;
    z-index: 999;
    background-color: var(--main-color);
    color: var(--bg-color);
    border: none;
    border-radius: 50%;
    width: 5rem;
    height: 5rem;
    font-size: 2.4rem;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(0, 255, 238, 0.3);
    opacity: 0;
    transform: translateY(30px);
    transition: background-color 0.3s, transform 0.3s, opacity 0.3s;
    pointer-events: none;
}

#scrollTopBtn.show {
    opacity: 0.85;
    transform: translateY(0);
    pointer-events: auto;
}

#scrollTopBtn:hover {
    background-color: var(--main-color-darker);
    transform: scale(1.1);
    opacity: 1;
}

@media (max-width: 768px) {
    #menu-icon {
        display: block;
    }

    .navbar {
        position: fixed;
        top: 0;
        left: -100%;
        width: 100%;
        height: 100vh;
        background-color: rgba(10, 10, 10, 0.98);
        backdrop-filter: blur(8px);
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        transition: left 0.6s cubic-bezier(0.77, 0, 0.175, 1);
        padding: 0;
        z-index: 1000;
    }

    .navbar.active {
        left: 0;
        z-index: 1050;
    }

    .navbar a {
        font-size: clamp(2.2rem, 6vw, 3rem);
        margin: 1.8rem 0;
        padding: 1.2rem 2.5rem;
        display: block;
        text-align: center;
        color: var(--text-color);
        width: 85%;
        opacity: 0;
        transform: translateY(20px);
        transition: color 0.3s ease, background-color 0.3s ease, opacity 0.3s ease, transform 0.3s ease, box-shadow 0.3s ease;
    }

    .navbar.active a {
        opacity: 1;
        transform: translateY(0);
    }

    .navbar.active a:nth-child(1) { transition-delay: 0.15s; }
    .navbar.active a:nth-child(2) { transition-delay: 0.23s; }
    .navbar.active a:nth-child(3) { transition-delay: 0.31s; }
    .navbar.active a:nth-child(4) { transition-delay: 0.39s; }

    .navbar a::after {
        display: none;
    }

    .navbar a:hover {
        color: var(--main-color);
        background-color: rgba(0, 255, 238, 0.08);
        border-radius: 8px;
    }

    .navbar a.active {
        color: var(--main-color);
        background-color: rgba(0, 255, 238, 0.15);
        border-radius: 8px;
        font-weight: 700;
        box-shadow: inset 0 0 15px rgba(0, 255, 238, 0.1);
    }

    .about {
        padding-top: calc(var(--header-height) + 3rem);
    }

    .section-title {
        margin-bottom: 3rem;
    }

    .about-content {
        flex-direction: column;
        padding: clamp(1.5rem, 3vw, 3rem);
        gap: 3rem;
    }

    .about-img {
        width: clamp(20rem, 50vw, 28rem);
        height: clamp(20rem, 50vw, 28rem);
        margin-bottom: 0;
    }

    .about-text {
        text-align: center;
    }

    .about-text h3 {
        text-align: center;
    }

    .skills-section h3 {
        text-align: center;
    }

    .skills-list {
        justify-content: center;
    }

    #scrollTopBtn {
        width: 4.5rem;
        height: 4.5rem;
        font-size: 2rem;
        bottom: 2rem;
        right: 2rem;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 58%;
    }

    .about-img {
        width: clamp(18rem, 55vw, 25rem);
        height: clamp(18rem, 55vw, 25rem);
    }

    .skills-list span {
        padding: 0.7rem 1.2rem;
    }
}

#preloader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--bg-color);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 9999;
    opacity: 1;
    visibility: visible;
    transition: opacity 0.5s ease-out, visibility 0s linear 0.5s;
}

#preloader.loaded {
    opacity: 0;
    visibility: hidden;
}

.loader-text {
    color: var(--main-color);
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 600;
    margin-bottom: 20px;
    letter-spacing: 1px;
    animation: pulseText 1.5s infinite alternate;
}

.loader-spinner {
    width: 50px;
    height: 50px;
    border: 5px solid rgba(0, 255, 238, 0.3);
    border-top-color: var(--main-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

@keyframes pulseText {
    from {
        opacity: 0.7;
        transform: scale(0.98);
    }
    to {
        opacity: 1;
        transform: scale(1.02);
    }
}

.timeline-section {
    width: 100%;
    margin-top: calc(var(--padding-section-y));
    padding: var(--padding-section-y) var(--padding-section-x);
    background-color: var(--second-bg-color);
    position: relative;
    overflow: hidden;
}

.timeline-section::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 700px;
    height: 700px;
    background: radial-gradient(circle, rgba(0, 255, 238, 0.1), transparent 70%);
    transform: translate(-50%, -50%);
    z-index: 0;
    pointer-events: none;
}

.timeline-items {
    max-width: 1000px;
    margin: auto;
    display: flex;
    flex-wrap: wrap;
    position: relative;
    z-index: 1;
}

.timeline-items::after {
    content: '';
    position: absolute;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, var(--main-color), var(--main-color-darker), var(--main-color));
    background-size: 100% 300%;
    animation: gradient-flow 5s linear infinite;
    left: calc(50% - 2px);
    border-radius: 2px;
}

@keyframes gradient-flow {
    0% { background-position: 0% 0%; }
    100% { background-position: 0% 300%; }
}

.timeline-item {
    margin-bottom: 50px;
    width: 100%;
    position: relative;
}

.timeline-item:nth-child(2n) {
    padding-left: calc(50% + 40px);
}

.timeline-item:nth-child(2n-1) {
    padding-right: calc(50% + 40px);
    text-align: right;
}

.timeline-item:last-child {
    margin-bottom: 0;
}

.timeline-dot {
    height: 22px;
    width: 22px;
    background: var(--main-color);
    border: 4px solid var(--second-bg-color);
    position: absolute;
    left: calc(50% - 11px);
    border-radius: 50%;
    top: 15px;
    z-index: 2;
    transition: transform 0.4s ease, box-shadow 0.4s ease;
    box-shadow: 0 0 0 4px var(--bg-color), 0 0 20px 5px var(--main-color);
}

.timeline-item:hover .timeline-dot {
    transform: scale(1.4);
    box-shadow: 0 0 0 4px var(--bg-color), 0 0 30px 10px var(--main-color);
}

.timeline-date {
    font-size: clamp(1.6rem, 2vw, 1.8rem);
    font-weight: 700;
    color: var(--main-color);
    margin: 12px 0 15px;
    text-shadow: 0 0 5px rgba(0, 255, 238, 0.7);
}

.timeline-content {
    background: rgba(26, 26, 26, 0.6);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    padding: 25px 30px;
    border-radius: 12px;
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
    border: 1px solid rgba(255, 255, 255, 0.18);
    transition: transform 0.4s cubic-bezier(0.2, 0.8, 0.2, 1), box-shadow 0.4s ease;
    position: relative;
}

.timeline-item:hover .timeline-content {
    transform: translateY(-8px) scale(1.02);
    box-shadow: 0 16px 40px 0 rgba(0, 0, 0, 0.5), 0 0 30px rgba(0, 255, 238, 0.2);
}

.timeline-icon {
    position: absolute;
    top: -20px;
    font-size: 2.8rem;
    color: var(--bg-color);
    background-color: var(--main-color);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 0 15px rgba(0, 255, 238, 0.5);
}

.timeline-item:nth-child(2n-1) .timeline-icon {
    right: -20px;
}

.timeline-item:nth-child(2n) .timeline-icon {
    left: -20px;
}

.timeline-content h3 {
    font-size: clamp(2rem, 2.5vw, 2.4rem);
    color: var(--main-color);
    margin: 0 0 10px;
    font-weight: 700;
    padding-top: 10px;
}

.timeline-content p {
    color: #e0e0e0;
    font-size: clamp(1.4rem, 2vw, 1.6rem);
    line-height: 1.8;
    margin: 0;
}

@media (max-width: 768px) {
    .timeline-items::after {
        left: 11px;
    }

    .timeline-item:nth-child(2n),
    .timeline-item:nth-child(2n-1) {
        width: 100%;
        text-align: left;
        padding-right: 0;
        padding-left: 60px;
    }

    .timeline-item:nth-child(2n-1) .timeline-icon,
    .timeline-item:nth-child(2n) .timeline-icon {
        left: -30px;
        right: auto;
    }

    .timeline-dot {
        left: 0;
    }
}